U.S. patent number 3,656,478 [Application Number 05/027,772] was granted by the patent office on 1972-04-18 for infusion monitor utilizing weight detecting means.
This patent grant is currently assigned to Brookline Instrument Company. Invention is credited to Burt L. Swersey.
United States Patent |
3,656,478 |
Swersey |
April 18, 1972 |
INFUSION MONITOR UTILIZING WEIGHT DETECTING MEANS
Abstract
The infusion monitor is adapted to operate at a high speed or a
low speed in dependence upon a variable characteristic of the
patient, such as weight. If during infusion, the weight of the
patient deviates from a preset value the infusion monitor speed is
changed. For example, with the infusion monitor operating at the
normal low speed, if the weight decreases, the infusion monitor is
switched to the high speed. When the weight subsequently returns to
the preset value, the infusion monitor switches back to the low
speed.
Inventors: |
Swersey; Burt L. (Hartsdale,
NY) |
Assignee: |
Brookline Instrument Company
(Elmsford, NY)
|
Family
ID: |
21839712 |
Appl.
No.: |
05/027,772 |
Filed: |
April 13, 1970 |
Current U.S.
Class: |
604/66; 177/144;
177/164; 222/77; 177/60; 222/56; 604/153 |
Current CPC
Class: |
A61M
5/16895 (20130101); A61M 5/16845 (20130101) |
Current International
Class: |
A61M
5/168 (20060101); A61m 005/00 () |
Field of
Search: |
;128/214R,214E,214F,214.2,2 ;177/60,144,164 ;222/56,77
;141/83,94,95 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Truluck; Dalton L.
Claims
What is claimed is:
1. An infusion monitor comprising
a conduit for connection to a consumer;
a pump for delivering fluid through said conduit to the
consumer;
first means connected to said pump for actuating said pump to
deliver fluid at a low rate through said conduit;
second means connected to said pump for actuating said pump to
deliver fluid at a high rate through said conduit; and
a scale means for indicating deviations of weight of the consumer
about a predetermined value, said scale means being connected to
said first means and said second means to selectively actuate one
of said first and second means in response to predetermined
deviations of the weight about said predetermined value whereby in
response to a deviation in excess of said predetermined value said
scale means actuates said first means and in response to a
deviation less than said predetermined value said scale means
actuates said second means to maintain the consumer at a constant
weight.
2. An infusion monitor as set forth in claim 1 wherein said
predetermined value is a variable value.
3. An infusion monitor as set forth in claim 1 wherein said pump is
an eccentric wobble plate pump.
4. An infusion monitor as set forth in claim 1 further comprising
means connected between said scale means and said second means for
adjusting the value of said predetermined deviation.
5. An infusion monitor as set forth in claim 1 which further
comprises one digital read-out for indicating a low pumping rate
and a second digital read-out for indicating a high pumping
rate.
6. An infusion monitor as set forth in claim 1 which further
comprises a digital read out connected to said pump means for
indicating the total amount of fluid pumped therethrough.
7. An infusion monitor as set forth in claim 1 further comprising
an adjusting means in said housing for adjusting said switch means
to switch the operation of said pump means from one rate to the
other rate in response to the measured deviation exceeding a preset
amount.
8. An infusion monitor comprising
a pump for pumping fluid through a conduit to a consumer;
first means connected to said pump to selectively actuate said pump
at one of a high speed and a low speed to pump different rates of
fluid flow through the conduit;
a read out scale for determining the weight of a consumer, said
scale being connected to said first means to cause said first means
to actuate said pump at said low speed in response to said weight
exceeding a predetermined value and to actuate said pump at said
high speed in response to said weight falling below the
predetermined value.
9. An infusion monitor as set forth in claim 8 wherein said
predetermined value is variable.
10. An infusion monitor as set forth in claim 8 which further
comprises an adjustable means for adjusting the predetermined value
for actuation of said pump at said high speed.
11. In combination
a scale for weighing a patient;
first means for infusing fluid into the patient at one of two rates
of infusion, and
second means connected to said scale and said first means for
determining deviations in weight of the patient and selectively
actuating said first means to one of said two rates of infusion in
response to predetermined deviations of weight from a preset value
of weight, said second means actuating said first means to infuse
fluid into the patient at the lower of said two rates in response
to the weight of the patient exceeding the preset value and said
second means actuating said first means to infuse fluid into the
patient at the higher of said two rates in response to the weight
of the patient falling below the preset value.
12. The combination as set forth in claim 11 wherein said second
means actuates said first means to infuse fluid into the patient at
the higher of said two rates in response to the weight of the
patient falling a predetermined amount below the preset value.
13. In combination
a scale for measuring the weight of a patient including a line for
emitting a signal in response to a deviation in weight from a
predetermined value;
a rate monitor for changing said value during a measurement of
weight of the patient; and
an infusion monitor connected to said scale for infusing a fluid
into the patient at at least one of a low speed rate and a high
speed rate, said infusion monitor having means therein for
selectively infusing fluid into the patient at the high speed rate
in response to a decrease in weight of the patient from said value
and at a low speed in response to an increase in weight of the
patient from said value, and means for adjusting said rate monitor
to change said value at a predetermined rate.
14. The combination as set forth in claim 13 wherein said means for
adjusting said rate monitor includes a digital readout.
15. The combination as set forth in claim 14 wherein said digital
readout is manually adjustable.
Description
This invention relates to an infusion monitor. More particularly,
this invention relates to an infusion monitor for infusing liquids
into a patient.
Various devices have been known for infusing liquids or fluids,
such as blood, glucose and the like into a patient for various
purposes such as intravenous feedings, blood transfusions, and the
like. For example, it has been known to mount a bottle of the fluid
to be infused on a stand above a patient and to connect a tubing
between the bottle and a vein of the patient. The fluid is then
dripped from the bottle in the tubing to the patient. In order to
regulate the flow of fluid into the patient, the rate of drops per
minute from the bottle into the tubing is measured, usually
visually, and a valve in the bottle outlet is adjusted in
correspondence to the measured rate of drops to obtain the desired
rate In other instances, constant speed pumps or syringes pumps
have been used to infuse the fluid into the patient. However, these
various devices have not been totally accurate in all the cases.
Further, as in the case of the pumps, such have required relatively
expensive equipment.
Also, in the case of pumps where the rates of infusion have been
set at constant rates, the infusion rates can sometimes be
insufficient or excessive. For example, if a patient such as a
premature infant is being fed intraveneously and the infant's
weight is to be maintained constant, deviations in weight can occur
because the infant loses fluid at a different rate than the intake.
In such cases, the constant rate pumps have been inadequate to
compensate for such changes.
Accordingly, it is an object of the invention to provide a
relatively simple method of infusing fluid into a patient.
It is another object of the invention to provide an automatic
system for infusing fluid into a patient to maintain a constant
weight of the patient.
It is another object of the invention to provide a relatively
inexpensive automatic system for delivering fluids to a
consumer.
It is another object of the invention to infuse fluid into a
patient at a low or high rate in dependence with a measureable
characteristic of the patient.
It is another object of the invention to infuse a liquid into a
consumer at selective rates in dependence upon a variable
characteristic of the consumer.
Briefly, the invention provides an infusion monitor for infusing
fluids at selective rates in dependence upon a variable
characteristic. The infusion monitor, for example, is operable at
either a low speed or a high speed to infuse a fluid and can be
used, for example, to intravenously feed medical patients such that
in dependence upon a measureable characteristic of the patient,
such as weight, the rate of infusion is switched from the low speed
to the high speed and vice versa.
The infusion monitor includes a pump for pumping fluid through a
conduit to a consumer, means for selectively actuating the pump to
deliver fluid at the high speed rate or the low speed rate through
the conduit, and a means for indicating deviations of the variable
characteristic of the consumer. Depending upon the sense of a
deviation (i.e. plus or minus) about a predetermined value, the
pump is switched from the one speed to the other speed so as to
compensate for the deviation. For example, if the deviation falls
below a predetermined value then the pump is switched from the low
speed to the high speed.
In one embodiment, the means for indicating the deviations of the
variable characteristic includes a scale, e.g. a scale as described
in U.S. Pat. No. 3,338,323 which measures the weight of a patient
to establish a preset value and subsequent deviations in weight
from the preset value. The pump of the infusion monitor is
interconnected with the scale so as to infuse fluid into the
patient at a slow rate or a high rate in dependence upon a
deviation of weight being detected while a read-out scale is
mounted on the face of a housing of the infusion monitor to
indicate the deviations. In operation, when the scale detects a
weight deviation a suitable signal is transmitted to the infusion
monitor so that the pump is switched from the low speed to the high
speed or vice versa. For example, should the indicating and
measuring means indicate a decrease of weight of the patient, the
pump is switched from the normally operating low speed to the high
speed to compensate for this weight loss by increasing the fluid
delivered to the patient. Once the weight of the patient returns to
the predetermined value, the pump switches back to the low
speed.
The infusion monitor is further provided with an adjusting means
which is able to adjust the point at which the deviation measuring
means actuates the pump to switch from the low speed to the high
speed. For example, the adjusting means can be set for a
predetermined loss of weight below a predetermined value before the
pump is switched to the high speed. This will permit slight
variations in weight loss to be accepted before switching to the
high rate of infusion.
In another embodiment, the scale for measuring the weight of a
patient can be coupled with a rate monitor which indicates a
predetermined rate of increase or decrease in weight which is
desired for a patient undergoing treatment. An example of this type
of apparatus is described in U.S. patent application Ser. No.
815,722 filed Apr. 14, 1969. For example, should it be desired that
a patient lose weight at a predetermined rate, the rate monitor
automatically subtracts the weight loss due to the programmed rate
of weight loss from the actual patient's weight during weighing so
that the resultant differential, if any, is indicated on the
read-out scale and the pump speed switched, if necessary. Thus,
should a patient lose weight at a different rate from a desired
rate of loss during an infusion operation, the rate of infusion is
speeded up as above. Conversely, if a patient is to gain weight at
a predetermined rate during an infusion process, such is also
monitored in the same manner as above.
It is to be noted that it is not necessary to only measure the
weight of the patient in order to actuate the infusion monitor.
That is, any variable characteristic of a patient can be monitored
such as blood pressure, pulse rate, temperature and the like.
Furthermore, use of the infusion monitor is not limited to medical
patients That is, the infusion monitor can be used in any situation
where a fluid is to be infused into a consumer, such as a
container, at predetermined rates in dependence upon a measureable
characteristic of the consumer.
These and other objects and advantages of the invention will become
more apparent from the following detailed description and appended
claims taken in conjunction with the accompanying drawings in
which:
FIG. 1 illustrates an infusion monitor according to the invention
interconnected with a patient weight measuring scale;
FIG. 2 illustrates a front view of a housing of an infusion monitor
according to the invention; and
FIG. 3 schematically illustrates the interconnection between an
infusion monitor of the invention with a scale as shown in FIG.
1.
Referring to FIG. 1, the infusion monitor 10 is interconnected with
a scale 11 for feeding fluid such as a parenteral fluid from a
fluid source 12 through a conduit 13 to a bed ridden patient 14 on
the scale 11. The infusion monitor 10 is constructed so as to
monitor the rate of fluid flow from the source 12 through the
conduit 13 into the patient 14 and to vary the rate of flow between
a low rate and a high rate in dependence upon a variation of weight
of the patient as measured and indicated by the scale 11.
Referring to FIGS. 1 and 2, the infusion monitor 10 includes a
housing 15 in which a pump 16 and control means for actuating the
pump 16 at a low speed or high speed are mounted. The pump 16, for
example, an eccentric wobble plate pump, is disposed in the conduit
13 so as to pump the flow of fluid through the conduit 13 to the
patient 14. The control means includes a suitable motor 17 (FIG. 3)
for running the pump 16 as well as a suitable means for running the
pump 16 at a low speed or a high speed. For example, the motor 17
can be a variable speed motor such as a stepper motor which can be
set to operate at either of a predetermined low speed or high
speed. In order to set the operating speeds of the motor 17, a pair
of readout means 18, 18' such as digital read-out pots are mounted
on the face of the housing 15 and are connected, e.g. electrically,
to the motor 17. One pot 18 serves to set the motor 17 to run at a
low speed while the other pot 18' sets the motor 17 to run at a
high speed. Both pots 18, 18' can be manually adjusted as is known
to set the desired rates. The control means further includes a
suitable switching means 23 such as an electrical switching contact
for switching the pump 16 between the low and high speeds.
In addition, a readout scale 19 is mounted on the face of the
housing 15. This readout scale 19 includes a graded scale 20 having
plus and minus gradations about a zero point as well as a pointer
21 which is normally over the zero point. The zero point is used as
a norm or null point to establish a point on the scale 20 which
corresponds to a predetermined weight for the patient. Thus, when
the pointer 21 moves, the scale 19 indicates whether or not the
weight of the patient on the scale 11 is more or less than the
predetermined weight. The patient 14 is connected via suitable
means (not shown), as is known to the scale 11 so as to indicate
measurements of, e.g. D.C. microamperes.
The scale 11 is connected to the infusion monitor 10 for example,
over an electrical line 22 which connects the scale 11 electrically
to the motor 17 as well as to the readout scale 19. The scale 11 is
of any construction, such as described in U.S. Pat. No. 3,338,323
in order to determine variations in weight of a patient about a
predetermined constant weight. For example, after taring out or
balancing the weight of the various items, such as clothing, bed,
and the like and obtaining the weight of the patient, the scale 11
indicates and measures any subsequent deviation in the patient's
weight and emits a signal in correspondence with the deviation to a
read-out means. In the present case, the initial weight of the
patient will be reflected on the read-out scale 20 as the zero
point. Thereafter, should the patient gain or lose weight, the
deviation weight will cause the scale 11 to emit a signal over line
22 in correspondence to the deviation to the pointer 21 of the
read-out scale 19 to deflect the pointer 21 an amount corresponding
to the deviation. To this end, the graded scale 20 of the readout
scale 19 can be graded in D.C. microamps to indicate the intensity
of the deviation or can be graded directly in grams to indicate the
amount of the deviation. In addition, the line 22 is connected to a
suitable switching means 23 in the motor 17 so as to switch the
motor 17 from a normally operating low speed to a high speed in
response to the measured deviation exceeding a predetermined
negative value representing a loss in weight. In addition, the
switching means 23 is operable to switch the motor from the high
speed back to the normal low speed in response to the absence of a
signal from the scale 11 or upon receiving a signal corresponding
to a deviation representing a positive increase over the zero
point.
The infusion monitor 10 further includes a digital readout 24 for
indicating the amount of fluid actually infused into a patient.
This digital readout 24 can be connected to the pump 16 in any
suitable manner so as to count the number of pump revolutions and
thus the amount of fluid infused. Alternatively, the digital
readout 24 can be interconnected with the source 12 of the fluid so
as to indicate the amount of fluid flowing therefrom. Further, the
infusion monitor 10 is provided with an adjusting means 25 having a
knob 26 projecting from the face of the housing 15. This adjusting
means 25 is interconnected with the switching means 23 for the
motor 17 so as to delay the actuation of the motor 17 from the low
speed to the high speed until the negative value signal from the
scale 11 via line 22 exceeds a predetermined amount. For example,
the adjusting means 25 can be set so that the motor 17 does not
switch from the low speed to the high speed until there is a weight
loss of more than one, two, three, four or five grams in the
patient. Such differentials can be set by turning the knob 26 a
sufficient extent as indicated by a scale 27 on the monitor housing
15. This, in turn, effects the switching means 23. Also, the
adjusting means 25 can be set so that the motor 17 can only run at
the high speed.
The infusion monitor 10 can also be provided with suitable alarms
30 so to indicate when the weight of a patient falls below a
certain value or exceeds a certain value. Also, various reset
buttons 31 can be placed on the housing for resetting the readout
for the total fluid infused to a patient so that a zero reading can
be obtained at any time. Also, various signals 32 such as lights
can be provided on the housing 15 so as to indicate when the
infusion monitor is in operation.
Referring to FIGS. 1 and 3, in operation, should it be desired to
infuse a fluid into a patient 14 so as to maintain the weight of
the patient at a constant level, the patient is initially placed on
the scale 11 and weighed. This weight then corresponds to the zero
point on the readout scale 19. The digital readout pots 18, 18' are
then set to the desired low and high rates. Next, the infusion pump
16 is then switched on via a switch S so as to operate at a normal
low rate to infuse fluid at a steady rate of, e.g. from 0 to 10
millimeters per hour, as set by one pot 18. This rate is provided
so as to keep the intraveneous route to the patient open and can
usually be set, e.g. for an infant, at 1 millimeter per hour. In
the event that the weight of the patient should subsequently
decrease during operation of the infusion monitor 10, the scale 11
measures and indicates this decrease in weight and transmits a
signal via line 22 to the infusion monitor 10. The deviation is
indicated by the pointer 21 of the read-out scale 19, for example,
by deflecting to the left as viewed. At the same time, the signal
is transmitted to the switching means 23 for the motor 17. Should
the signal be greater than the desired deviation as determined from
the adjusting means 25, the motor is then switched to the high
speed. The rate of infusion then increases, e.g. to 60 millimeters
per hour. This fast rate provides for a generally rapid correction
of the patient's weight loss. As soon as the patient's weight
returns to the predetermined amount, the scale 11 ceases to
transmit a signal so that the pointer 21 of the read-out scale 19
returns to the zero point. At the same time, the switching means 23
for the motor 17 switches the motor 17 from the high speed back to
the low speed. The low rate of operation then continues until a
subsequent decrease in weight of the patient occurs.
Referring to FIG. 2, in the event that a patient is to loose or
gain weight at a predetermined rate during an infusion operation,
the infusion monitor 10 is further provided with a digital readout
28 such as a pot which is connected, for example, electrically to a
rate monitor (not shown) in the scale 11. To this end, the readout
28 is manually operated to set the rate monitor so that a
predetermined rate of increase or decrease in weight is
superimposed on the scale readings. For example, if it is desired
to have a patient increase in weight at a particular rate over a
period of time, the readout 28 is adjusted to the desired rate so
as to control the rate monitor to obtain this rate. Thus, so long
as the patient is actually increasing in weight in accordance with
the rate of programmed increase no signal will be transmitted via a
line 22 through the infusion monitor 10. The readout point 21 of
the read-out scale 19 will therefor remain at zero. However, should
the patient be increasing in weight at an amount less than the
desired rate, a signal would be transmitted via line 22 to the
infusion monitor 10 to indicate a negative differential. This will
cause the infusion monitor to actuate the pump 16 to operate at the
higher speed. When the actual weight of the patient catches up to
the predetermined rate so that the weight differential disappears,
the pump 16 will be switched back to the low speed. In the event
that a patient exceeds a rate of desired increase in weight, the
infusion monitor will remain at the low speed; however, the alarm
signal indicating the excessive weight as indicated on the read-out
scale 19 will be actuated. Attention can then be given to the
patient to compensate for this fast increase in weight.
In this latter embodiment, a suitable digital readout 29 is also
mounted in the face of the housing 15 of the infusion monitor 10 so
as to give a reading of the actual gain or loss of a patient with
respect to the programmed rate of increase or decrease.
The invention thus provides an infusion monitor which is capable of
infusing fluids into a patient in an automatic manner depending
upon changes of weight in the patient. Furthermore, the infusion
monitor can also be actuated in dependence upon other variable
characteristics of the patient such as pulse rate, body
temperature, heart beat or any other suitable characteristics or
combination of characteristics.
The invention further provides an infusion monitor which can be
used to regulate flow of a fluid into any suitable consumer.
The invention also provides an infusion monitor which can be used
to selectively infuse one of a number of fluids into a patient in
dependence upon different measureable characteristics of the
patient. For example, the monitor can be provided with two pumps,
as above, each of which is selectively connected over suitable
motors and digital readouts to a means for measuring the
characteristics of the patient such as weight or blood pressure.
Should one of the measured characteristics deviate from a
programmed norm, the respective motor is switched over to deliver
the appropriate fluid at the high rate. Thus, should a patient
require blood at the high rate, the fluid needed to maintain a
preset weight need only be infused at the low rate if the added
blood also supplies the function of the other fluid.
* * * * *