U.S. patent application number 10/864606 was filed with the patent office on 2005-01-27 for method of balloon pumping and a balloon pump driving apparatus.
This patent application is currently assigned to AISIN SEIKI KABUSHIKI KAISHA. Invention is credited to Suzuki, Akira, Yamaguchi, Hideaki.
Application Number | 20050020870 10/864606 |
Document ID | / |
Family ID | 34074226 |
Filed Date | 2005-01-27 |
United States Patent
Application |
20050020870 |
Kind Code |
A1 |
Suzuki, Akira ; et
al. |
January 27, 2005 |
Method of balloon pumping and a balloon pump driving apparatus
Abstract
A balloon pumping method of inflating and deflating a balloon
includes the steps of setting a pressure in the balloon at a first
pressure value, which is higher than a minimum pressure value and
is substantially equal to or lower than a maximum pressure value,
when the balloon is shifted from a deflated condition to an
inflated condition, and setting the pressure in the balloon at a
second pressure value, which is substantially equal to or higher
than the minimum pressure value and lower than the first pressure
value, when the balloon is estimated to have completely inflated at
the first pressure value.
Inventors: |
Suzuki, Akira; (Nishio-shi,
JP) ; Yamaguchi, Hideaki; (Toyota-shi, JP) |
Correspondence
Address: |
OBLON, SPIVAK, MCCLELLAND, MAIER & NEUSTADT, P.C.
1940 DUKE STREET
ALEXANDRIA
VA
22314
US
|
Assignee: |
AISIN SEIKI KABUSHIKI
KAISHA
Kariya-shi
JP
|
Family ID: |
34074226 |
Appl. No.: |
10/864606 |
Filed: |
June 10, 2004 |
Current U.S.
Class: |
600/16 |
Current CPC
Class: |
A61M 2025/102 20130101;
A61M 25/10188 20131105; A61M 60/274 20210101; A61M 60/40 20210101;
A61M 2230/04 20130101; A61M 60/268 20210101; A61M 60/135 20210101;
A61M 60/50 20210101; A61M 25/10184 20131105; A61M 25/10185
20131105; A61M 25/10181 20131105 |
Class at
Publication: |
600/016 |
International
Class: |
A61N 001/362 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 11, 2003 |
JP |
2003-166734 |
Claims
1. A balloon pumping method of inflating and deflating a balloon in
a blood vessel at a predetermined timing comprising the steps of:
setting a pressure in the balloon at a first pressure value, which
is higher than a minimum pressure value for maintaining an inflated
condition and is substantially equal to or lower than a maximum
pressure value for maintaining the inflated condition, when the
balloon is shifted from a deflated condition to the inflated
condition; and decreasing the pressure in the balloon to a second
pressure value, which is substantially equal to or higher than the
minimum pressure value and lower than the first pressure value,
after the balloon is estimated to have completely inflated at the
first pressure value.
2. A balloon pumping method of inflating and deflating a balloon in
a blood vessel at a predetermined timing comprising the steps of:
setting a pressure in the balloon at a third pressure value, which
is lower than a maximum pressure value for maintaining a deflated
condition and is substantially equal to or higher than a minimum
pressure value for maintaining the deflated condition, when the
balloon is shifted from an inflated condition to the deflated
condition; and increasing the pressure in the balloon to a fourth
pressure value, which is substantially equal to or lower than the
maximum pressure value and higher than the third pressure value,
after the balloon is estimated to have completely deflated at the
third pressure value.
3. A balloon pump driving apparatus connected to a balloon in a
blood vessel and adapted to inflate and deflate the balloon at a
predetermined timing by applying a predetermined pressure to the
balloon comprising: inflation judging means for judging a timing
for inflating the balloon based upon an inputted bio signal; first
inflation pressure applying means for applying a first inflation
pressure to the balloon at an appropriate timing judged by the
inflation judging means, the first inflation pressure being higher
than a minimum pressure value at which the balloon is maintained at
an inflated condition; complete inflation estimating means for
estimating whether the balloon has completely inflated by applying
the first inflation pressure to the balloon by the first inflation
pressure applying means; and second inflation pressure applying
means for applying a second inflation pressure to the balloon when
the complete inflation estimating means estimates that the balloon
has completely inflated, the second inflation pressure being
substantially equal to or higher than the minimum pressure value
and lower than the first inflation pressure, wherein the pressure
in the balloon is decreased.
4. A balloon pump driving apparatus connected to a balloon inserted
in to a blood vessel and adapted to inflate and deflate the balloon
at a predetermined timing by applying a predetermined pressure to
the balloon comprising: deflation judging means for judging a
timing for deflating the balloon based upon an inputted bio signal;
first deflation pressure applying means for applying a first
deflation pressure to the balloon at an appropriate timing judged
by the deflation judging means, the first deflation pressure being
lower than a maximum pressure value at which the balloon is
maintained at a deflated condition; complete deflation estimating
means for estimating whether the balloon has completely deflated by
applying the first deflation pressure by the first deflation
pressure applying means; and second deflation pressure applying
means for applying a second deflation pressure to the balloon when
the complete deflation estimating means estimates that the balloon
has completely deflated, the second deflation pressure being
substantially equal to or lower than the maximum pressure value and
higher than the first deflation pressure.
5. A balloon pump driving apparatus comprising: a pressure
accumulator connected to a balloon in a blood vessel and adapted to
accumulate a pressure to be supplied to the balloon at a
predetermined timing; a pressure control valve disposed between the
pressure accumulator and the balloon; and means for controlling the
pressure accumulated in the pressure accumulator and an open/closed
condition of the pressure control valve, wherein the means for
controlling performs; a first inflation pressure control for
controlling the pressure accumulator so as to set the pressure
accumulated in the pressure accumulator at a first inflation
pressure, the first inflation pressure being higher than a minimum
pressure value at which the balloon is maintained at an inflated
condition; an inflation-time valve opening control for connecting
the pressure accumulator with the balloon by opening the pressure
control valve after accumulating the first inflation pressure in
the pressure accumulator through the first inflation pressure
control; a time judgment control for judging whether an opening
period of the pressure control valve has reached a first
predetermined period; an inflation-time intermediate valve closing
control for closing the pressure control valve when the opening
period of the pressure control valve is judged to be have reached
the first predetermined period by the time judgment control; a
pressure decrease control for decreasing the pressure accumulated
in the pressure accumulator when the opening period of the pressure
control valve is judged to have reached the predetermined period by
the time judgment control; a complete inflation estimating control
for estimating whether the balloon has completely inflated; an
inflation-time intermediate valve opening control for opening the
pressure control valve when the balloon is estimated to have
completely inflated by the complete inflation estimating control;
and an inflation-time valve closing control for closing the
pressure control valve in a second predetermined time set at a time
value at which the pressure in the balloon is expected to become
higher than a minimum pressure value and lower than the first
inflation pressure after opening the pressure control valve by the
inflation-time intermediate valve opening control, the minimum
pressure value at which the balloon is maintained under the
inflated condition.
6. A balloon pump driving apparatus according to claim 5, wherein
the means for controlling performs a correcting control for
correcting the second predetermined time based upon the pressure
applied to the balloon after closing the pressure control valve by
the inflation-time valve closing control.
7. A balloon pump driving apparatus comprising: a pressure
accumulator connected to a balloon inserted in a blood vessel and
adapted to accumulate a pressure to be supplied to the balloon at a
predetermined timing; a pressure control valve disposed between the
pressure accumulator and the balloon; and means for controlling the
pressure accumulated in the pressure accumulator and an open/closed
condition of the pressure control valve, wherein the means for
controlling performs; a first deflation pressure control for
controlling the pressure accumulator so as to set the pressure
accumulated in the pressure accumulator at a first deflation
pressure, the first deflation pressure being lower than a maximum
pressure value at which the balloon is maintained at a deflated
condition; a deflation-time valve opening control for connecting
the pressure accumulator with the balloon by opening the pressure
control valve after accumulating the first deflation pressure in
the pressure accumulator through the first deflation pressure
control; a complete deflation estimating control for estimating
whether the balloon has completely deflated; a pressure increase
control for increasing the pressure accumulated in the pressure
accumulator when the balloon is estimated to have completely
deflated by the complete deflation estimating control; a deflation
pressure estimating control for estimating whether the pressure in
the balloon has reached a predetermined pressure being lower than
the maximum pressure and higher than the first deflation pressure;
and a deflation valve closing control for closing the pressure
control valve when the pressure in the balloon has reached the
predetermined pressure by the deflation pressure estimating
control.
8. A balloon pump driving apparatus comprising: a pressure
accumulator connected to a balloon inserted in a blood vessel and
adapted to accumulate a pressure to be supplied to the balloon at a
predetermined timing; an auxiliary reservoir; a pressure control
valve disposed between the pressure accumulator and the balloon; a
first connecting passage connecting the auxiliary reservoir tank
with the balloon; a first auxiliary switching valve disposed in the
first connecting passage; and means for controlling the pressure
accumulated in the pressure accumulator, an open/closed condition
of the pressure control valve, and an open/closed condition of the
first auxiliary switching valve, wherein the means for controlling
performs; a first inflation pressure control for controlling the
pressure accumulator so as to set the pressure accumulated in the
pressure accumulator at a first inflation pressure, the first
inflation pressure being higher than a minimum pressure value at
which the balloon is maintained at an inflated condition; an
inflation-time valve opening control for connecting the pressure
accumulator with the balloon by opening the pressure control valve
after accumulating the first inflation pressure in the pressure
accumulator through the first inflation pressure control; a time
judgment control for judging whether an opening period of the
pressure control valve has reached a first predetermined period; an
inflation-time intermediate valve closing control for closing the
pressure control valve when the opening period of the pressure
control valve is judged to be have reached the first predetermined
period by the time judgment control; a pressure decrease control
for decreasing the pressure accumulated in the pressure accumulator
when the pressure control valve is closed by the inflation-time
intermediate valve closing control; a complete inflation estimating
control for estimating whether the balloon has completely inflated;
an inflation-time intermediate valve opening control for setting
the pressure in the balloon higher than the minimum pressure and
lower than the first inflation pressure by establishing a
communication between the auxiliary reservoir tank and the balloon
by opening the first auxiliary switching valve when the balloon is
estimated to have completely inflated by the complete inflation
estimating control, the pressure in the auxiliary reservoir tank
having been set at a second inflation pressure; an inflation-time
valve closing control for interrupting the communication between
the auxiliary reservoir tank and the balloon by closing the first
auxiliary switching valve in a predetermined period of time after
opening the first auxiliary switching valve by the inflation-time
intermediate valve opening control; an auxiliary reservoir pressure
setting control for setting the pressure in the auxiliary reservoir
tank at a predetermined pressure.
9. A balloon pump driving apparatus comprising: a pressure
accumulator connected to a balloon in a blood vessel and adapted to
accumulate a pressure to be supplied to the balloon at a
predetermined timing; a pressure control valve disposed between the
pressure accumulator and the balloon; a first connecting passage
connecting the auxiliary reservoir and the balloon; a first
auxiliary switching valve disposed in the first connecting passage;
and means for controlling the pressure accumulated in the pressure
accumulator, an open/closed condition of the pressure control
valve, and an open/closed condition of the first auxiliary
switching valve, wherein the means for controlling performs; a
first deflation pressure control for controlling the pressure
accumulator so as to set the pressure accumulated in the pressure
accumulator at a first deflation pressure, the first deflation
pressure being lower than a maximum pressure value at which the
balloon is maintained at a deflated condition; a deflation-time
valve opening control for connecting the pressure accumulator with
the balloon by opening the pressure control valve after
accumulating the first deflation pressure in the pressure
accumulator through the first deflation pressure control; a
complete deflation estimating control for estimating whether the
balloon has completely deflated; a deflation-time intermediate
valve opening control for setting the pressure in the balloon to be
lower than the maximum pressure and higher than the first deflation
pressure by establishing a communication between the auxiliary
reservoir tank and the balloon by opening the first auxiliary
switching valve while the pressure control valve is opened when the
balloon is estimated to have completely deflated by the complete
deflation estimate control, the pressure in the auxiliary reservoir
tank having been set at a second deflation pressure; a
deflation-time valve closing control for interrupting the
communication between the pressure accumulator and the balloon by
closing the pressure control valve in a predetermined period of
time after opening the first auxiliary switching valve by the
deflation-time intermediate valve opening control; a pressure
increase control for increasing the pressure accumulated in the
pressure accumulator after closing the pressure control valve by
the deflation-time valve closing control; a deflation-time
intermediate valve closing control for interrupting the
communication between the auxiliary reservoir tank and the balloon
by closing the first auxiliary switching valve substantially at a
same time as the closing operation of the pressure control valve by
the deflation-time valve closing control or after the closing
operation thereof; and an auxiliary reservoir pressure setting
control for setting the pressure in the auxiliary reservoir tank at
a predetermined pressure.
10. A balloon pump driving apparatus according to any one of claims
5 through 9, wherein the pressure accumulator including; an
isolator housing of which inside is a hollow, isolator means having
a movable membrane disposed in the isolator housing, the inside of
the isolator housing divided into an output chamber and an input
chamber by the movable membrane, the output chamber connected to
the balloon via the pressure control valve; and movable membrane
driving means for displacing the movable membrane in the isolator
housing.
11. A balloon pump driving apparatus according to claim 10, wherein
the movable membrane driving means is a fluid-type pump connected
to the input chamber of the isolator means, wherein the movable
membrane is displaced in response to oil flow back and forth
between the fluid type pump and the input chamber.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is based on and claims priority under 35
U.S.C. .sctn. 119 with respect to Japanese Patent Application
2003-166734, filed Jun. 11, 2003, the entire content of which is
incorporated herein by reference.
FIELD OF THE INVENTION
[0002] This invention generally relates to a balloon pump driving
apparatus applied for an intra-aortic balloon pump therapy, which
is one of methods of aiding heart function.
BACKGROUND
[0003] An intra-aortic balloon pumping therapy is prescribed for
patients who have suffered from deterioration of heart function
such as heart failure. Hereinafter, the intra-aortic balloon
pumping is referred to as the IABP. More particularly, a balloon
catheter is inserted into the patient's aorta such as a descending
aorta. A pressurized fluid is introduced or derived from a balloon
pump driving system into the balloon catheter in time of the
patient's heartbeat. A blood pressure in the patient's aorta can be
increased or decreased in response to inflation of a balloon
positioned in the aorta or deflation thereof. Therefore, the IABP
is an auxiliary circulation apparatus for aiding the deteriorated
heart function.
[0004] The inflation or deflation of the balloon should be operated
relying upon the patient's heartbeat, thereby requiring a speedy
response to the patient's heartbeat. In light of foregoing, recent
developments have lead to an apparatus in which helium with high
response is applied as the pressurized fluid flowing in the balloon
catheter, improvements of a balloon pump driving system, and so
on.
[0005] Japanese Patent Application Publication No. 5 (1993)-16870
discloses one of the above described recent developments. In
general, a balloon pump driving system is provided with an isolator
divided into an input chamber space and an output chamber space by
a movable membrane. The output chamber space communicates with a
balloon catheter via a common valve, while the input chamber space
communicates with a positive pressure source or a negative pressure
source. According to the invention described in the above-described
reference, the common valve is closed when the balloon is deflating
or while the balloon is under a deflated condition. In this case,
the pressure in the output chamber space is increased and
maintained at a positive pressure level. The balloon catheter is
then set at the positive pressure level at a blast by opening the
common valve at a predetermined timing. In the same manner, the
common valve is closed when the balloon is inflating or while the
balloon is under an inflated condition. In this case, the pressure
in the output chamber space is decreased and maintained at a
negative pressure level. The balloon catheter is then set at the
negative pressure level at a blast by opening the common valve at a
predetermined timing.
[0006] As described above, a following process can be prepared
during a previous process by operatively associating the
opening/closing control of the common valve and the pressure
control in the output chamber space, thereby enabling to achieve a
speedy pressure control.
[0007] In the meantime, Japanese Patent Laid-Open Publication No.
10(1998)-328296 discloses an intra-aortic balloon pump having three
isolators; a main isolator, a positive pressure isolator, and a
negative pressure isolator. In a process for inflating a balloon, a
positive pressure is applied to the balloon by communicating the
main isolator and the positive pressure isolator with the balloon.
Subsequently, the communication between the positive pressure
isolator and the balloon is interrupted, while a predetermined gas
is drawn out from the balloon side by the main isolator.
Accordingly, an inflation pressure can be assured when the balloon
is fully inflated. In the same manner, in a process for deflating
the balloon, a negative pressure is applied to the balloon by
communicating the main isolator and the negative pressure isolator
with the balloon. Subsequently, the communication between the
negative pressure isolator and the balloon is interrupted, while a
predetermined gas is supplied to the balloon side by the main
isolator. Accordingly, a deflation pressure can be assured when the
balloon is fully deflated. As described above, in the process for
inflating (for deflating) the balloon, a great volume of gas is
drawn out of the balloon (is supplied to the balloon) by the main
isolator and the positive (negative) pressure isolator. Therefore,
a pressure differential can be maintained between the balloon side
and the isolator side for a long period of time.
[0008] In a conventional system prior to the above-described
systems, the pressure differential between the balloon side and the
isolator side was decreased with a time-lapse. The balloon
inflating speed (the balloon deflating speed) was slowed in
response to the decrease of the pressure differential. However,
according to the system described in the reference 2, the pressure
differential can be maintained until the balloon is fully inflated
(deflated). In this case, the pressure differential does not have
to be decreased. Therefore, a time required for fully inflating
(fully deflating) the balloon can be shortened.
SUMMARY OF THE INVENTION
[0009] According to a first aspect of the present invention, a
balloon pumping method of inflating and deflating a balloon in a
blood vessel at a predetermined timing includes the steps of
setting a pressure in the balloon at a first pressure value, which
is higher than a minimum pressure value for maintaining an inflated
condition and is substantially equal to or lower than a maximum
pressure value for maintaining the inflated condition, when the
balloon is shifted from a deflated condition to an inflated
condition, and decreasing the pressure in the balloon at a second
pressure value, which is substantially equal to or higher than the
minimum pressure value and lower than the first pressure value,
after the balloon is estimated to have completely inflated at the
first pressure value.
[0010] The minimum pressure value, at which the balloon can be
maintained under the inflated condition, represents a bottom
limiting value that the balloon can be inflated. The pressure in
the vessel is an aortic pressure. Therefore, in order to inflate
the balloon in the vessel, the balloon has to be maintained at a
pressure higher than the aortic pressure. Therefore, the minimum
pressure value can be higher than the aortic pressure. The aortic
pressure fluctuates periodically and is different among patients.
Therefore, the minimum pressure value cannot be always a fixed
pressure value.
[0011] The maximum pressure value, at which the balloon can be
maintained under the inflated condition, represents an upper
limiting value that the balloon in the vessel does not deform and
is not damaged. A load applied to a membrane forming the balloon
fluctuates depending on a pressure differential between the aortic
pressure and the balloon internal pressure. When the balloon
internal pressure is too high relative to the aortic pressure, the
membrane of the balloon may be excessively applied with the load,
wherein the balloon membrane may be damaged, for example may be
torn out. The maximum pressure value represents the upper limiting
value that the balloon is not damaged as described above.
[0012] According to a second aspect of the present invention, the
balloon pumping method of inflating and deflating a balloon in a
blood vessel at a predetermined timing includes the steps of
setting a pressure in the balloon at a third pressure value, which
is lower than a maximum pressure value for maintaining a deflated
condition and is substantially equal to or higher than a minimum
pressure value for maintaining the deflated condition, when the
balloon is shifted from an inflated condition to the deflated
condition; and increasing the pressure in the balloon to a fourth
pressure value, which is substantially equal to or lower than the
maximum pressure value and higher than the third pressure value,
after the balloon is estimated to have completely deflated at the
third pressure value.
[0013] The maximum pressure value, at which the balloon can be
maintained under the deflated condition, represents an upper
limiting value that the balloon can be deflated. The pressure in
the vessel is an aortic pressure. Therefore, in order to deflate
the balloon in the vessel, the balloon has to be maintained at a
pressure lower than the aortic pressure. Therefore, the maximum
pressure value can be lower than the aortic pressure. The aortic
pressure fluctuates periodically and is different among patients.
Therefore, the maximum pressure value cannot be always a fixed
pressure value.
[0014] The minimum pressure value, at which the balloon can be
maintained under the deflated condition, represents a bottom
limiting value that the balloon in the vessel does not deform and
is not damaged. A load applied to a membrane forming the balloon
fluctuates depending on a pressure differential between the aortic
pressure and the balloon internal pressure. When the balloon
internal pressure is too low relative to the aortic pressure, the
membrane of the balloon may be excessively applied with the load,
wherein stress may be applied to a connecting portion between the
balloon and the balloon catheter. Therefore, the durability may be
deteriorated. The minimum pressure value represents the bottom
limiting value that the balloon does not face the above-described
states.
[0015] According to a third aspect of the present invention, a
balloon pump driving apparatus connected to a balloon in a blood
vessel and adapted to inflate and deflate the balloon at a
predetermined timing by applying a predetermined pressure to the
balloon includes inflation judging means for judging a timing for
inflating the balloon based upon an inputted bio signal, first
inflation pressure applying means for applying a first inflation
pressure to the balloon at an appropriate timing judged by the
inflation judging means, the first inflation pressure being higher
than a minimum pressure value at which the balloon is maintained at
an inflated condition, complete inflation estimating means for
estimating whether the balloon has completely inflated by applying
the first inflation pressure to the balloon by the first inflation
pressure applying means, and second inflation pressure applying
means for applying a second inflation pressure to the balloon when
the complete inflation estimating means estimates that the balloon
has completely inflated, the second inflation pressure being
substantially equal to or higher than the minimum pressure value
and lower than the first inflation pressure. Therefore, the
pressure in the balloon is decreased.
[0016] In light of foregoing, according to a fourth aspect of the
present invention, the balloon pump driving apparatus connected to
a balloon inserted in to a blood vessel and adapted to inflate and
deflate the balloon at a predetermined timing by applying a
predetermined pressure to the balloon includes deflation judging
means for judging a timing for deflating the balloon based upon an
inputted bio signal, first deflation pressure applying means for
applying a first deflation pressure to the balloon at an
appropriate timing judged by the deflation judging means, the first
deflation pressure being lower than a maximum pressure value at
which the balloon is maintained at a deflated condition, complete
deflation estimating means for estimating whether the balloon has
completely deflated by applying the first deflation pressure by the
first deflation pressure applying means, and second deflation
pressure applying means for applying a second deflation pressure to
the balloon when the complete deflation estimating means estimates
that the balloon has completely deflated, the second deflation
pressure being substantially equal to or lower than the maximum
pressure value and higher than the first deflation pressure.
[0017] According to a fifth aspect of the present invention, the
balloon pump driving apparatus includes a pressure accumulator
connected to a balloon in a blood vessel and adapted to accumulate
a pressure to be supplied to the balloon at a predetermined timing,
a pressure control valve disposed between the pressure accumulator
and the balloon, and means for controlling the pressure accumulated
in the pressure accumulator and an open/closed condition of the
pressure control valve. The means for controlling performs a first
inflation pressure control for controlling the pressure accumulator
so as to set the pressure accumulated in the pressure accumulator
at a first inflation pressure, the first inflation pressure being
higher than a minimum pressure value at which the balloon is
maintained at an inflated condition, an inflation-time valve
opening control for connecting the pressure accumulator with the
balloon by opening the pressure control valve after accumulating
the first inflation pressure in the pressure accumulator through
the first inflation pressure control, a time judgment control for
judging whether an opening period of the pressure control valve has
reached a first predetermined period, an inflation-time
intermediate valve closing control for closing the pressure control
valve when the opening period of the pressure control valve is
judged to be have reached the first predetermined period by the
time judgment control, a pressure decrease control for decreasing
the pressure accumulated in the pressure accumulator when the
opening period of the pressure control valve is judged to have
reached the predetermined period by the time judgment control, a
complete inflation estimating control for estimating whether the
balloon has completely inflated, an inflation-time intermediate
valve opening control for opening the pressure control valve when
the balloon is estimated to have completely inflated by the
complete inflation estimating control, and an inflation-time valve
closing control for closing the pressure control valve in a second
predetermined time set at a time value at which the pressure in the
balloon is expected to become higher than a minimum pressure value
and lower than the first inflation pressure after opening the
pressure control valve by the inflation-time intermediate valve
opening control, the minimum pressure value at which the balloon is
maintained under the inflated condition.
[0018] According to a seventh aspect of the present invention, the
balloon pump driving apparatus includes a pressure accumulator
connected to a balloon inserted in a blood vessel and adapted to
accumulate a pressure to be supplied to the balloon at a
predetermined timing, a pressure control valve disposed between the
pressure accumulator and the balloon, and means for controlling the
pressure accumulated in the pressure accumulator and an open/closed
condition of the pressure control valve. The means for controlling
performs a fist deflation pressure control for controlling the
pressure accumulator so as to set the pressure accumulated in the
pressure accumulator at a first deflation pressure, the first
deflation pressure being lower than a maximum pressure value at
which the balloon is maintained at a deflated condition, a
deflation-time valve opening control for connecting the pressure
accumulator with the balloon by opening the pressure control valve
after accumulating the first deflation pressure in the pressure
accumulator through the first deflation pressure control, a
complete deflation estimating control for estimating whether the
balloon has completely deflated, a pressure increase control for
increasing the pressure accumulated in the pressure accumulator
when the balloon is estimated to have completely deflated by the
complete deflation estimating control, a deflation pressure
estimating control for estimating whether the pressure in the
balloon has reached a predetermined pressure being lower than the
maximum pressure and higher than the first deflation pressure, and
a deflation valve closing control for closing the pressure control
valve when the pressure in the balloon has reached the
predetermined pressure by the deflation pressure estimating
control.
[0019] According to an eighth aspect of the present invention, the
balloon pump driving apparatus includes a pressure accumulator
connected to a balloon inserted in a blood vessel and adapted to
accumulate a pressure to be supplied to the balloon at a
predetermined timing, a pressure control valve disposed between the
pressure accumulator and the balloon, a first connecting passage
connecting the auxiliary reservoir tank with the balloon, a first
auxiliary switching valve disposed in the first connecting passage,
and means for controlling the pressure accumulated in the pressure
accumulator, an open/closed condition of the pressure control
valve, and an open/closed condition of the first auxiliary
switching valve. The means for controlling performs a first
inflation pressure control for controlling the pressure accumulator
so as to set the pressure accumulated in the pressure accumulator
at a first inflation pressure, the first inflation pressure being
higher than a minimum pressure value at which the balloon is
maintained at an inflated condition, an inflation-time valve
opening control for connecting the pressure accumulator with the
balloon by opening the pressure control valve after accumulating
the first inflation pressure in the pressure accumulator through
the first inflation pressure control, a time judgment control for
judging whether an opening period of the pressure control valve has
reached a first predetermined period, an inflation-time
intermediate valve closing control for closing the pressure control
valve when the opening period of the pressure control valve is
judged to be have reached the first predetermined period by the
time judgment control, a pressure decrease control for decreasing
the pressure accumulated in the pressure accumulator when the
pressure control valve is closed by the inflation-time intermediate
valve closing control, a complete inflation estimating control for
estimating whether the balloon has completely inflated, an
inflation-time intermediate valve opening control for setting the
pressure in the balloon higher than the minimum pressure and lower
than the first inflation pressure by establishing a communication
between the auxiliary reservoir tank and the balloon by opening the
first auxiliary switching valve when the balloon is estimated to
have completely inflated by the complete inflation estimating
control, the pressure in the auxiliary reservoir tank having been
set at a second inflation pressure, an inflation-time valve closing
control for interrupting the communication between the auxiliary
reservoir tank and the balloon by closing the first auxiliary
switching valve in a predetermined period of time after opening the
first auxiliary switching valve by the inflation-time intermediate
valve opening control, an auxiliary reservoir pressure setting
control for setting the pressure in the auxiliary reservoir tank at
a predetermined pressure.
[0020] According to a ninth aspect of the present invention, the
balloon pump driving apparatus includes a pressure accumulator
connected to a balloon in a blood vessel and adapted to accumulate
a pressure to be supplied to the balloon at a predetermined timing,
a pressure control valve disposed between the pressure accumulator
and the balloon, a first connecting passage connecting the
auxiliary reservoir and the balloon, a first auxiliary switching
valve disposed in the first connecting passage, and means for
controlling the pressure accumulated in the pressure accumulator,
an open/closed condition of the pressure control valve, and an
open/closed condition of the first auxiliary switching valve. The
means for controlling performs a first deflation pressure control
for controlling the pressure accumulator so as to set the pressure
accumulated in the pressure accumulator at a first deflation
pressure, the first deflation pressure being lower than a maximum
pressure value at which the balloon is maintained at a deflated
condition, a deflation-time valve opening control for connecting
the pressure accumulator with the balloon by opening the pressure
control valve after accumulating the first deflation pressure in
the pressure accumulator through the first deflation pressure
control, a complete deflation estimating control for estimating
whether the balloon has completely deflated, a deflation-time
intermediate valve opening control for setting the pressure in the
balloon to be lower than the maximum pressure and higher than the
first deflation pressure by establishing a communication between
the auxiliary reservoir tank and the balloon by opening the first
auxiliary switching valve while the pressure control valve is
opened when the balloon is estimated to have completely deflated by
the complete deflation estimate control, the pressure in the
auxiliary reservoir tank having been set at a second deflation
pressure, a deflation-time valve closing control for interrupting
the communication between the pressure accumulator and the balloon
by closing the pressure control valve in a predetermined period of
time after opening the first auxiliary switching valve by the
deflation-time intermediate valve opening control, a pressure
increase control for increasing the pressure accumulated in the
pressure accumulator after closing the pressure control valve by
the deflation-time valve closing control, a deflation-time
intermediate valve closing control for interrupting the
communication between the auxiliary reservoir tank and the balloon
by closing the first auxiliary switching valve substantially at a
same time as the closing operation of the pressure control valve by
the deflation-time valve closing control or after the closing
operation thereof, and an auxiliary reservoir pressure setting
control for setting the pressure in the auxiliary reservoir tank at
a predetermined pressure.
[0021] According to a tenth aspect of the present invention, the
balloon pump driving apparatus includes the pressure accumulator
having an isolator housing of which inside is a hollow, isolator
means having a movable membrane disposed in the isolator housing,
the inside of the isolator housing divided into an output chamber
and an input chamber by the movable membrane, the output chamber
connected to the balloon via the pressure control valve; and
movable membrane driving means for displacing the movable membrane
in the isolator housing.
[0022] In this case, the pressure accumulator can be configured
with a simple structure.
[0023] According to an eleventh aspect of the present invention, a
fluid-type pump displaces the movable membrane. Generally, the
movable membrane is displaced by a compressor as a non-limiting
example. However, according to the ninth aspect of the present
invention, the size of the isolator can be downsized. Further, the
pressure accumulated by the isolator means continuously varies by
adjusting the fluid amount in the fluid-type pump.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] The foregoing and additional features and characteristics of
the present invention will become more apparent from the following
detailed description considered with reference to the accompanying
drawings, wherein:
[0025] FIG. 1 is a schematic view illustrating a balloon pumping
system according to a first embodiment of the present
invention;
[0026] FIG. 2 is a timing chart for explaining transitions of a
timing for inflating and deflating a balloon, an inflated and
deflated condition of the balloon, a rotational direction of an oil
pump, a timing for switching a pressure control valve, a pressure
in an output chamber, and a pressure applied to the balloon
according to the first embodiment of the present invention;
[0027] FIG. 3 is a main flowchart of a controller for inflating and
deflating the balloon by the balloon pumping system illustrated in
FIG. 1;
[0028] FIG. 4 is a schematic view illustrating a balloon pumping
system according to a second embodiment of the present
invention;
[0029] FIG. 5 is a timing chart for explaining transitions of the
timing for inflating and deflating the balloon, the inflated and
deflated condition of the balloon, the rotational direction of the
oil pump, the timing for switching the pressure control valve, the
timings for switching first and second switching valves, the
pressure in the output chamber, the pressure applied to the
balloon, and a pressure in an auxiliary reservoir tank according to
the second embodiment of the present invention;
[0030] FIG. 6 is a main flowchart of the controller for inflating
and deflating the balloon by the balloon pumping system illustrated
in FIG. 4;
[0031] FIG. 7 is a timing chart for explaining transitions of the
timing for inflating and deflating the balloon, the inflated and
deflated condition of the balloon, the rotational direction of the
oil pump, the timing for switching the pressure control valve, the
timings for switching first and second switching valves, the
pressure in the output chamber, the pressure applied to the
balloon, and a pressure in an auxiliary reservoir tank according to
the third embodiment of the present invention;
[0032] FIG. 8 is a main flowchart of the controller for inflating
and deflating the balloon by the balloon pumping system according
to the third embodiment of the present invention;
[0033] FIG. 9 is a schematic view illustrating a balloon pumping
system according to a fourth embodiment of the present
invention;
[0034] FIG. 10 is a timing chart for explaining transitions of the
timing for inflating and deflating the balloon, the inflated and
deflated condition of the balloon, the rotational direction of the
oil pump, the timing for switching the pressure control valve, the
timing for switching the first switching valve, the pressure in the
output chamber, the pressure applied to the balloon, and a pressure
in an auxiliary reservoir tank according to the fourth embodiment
of the present invention; and
[0035] FIG. 11 is a main flowchart of the controller for inflating
and deflating the balloon by the balloon pumping system illustrated
in FIG. 9.
DETAILED DESCRIPTION
[0036] As illustrated in FIG. 1, a balloon pumping system 100
according to a first embodiment of the present invention includes a
balloon catheter 90 and a balloon pump driving apparatus 10. The
balloon catheter 90 includes a catheter 91 and a balloon 92. The
catheter 91 is a long tube with a lumen and is made of a material
possessing certain degree of flexibility. The balloon 92 is
equipped at a distal end 91a of the catheter 91, i.e. is equipped
at an end of the catheter 91 that is away from the balloon pump
driving apparatus 10, while the balloon pump driving apparatus 10
is equipped at a proximal end 91b of the catheter 91, i.e. is
equipped at an end of the catheter 91 opposite to the distal end
91a.
[0037] The balloon pump driving apparatus 10 is provided with an
outer shell of an apparatus housing 11 which houses an oil
reservoir 20, an oil pump 30, and an isolator 40. The oil pump 30
includes a pump housing 31 having a first input-output port 31a (a
first I/O port) and a second input-output port 31b (a second I/O
port). The pump housing 31 includes a pumping chamber (not
illustrated) having an impeller blade, and a driving power source
(not illustrated) such as a motor that is connected to the impeller
blade. A rotational shaft of the motor can be rotated in normal and
reverse directions. The first I/O port 31a is connected to the oil
reservoir 20, while the second I/O port 31b is connected to the
isolator 40.
[0038] The oil reservoir 20 includes a reservoir housing 21 and a
reservoir diaphragm (i.e., a movable membrane) 22 disposed in the
reservoir housing 21. The reservoir housing 21 is divided into an
oil chamber 23 and an air-releasing chamber 24 by the reservoir
diaphragm 22. As illustrated in FIG. 1, the oil chamber 23
communicates with the first 10 port 31a, while the air-releasing
chamber 24 communicates with an air such that an internal pressure
in the air-releasing chamber 24 is always maintained at an
atmospheric pressure level.
[0039] The isolator 40 is referred to as a volume limiting device
(VLD) and corresponds to a pressure accumulator. The isolator 40
includes an isolator housing 41 and an isolator diaphragm 42
disposed in the isolator housing 41. The isolator housing 41 is
divided into two chambers by the isolator diaphragm 42; one is an
input chamber 43 and the other one is an output chamber 44. As
illustrated in FIG. 1, the input chamber 43 communicates with the
second I/O port 31b of the oil pump 30, while the output chamber 44
communicates with a one end 51a of an output conduit 51. The other
end 51b of the output conduit 51 communicates with an output port
12 formed at a surface of the apparatus housing 11. The output port
12 is connected to the proximate end 91b of the catheter 91, such
that the balloon catheter 90 communicates with the output conduit
51.
[0040] A pressure control valve 52 referred to as a common valve is
disposed in the output conduit 51. A flow passage area of the
pressure control valve 52 under an open condition is designed to be
larger than the one of a normal switching valve. Therefore,
pressure loss can be effectively prevented, which may be caused
upon opening the pressure control valve 52.
[0041] As illustrated in FIG. 1, the output chamber 44 further
communicates with a helium gas supply-drain conduit 53 which
branches to a gas drain conduit 54 and a gas supply conduit 55.
There is a drain switching valve 56 disposed in the gas drain
conduit 54. An opening end of the gas drain conduit 54 communicates
with an air. In the meantime, there is a supply switching valve 57
disposed in the gas supply conduit 55. An end of the gas supply
conduit 55, which is different from a branched end thereof, is
connected to a helium gas tank 58. According to the first
embodiment of the present invention, the gas drain conduit 54 and
the gas supply conduit 55 are merged in midstream to communicate
with the output chamber 44. Alternatively, the gas drain conduit 54
and the gas supply conduit 55 can communicate with the output
chamber 44 independently.
[0042] A first pressure sensor 61 is equipped in the output chamber
44 of the isolator 40 so as to detect the pressure in the output
chamber 44. A second pressure sensor 62 is equipped at a downstream
side of the pressure control valve 52 at the output conduit 51,
i.e., at a side near the balloon catheter 90. A portion equipped
with the second pressure sensor 62 at the output conduit 51 always
communicates with the balloon catheter 90 via the output port 12.
Therefore, the second pressure sensor 62 can detect a pressure
applied to the balloon 92.
[0043] The balloon pump driving apparatus 10 is further provided
with a controller 70. The controller 70 is electrically connected
to a driving means of the oil pump 30, the supply switching valve
57, the drain switching valve 56, the pressure control valve 52,
the first pressure sensor 61, and the second pressure sensor 62.
The controller 70 is further electrically connected to a biological
signal output device 81 and a display-operating panel 82. The
biological signal output device 81 outputs an electrocardiographic
(ECG) signal and/or an aortic pressure (Aop) signal. The controller
70 is transmitted with requisite information such as the ECG signal
and/or the Aop signal outputted from the biological signal output
unit 81, the pressure information detected by the first and second
pressure sensors 61 and 62, and so on. The controller 70 then
outputs a drive control signal to the driving means of the oil pump
30, and outputs switching signals to the supply switching valve 57,
the drain switching valve 56, and the pressure control valve 52,
respectively. The controller 70 is still further connected to an
AC/DC adapter 83 connected to a normal alternator and a battery 84
as an auxiliary power source.
[0044] The oil chamber 23 of the oil reservoir 20 has been charged
with oil. This oil is supplied to or drained from the input chamber
43 of the isolator 40 by the oil pump 30. That is, a primary space
defined by the oil chamber 23 of the oil reservoir 20, the pumping
chamber of the oil pump 30, and the input chamber 43 of the
isolator 43 can be charged with the oil. Any type of oil can be
applied. However, it is preferable to apply silicon oil in light of
safety level and response.
[0045] The output chamber 44 has been charged with helium gas. The
helium gas is supplied from the helium gas tank 58 to the output
chamber 44 when the supply switching valve 57 is opened. The amount
of the helium gas charging the output chamber 44 can be determined
based upon a value of the pressure detected by the first pressure
sensor 61 at a predetermined timing while the balloon pump driving
apparatus 10 has been normally operated. When the amount of the
helium gas is judged to have not been sufficiently supplied to the
output chamber 44, the supply switching valve 57 is opened so as to
supply more helium gas to the output chamber 44.
[0046] Next, operation of the balloon pumping system 100 will be
explained hereinbelow with reference to FIGS. 2 and 3. As explained
by a timing chart illustrated in FIG. 2, a sequential line graph
denoted with a solid line explains how a pressure Pi in the output
chamber 44 detected by the first pressure sensor 61 transits, while
a sequential line graph denoted with a dotted line explains how a
pressure Pb applied to the balloon 92 and detected by the second
pressure sensor 62 transits. The pressure Pb substantially
corresponds to a pressure in the balloon 92. The balloon pumping
system 100 repeats inflation and deflation of the balloon 92, such
that there is no clear definition of a starting point. Therefore,
the following explanation will be initiated from a point Q in FIG.
2, i.e., from a condition where the pressure control valve 52 is
closed and the balloon 92 has deflated with the applied pressure Pb
at a second deflation pressure P4.
[0047] Under the above-described condition, the oil pump 30 is
driven for rotation in the normal direction as explained at step
S101 in FIG. 3. In response to the normal rotation of the oil pump
30, the oil in the oil reservoir 20 is introduced to the oil pump
30 through the first I/O port 31a. The oil is then drained to the
input chamber 43 of the isolator 40 through the second I/O port
31b. In this case, the isolator diaphragm 42 moves and extends in a
right direction in FIG. 1. In response to the extension of the
isolator diaphragm 42, the volume of the output chamber 44 is
decreased such that the pressure Pi of the output chamber 44 is
detected at a higher pressure value by the first pressure sensor
61. When the pressure Pi in the output chamber 44 reaches a first
inflation pressure P1, the rotational speed of the oil pump 30 is
slowed down so as not to increase the pressure Pi any more. The
amount of oil discharged from the oil pump 30 to the isolator 40
can be balanced with the amount of oil flowing back from the
isolator 40 to the oil pump 30. Accordingly, the pressure Pi in the
output chamber 44 can be maintained at the first inflation pressure
P1 (a first inflation pressure control). The first inflation
pressure P1 is far higher than a pressure required for inflating
the balloon 92.
[0048] At step S102, the controller 70 judges the presence or
absence of an inflation signal for the balloon 92 (inflation
judging means). The controller 70 computes timing for inflating the
balloon 92, which is appropriate for a body condition of a patient,
based upon the ECG signal and/or the Aop signal. The controller 70
outputs the inflation signal in response to the computed timing.
When the controller 70 judges that the inflation signal has not
been outputted, the program returns to step S101. When the
controller 70 judges that the inflation signal has been outputted,
the program proceeds to step S103. An explanation of a method of
computing the appropriate inflation timing will be omitted
herein.
[0049] When the inflation signal is outputted at step S102, the
controller 70 recognizes that the balloon 92 is under an inflating
period, i.e., the balloon 92 is shifting from a deflation condition
to an inflation condition. At step S103, the controller 70 outputs
a command signal for opening the pressure control valve 52 (an
inflation-time valve opening control). In response to the opening
operation of the pressure control valve 52, the output chamber 44
of the isolator 40 communicates with the balloon 92 such that the
first inflation pressure P1 in the output chamber 44 is applied to
the balloon 92. In this case, the pressure Pb is rapidly increased
up to a pressure P1' from the second deflation pressure P4.
[0050] As described above, the output chamber 44 has been charged
with the first inflation pressure P1 higher than the pressure
required for inflating the balloon 92 until a timing immediately
before the pressure control valve 52 is opened. Therefore, once the
pressure control valve 52 is opened, the helium gas in the output
chamber 44 at a blast flows into the balloon 92. Therefore,
according to the first embodiment of the present invention, the
balloon 92 can be inflated much faster than the conventional
method.
[0051] The program then proceeds to step S104 after opening the
pressure control valve 52, at which the controller 70 judges
whether the pressure control valve 52 has opened for a set period
T1set (i.e., a first predetermined period), i.e., judges whether an
opening period T1 of the pressure control valve 52 is substantially
equal to or greater than the set period T1set (a T1 judging
control). When the controller 70 judges that the opening period T1
has not reached the set period T1set, the program returns to step
S103. In the meantime, when the controller 70 judges that the
opening period T1 has reached the set period T1set, the program
proceeds to step S105. The set period T1set is designed as needed
based upon a material of the balloon 92, the information of the
signal outputted from the biological signal output device 81, and
so on. However, it is preferable that the set period T1set be
designed at an expected period of time for supplying the sufficient
amount of helium gas required for completely inflating the balloon
92 at a predetermined pressure level.
[0052] At step S105, the controller 70 closes the pressure control
valve 52 (an inflation-time intermediate valve closing control).
The communication between the output chamber 44 and the balloon 92
is interrupted in response to the closing operation of the pressure
control valve 52. The program then proceeds to step S106.
[0053] At step S106, the controller 70 drives the oil pump 30 for
rotation in a reverse direction. The oil in the input chamber 43 of
the isolator 40 is then sucked into the oil pump 30 through the
second 110 port 31b. The oil in the oil pump 30 is then drained
into the oil chamber 23 of the oil reservoir 20 through the first
I/O port 31a. Therefore, the isolator diaphragm 42 then moves in a
left direction in FIG. 1. The volume of the output chamber 44 is
increased corresponding to the movement of the diaphragm 42 such
that the pressure Pi in the output chamber 44 is decreased as
explained in FIG. 2 (a pressure decrease control).
[0054] A pressure change rate (with time) of the pressure value Pb
detected by the second pressure sensor 62 is denoted with a
pressure change rate Pb with time. At step S107, the controller 70
judges whether the pressure change rate Pb is zero or within a
predetermined range .ang.b, i.e., judges whether the balloon 92 has
completely inflated (a complete inflation estimating control). The
balloon 92 has not completely inflated immediately after closing
the pressure control valve 52 at step S105 such that the balloon 92
is inflating even after the valve closing operation. The helium gas
flows from the output chamber 44 to the balloon 92 in response to
this balloon inflation. Therefore, the pressure Pb applied to the
balloon 92 is decreased. However, when the balloon 92 approaches
the completely inflated condition, the amount of helium gas flowing
into the balloon 92 is decreased, wherein the decreasing amount of
the pressure Pb becomes less, i.e., the pressure change rate Pb
with time becomes slow. When the balloon 92 is completely inflated,
no more helium gas flow into the balloon 92. In this case, the
decrease of the pressure Pb is stopped, and the pressure Pb is
maintained at a flat pressure level. As described above, the
balloon 92 can be judged whether it has completely inflated, based
upon the pressure change rate Pb.
[0055] As explained in FIG. 2, according to the first embodiment of
the present invention, the pressure change rate Pb becomes
approximately zero during the inflating period. In this case, the
pressure Pb has reached the pressure P1'. The pressure P1' is
higher than the minimum pressure value capable of maintaining the
balloon 92 at the inflated condition, and is lower than the maximum
pressure value capable of maintaining the balloon 92 at the
inflated condition. On the other hand, according to a conventional
balloon pump driving apparatus, the pressure in the balloon is set
around the minimum pressure level capable of maintaining the
balloon under the inflated condition when the balloon is completely
inflated. Comparing the balloon pump driving apparatus 10 with this
type of conventional balloon pump driving apparatus, the balloon 92
can be inflated faster because the balloon 92 has been applied with
the pressure P1' higher than the conventional applied pressure even
when the balloon 92 has completely inflated. It is preferable that
the pressure P1' be set at a pressure value proximal to the maximum
pressure at which the balloon 92 is maintained at the inflated
condition. That is, it is preferable that the pressure P1' be set
at a pressure value as high as possible within an allowable
pressure range. By setting the pressure P1' at a relatively high
value, the balloon 92 can be effectively inflated at a much faster
inflating speed.
[0056] When the pressure change rate Pb is judged to have been
substantially equal to zero or to be within the range .ang.b, the
program proceeds to step S108, wherein the pressure control valve
52 is opened again (the inflation-time intermediate valve opening
control). The oil pump 30 has rotated in the reverse direction
after the closing operation of the pressure control valve 52 at
step S105, such that the pressure Pi in the output chamber 44 of
the isolator 40 has been decreased down to the second inflation
pressure P2. Therefore, in response to the opening operation of the
pressure control valve 52, the output chamber 44 set at a decreased
pressure level communicates with the balloon 92 set at a high
pressure level, wherein the helium gas in the balloon 92 is drawn
back to the output chamber 44. Therefore, the pressure level in the
balloon 92 is decreased.
[0057] The program then proceeds to step S109 after opening the
pressure control valve 52 at step S108, at which the controller 70
judges whether the pressure control valve 52 has opened for a set
period T2set (i.e., a second predetermined time), i.e., judges
whether an opening period T2 of the pressure control valve 52 is
substantially equal to or greater than the set period T2set. When
the controller 70 judges that the opening period T2 has not reached
the set period T2set, the program returns to step S108. When the
controller 70 judges that the opening period T2 has reached the set
period T2set, the program proceeds to step S110.
[0058] At step S110, the controller 70 closes the pressure control
valve 52 (an inflation-time valve closing control). The
communication between the output chamber 44 and the balloon 92 is
interrupted in response to the closing operation of the pressure
control valve 52. The balloon 92 is then maintained under the
inflated condition at an applied pressure P2'. The program then
proceeds to step S111. As explained in FIG. 2, the applied pressure
Pb is constantly maintained at the pressure P2' while the balloon
92 has been under the inflated condition. The balloon 92 can be
hence expected to be maintained at this pressure P2' level. It is
preferable that the pressure P2' be set at a value proximate to the
minimum pressure value capable of maintaining the balloon 92 under
the inflated condition. That is, it is preferable that the pressure
P2' be set at a pressure value as low as possible within an
allowable pressure range. By setting the pressure P2' at a low
value as described above, a pressure differential can be minimized
when the balloon 92 is next shifted from the inflated condition to
the deflated condition.
[0059] An appropriate pressure Pb to be applied to the balloon 92
is denoted with a set pressure Pset. A pressure differential
between the set pressure Pset and the actual pressure Pb is denoted
with an absolute pressure value P. At step S111, the controller 70
judges whether the absolute pressure value P is substantially zero
or within a predetermined range .ang.. When the controller 70
judges that the absolute pressure value P is substantially zero, or
the absolute pressure value P is substantially equal to or smaller
than the predetermined range .ang., the program proceeds to step
S113. On the other hand, when the controller 70 judges that the
absolute value P is not substantially zero, or the absolute
pressure value P is substantially equal to or greater than the
predetermined range .ang., the program proceeds to step S112, at
which the set period T2set is corrected (a correcting control).
[0060] The set period T2set is designed beforehand through
experimentations. More particularly, the set period T2set is
designed by measuring a transit time of the pressure Pb from the
second inflation pressure P2 to the set pressure Pset upon the
opening operation of the pressure control valve 52 at step S108.
The set period T2set is set at a value obtained through the
experimentation. However, the set period T2set may fluctuate due to
the condition of the patient or a dimension of the balloon 92.
Therefore, the pressure Pb does not always reach the pressure Pset
in the set period T2set. In this case, the set period T2set is
required to be corrected. The detailed description of the method of
correcting the set period T2set will be omitted herein. For
example, when the value P at step S111 is a positive value, the set
period T2set is corrected to be longer corresponding to the
positive value P. On the other hand, when the value P at step S111
is a negative value, the set period T2set is corrected to be
shorter corresponding to the negative value P. The program then
proceeds to step S113.
[0061] The oil pump 30 has still rotated in the reverse direction
even after closing the pressure control valve 52 at step S110. In
this case, the isolator diaphragm 42 has expanded in the left
direction in FIG. 1, wherein the volume of the output chamber 44 is
increased. In this case, the pressure Pi in the output chamber 44
is further decreased down to a first deflation pressure P3. The
rotational speed of the oil pump 30 in the reverse direction is
slowed down to prevent occurrence of a further pressure decrease in
the output chamber 44. The amount of oil introduced from the
isolator 40 to the oil pump 30 is substantially balanced with the
amount of oil flown back to the isolator 40 from the oil pump 30.
Therefore, the pressure Pi in the output chamber 44 can be
maintained at the first deflation pressure P3 (a first deflation
pressure control). The first deflation pressure P3 is designed to
be far lower than a pressure required for deflating the balloon
92.
[0062] At step S113, the controller 70 judges the presence or
absence of a deflation signal of the balloon 92 (a deflation
judging means). In the same manner as the judgment of the presence
of absence of the inflation signal, the controller 70 computes
timing for deflating the balloon 92, which is appropriate for the
body condition of the patient, based upon the ECG signal and/or the
Aop signal. The controller 70 outputs the deflation signal in
response to the computed timing. When the controller 70 judges that
the deflation signal has not been outputted, the program returns to
step S113. When the controller 70 judges that the deflation signal
has been outputted, the program proceeds to step S114.
[0063] When the deflation signal is outputted at step S113, the
controller 70 recognizes that the balloon 92 is under the deflating
period, i.e., the balloon 92 is shifted from the inflation
condition to the deflation condition. At step S114, the controller
70 outputs a command signal for opening the pressure control valve
52 (a deflation-time valve opening control). In response to the
opening operation of the pressure control valve 52, the output
chamber 44 of the isolator 40 communicates with the balloon 92. The
pressure Pb at the second inflation pressure P2' is higher than the
pressure P3 in the output chamber 44. Therefore, the helium gas in
the balloon 92 is drawn to the output chamber 44. In this case, the
pressure Pb of the balloon 92 is suddenly decreased from the second
inflation pressure P2' to a pressure P3'. The output chamber 44 has
been charged with the first inflation pressure P3 until timing
immediately before the opening operation of the pressure control
valve 52. Therefore, in response to the opening operation of the
pressure control valve 52, the helium gas at a blast flows from the
balloon 92 to the output chamber 44. Therefore, according to the
first embodiment of the present invention, the deflation of the
balloon 92 can be performed faster than the conventional balloon
pumping system.
[0064] After opening the pressure control valve 52 at step S114,
the program proceeds to step S115, at which the controller 70
judges whether the pressure change rate Pb of the pressure Pb for
the balloon 92 is substantially zero or within the predetermined
range .ang.b, i.e., judges whether the balloon 92 has completely
deflated (a complete deflation estimating control). The balloon 92
has not completely deflated immediately after opening the pressure
control valve 52 at step S114 such that the balloon 92 is deflating
even after the valve opening operation. The helium gas flows from
the balloon 92 to the output chamber 44 in response to this balloon
deflation. Therefore, the pressure Pb applied to the balloon 92 is
increased. However, when the balloon 92 approaches the completely
deflated condition, the amount of helium gas flowing from the
balloon 92 is decreased, wherein the increasing amount of the
pressure Pb becomes less, i.e., the pressure change rate Pb with
time becomes slow. When the balloon 92 is completely deflated, no
more helium gas flows from the balloon 92. In this case, the
increase of the pressure Pb is stopped, and the pressure Pb is
maintained at a flat pressure level. As described above, the
balloon 92 can be judged whether it has completely deflated, based
upon the pressure change rate Pb.
[0065] As explained in FIG. 2, according to the first embodiment of
the present invention, the pressure change rate Pb becomes
approximately zero during the deflating period. In this case, the
pressure Pb has reached the pressure P3'. The pressure P3' is lower
than the maximum pressure value capable of maintaining the balloon
92 at the deflated condition, and is higher than the minimum
pressure value capable of maintaining the balloon 92 at the
deflated condition. On the other hand, according to a conventional
balloon pump driving apparatus, the pressure in the balloon is set
around the maximum pressure level capable of maintaining the
balloon under the deflated condition when the balloon is completely
deflated. Comparing the balloon pump driving apparatus 10 with this
type of conventional balloon pump driving apparatus, the balloon 92
can be deflated faster because the balloon 92 has been applied with
the pressure P3' lower than the conventional applied pressure even
when the balloon 92 has completely deflated. It is preferable that
the pressure P3' be set at a pressure value proximate to the
minimum pressure value at which the balloon 92 is maintained at the
deflated condition. That is, it is preferable that the pressure P3'
be set at a pressure value as low as possible within an allowable
pressure range. By setting the pressure P3' at a relatively low
value as described above, the balloon 92 can be effectively
deflated at a much faster deflating speed.
[0066] When the pressure change rate Pb is judged to have been
substantially equal to zero or to be within the range .ang.b, the
program proceeds to step S116, wherein the oil pump 30 is driven
for rotation in the normal direction. The oil in the oil reservoir
20 is suck into the oil pump 30. The oil in the oil pump 30 is
drained to the input chamber 43 of the isolator 30. In this case,
the isolator diaphragm 42 expands in the right direction in FIG. 1.
In response to the movement of the isolator diaphragm 42, the
volume of the output chamber 44 is decreased, wherein the pressure
Pi in the output chamber 44 is increased (a pressure increase
control).
[0067] At step S117, the controller 70 judges whether the pressure
Pi in the output chamber 44 detected by the first pressure sensor
61 is substantially equal to the second deflation pressure P4 (a
deflation pressure estimating control). At this point, the pressure
control valve 52 is at the open condition. That is, the pressure Pi
in the output chamber 44 can be substantially equal to the pressure
Pb applied to the balloon 92. When the controller 70 judges that
the pressure Pi in the output chamber 44 is not substantially equal
to the pressure P4, the program returns to step S116. When the
controller 70 judges that the pressure Pi in the output chamber 44
is substantially equal to the pressure P4, the program proceeds to
step S118, at which the pressure control valve 52 is closed (a
deflation-time valve closing control). The communication between
the output chamber 44 and the balloon 92 is interrupted. The
pressure Pb applied to the balloon 92 is maintained at the pressure
P4, and the balloon 92 is maintained under the deflated condition.
The program then returns to step S102 so as to output the inflation
signal for the next inflation. According to the first embodiment of
the present invention, the balloon 92 can be effectively inflated
and deflated at an appropriate timing by repeatedly performing the
above-described procedure.
[0068] As described above, a balloon pumping method of inflating
and deflating the balloon 92 in a vessel at a predetermined timing
includes the step of setting the pressure in the balloon at the
pressure P1' (i.e., a first pressure value), which is higher than
the minimum pressure value and is substantially equal to or lower
than the maximum pressure value, when the balloon 92 is shifted
from the deflated condition to the inflated condition. The balloon
92 can be maintained under the inflated condition when the pressure
in the balloon 92 is between the minimum pressure value and the
maximum pressure value. The balloon pumping method further includes
the step of decreasing the pressure in the balloon 92 to the
pressure P2' (i.e., a second pressure value), which is
substantially equal to or higher than the minimum pressure value
and lower than the first pressure value, when the balloon 92 is
estimated to have completely inflated at the first pressure
value.
[0069] Taking the balloon pumping apparatus disclosed in the
reference 2 as an example, when the balloon is inflating, the
balloon is applied with a pressure higher than the minimum pressure
at which the balloon can be maintained at the inflated condition.
As the balloon is approaching the completely inflated condition,
the applied pressure is reduced. When the balloon was shifted to
the completely inflated condition, the pressure in the balloon is
maintained at the minimum pressure at which the balloon can be
maintained at the inflated condition. In this case, the pressure
differential can be minimized when the balloon is shifted to the
deflated condition from the inflated condition. Some of the main
reasons of setting the pressure in the balloon at the minimum
pressure are in order to ensure quick response for deflating the
balloon, to prevent the balloon from unnecessary deformation, which
may occur by applying excessive pressure to the balloon.
[0070] On the other hand, according to the first embodiment of the
present invention, the pressure in the balloon 92 is set at the
pressure P1', which is higher than the minimum pressure at which
the balloon 92 can be maintained at the inflated condition and
substantially equal to and lower than the maximum pressure value.
The pressure in the balloon 92 is maintained at the pressure higher
than the minimum pressure even when the balloon 92 has completely
inflated. Therefore, the balloon inflation can be performed at a
faster inflating speed corresponding to the pressure in the balloon
92. If the balloon pressure is maintained at this pressure level
even when the balloon is shifted from the inflated condition to the
deflated condition, the pressure differential may be unnecessarily
increased. In this case, it may be difficult to deflate the balloon
92 at a quick deflating speed. In light of foregoing, the pressure
in the balloon 92 is reduced to the pressure P2' when the balloon
92 is estimated to have completely inflated at the pressure P1'.
The pressure P2' is substantially equal to or higher than the
minimum pressure and is lower than the pressure P1'. Accordingly,
the pressure differential upon deflating the balloon 92 can be
decreased. Therefore, the balloon deflation can be performed
quickly.
[0071] As described above, according to the first embodiment of the
present invention, the balloon inflating/deflating response can be
effectively improved by assuring the quick inflating response and
the quick deflating response for the next balloon deflation.
[0072] The pressure P1' can be set at any pressure level between
the minimum pressure value at which the balloon 92 can be
maintained at the inflated condition and the maximum pressure value
at which the balloon 92 can be maintained at the inflated
condition. However, the higher the pressure P1' is set, the more
quickly the balloon 92 can be inflated. Therefore, it is preferable
that the pressure P1' be proximate to the maximum pressure
value.
[0073] As far as the pressure P2' is lower than the pressure P1',
the pressure P2' can be set at any pressure level between the
minimum pressure value at which the balloon 92 can be maintained at
the inflated condition and at the maximum pressure value at which
the balloon 92 can be maintained at the inflated condition.
However, the lower the pressure P2' is set, the pressure
differential upon the next balloon inflation can be reduced.
Therefore, it is preferable that the pressure P2' be proximate to
the minimum pressure value, wherein the deflating response can be
quickly performed at the next deflation.
[0074] The pumping method of inflating and deflating the balloon 92
in a vessel at the predetermined timing includes the step of
setting the pressure in the balloon 92 at the pressure P3' (i.e., a
third pressure value), which is lower than the maximum pressure
value and is substantially equal to or higher than the minimum
pressure value, when the balloon 92 is shifted from the inflated
condition to the deflated condition. The balloon 92 can be
maintained under the deflated condition when the pressure in the
balloon 92 is between the minimum pressure value and the maximum
pressure value. The balloon pumping method further includes the
step of increasing the pressure in the balloon 92 to the pressure
P4 (i.e., a fourth pressure value), which is substantially equal to
or lower than the maximum pressure value and higher than the
pressure P3', when the balloon 92 is estimated to have completely
deflated at the third pressure value.
[0075] Taking a conventional balloon pumping apparatus as an
example, when the balloon is inflating, the balloon is applied with
a pressure lower than the maximum pressure at which the balloon can
be maintained at the deflated condition. As the balloon is
approaching the completely deflated condition, the applied pressure
is increased. When the balloon was shifted to the completely
deflated condition, the pressure in the balloon is maintained at
the maximum pressure at which the balloon can be maintained at the
deflated condition. In this case, the pressure differential can be
minimized when the balloon is shifted to the inflated condition
from the deflated condition. Some of the main reasons of setting
the pressure in the balloon at the maximum pressure level are in
order to ensure quick response for inflating the balloon, in order
to prevent the balloon from unnecessary deformation, which may
occur by applying excessive pressure to the balloon, and so on.
[0076] On the other hand, according to the first embodiment of the
present invention, the pressure in the balloon 92 is set at the
pressure P3', which is lower than the maximum pressure at which the
balloon 92 can be maintained at the deflated condition, and is
substantially equal to and higher than the minimum pressure value.
The pressure in the balloon 92 is maintained at a pressure lower
than the maximum pressure even when the balloon 92 has completely
deflated. Therefore, the balloon deflation can be performed at a
faster deflating speed corresponding to the pressure in the balloon
92. If the balloon pressure is maintained at this pressure level
P3' even when the balloon 92 is shifted from the deflated condition
to the inflated condition, the pressure differential may be
unnecessarily increased. In this case, it may be difficult to
inflate the balloon 92 at a quick inflating speed. In light of
foregoing, the pressure in the balloon 92 is increased to the
pressure P4 when the balloon 92 is estimated to have completely
deflated at the pressure P3'. The pressure P4 is substantially
equal to or higher than the maximum pressure and is higher than the
pressure P3'. Accordingly, the pressure differential upon inflating
the balloon 92 can be decreased. Therefore, the balloon inflation
can be performed quickly.
[0077] As described above, according to the first embodiment of the
present invention, the balloon inflating/deflating response can be
effectively improved by assuring the quick deflating response and
the quick inflating response for the next balloon inflation.
[0078] The pressure P3' can be set at any pressure level between
the maximum pressure value at which the balloon 92 can be
maintained at the deflated condition and the minimum pressure value
at which the balloon 92 can be maintained at the deflated
condition. However, the lower the pressure P3' is set, the more
quickly the balloon 92 can be deflated. Therefore, it is preferable
that the pressure P3' be proximate to the minimum pressure
value.
[0079] As far as the pressure P4 is higher than the pressure P3',
the pressure P4 can be set at any pressure level between the
maximum pressure value at which the balloon 92 can be maintained at
the deflated condition and the minimum pressure value at which the
balloon 92 can be maintained at the deflated condition. However,
the higher the pressure P4 is set, the pressure differential upon
the next balloon inflation can be reduced. Therefore, it is
preferable that the pressure P4 be proximate to the maximum
pressure value.
[0080] The balloon pump driving apparatus 10 according to the first
embodiment of the present invention includes inflation judging
means (step S102) for judging a timing for inflating the balloon 92
based upon an inputted bio signal, first inflation pressure
applying means (step S103, the isolator 40, the pressure control
valve 52) for applying a first inflation pressure to the balloon 92
at an appropriate timing judged by the inflation judging means, the
first inflation pressure being higher than the minimum pressure
value at which the balloon 92 can be maintained at the inflated
condition, complete inflation estimating means (step S107) for
estimating whether the balloon 92 has completely inflated by having
applied the first inflation pressure to the balloon 92 by the first
inflation pressure applying means, and second inflation pressure
applying means (step S108, the isolator 40, the pressure control
valve 52) for applying a second inflation pressure to the balloon
92 when the complete inflation estimating means estimates that the
balloon 92 has completely inflated, the second inflation pressure
being substantially equal to or higher than the minimum pressure
value and lower than the first inflation pressure applied by the
first inflation pressure applying means. Therefore, the pressure in
the balloon can be decreased.
[0081] That is, the pressure P1 is applied to the balloon 92 by the
first inflation pressure applying means when the inflation judging
means judges that it is a time to inflate the balloon 92. The
pressure Pb in the balloon 92 is set at the pressure P1', which is
higher than the minimum pressure value and is substantially equal
to or lower than the maximum pressure value. As described above,
even when the balloon 92 has reached to the completely inflated
condition by the first inflation pressure applying means, the
balloon 92 can be still applied with the pressure that is higher
than the minimum pressure required for maintaining the balloon 92
under the inflated condition. Therefore, the balloon inflation can
be performed at a still faster inflating speed.
[0082] When the complete inflation estimating means estimates that
the balloon 92 has completely inflated, the balloon 92 is applied
with the pressure P2 by the second inflation pressure applying
means. The applied pressure P2 is substantially equal to or higher
than the minimum pressure capable of maintaining the balloon 92 at
the inflated condition, and but is lower than the pressure P1
applied by the first inflation pressure applying means. Therefore,
the pressure in the balloon 92 is reduced by the second inflation
pressure applying means. In this case, the pressure differential
upon the next balloon deflation can be reduced. Therefore, the
following balloon deflation can be quickly performed. Therefore,
the quick inflation response upon the balloon inflation can be
ensured, while the quick balloon deflation response upon the
following balloon deflation can be ensured. That is, the balloon
response can be improved.
[0083] The pressure P1 applied by the first inflation pressure
applying means is designed to set the pressure in the completely
inflated balloon 92 within a range of the pressure P1'. For
example, when the first inflation pressure applying means always
applies a constant pressure to the balloon 92, the pressure applied
to the balloon 92 substantially corresponds to the pressure P1'. On
the other hand, the first inflation pressure applying means applies
the first inflation pressure to the balloon through a space having
a constantly limited volume, according to the first embodiment of
the present invention. In this case, the pressure itself is reduced
while passing through the space. That is, the applied pressure is
reduced with time. The pressure immediately after being applied by
the first inflation pressure applying means can be different from
the pressure applied to the balloon approaching to the completely
inflated condition. In this case, the initially applied pressure is
set higher than the pressure P1'. In any case, it is preferable
that the balloon 92 be applied with a pressure so as to bring the
pressure in the completely inflated balloon 92 to the pressure
P1'.
[0084] The pressure P2 applied by the second inflation pressure
applying means is designed to set the pressure in the deflating
balloon 92 within a range of the pressure P2'. For example, when
the second inflation pressure applying means always applies a
constant pressure to the balloon 92, the pressure applied to the
balloon 92 substantially corresponds to the pressure P2'. On the
other hand, the second inflation pressure applying means applies
the second inflation pressure through the space having the
constantly limited volume to the balloon 92, according to the first
embodiment of the present invention. In this case, the second
inflation pressure itself is increased while passing through the
space. That is, the applied pressure is increased with time. The
pressure immediately after being applied by the second inflation
pressure applying means can be different from the balloon pressure
in a predetermined period of time. In this case, the initially
applied pressure is lower than the pressure P2'. In any case, it is
preferable that the balloon 92 be applied with a pressure so as to
bring the pressure in the balloon 92 to the pressure P2'.
[0085] The balloon pump driving apparatus 10 according to the first
embodiment of the present invention includes deflation judging
means (step S113) for judging a timing for deflating the balloon 92
based upon the inputted bio signal, first deflation pressure
applying means (step S114, the isolator 40, the pressure control
valve 52) for applying a first deflation pressure to the balloon 92
at an appropriate timing judged by the deflation judging means, the
first deflation pressure being lower than the maximum pressure at
which the balloon 92 can be maintained at the deflated condition,
complete deflation estimating means (step S115) for estimating
whether the balloon 92 has completely deflated by applying the
pressure to the balloon 92 by the first deflation pressure applying
means, and second deflation pressure applying means (step S116, the
isolator 40, the pressure control valve 52) for applying a second
deflation pressure to the balloon 92 when the complete deflation
estimating means estimates that the balloon 92 has completely
deflated, the second deflation pressure being substantially equal
to or lower than the maximum pressure value and higher than the
pressure applied by the first deflation pressure applying
means.
[0086] That is, the pressure P3 is applied to the balloon 92 by the
first deflation pressure applying means when the deflation judging
means judges that it is a time to deflate the balloon 92. The
pressure in the balloon 92 is set at the pressure P3' which is
lower than the maximum pressure value and is substantially equal to
or higher than the minimum pressure value. As described above, even
when the balloon 92 has reached to the completely deflated
condition by the first deflation pressure applying means, the
balloon 92 can be still applied with the pressure that is lower
than the maximum pressure required for deflating the balloon 92.
Therefore, the balloon deflation can be performed at a still faster
deflating speed.
[0087] When the complete deflation estimating means estimates that
the balloon 92 has completely deflated, the balloon 92 is applied
with the pressure P4 by the second deflation pressure applying
means. The applied pressure P4 is substantially equal to or lower
than the maximum pressure capable of maintaining the balloon 92 at
the deflated condition, and but is higher than the pressure P3
applied by the first deflation pressure applying means. Therefore,
the pressure in the balloon 92 is increased by the second deflation
pressure applying means. In this case, the pressure differential
upon the next balloon inflation can be reduced. Therefore, the
following balloon inflation can be quickly performed. Therefore,
the quick deflation response upon the balloon deflation can be
ensured, while the quick balloon inflation response upon the
following balloon inflation can be ensured. That is, the balloon
response can be effectively improved.
[0088] The pressure P3 applied by the first deflation pressure
applying means is designed to set the pressure in the completely
deflated balloon 92 within a range of the pressure P3'. For
example, when the first deflation pressure applying means always
applies a constant pressure to the balloon 92, the pressure applied
to the balloon 92 substantially corresponds to the pressure P3'. On
the other hand, the first deflation pressure applying means applies
a first deflation pressure through a space having a constantly
limited volume to the balloon 92, according to the first embodiment
of the present invention. In this case, the first deflation
pressure itself is increased while passing through the space. That
is, the applied pressure is increased with time. The pressure
immediately after being applied by the first deflation pressure
applying means can be different from the pressure applied to the
balloon approaching to the completely deflated condition. In this
case, the initially applied pressure is lower than the pressure
P3'. In any case, it is preferable that the balloon 92 be applied
with a pressure so as to bring the pressure in the completely
deflated balloon 92 to the pressure P3'.
[0089] The pressure applied by the second deflation pressure
applying means is designed to set the pressure in the balloon 92
within a range of the pressure P4. For example, when the second
deflation pressure applying means always applies a constant
pressure to the balloon 92, the pressure applied to the balloon 92
substantially corresponds to the pressure P4. On the other hand,
the second deflation pressure applying means applies a second
deflation pressure through the space having the constantly limited
volume to the balloon 92, according to the first embodiment of the
present invention. In this case, the second deflation pressure
itself is decreased while passing through the space. That is, the
applied pressure is decreased with time. The pressure immediately
after being applied by the second deflation pressure applying means
can be different from the balloon pressure in a predetermined
period of time. In this case, the initially applied pressure is
higher than the pressure P4. In any case, it is preferable that the
balloon 92 be applied with a pressure so as to bring the pressure
in the balloon 92 to the pressure P4.
[0090] According to the first embodiment of the present invention,
in response to the opening operation of the pressure control valve
52 after accumulating the first inflation pressure P1 in the
isolator 40, the first inflation pressure P1 is applied to the
balloon 92 such that the balloon 92 is inflated. In the elapsed
time T1set after the opening operation of the pressure control
valve 52, the pressure control valve 52 is closed, and the pressure
Pi in the isolator 40 is decreased. When the controller 70
estimates that the balloon 92 has completely inflated, the pressure
control valve 52 is opened again. In this case, the isolator 40
communicates with the balloon 92. However, since the pressure Pi in
the isolator 40 has been decreased, the pressure in the balloon 92
is also decreased. In the elapsed time 72 after the opening
operation of the pressure control valve 52, the pressure control
valve 52 is closed. As described above, according to the first
embodiment of the present invention, the balloon 92 can be applied
with a pressure higher than the minimum pressure required for
inflating the balloon 92 even when the balloon 92 has been
completely inflated. Therefore, the balloon 92 can be inflated at a
further faster inflating speed.
[0091] When the controller 70 estimates that the balloon 92 has
completely inflated, the pressure control valve 52 is opened again.
In this case, the isolator 40 communicates with the balloon 92.
However, since the pressure Pi in the isolator 40 has been
decreased, the pressure in the balloon 92 is also decreased.
Therefore, the pressure differential upon the following deflation
can be decreased, thereby not hindering the following quick
deflation. As described above, according to the first embodiment of
the present invention, the quick inflation response upon the
balloon inflation can be ensured, while the quick balloon deflation
response upon the following balloon deflation can be ensured.
Overall, the balloon inflating/deflating response can be
effectively improved.
[0092] If sufficient pressure for completely inflating the balloon
92 at a predetermined pressure level is supplied to the balloon 92
from the pressure accumulator while the communication between the
isolator 40 and the balloon 92 has been established with the opened
pressure control valve 52, there is no need to keep the
communication between the isolator 40 and the balloon 92. Rather
than keeping the communication therebetween, it is preferable that
the pressure control valve 52 is closed after opening the pressure
control valve 52 for the predetermined elapsed time, and the
pressure in the isolator 40 is decreased while the pressure control
valve 52 is closed. In this case, the balloon can be quickly
applied with the decreased balloon when the pressure control valve
52 is next opened. In light of foregoing, according to the first
embodiment of the present invention, the balloon 92 is first
applied with the first inflation pressure P1 by opening the
pressure control valve 52. When the controller 70 estimates that
the balloon 92 has completely inflated after closing the pressure
control valve 52, the pressure lower than the first inflation
pressure P1 is applied to the balloon 92 by opening the pressure
control valve 52 again. Therefore, the pressure decrease in the
balloon 92 can be smoothly performed. Further, the period for which
the balloon 92 is applied with a relatively high pressure can be
reduced, thereby enabling to improving durability of the balloon
92.
[0093] Further, according to the first embodiment of the present
invention, the time T2 is corrected based upon the pressure being
applied to the balloon 92 after closing the pressure control valve
52. Therefore, the inflation pressure in the balloon 92 can be
accurately maintained.
[0094] According to the first embodiment of the present invention,
in response to the opening operation of the pressure control valve
52 after accumulating the first deflation pressure in the isolator
40, the first deflation pressure is applied to the balloon 92 such
that the balloon 92 is deflated. When the controller 70 estimates
that the balloon 92 has completely deflated, the pressure
accumulated in the isolator 40 is increased. The pressure control
valve 52 is then closed when the pressure in the balloon 92 reaches
the predetermined pressure. As described above, according to the
first embodiment of the present invention, the balloon 92 can be
applied with a pressure lower than the maximum pressure required
for deflating the balloon 92 even when the balloon 92 has
been-completely deflated. Therefore, the balloon 92 can be deflated
at a further faster deflating speed.
[0095] When the controller 70 estimates that the balloon 92 has
completely deflated, the pressure in the balloon 92 is increased.
In this case, the pressure differential upon the following
inflation can be decreased, thereby not hindering the following
quick inflation. As described above, according to the first
embodiment of the present invention, the quick deflation response
upon the balloon deflation can be ensured, while the quick balloon
inflation response upon the following balloon inflation can be
ensured. Overall, the balloon inflating/deflating response can be
effectively improved.
[0096] Next, following explanation will be given for explaining the
balloon pump driving apparatus according to a second embodiment of
the present invention with reference to FIGS. 4, 5, and 6. The
fundamental structure of the balloon pump driving apparatus 10
according to the second embodiment is substantially identical to
the one according to the first embodiment. A major difference
therebetween is that the balloon pump driving apparatus according
to the second embodiment is additionally provided with an auxiliary
reservoir tank communicating with the output conduit 51.
Accordingly, explanation of the identical portions to the first
embodiment of the present invention will be omitted herein, and the
identical portions are denoted with the identical reference
numerals.
[0097] With reference to FIG. 4, a balloon pumping system 200
according to the second embodiment of the present invention
includes the balloon catheter 90 and the balloon pump driving
apparatus 10. The structure of the balloon catheter 90 is
substantially identical to the one according to the first
embodiment of the present invention, so that the explanation
thereof will be omitted herein for simplifying the explanation.
[0098] The balloon pump driving apparatus 10 is provided with the
outer shell of the apparatus housing 11 which houses the oil
reservoir 20, the oil pump 30, and the isolator 40. The respective
structures of the oil reservoir 20, the oil pump 30 and the
isolator 40 are identical to the ones according to the first
embodiment of the present invention, so that the explanation
thereof will be omitted herein for simplifying the explanation.
[0099] In the same manner as the first embodiment of the present
invention, the output chamber 44 communicates with the one end 51a
of the output conduit 55, while the other end 51b of the output
conduit 51 communicates with the output port 12 formed at the
surface of the apparatus housing 11. The output port 12 is
connected to the proximal end 91b of the catheter 91, such that the
balloon catheter 90 communicates with the output conduit 51.
[0100] The pressure control valve 52 is disposed in the output
conduit 51. The structure of the pressure control valve 52 is the
same as the one according to the first embodiment.
[0101] The first pressure sensor 61 is equipped in the output
chamber 44 of the isolator 40 so as to detect the pressure in the
output chamber 44. The second pressure sensor 62 is equipped at the
downstream side of the pressure control valve 52 at the output
conduit 51, i.e., at the side near the balloon catheter 90.
[0102] One ends of first auxiliary conduit (i.e., a first
connecting passage) 112 and second auxiliary conduit 113 are
connected to the output conduit 51, respectively. More
particularly, the communication between the first auxiliary conduit
112 and the output conduit 51 is established at a portion between
the pressure control valve 52 and the output port 12. The
communication between the second auxiliary conduit 113 and the
output conduit 51 is established at a portion between the output
chamber 44 and the pressure control valve 52. The other ends of the
first and second auxiliary conduits 112 and 113 are connected to an
auxiliary reservoir tank 111, respectively. A first auxiliary
switching valve 114 is disposed in the fist auxiliary conduit 112,
while a second auxiliary switching valve 115 is disposed in the
second auxiliary conduit 113. The auxiliary reservoir tank 111 has
been charged with helium gas. The internal pressure in the
auxiliary reservoir tank 111 is detected by a third pressure sensor
63.
[0103] As illustrated in FIG. 4, the balloon pump driving apparatus
10 includes the controller 70. The controller 70 is electrically
connected to the driving means of the oil pump 30, the supply
switching valve 57, the drain switching valve 56, the pressure
control valve 52, the first auxiliary switching valve 114, the
second auxiliary switching valve 115, the first pressure sensor 61,
the second pressure sensor 62, and the third pressure sensor 63.
The controller 70 is further electrically connected to the
biological signal output device 81 and the display-operating panel
82. The biological signal output device 81 outputs the ECG signal
and/or the Aop signal to the controller 70. The controller 70 is
still further connected to the AC/DC adapter 83 connected to the
normal alternator and the battery 84 as the auxiliary power
source.
[0104] The oil chamber 23 of the oil reservoir 20 has been charged
with oil, in the same manner as the first embodiment. That is, the
primary space defined by the oil chamber 23 of the oil reservoir
20, the pumping chamber of the oil pump 30, and the input chamber
43 of the isolator 43 can be charged with the oil. The output
chamber 44 has been charged with helium gas, in the same manner as
the first embodiment.
[0105] Next, the operation of the balloon pumping system 200 will
be explained hereinbelow with reference to FIGS. 5 and 6. As
explained by a timing chart illustrated in FIG. 5, a sequential
line graph denoted with a solid line explains how the pressure Pi
in the output chamber 44 detected by the first pressure sensor 61
transits, while a sequential line graph denoted with a dotted line
explains how the pressure Pb detected by the second pressure sensor
62 transits. The pressure Pb substantially corresponds to the
pressure in the balloon 92. A sequential line graph denoted with a
chain line explains how a pressure Pr in the auxiliary reservoir
tank 111 transits. The balloon pumping system 200 repeats inflation
and deflation of the balloon 92, such that there is no clear
definition of a starting point. Therefore, the following
explanation will be initiated from a point Q in FIG. 5, i.e., from
a condition where the pressure control valve 52, the fist auxiliary
switching valve 114, and the second auxiliary switching valve 115
are closed, the balloon 92 has deflated with the applied pressure
Pb at the second deflation pressure P4, and the pressure in the
auxiliary reservoir tank 111 is set at an auxiliary pressure
P5.
[0106] Under the above-described condition, the oil pump 30 is
driven for rotation in the normal direction as explained at step
S201 in FIG. 5. In response to the normal rotation of the oil pump
30, the oil in the oil reservoir 20 is introduced to the oil pump
30 through the first I/O port 31a. The oil is then drained to the
input chamber 43 of the isolator 40 through the second 110 port
31b. In this case, the isolator diaphragm 42 moves and extends in a
right direction in FIG. 4. In response to the extension of the
isolator diaphragm 42, the volume of the output chamber 44 is
decreased such that the pressure Pi of the output chamber 44 is
detected at an increased pressure value by the first pressure
sensor 61. When the pressure Pi in the output chamber 44 reaches
the first inflation pressure P1, the rotational speed of the oil
pump 30 is slowed down so as not to increase the pressure Pi any
more. The amount of oil discharged from the oil pump 30 to the
isolator 40 can be balanced with the amount of oil flowing back
from the isolator 40 to the oil pump 30. Accordingly, the pressure
Pi in the output chamber 44 can be maintained at the first
inflation pressure P1 (the first inflation pressure control). The
first inflation pressure P1 is far higher than the pressure
required for inflating the balloon 92.
[0107] At step S202, the controller 70 judges the presence or
absence of the inflation signal for the balloon 92 (inflation
judging means). When the controller 70 judges that the inflation
signal has not been outputted, the program returns to step S201.
When the controller 70 judges that the inflation signal has been
outputted, the program proceeds to step S203.
[0108] When the inflation signal is outputted at step S202, the
controller 70 recognizes that the balloon 92 is under the inflating
period, i.e., the balloon 92 is shifting from the deflated
condition to the inflated condition. At step S203, the controller
70 outputs the command signal for opening the pressure control
valve 52 (the inflation-time valve opening control). In response to
the opening operation of the pressure control valve 52, the output
chamber 44 of the isolator 40 communicates with the balloon 92 such
that the first inflation pressure P1 in the output chamber 44 is
applied to the balloon 92. In this case, the pressure Pb is rapidly
increased from the second deflation pressure P4.
[0109] As described above, the output chamber 44 has been charged
with the first inflation pressure P1 higher than the pressure
required for inflating the balloon 92 until the timing immediately
before the pressure control valve 52 is opened. Therefore, once the
pressure control valve 52 is opened, the helium gas in the output
chamber 44 at a blast flows into the balloon 92. Therefore,
according to the second embodiment of the present invention, the
balloon 92 can be inflated much faster than conventional
methods.
[0110] The program then proceeds to step S204 after opening the
pressure control valve 52, at which the controller 70 judges
whether the pressure control valve 52 has opened for the set period
T1set, i.e., judges whether the opening period T1 of the pressure
control valve 52 is substantially equal to or greater than the set
period T1set (the T1 judging control). When the controller 70
judges that the opening period T1 has not reached the set period
T1set, the program returns to step S203. In the meantime, when the
controller 70 judges that the opening period T1 has reached the set
period T1set, the program proceeds to step S205.
[0111] At step S205, the controller 70 closes the pressure control
valve 52 (the inflation-time intermediate valve closing control).
The communication between the output chamber 44 and the balloon 92
is interrupted in response to the closing operation of the pressure
control valve 52. The program then proceeds to step S206.
[0112] At step S206, the controller 70 drives the oil pump 30 for
rotation in the reverse direction. The oil in the input chamber 43
in the isolator 40 is then sucked into the oil pump 30 through the
second I/O port 31b. The oil in the oil pump 30 is then drained
into the oil chamber 23 of the oil reservoir 20 through the first
I/O port 31a. Therefore, the isolator diaphragm 42 then moves in a
left direction in FIG. 4. The volume of the output chamber 44 is
increased corresponding to the movement of the diaphragm 42 such
that the pressure Pi in the output chamber 44 is decreased as
explained in FIG. 5 (the pressure decrease control).
[0113] The pressure change rate (with time) of the pressure value
Pb detected by the second pressure sensor 62 is denoted with the
pressure change rate Pb with time. At step S207, the controller 70
judges whether the pressure change rate Pb is zero or within a
predetermined range .ang.b.
[0114] When the pressure change rate Pb is judged to have not been
substantially equal to zero or to have not been within the range
.ang.b at step S207, the controller 70 judges that the balloon 92
has not been completely inflated yet. Therefore, the program
returns to step S206. When the pressure change rate Pb is judged to
have been substantially equal to zero or to have been within the
range .ang.b at step S207, the program proceeds to step S208.
[0115] As explained in FIG. 5, according to the second embodiment
of the present invention, the pressure change rate Pb becomes
approximately zero during the inflating period. In this case, the
pressure Pb has reached the pressure P1'. The pressure P1' is
higher than the minimum pressure value capable of maintaining the
balloon 92 at the inflated condition, and is lower than the maximum
pressure value capable of maintaining the balloon 92 at the
inflated condition. On the other hand, according to a conventional
balloon pump driving apparatus, the pressure in the balloon is set
around the minimum pressure level capable of maintaining the
balloon under the inflated condition when the balloon is completely
inflated. Comparing the balloon pump driving apparatus 10 with this
type of conventional balloon pump driving apparatus, the balloon 92
can be inflated faster because the balloon 92 has been applied with
the pressure P1' higher than the conventional applied pressure even
when the balloon 92 has completely inflated. It is preferable that
the pressure P1' be set at a pressure value proximate to the
maximum pressure value capable of maintaining the balloon 92 at the
inflated condition. That is, it is preferable that the pressure P1'
be set at a pressure value as high as possible within the allowable
pressure range. By setting the pressure P1' at a relatively high
value as described above, the balloon 92 can be effectively
inflated at a much faster inflating speed.
[0116] When the pressure change rate .DELTA.Pb is judged to have
been substantially equal to zero or to have been within the range
.ang.b at step S207, the program proceeds to step S208, wherein the
auxiliary switching valve 114 is opened (the inflation-time
intermediate valve opening control). In response to the opening
operation of the auxiliary switching valve 114, the communication
between the auxiliary reservoir tank 111 and the balloon 92 is
established. The pressure Pr in the auxiliary reservoir tank 111
has been set at an inflation auxiliary pressure P5 until a timing
immediately before the first auxiliary switching valve 114 is
opened. As explained in FIG. 5, the pressure P5 is lower than the
pressure P1'. Therefore, when the first auxiliary switching valve
114 is opened, the helium gas in the balloon 92 flows into the
auxiliary reservoir tank 111, wherein the pressure Pb applied to
the balloon 92 is quickly decreased.
[0117] The program then proceeds to step S209 after opening the
first auxiliary switching valve 114 at step S208. At step S209, the
controller 70 judges whether the first auxiliary switching valve
114 has opened for the set period T2set, i.e., judges whether the
opening period 12 of the first auxiliary switching valve 114 is
substantially equal to or greater than the set period T2set. When
the controller 70 judges that the opening period T2 has not reached
the set period T2set, the program returns to step S208. When the
controller 70 judges that the opening period T2 has reached the set
period T2set, the program proceeds to step S210.
[0118] At step S210, the controller 70 closes the first auxiliary
switching valve 114 (the inflation-time valve closing control). The
communication between the auxiliary reservoir tank 111 and the
balloon 92 is interrupted in response to the closing operation of
the first auxiliary switching valve 114. The balloon 92 is then
maintained under the inflated condition at the applied pressure
P2'. The program then proceeds to step S211. Through steps S207,
S208, and S209, the pressure Pb applied to the balloon 92 is set at
the pressure P2'. This pressure can be estimated as the pressure in
the balloon 92. Therefore, the balloon 92 is maintained under the
inflated condition at the pressure P2'. It is preferable that the
pressure P2' be set at a value proximate to the minimum pressure
value capable of maintaining the balloon 92 under the inflated
condition. That is, it is preferable that the pressure P2' be set
at a pressure value as low as possible within the allowable
pressure range. By setting the pressure P2' at a low value as
described above, a pressure differential can be minimized when the
balloon 92 is shifted from the inflated condition to the deflated
condition.
[0119] At step S211, the controller 70 opens the second auxiliary
switching valve 115. The communication between the auxiliary
reservoir tank 111 and the output chamber 44 is established. At
this point, the oil pump 30 has rotated in the reverse direction.
Therefore, the pressure Pi in the output chamber 44 has decreased.
Further, the pressure Pi in the output chamber 44 is lower than the
pressure Pr in the auxiliary reservoir tank 111(in this case, the
pressure Pr is the pressure P2'). Therefore, the helium gas in the
auxiliary reservoir tank 111 is sucked into the output chamber 44
in response to the opening operation of the second auxiliary
switching valve 115, wherein the pressure Pr in the auxiliary
reservoir tank 111 is decreased.
[0120] The program then proceeds to step S212 after opening the
second auxiliary switching valve 115. At step S212, the controller
70 judges whether the pressure Pr in the auxiliary reservoir tank
111 has decreased to a predetermined pressure P6. When the
controller 70 judges that the pressure Pr in the auxiliary
reservoir tank 111 has not decreased to the predetermined pressure
P6, the program returns to step S212. On the other hand, when the
controller 70 judges that the pressure Pr in the auxiliary
reservoir tank 111 has decreased to the predetermined pressure P6,
the program proceeds to step S213, at which the second auxiliary
switching valve 115 is closed. In response to the closing operation
of the second auxiliary switching valve 115, the communication
between the auxiliary reservoir tank 111 and the output chamber 44
is interrupted. As described above, the pressure Pr in the
auxiliary reservoir tank 111 is set approximately at the
predetermined pressure P6 (an auxiliary reservoir pressure setting
control). It is preferable to set the pressure Pr approximately at
the predetermined pressure P6 when the pressure Pb in the balloon
92 is set at the second deflation pressure P4 (described
later).
[0121] The oil pump 30 has still rotated in the reverse direction
even after closing the second auxiliary switching valve 115 at step
S210. In this case, the isolator diaphragm 42 has expanded in the
left direction in FIG. 4, wherein the volume of the output chamber
44 is increased. In this case, the pressure Pi in the output
chamber 44 is further decreased down to the first deflation
pressure P3. The rotational speed of the oil pump 30 in the reverse
direction is slowed down to prevent occurrence of a further
pressure decrease in the output chamber 44. The amount of oil
introduced from the isolator 40 to the oil pump 30 is substantially
balanced with the amount of oil flown back to the isolator 40 from
the oil pump 30. Therefore, the pressure Pi in the output chamber
44 can be maintained at the first deflation pressure P3 (the first
deflation pressure control). The first deflation pressure P3 is
designed to be far lower than the pressure required for deflating
the balloon 92.
[0122] At step S214, the controller 70 judges the presence or
absence of the deflation signal of the balloon 92 (the deflation
judging means). In the same manner as the judgment of the presence
of absence of the inflation signal, the controller 70 computes the
timing for deflating the balloon 92, which is appropriate for the
body condition of the patient, based upon the ECG signal and/or the
Aop signal. The controller 70 outputs the deflation signal in
response to the computed timing. When the controller 70 judges that
the deflation signal has not been outputted, the program returns to
step S212. When the controller 70 judges that the deflation signal
has been outputted, the program proceeds to step S215.
[0123] When the deflation signal is outputted at step S214, the
controller 70 recognizes that the balloon 92 is under the deflating
period, i.e., the balloon 92 is shifted from the inflated condition
to the deflated condition. At step S215, the controller 70 outputs
a command signal for opening the pressure control valve 52 (the
deflation-time valve opening control). In response to the opening
operation of the pressure control valve 52, the output chamber 44
of the isolator 40 communicates with the balloon 92. The first
deflation pressure P3 accumulated in the output chamber 44 is then
applied to the balloon 92 so that the pressure Pb in the balloon 92
is suddenly decreased from the second inflation pressure P2'. The
output chamber 44 has been charged with the first inflation
pressure P3 until timing immediately before the opening operation
of the pressure control valve 52. Therefore, in response to the
opening operation of the pressure control valve 52, the helium gas
at a blast flows from the balloon 92 to the output chamber 44.
Therefore, according to the second embodiment of the present
invention, the deflation of the balloon 92 can be performed faster
than the conventional balloon pumping system.
[0124] After opening the pressure control valve 52 at step S215,
the program proceeds to step S216, at which the controller 70
judges whether the pressure change rate Pb of the pressure Pb for
the balloon 92 is substantially zero or within the predetermined
range .ang.b (the complete deflation estimating means). That is,
the controller 70 judges whether the balloon 92 has completely
deflated in the same manner as the first embodiment of the present
invention. When the controller 70 judges at step S216 that the
pressure change rate Pb for the balloon 92 is not substantially
zero or not within the predetermined range .ang.b, the program
returns to step S216. On the other hand, when the controller 70
judges at step S216 that the pressure change rage Pb for the
balloon 92 is substantially zero or within the predetermined rage
.ang.b, the program proceeds to step S217.
[0125] As explained in FIG. 5, according to the second embodiment
of the present invention, the pressure change rate Pb becomes
approximately zero during the deflating period. In this case, the
pressure Pb has reached the pressure P3'. The pressure P3' is lower
than the maximum pressure value capable of maintaining the balloon
92 at the deflated condition, and is higher than the minimum
pressure value capable of maintaining the balloon 92 at the
deflated condition. On the other hand, according to a conventional
balloon pump driving apparatus, the pressure in the balloon is set
around the maximum pressure level capable of maintaining the
balloon under the deflated condition when the balloon is completely
deflated. Comparing the balloon pump driving apparatus 10 with a
conventional balloon pump driving apparatus, the balloon 92 can be
deflated faster because the balloon 92 has been applied with the
pressure P3' lower than the conventional applied pressure even when
the balloon 92 has completely deflated. Therefore, the balloon
deflation can be performed quickly. It is preferable that the
pressure P3' be set at a pressure value proximate to the minimum
pressure value capable of maintaining the balloon 92 at the
deflated condition. By setting the pressure P3' at a relatively low
value as described above, the balloon 92 can be effectively
deflated at a much faster deflating speed.
[0126] When the pressure change rate Pb is judged to have been
substantially equal to zero or to be within the range .ang.b, the
program proceeds to step S217, wherein the first auxiliary
switching valve 114 is opened (the deflation-time intermediate
valve opening control). The communication between the auxiliary
reservoir tank 111 and the balloon 92 is established in response to
the opening operation of the first auxiliary switching valve 114.
The pressure Pr in the auxiliary reservoir tank 111 has been set at
the deflation auxiliary pressure P6 until the timing immediately
before the opening operation of the first auxiliary switching valve
114. As explained in FIG. 5, the pressure P6 is higher than the
pressure P3' of the pressure Pb of the balloon 92. Therefore, when
the first auxiliary switching valve 114 is opened, the helium gas
in the auxiliary reservoir tank 111 flows into the balloon 92,
thereby rapidly increasing the pressure Pb.
[0127] The program then proceeds to step S218 after opening the
first auxiliary switching valve 114 at step S217. At step S218, the
controller 70 judges whether the pressure Pb of the balloon 92 has
reached the pressure P4. When the pressure Pb has not reached the
pressure P4, the program returns to step S217. On the other hand,
when the pressure Pb has reached the pressure P4, the program
proceeds to step S219, wherein the pressure control valve 52 is
closed (the deflation-time valve closing control). In response to
the closing operation of the pressure control valve 52, the
communication between the output chamber 44 and the balloon 92 is
interrupted. Therefore, the pressure Pb of the balloon 92 is
maintained at the pressure P4. As described above, through steps
S217, S218, and S219, the pressure Pb is set at the pressure P4
while the balloon 92 is deflating. This pressure can be estimated
as a pressure in the balloon 92 at this moment. Therefore, the
balloon 92 can be maintained under the deflated condition at the
pressure P4. It is preferable that the pressure P4 be set proximate
to the maximum pressure capable of maintaining the balloon 92 under
the deflated condition. By setting the pressure P4 at a relatively
high pressure as described above, the pressure differential can be
minimized when the balloon 92 is shifted from the deflated
condition to the inflated condition.
[0128] The first auxiliary switching valve 114 is closed at step
S220 substantially at the same time when the pressure control valve
52 is closed at step S219 or after the closing operation at step
S219. The communication between the balloon 92 and the auxiliary
reservoir tank 111 is hence interrupted. The program then proceeds
to step S221.
[0129] At step S221, the oil pump 30 is driven for rotation in the
normal direction. The oil in the oil reservoir 20 is suck into the
oil pump 30. The oil in the oil pump 30 is drained to the input
chamber 43 of the isolator 30. In this case, the isolator diaphragm
42 expands in the right direction in FIG. 4. In response to the
movement of the isolator diaphragm 42, the volume of the output
chamber 44 is decreased, wherein the pressure Pi in the output
chamber 44 is increased (the pressure increase control).
[0130] The program then proceeds to step S222 from step S221. At
step S222, the second auxiliary switching valve 115 is opened. In
response to the opening operation of the second auxiliary switching
vale 115, the communication between the auxiliary reservoir tank
111 and the output chamber 44 of the isolator 40 can be
established. Since the oil pump 30 is driven for rotation in the
normal direction at step S221, the volume of the output chamber 44
is decreased, wherein the pressure Pi in the output chamber 44 is
increased. Therefore, when the communication between the output
chamber 44 and the auxiliary reservoir tank 111 is established, the
pressure Pr in the auxiliary reservoir tank 111 is increased in
response to the increase of the pressure Pi in the output chamber
44.
[0131] The program then proceeds to step S223 from step S222. At
step S223, the controller 70 judges whether the pressure in the
auxiliary reservoir tank 11 has reached the predetermined pressure
P5. When the pressure Pr has not reached the predetermined pressure
P5 yet, the program then returns to step S222. On the other hand,
when the pressure Pr has reached the predetermined pressure P5, the
program proceeds to step S224. At step S224, the second auxiliary
switching valve 115 is closed (inflation-time auxiliary reservoir
pressure setting terminate control). In response to the closing
operation of the second auxiliary switching valve 115, the
communication between the auxiliary reservoir tank 111 and the
output chamber 44 is interrupted.
[0132] Through steps S222, S223, and S224, the pressure Pr in the
auxiliary reservoir tank 111 reaches the predetermined pressure P5
(auxiliary reservoir pressure setting control). It is necessary to
maintain the pressure Pr in the auxiliary reservoir tank 111 at the
pressure P5 in order to bring the pressure Pb in the balloon 92 to
the second inflation pressure P2. The program then returns to step
S202. By repeatedly performing the above-described steps, the
balloon 92 can be inflated and deflated at a predetermined
timing.
[0133] As described above, the balloon pumping method of inflating
and deflating the balloon 92 according to the second embodiment of
the present invention includes the step of setting the pressure Pb
in the balloon 92 at the pressure P1', which is higher than the
minimum pressure value and substantially equal to or lower than the
maximum pressure value, when the balloon 92 is shifted from the
deflated condition to the inflated condition. The balloon 92 can be
maintained under the inflated condition when the pressure in the
balloon 92 is between the minimum pressure value and the maximum
pressure value. The balloon pumping method further includes the
step of setting the pressure Pb in the balloon 92 at the pressure
P2', which is substantially equal to or higher than the minimum
pressure value and lower than the pressure P1', when the balloon 92
is estimated to have completely inflated at the pressure P1'. By
performing the above-described steps, the balloon 92 can be
completely inflated at the pressure P1' which is higher than the
minimum pressure at which the balloon 92 is maintained at the
inflated condition. Therefore, the inflation of the balloon 92 can
be quickly performed. The pressure Pb in the balloon 92 is reduced
to the pressure P2' when the balloon 92 is estimated to have
completely inflated at the pressure P1'. The pressure P2' is
substantially equal to or higher than the minimum pressure and is
lower than the pressure P1'. Accordingly, the pressure differential
upon deflating the balloon 92 can be decreased, wherein the balloon
deflation can be performed quickly. Therefore, according to the
second embodiment of the present invention, much faster inflation
response can be assured upon the balloon inflation, while quick
deflation response can be assured for the next balloon deflation.
Overall, the balloon response can be effectively improved.
[0134] The balloon pumping method of inflating and deflating the
balloon 92 includes the step of setting the pressure in the balloon
92 at the pressure P3', which is lower than the maximum pressure
value and is substantially equal to or higher than the minimum
pressure value, when the balloon 92 is shifted from the inflated
condition to the deflated condition. The balloon pumping method
further includes the step of setting the pressure in the balloon 92
at the pressure P4, which is substantially equal to or lower than
the maximum pressure value and higher than the pressure P3', when
the balloon 92 is estimated to have completely deflated at the
pressure value P3'. By performing the above-described steps, the
balloon 92 can be completely deflated at the pressure P3' which is
lower than the maximum pressure value at which the balloon 92 is
maintained under the deflated condition. Therefore, the deflation
of the balloon 92 can be quickly performed. By performing the
above-described steps, the balloon 92 can be completely deflated at
the pressure P3' which is lower than the maximum pressure.
Therefore, the deflation of the balloon 92 can be quickly
performed. The pressure Pb in the balloon 92 is increased to the
pressure P4 when the balloon 92 is estimated to have completely
deflated at the pressure P3'. The pressure P4 is substantially
equal to or lower than the maximum pressure and is higher than the
pressure P3'. Accordingly, the pressure differential upon inflating
the balloon 92 can be decreased, wherein the balloon deflation can
be performed quickly. Therefore, according to the second embodiment
of the present invention, much faster deflation response can be
assured upon the balloon deflation, while quick inflation response
can be assured for the next balloon inflation. Overall, the balloon
response can be effectively improved.
[0135] The balloon pump driving apparatus 10 according to the
second embodiment of the present invention includes the inflation
judging means (step S202) for judging whether the balloon 92 is
required to be inflated based upon the inputted bio signal, the
first inflation pressure applying means (step S203, the isolator
40, the pressure control valve 52) for applying the first inflation
pressure to the balloon 92, which is higher than the minimum
pressure at which the balloon 92 can be maintained at the inflated
condition, when the inflation judging means judges that it is
necessary to inflate the balloon 92, the complete inflation
estimating means (step S207) for estimating whether the balloon 92
has completely inflated by applying the first inflation pressure to
the balloon 92 by the first inflation pressure applying means, and
second inflation pressure applying means (step S208, the isolator
40, the first auxiliary switching valve 114) for decreasing the
pressure Pb in the balloon 92 by applying the second inflation
pressure to the balloon 92 when the completely inflation estimating
means estimates that the balloon 92 has completely inflated. In
this case, the second inflation pressure should be substantially
equal to and higher the minimum pressure and is lower than the
first inflation pressure applied by the first inflation pressure
applying means. Therefore, the quick inflation response can be
assured upon the balloon inflation, while the quick deflation
response can be assured for the next deflation, thereby enabling to
improve the balloon pressure response.
[0136] The balloon pump driving apparatus 10 according to the
second embodiment of the present invention includes the deflation
judging means (step S214) for judging whether it is necessary to
deflate the balloon 92 based upon the inputted bio signal, the
first deflation pressure applying means (step S215, the isolator
40, the pressure control valve 52) for applying the first deflation
pressure to the balloon 92, which is lower than the maximum
pressure at which the balloon 92 can be maintained at the deflated
condition, when the deflation judging means judges that it is
necessary to deflate the balloon 92, the complete deflation
estimating means (step S216) for estimating whether the balloon 92
has completely deflated by applying the pressure to the balloon 92
by the first deflation pressure applying means, and the second
deflation pressure applying means (step S217, the isolator 40, the
first auxiliary switching valve 114) for increasing the pressure Pb
in the balloon 92 by applying the second deflation pressure to the
balloon 92 when the completely deflation estimating means estimates
that the balloon 92 has completely deflated. In this case, the
second deflation pressure should be substantially equal to and
lower than the maximum pressure and is higher than the first
deflation pressure applied by the first deflation pressure applying
means. Therefore, the quick deflation response can be assured upon
the balloon inflation, while the quick inflation response can be
assured for the next inflation, thereby enabling to improve the
balloon pressure response.
[0137] According to the second embodiment of the present invention,
in response to the opening operation of the pressure control valve
52 after accumulating the first inflation pressure P1 in the
isolator 40, the first inflation pressure P1 is applied to the
balloon 92 such that the balloon 92 is inflated. In the elapsed
time T1set after the opening operation of the pressure control
valve 52, the pressure control valve 52 is closed. The controller
70 then judges whether the balloon 92 has completely inflated. When
the controller 70 judges that the balloon 92 has completely
inflated, the communication between the auxiliary reservoir tank
111 and the balloon 92 is established by opening the first
auxiliary switching valve 114. Although the communication between
the auxiliary reservoir tank 111 and the balloon 92 is established,
the pressure Pr in the auxiliary reservoir tank 111 has been set at
the predetermined second inflation pressure P5. Therefore, the
pressure Pb in the balloon 92 is, decreased by applying the second
inflation pressure P5 to the balloon 92. The pressure control valve
52 is then closed in the elapsed time T2. As described above,
according to the second embodiment of the present invention, the
balloon 92 can be applied with a pressure higher than the minimum
pressure required for inflating the balloon 92 even when the
balloon 92 has been completely inflated. Therefore, the balloon 92
can be inflated at a further faster inflating speed.
[0138] When the controller 70 estimates that the balloon 92 has
completely inflated, the pressure in the balloon 92 is decreased by
applying the second inflation pressure to the balloon 92.
Therefore, the pressure differential upon the following deflation
can be decreased, thereby not hindering the following quick
deflation. As described above, according to the second embodiment
of the present invention' the quick inflation response upon the
balloon inflation can be ensured, while the quick balloon deflation
response upon the following balloon deflation can be ensured.
Overall, the balloon inflating/deflating response can be
effectively improved. Further, the pressure Pr in the auxiliary
reservoir tank 111 is set or adjusted at a predetermined pressure
level by the auxiliary reservoir pressure setting control.
Therefore, the auxiliary reservoir tank 11 can be employed as a
pressure supplying source for supplying a predetermined pressure
level to the balloon 92.
[0139] During the balloon inflation step, the second auxiliary
switching valve 115 is opened after closing the first auxiliary
switching valve 114 (step S210), wherein the communication between
the auxiliary reservoir tank 111 and the isolator 40 is
established. Therefore, the pressure Pr in the auxiliary reservoir
tank 111 is set at the predetermined pressure P6 for the balloon
deflation step (steps S211, S212, S213). Further, during the
balloon deflation step, the second auxiliary switching valve 115 is
opened (step S222) after closing the first auxiliary switching
valve 114 (step S220), wherein the communication between the
auxiliary reservoir tank 111 and the isolator 44 is established.
Therefore, the pressure Pr in the auxiliary reservoir tank 111 can
be set at the predetermined pressure P5 for the balloon inflation
step (steps S222, S223, S224). That is, while the inflation step
has been performed, the pressure Pr in the auxiliary reservoir tank
111 is set at the pressure P6 for the balloon deflation. While the
deflation step has been performed, the pressure Pr in the auxiliary
reservoir tank 111 is set at the pressure P5 for the balloon
inflation. As described above, according to the second embodiment
of the present invention, the pressure in the auxiliary reservoir
tank 111 can be adjusted through the balloon pumping system 200.
Therefore, there is no need to additionally provide an apparatus
for adjusting the pressure Pr in the auxiliary reservoir tank 111,
thereby enabling to downsize the system.
[0140] Further, according to the second embodiment of the present
invention, the pressure supply can be performed through a system
having the isolator 40 and the other system having the auxiliary
reservoir tank 111. Therefore, the balloon pumping system 200 can
effectively function even when extra systole or premature beat is
caused due to abnormal cardiac rhythms. For example, if a signal
for the extra systole interrupts when the balloon 92 has inflated
with the pressure control valve 52 opened at step S203 illustrated
in FIG. 6, the pressure control valve 52 is closed, and the second
auxiliary switching valve 114 is opened, wherein the communication
between the balloon 92 and the auxiliary reservoir tank 111 is
established. Therefore, the balloon inflation can be restrained, or
the operation by the system 200 can be shifted from the inflation
operation to the deflation operation. Then balloon 92 can be then
deflated at much faster deflating speed than the normal deflating
speed.
[0141] According to the second embodiment of the present invention,
in response to the opening operation of the pressure control valve
52 after accumulating the first deflation pressure P3 in the
isolator 40, the first deflation pressure P3 is applied to the
balloon 92, wherein the balloon 92 is deflated. The controller 70
then estimates whether the balloon 92 has completely deflated. When
the controller 70 estimates that the balloon 92 has completely
deflated, the communication between the auxiliary reservoir tank
111 and the balloon 92 is established by opening the fist auxiliary
switching valve 114. In this case, although the communication
between the auxiliary reservoir tank 111 and the balloon 92 is
established, the pressure Pr in the auxiliary reservoir tank 111
has been set at the predetermined second deflation pressure P6. The
balloon 92 is applied with the second deflation pressure P6 so that
the pressure in the balloon 92 is increased. The pressure control
valve 52 is then closed in a predetermined elapsed time. As
described above, according to the second embodiment of the present
invention, the balloon 92 is applied with a pressure lower than the
maximum pressure required for deflating the balloon 92 even when
the balloon 92 has been completely deflated. Therefore, the balloon
92 can be deflated at a further faster deflating speed.
[0142] Further, when the controller 70 judges that the balloon 92
has completely inflated, the pressure differential upon the next
inflation can be reduced by decreasing the pressure Pb in the
balloon 92 by applying the second deflation pressure to the balloon
92, thereby not hindering the quick inflation upon the next
inflation timing. Therefore, the much faster deflation can be
assured, and the quick inflation response is not hindered, thereby
enabling to improve the balloon pressure response.
[0143] Next, following explanation will be given for explaining the
balloon pump driving apparatus according to a third embodiment of
the present invention. The structure of the balloon pump driving
system according to the third embodiment is substantially identical
to the structure illustrated in FIG. 4, so that the explanation of
the structure will be omitted herein.
[0144] The method of pumping the balloon is briefly described
hereinbelow. In order to inflate the balloon 92, the pressure in
the isolator 40 and the switching operation of the pressure control
valve 52 are controlled. In order to deflate the balloon 92, the
pressure in the isolator 40 and the auxiliary reservoir tank 111,
and the switching operations of the pressure control valve 52 and
the first auxiliary switching vale 114 are controlled At the point
Q in FIG. 7, the oil pump 30 is driven for rotation in the normal
rotational direction with the closed pressure control valve 52
(step S301). Therefore, the pressure Pi in the output chamber 44 is
increased, so that the pressure Pi is increased up to the first
inflation pressure P1. The controller 70 judges the presence or
absence of the inflation signal for the balloon 92 (step S302).
When the inflation signal is detected, the pressure control valve
52 is opened (step S303). The communication between the output
chamber 44 and the balloon 92 is established in response to the
opening operation of the pressure control valve 52, wherein the
balloon 92 is applied with the first inflation pressure P1 so that
the balloon 92 is inflated.
[0145] The controller 70 then judges whether the opening period T1
of the pressure control valve 52 reached the set period T1set (step
S304). The controller 70 closes the pressure control valve 52 (step
S305). The oil pump 30 is driven for rotation in the reverse
direction (step S306), wherein the pressure in the output chamber
44 is decreased. Although the balloon 92 has not completely
inflated yet when the pressure control valve 52 is closed, the
balloon 92 is inflated as time goes and is completely inflated
eventually. When the balloon 92 approaches the completely inflated
condition, the amount of helium gas to flow to the balloon 92 is
gradually decreased, and the pressure Pb in the balloon 92 becomes
a constant pressure value. The controller 70 judges whether the
balloon 92 has completely inflated based upon the pressure change
rate Pb with time (step S307). As explained in FIG. 7, the pressure
Pb becomes approximately constant at the pressure P1'. The pressure
P1' is higher than the pressure value at which the balloon 92 is
generally inflated. According to the third embodiment of the
present invention, the balloon 92 is inflated at the pressure P2'.
As described above, the balloon 92 has been applied with the
pressure higher than the conventional pressure level even when the
balloon 92 is completely inflated. Therefore, the balloon 92 can be
quickly inflated. The pressure control valve 52 is opened again
when the balloon 92 is estimated to have completely inflated (step
S308).
[0146] When the pressure control valve 52 is opened again, the
pressure Pi in the output chamber 44 is decreased and becomes lower
than the pressure P2. In response to the opening operation of the
pressure control valve 52, the helium gas is introduced from the
balloon 92 to the output chamber 44, wherein the applied pressure
Pb to the balloon 92 is decreased. The controller 70 then judges
that the opening period T2 has reached the set period T2set (step
S309). The pressure control valve 52 is then closed in the set
period T2set (step S310). Therefore, the pressure Pb in the balloon
92 can be maintained at the pressure P2', wherein the balloon 92
can be inflated at this pressure level.
[0147] Upon the inflation of the balloon 92, the balloon 92 has
been initially applied with the pressure P1 that is relatively
high. Therefore, the balloon, 92 can be inflated at a high
inflating speed. When the balloon 92 is shifted to the completely
inflated condition, the pressure Pb of the balloon 92 is decreased
down to the pressure P2'. Therefore, the time for applying the high
pressure to the balloon 92 is decreased, wherein the durability of
the balloon 92 can be improved. Further, the pressure differential
of the balloon internal pressure can be decreased when the balloon
92 is next deflated, thereby enabling to improve the balloon
deflation response for the next deflation.
[0148] The controller 70 judges at step S311 whether the absolute
pressure value P is within the predetermined range .ang.. The set
period T2set is corrected based upon the judgment result at step
S311 (step S312). The controller then judges the presence or
absence of the deflation signal (step S313). When the deflation
signal is detected at step S313, the first auxiliary switching
valve 114 is opened (step S314). In response to the opening
operation of the first auxiliary switching valve 114, the
communication between the auxiliary reservoir tank 111 and the
balloon 92 is established. The auxiliary reservoir tank 111 has
been set at the pressure P5. The pressure P5 is lower than the
pressure P2' applied to the balloon 92 immediately before opening
the first auxiliary switching valve 114 at step S314. Therefore,
the helium gas is introduced from the balloon 92 to the auxiliary
reservoir tank 111, wherein the pressure Pb applied to the balloon
92 is decreased.
[0149] The controller 70 judges whether an opening period T3 has
reached a set period T3set after opening the first auxiliary
switching valve 114 (step S315). When the opening period T3 has
reached the set period T3set, the first auxiliary switching valve
114 is closed (step S316). Through steps S315 and S316, the
pressure Pr in the auxiliary reservoir tank 111 is set at a
predetermined pressure P6. The pressure control valve 52 is then
opened (step S317). In this case, the communication between the
output chamber 44 and the balloon 92 is established. The pressure
Pi in the output chamber 44 is decreased in response to the reserve
rotation of the oil pump 30 immediately before opening the pressure
control valve 52 at step S317. The pressure Pi in the output
chamber 44 is hence maintained at the first deflation pressure P3
that is lower than the normal deflation pressure. Therefore, in
response to the opening operation of the pressure control valve 52
at step S317, the helium gas in the balloon 92 is introduced to the
output chamber 44, wherein the pressure Pb applied to the balloon
92 is rapidly decreased. The balloon 92 has not completely deflated
yet immediately after opening the pressure control valve 52. As
time goes, the balloon 92 is deflated and is completely deflated
eventually. When the balloon 92 approaches the completely deflated
condition, the amount of helium gas flowing from the balloon 92 is
reduced. Therefore, the pressure Pb is maintained at a constant
pressure level. The controller 70 then judges the balloon 92 has
completely deflated based upon the pressure change rate Pb with
time (step S318). As explained in FIG. 7, the pressure Pb becomes
approximately constant at the pressure P3'. The pressure P3' is
greater than the pressure at which the balloon 92 is generally
deflated. According to the third embodiment of the present
invention, the pressure, at which the balloon 92 is generally
deflated, is the pressure P4. As described above, the balloon 92
has been applied with the pressure lower than the conventional
applied pressure even when the balloon 92 has completely deflated.
Therefore, the balloon 92 can be quickly deflated. The second
auxiliary switching valve 115 is opened when the balloon 92 is
estimated to have completely deflated (step S319). Therefore, the
communication between the auxiliary reservoir tank 111 and the
output chamber 44 is established.
[0150] The controller 70 judges whether the pressure Pb has reached
the predetermined pressure P5 (step S320). When the pressure Pb is
judged to have reached the predetermined pressure P5, the second
auxiliary switching valve 115 is closed (step S321). Therefore, the
communication between the auxiliary reservoir tank 111 and the
output chamber 44 is interrupted, wherein the pressure Pr in the
auxiliary reservoir tank 111 is set at the predetermined pressure
P5.
[0151] The oil pump 30 is driven for rotation in the normal
direction after closing the second auxiliary switching valve 115
(step S322). The diaphragm spring in the isolator 40 is moved so
that the pressure in the output chamber 44 can be increased. In
this case, the pressure control valve 52 has been opened.
Therefore, the pressure Pb applied to the balloon 92 is increased
in response to the pressure increase in the output chamber 44. The
controller 70 then judges whether the pressure Pb has reached the
second inflation pressure P4 (step S323). When the pressure Pb is
judged to have reached the second inflation pressure P4, the
pressure control valve 52 is closed (step S324). The program then
returns to step S302.
[0152] As described above, upon deflation of the balloon 92, the
communication between the auxiliary reservoir tank 111 and the
balloon 92 is established, wherein the pressure Pb in the balloon
92 is first decreased. Next, the balloon 92 is applied with the
pressure P3 which is much lower, wherein the pressure Pb in the
balloon 92 is decreased. Therefore, the balloon 92 can be quickly
deflated. Further, in response to the communication between the
auxiliary reservoir tank 111 and the output chamber 44, the helium
gas in the auxiliary reservoir tank 111 is drawn back to the output
chamber 44, wherein the pressure Pr in the auxiliary reservoir tank
111 can be brought back to the pressure required for the next
deflation. Further, the pressure Pb in the balloon 92 can be
maintained at the pressure P4 that is the second deflation
pressure, wherein the balloon 92 can be prepared for the next
inflation.
[0153] Further, the second auxiliary switching valve 115
communicates between the auxiliary reservoir tank 111 and the
isolator 40. Therefore, the pressure Pr in the auxiliary reservoir
tank 111 is set or adjusted at the predetermined pressure by
opening/closing the second auxiliary switching valve 115 at a
predetermined timing, or the pressure Pr the auxiliary reservoir
tank 111 can be adjusted.
[0154] Next, following explanation will be given for explaining the
balloon pump driving apparatus according to a fourth embodiment of
the present invention. The structure of the balloon pump driving
apparatus is illustrated in FIG. 9. The structure thereof is
similar to the system illustrated in FIG. 4. However, according to
the fourth embodiment, there is not the conduit connecting the
auxiliary reservoir tank 111 and the output chamber provided.
Further, there is not the second auxiliary switching valve 115. The
other structure of the balloon pump driving apparatus according to
the fourth embodiment is substantially identical to the one
according to the third embodiment, so that the detailed explanation
will be omitted herein.
[0155] In the same manner as the second embodiment of the present
invention, when the balloon 92 is inflated, the relatively high
pressure is initially applied to the balloon 92 and is decreased by
use of the auxiliary reservoir tank 111. When the balloon 92 is
deflated, the relatively low pressure is initially applied to the
balloon 92 and is increased by use of the auxiliary reservoir tank
111. However, according to the fourth embodiment of the present
invention, the pressure in the auxiliary reservoir tank 111 to be
applied to the inflating balloon 92 is set to be substantially
equal to the deflation pressure of the balloon 92. Further, the
pressure in the auxiliary reservoir tank 111 to be applied to the
deflating balloon 92 is set to be substantially equal to the
inflation pressure of the balloon 92. Therefore, the step for
adjusting the pressure Pr in the auxiliary reservoir tank 111 can
be omitted
[0156] At the point Q in FIG. 10, the oil pump 30 is driven for
rotation in the normal rotational direction with the closed
pressure control valve 52 (step S401). Therefore, the pressure Pi
in the output chamber 44 is increased, so that the pressure Pi is
increased up to the first inflation pressure P1. The controller 70
judges the presence or absence of the inflation signal for the
balloon 92 (step S402). When the inflation signal is detected, the
pressure control valve 52 is opened (step S403). The communication
between the output chamber 44 and the balloon 92 is established in
response to the opening operation of the pressure control valve 52,
wherein the balloon 92 is applied with the first inflation pressure
P1 so that the balloon 92 is inflated.
[0157] The controller 70 then judges whether the opening period T1
of the pressure control valve 52 reached the set period T1set (step
S404). The controller 70 closes the pressure control valve 52 in
the period T1set (step S405). The oil pump 30 is driven for
rotation in the reverse direction (step S406), wherein the pressure
in the output chamber 44 is decreased. Although the balloon 92 has
not completely inflated yet when the pressure control valve 52 is
closed, the balloon 92 is inflated as time goes and is completely
inflated eventually. When the balloon 92 approaches the completely
inflated condition, the amount of helium gas to flow to the balloon
92 is gradually decreased, and the pressure Pb in the balloon 92
becomes a constant pressure value. The controller 70 judges whether
the balloon 92 has completely inflated based upon the pressure
change rate Pb with time (step S407). As explained in FIG. 10, the
pressure Pb becomes approximately constant at the pressure P1'. The
pressure P1' is generally higher than the pressure value at which
the balloon 92 is generally inflated. According to the fourth
embodiment of the present invention, the balloon 92 is inflated at
the pressure P2'. As described above, the balloon 92 has been
applied with the pressure higher than the conventional pressure
level even when the balloon 92 has completely inflated. Therefore,
the balloon 92 can be quickly inflated. The first auxiliary
switching valve 114 is opened when the balloon 92 is estimated to
have completely inflated (step S408).
[0158] When the first auxiliary switching valve 114 is opened (step
S408), the communication between the auxiliary reservoir tank 111
and the balloon 92 is established. The pressure in the auxiliary
reservoir tank 111 has been set at the pressure P4 until a timing
immediately before the opening operation of the first auxiliary
switching valve 114 at step S408. The pressure P4 is substantially
equal to the second deflation pressure P4 that is described later.
The pressure P4 is lower than the current pressure Pb in the
balloon 92. Therefore, in response to the opening operation of the
first auxiliary switching valve 114, the helium gas is introduced
from the balloon 92 to the auxiliary reservoir tank 111. Therefore,
the pressure Pb applied to the balloon 92 is rapidly decreased. The
controller 70 then judges whether the pressure Pb has reached the
second inflation pressure P2' (step S409). When the pressure Pb is
judged to have reached the second inflation pressure P', the first
auxiliary switching valve 114 is closed (step S410). Therefore, the
pressure Pb in the balloon 92 can be maintained at the pressure
P2', and the inflation of the balloon 92 can be continued at the
pressure P2'. Further, the pressure Pr in the auxiliary reservoir
tank 111 is set at the pressure
[0159] As described above, when the balloon 92 is inflated, the
balloon 92 is initially applied with the pressure P1 that is high.
Therefore, the balloon 92 can be quickly inflated. Further, the
pressure Pb of the balloon 92 is decreased down to the pressure P2'
when the balloon 92 is completely inflated. Therefore, the time for
applying the high pressure to the balloon 92 can be shortened,
wherein the durability of the balloon 92 can be extended Further,
the pressure differential in the balloon 92 can be reduced when the
balloon 92 is next deflated, thereby enabling to improve the
deflation response for the next balloon deflation.
[0160] After closing the first auxiliary switching valve 114 at
step S410, the controller 70 judges whether the inflation signal
has been detected (step S411). When the inflation signal has been
detected, the pressure control valve 52 is opened (step S412),
wherein the communication between the balloon 92 and the output
chamber 44 is established. The pressure Pi in the output chamber 44
has been sufficiently decreased in response to the reverse rotation
of the oil pump 30 until timing before the opening operation of the
first auxiliary switching valve 114 at step S411. Further, the
pressure Pi in the output chamber 44 is brought down to the first
deflation pressure P3 that is sufficiently low; Therefore, in
response to the opening operation of the pressure control valve 52,
the helium gas is introduced from the balloon 92 to the output
chamber 44. Therefore, the pressure Pb of the balloon 92 is
decreased.
[0161] The controller 70 judges whether the pressure change rate Pb
of the pressure Pb for the balloon 92 is within the predetermined
range .ang.b (step S413). Therefore, the controller 70 can judge
whether the balloon 92 has completely deflated. When the controller
70 judges that the balloon has completely deflated, the first
auxiliary switching valve 114 is opened (step S414), wherein the
communication between the auxiliary reservoir tank 111 and the
balloon 92 is established. The pressure Pr in the auxiliary
reservoir tank 111 has been set at the pressure P2' until a timing
immediately before the opening operation of the first auxiliary
switching valve 114. The pressure P2' is substantially equal to the
second inflation pressure P2'. The pressure P2' is higher than the
pressure Pb of the balloon 92. Therefore, in response to the
opening operation of the first auxiliary switching valve 114, the
helium gas flows from the auxiliary reservoir tank 111 to the
balloon 92, wherein the pressure Pb to be applied to the balloon 92
is rapidly increased. The controller 70 then judges whether the
pressure Pb has reached the second inflation pressure P4 (step
S415). When the controller 70 judges that the pressure Pb has
reached the second inflation pressure P4, the pressure control
valve 52 is closed (step S416). Further, the first auxiliary
switching valve 114 is closed (step S417). Therefore, the pressure
Pb of the balloon 92 can be maintained at the pressure P4, and the
balloon 92 can be continuously inflated at the pressure P4.
Further, the pressure Pr of the auxiliary reservoir tank 111 is set
at the pressure P4. The oil pump 30 is driven for rotation in the
normal direction (step S418). The program then returns to step
S402.
[0162] As described above, when the balloon 92 is inflated, the
balloon 92 is initially applied with the pressure P1 that is high.
Therefore, the balloon 92 can be quickly inflated. Further, the
pressure Pb of the balloon 92 is reduced down to the pressure P1'
when the balloon 92 is shifted to the completely inflated
condition. Therefore, the time for applying the balloon 92 with the
high pressure can be reduced, thereby enabling to extend the
durability of the balloon 92. Further, the pressure differential in
the balloon 92 can be decreased for the next deflation, thereby
enabling to improve the balloon deflation response for the next
balloon deflation. Further, according to the fourth embodiment of
the present invention, the second auxiliary switching valve 115 is
not provided. Therefore, the pressure Pb and Pr are adjusted only
by use of the first auxiliary switching valve 114. Therefore, the
size of the balloon pump driving apparatus can be reduced.
[0163] The principles, embodiments and modes of operation of the
present invention have been described in the foregoing
specification and drawings. However, the invention which is
intended to be protected is not to be construed as limited to the
particular embodiments disclosed. Further, the embodiments
described herein are to be regarded as illustrative rather than
restrictive. Plural objectives are achieved by the present
invention, and yet there is usefulness in the present invention as
far as one of the objectives are achieved Variations and changes
may be made by others, and equivalents employed, without departing
from the spirit of the present invention. Accordingly, it is
expressly intended that all such variations, changes and
equivalents which fall within the spirit and scope of the present
invention as defined in the claims, be embraced thereby.
* * * * *