U.S. patent number 3,799,702 [Application Number 05/306,937] was granted by the patent office on 1974-03-26 for apparatus for draining blood from a surgical wound and transmission to a heart-lung machine.
Invention is credited to Egon Georg Weishaar.
United States Patent |
3,799,702 |
Weishaar |
March 26, 1974 |
APPARATUS FOR DRAINING BLOOD FROM A SURGICAL WOUND AND TRANSMISSION
TO A HEART-LUNG MACHINE
Abstract
A pressure sensor is connected to the suction tube of an
apparatus for draining blood from a wound and supplying it to a
heart-lung machine. Means, which may be either a separate pump or
the pump connected to the tube for pumping blood, forms an
underpressure generator. The pressure sensor is responsive to a
first underpressure in the tube for increasing the pumping action
of the suction pump motor, and to ambient pressure for decreasing
the pumping action of the pump motor. The sensor may also be
responsive to a greater underpressure for stopping or reversing the
motor.
Inventors: |
Weishaar; Egon Georg (Munich,
DT) |
Family
ID: |
5799681 |
Appl.
No.: |
05/306,937 |
Filed: |
November 15, 1972 |
Current U.S.
Class: |
417/38; 604/153;
604/118; 417/477.1 |
Current CPC
Class: |
F04B
49/08 (20130101); F04B 43/1292 (20130101); A61M
1/74 (20210501); F04B 49/022 (20130101); A61M
1/75 (20210501) |
Current International
Class: |
A61M
1/00 (20060101); F04B 43/12 (20060101); F04B
49/02 (20060101); F04B 49/08 (20060101); F04b
049/00 (); A61m 001/00 (); F04b 043/12 () |
Field of
Search: |
;128/276-278,297-300,35V,230 ;417/38,36,44,45,325,326,477 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Croyle; Carlton R.
Assistant Examiner: Ward; Arnold
Attorney, Agent or Firm: Fasse; Wolfgang G.
Claims
What is claimed is:
1. An apparatus for draining blood from a surgical wound and
transporting this blood to a heart-lung machine by means of a
suction tube connected to a suction pump; said apparatus comprising
weakly acting underpressure generator means, a pressure sensor,
means for connecting said suction tube to said underpressure
generator means and to said pressure sensor, means for connecting
said pressure sensor to said pump for controlling the latter, said
pressure sensor being further responsive to a predetermined first
underpressure threshold value due to a rise of the blood level
above the mouth of the tube for gradually starting up the suction
pump, said pressure sensor being responsive to a second higher
underpressure value for turning off the suction pump and
transmitting atmospheric pressure to the suction tube, said
pressure sensor being further responsive to the disappearance of
the underpressure due to the blood level dropping below the suction
tube mouth for shutting the pump off.
2. The apparatus according to claim 1, wherein said underpressure
generator means comprises said suction pump, being automatically
set to low operating mode of operation.
3. The apparatus according to claim 1, comprising a valve for
connecting said suction tube to ambient, atmospheric pressure and
means for connecting said valve to said pressure sensor for opening
the valve in response to the occurence in said tube of a second
underpressure value.
4. The apparatus according to claim 1, comprising means for
reversing said suction pump whereby it starts gradually to produce
temporarily positive instead of negative pressure and whereby
atmospheric pressure is supplied to said suction tube.
5. In an apparatus for draining blood from a wound and supplying it
to a heart-lung machine, wherein the apparatus includes a suction
tube, a pump connected to the suction tube, and a motor connected
to operate the pump, the improvement comprising pressure sensing
means connected to sense pressure in said tube for controlling said
motor, said pressure sensor being responsive to a first
underpressure for controlling said motor to increase the pumping
action of said pump, said pressure sensor further being responsive
to ambient pressure for controlling said motor to decrease the
pumping action of said pump, and means for producing an
underpressure in said tube.
6. The apparatus according to claim 5, wherein said means for
producing an underpressure comprises said pump.
7. The apparatus according to claim 5, wherein said means for
producing an underpressure comprises a second pump connected to
said tube.
8. An automatic system for draining fluids comprising a suction
tube, a pump connected to said tube, a motor connected to operate
said pump, a pressure sensor connected to control said motor in
response to the pressure in said tube, and underpressure generating
means for reducing pressure in said tube, said pressure sensor
being responsive to a first underpressure for controlling said
motor to increase the pumping action of said pump, said pressure
sensor being further responsive to ambient pressure in said tube
for controlling said motor to decrease the pumping action of said
pump.
9. The system according to claim 8, wherein said pressure sensor is
responsive to an underpressure in said tube greater then said first
mentioned underpressure for controlling said motor to reverse the
pumping action of said pump.
Description
BACKGROUND OF THE INVENTION
The invention relates to an apparatus for draining blood from a
surgical wound and the transmission of this blood to a heart-lung
machine and is particularly directed to apparatus of this type
which employs a suction tube adapted to connect the wound with a
suction pump.
Difficulties have arisen in the past in the use of this type of
apparatus for draining blood from wounds, since air is entrained
with the blood when the blood level is lowered to the level of the
tube mouth, which is held adjacent the wound, thereby causing
foaming of the blood. Such foaming of the blood effects a
considerable degradation of the blood, and it is difficult to
remove the foam from the heart-lung machine.
This adverse effect has been dealt with in the past by providing a
manually controlled switch for on and off operation of the pump as
required. This manual control, however, necessitates an additional
assistant or, in case it is done by the surgeon himself, requires
his special attention. In the latter case, since the surgeon's
attention is fully occupied by the operation itself, the manual
actuation of the pump switch may be overlooked.
The most objectionable aspect of this inadvertent failure to use
the manual switch operation resides in the potential damaging
effect on the blood and in the possibility that the mouth of the
suction tube may suck itself onto some internal body organ. In such
event, it may be necessary to free the tube mouth from the wound by
force. An additional objectionable feature is occasioned by the
necessity of providing a special transmission line for the
actuation of the switch, which may create a problem with regard to
the required sterility.
OBJECTS OF THE INVENTION
It is an object of the present invention to provide means for
eliminating the problem as described above and to safely automate
the correct performance of the drainage operation.
It is a further object of this invention to provide an economical
apparatus for automatically controlling the pump of a blood
draining device so that the foaming of the blood is prevented.
SUMMARY OF THE INVENTION
According to the invention the above objects are achieved by
providing a suction tube coupled to a weakly acting underpressure
generator and to a pressure sensor. The pressure sensor, upon
discerning a predetermined first pressure drop due to the blood
level rising above the mouth of the suction tube is connected to
switch the suction pump on for a gradual speed-up. Upon discerning
a second predetermined higher underpressure value, the suction pump
is switched off and connects the suction tube to atmospheric
pressure. Upon the disappearance of any underpressure due to the
blood level falling below the mouth of the suction tube, the pump
is switched off. As a result, the suction pump is immediately shut
off as soon as the blood level falls below the mouth of the suction
tube such that the above mentioned air entrainment cannot take
place. During this operational state, in which the blood level is
below the mouth of the suction tube, the underpressure generator
and the pressure sensor continually monitor the blood level,
thereby assuring the drainage of blood as soon as the blood level
rises sufficiently, while also monitoring if the suction tube has
sucked itself onto a body organ. This, to be sure, can also happen
during normal blood drainage, e. g. due to displacement of the
suction tube and sudden attachment to a body organ.
The underpressure generator can be a small separate machine or
alternatively the suction pump itself may be used for this purpose,
in which case it is set to a lower output mode of operation.
The connection of the tube to atmospheric pressure may be effected
in various ways. For instance, the suction tube may be provided
with a valve connecting the tube to the ambient atmosphere by
automatically opening as soon as the second predetermined
underpressure value is reached. On the other hand, the suction pump
may be employed for this purpose by setting it for a limited time
on pressure operation. In this case the mouth of the suction tube
will automatically free itself from any part of the body to which
it may have attached itself by suction.
BRIEF FIGURE DESCRIPTION
In order that the invention may be clearly understood, it will now
be described, by way of example, with reference to the accompanying
drawings, wherein:
FIG. 1 shows a blood draining apparatus employing a suction pump as
an underpressure generator, in accordance with one embodiment of
the invention, and
FIG. 2 illustrates an arrangement employing a separate small
machine as an underpressure generator, in accordance with a further
embodiment of the invention.
DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS
Referring now to FIG. 1, a suction tube 1 is inserted into a wound
via the elbow 2. The blood level in the wound is indicated by a
wavy line 3. The suction tube 1 is connected to a suction pump 5 in
a heart-lung machine 4, and the blood is pumped from pump 5 to
other not illustrated components of the heart-lung machine. In the
illustrated arrangement a so called rollerpump is used, in which
two rollers 6 and 7 supported by an arm 20, rotate about the dashed
line axis 8, thereby squeezing the elastic suction tube 1. During
rotation, the roller 6 squeezes the blood that is contained in the
suction tube ahead of it in a forward direction, at the same time
sucking blood behind itself until it arrives at the position
occupied by the roller 7 as illustrated. Then the roller 7, which
has now reached the position which roller 6 previously occupied,
repeats the same action. Both rollers are driven via the shaft 8
(not shown) on the axis by the motor 9.
The roller pump 5 not only serves the purpose of draining the blood
from the wound, but also serves as underpressure generator. In
serving as underpressure generator, the two rollers 6 and 7 are
rotated very slowly by the motor 9. During an operational state
when -- as depicted in FIG. 1 --, the blood level 3 is below the
mouth 12 of the suction tube 1, an underpressure cannot build up in
the suction tube 1. When the blood level 3 rises and eventually
closes the suction tube mouth 12, the slowly advancing rollers 6
and 7 of the roller pump 5 create an underpressure in the suction
tube 1. A pressure sensor 10 is provided in order to monitor these
actions. The pressure sensor 10 responds as soon as an
underpressure of about 5 mm water column is attained, thereby
actuating the electronic control unit 11 which in turn then effects
a gradual speed-up of the motor 9. The gradual speed-up of the
motor is controlled by a conventional electronic delay element in
the control unit 11. The roller pump 5 is now on a suction mode of
operation, whereby an underpressure of up to 50 cm water column may
be produced. From now on the blood reaching the tube mouth 12 will
be continually drained off. When the blood level again falls below
the tube mouth 12, the pressure in the suction tube 1 rises to
atmospheric pressure again, thus allowing the pressure sensor 10 to
return to its zero position and, upon passing the first threshold
value of 5 mm water column, to reset the motor via the electronic
control unit 11 to the low speed which is appropriate for the
action of the roller pump 5 as underpressure generator. This
alternate rise and fall of the blood level relative to the tube
mouth 12 repeats itself continually. The entrainment of air in
blood as previously described, however, does not take place since
the roller pump actually feeds blood only during periods when the
blood level 3 is higher than the tube mouth 12, while acting merely
as underpressure generator as soon as the blood level 3 falls below
the tube mouth 12. As long as air can enter the tube mouth 12, the
slow movement of the rollers 6 and 7 will not entrain air in any
blood into the tube mouth 12. As soon as the tube mouth 12 is
closed again by the rising blood level, the roller pump 5 will
gradually run up to its full suction mode of operation.
In order now to detect the occurence of the tube mouth having
sucked itself against some body part, which may happen during the
draining of blood as well as in the case illustrated by FIG. 1, the
pressure sensor is provided with a second threshold value at a
higher underpressure, e. g. at 100 cm water column. Upon closure of
the tube mouth 12 by some body part, the roller pump will operate
as in the case of blood drainage or will start up for this
operating mode if the blood level is below the tube mouth 12. In
the latter case a rise of the blood level is simulated by the
closure of the tube mouth. However, since no blood is being sucked
in, the underpressure in the suction tube 1 increases. Upon
reaching the second threshold value the pressure sensor will
activate the electronic unit 11, which in turn shuts off the motor
9 and causes the pressure in the suction tube to rise to
atmospheric pressure, thereby facilitating removal of the tube
mouth 12 from the body part. This procedure is initiated by
reversing the direction of rotation of the motor 9 by the
electronic device 11, thereby causing the roller pump 5, by turning
in the reverse direction to that indicated by the arrow in the
illustration, to produce pressure in the suction tube 1. As soon as
the pressure in the suction tube reaches atmospheric pressure, the
tube mouth 12 will detach itself or may easily be removed from the
body organ.
The above described procedure provides a very gentle manner of
blood drainage, the blood never being subjected to sudden
movements. Conventional pressure sensing devices and threshold
circuits may be employed in the system of FIG. 1.
The apparatus shown in FIG. 2 contains several of the same elements
as in FIG. 1, which therefore carry the same reference indices. In
this embodiment of the invention, a separate suction pump 13 is
provided as underpressure generator. This pump is connected to the
suction tube via the check valve 14. The suction pump 13 runs
continuously, thus providing instantaneous effectiveness as soon as
the blood level 3 falls below the tube mouth 12. When the blood
level 3 rises again the suction pump 13 generates the above
underpressure, which, upon reaching the first threshold value,
activates the pressure sensor. The latter then, via the electronic
unit 11, turns on the motor 9, which then drives the roller pump in
the above described manner for the blood draining operation. The
higher underpressure in the suction tube created thereby cannot
influence the suction pump 13, because now the check valve 14
effectively separates the suction pump 13 from the suction tube
1.
Transmission of atmospheric pressure to the suction tube 1 in the
case of closure of the tube mouth 12 by some body part is provided
via the valve 15. The latter is opened by the electronic unit 11
when the underpressure in the suction tube 1 has risen to the
second threshold value of the pressure sensor 10. Opening of the
valve 15 allows air to enter the suction tube 1, thus permitting
the tube mouth 12 to be easily removed or to detach itself from a
body organ.
It should here be mentioned, that the valves 14 and 15 may be
combined in a two-way control valve. It is also feasible in the
arrangement of FIG. 2 to have the pump 5 reverse direction of
rotation in order to generate atmospheric pressure in the suction
tube 1 as has been described in reference to FIG. 1. It may,
however, be pointed out that the separate underpressure generator
pump provides the advantage of allowing the roller pump 5 to stand
still as long as the blood level 3 is below the tube mouth 12,
thereby eliminating any manipulation of the blood contained in the
roller pump 5 during this phase of operation.
Although the invention has been described with reference to
specific example embodiments, it is to be understood that it is
intended to cover all modifications and equivalents within the
scope of the appended claims.
* * * * *