Note: Descriptions are shown in the official language in which they were submitted.
~6g~7
MONITOR FOR LIQ~ID LE~EL AND URINE FLOW
Backaround of the Invention
Thi6 invention is concerned with an optical, liquid
level sen60r and apparatus incorporating that sen60r,
particularly for measuring the flow of urine from a
patient on a catheter.
There are many situations ~n which it is required to
sen6e when a rising level of liquid reaches a certain
point, such as to determine when a container is
approaching the fill point or to drain a container which
is being repeatedly filled. Because many liguids are
substantially transparent, optical means can be used to
determine when the liquid level is at a certain point.
Such systems have the advantage of operation without
interference with the liquid. One such liquid level
sensing arrangement is disclosed in U.S. Patent No.
3,549,893, to Gibbs. The patent discloses an apparatus
in which light is shone down a tube, across a container
for l~guid and then towards a photodetector which is in
the shadow of a baffle in the light beam. The baffle
casts a shadow on the detector and therefore renders it
substantially inactive until liguid rises in the
container to the level of the light beam. The liquid
then refracts the light inwardly behind the baffle so as
to activate the photodetector. The disadvantage with
this arrangement are that some light leakage will occur
to the photodetector during its inactive period, and
this adversely affects the signal to noise performance of
the equipment, and it is inconvenient to incorporate a
baffle in a simple, compact design. Various other types
~L~6~ 7
of optical liquid level detectors are ~hown, for example,
in u.S~ Patent Nos. 3, 384, 885, 4, 069, 838 and 4, 223, 231.
I n the medical field, it is often deeirable to
monitor liquid level in a container used in either the
supply of liquid to, or the withdrawal of liquid from, a
patient. In many 8 i tuations, particularly when a patient
is in a critical care unit, it i8 desirable to monitor
accurately the amount of urine that the patient is
expelling. The patient is on a catheter and the urine
flows from the catheter into a device for measuring the
flow and collecting the urine. Current devices are
inaccurate or inconvenient to use. Many of the6e devices
simply consi6t of a bag or cylinder with graduated
markings on it that enables the attendant to periodically
observe the level of urine collected. It is desirable
that the urine output from a patient be monitored over a
period of time and that the output rate be known.
Automated recording of output data is an attractive means
of achieving these ends which not only 6aves labor in the
collection of the data, but also provides it in a form
u6eful for the interpretation of the condition of the
patient. U.S. Patient No. 4,343,316 to Jesper6en
di6clo6es an automated urine collection and monitoring
apparatus in which urine passes into a calibrated
measuring chamber until the filling of the chamber is
sensed by interruption of a light beam by the rising
liquid level. At thi~ point, the contents of the chamber
are dumped into a collection bag and the volume dumped is
electronically recorded. The number of volumes dumped is
u6ed to display digitally the total volume of urine
collected and also the flow rate of urine per unit time.
The apparatus in this patent mu6t be connected to the
main electrical supply and this severely restricts its
portabilit~ and convenience. The measuring chamber in
this patent is not an optimum design. Because the
~Z69~7
chamber empties relatively slowly, a valve upstream is
closed to hold back the flow of urine. This blockage to
the patient is undesirable and although the patent
claims to have means to avoid blockage if the valve fails
S in the closed position it is still very desirable to
avoid such an arrangement. Further, the valve used is a
pinch type and this suffers from the disadvantage of
permanently crimping the tubing. This leads to
relatively slow opening of the tube with the valve and
the risk of tube fracture.
There is a need for a lightweight, relatively simply
constructed, accurate liquid level sensor which can be
used in the medical field. There is a need for such a
sensor in a sterilizable, disposable module for a
! 15 portable apparatus for monitoring the flow of urine from
a patient which provides an accurate, visual numerical
display of the amount of urine collected in a
predetermined collection period and which uses a
measuring chamber which empties rapidly and reliably.
Summary of the Invention
According to the invention there is provided a
liquid level sensor apparatus for placement between a
radiation source and a radiation detector, comprising
first means for conducting radiation received from the
source and second means for conducting radiation to the
detector, the first means being for alignment with the
sensor on a first axis and the second means for alignment
with the detector on a second axis, the first and second
means being spaced apart to form a liquid level sensing
zone between them such that, when the sensor is in place
between the source and detector and the liquid level has
not reached the zone, the radiation conducted by the
first means is directed away from the second means to
render said detector inactive, and in the presence of
:~2~;9~7
liquid in the zone the radiation from the first means i6
refracted by the l~quid to the second mean6 to be
conducted thereby along the second axis to the detector
to activate the detector. Preferably, the first and
second axes form a common optical axis.
The invention also provides for measuring the flow
of urine from a patient by repeatedly collecting in said
apparatus, and removing from said apparatus, a
predetermined volume of urine. The apparatus comprises a
measuring chamber for collecting said volume of urine; an
inlet to said chamber for connection to a patient; an
¦ outlet from said chamber for said removal of said urine;
! means for intermittently interrupting the flow of urine
from said outlet so as to allow said volume of urine
collected in or removed from said module; a plenum
chamber in communication with said measuring chamber for
promoting said removal of said urine; and means for
sensing when said volume of urine has been collected,
comprising means for accepting radiation into 8 aid
apparatus and means for emitting said radiation from said
apparatus in a predetermined path for detection, æaid
sensing means causing said radiation to be deflected from
that path until said volume of urine has been collected.
The accepting means comprise~ first radiation
; 25 transmissive means on a first axis and said emitting
means comprises second radiation transmi66ive means on a
second axis, caid first and second means being spaced
apart to form a urine level sensing zone between them.
Preferably said first and second axis are a common axis.
Preferably the firæt means has a face at the
interface with the sen6ing zone in the above embodiments
which is inclined in a plane at an acute angle to the
first axis so that the radiation from the first means is
refracted at that interface away from the second means.
Preferably, the second means ha6 a face at the interface
126~0~37
between sald zone and the second means lying in a plane
substantially parallel to the face of the fir6t means.
Preferably, each of the first and second means
comprises a solid, substantially cylindrical rod made of
S a material substantially transparent to the radiation,
such as a clear plastic material.
The invention also provides a lightweight, portable
apparatus incorporating this level sensor for monitoring
the flow of urine from a patient on a catheter which
provides an accurate measurement, i6 battery operated,
and includes a display of urine flow volume data which
enables the attendant to chart accurately the urine
output of the patient over a prolonged period of time,
for example, 24 hours. The data over this 24 hour period
is stored in the memory of the apparatus and can be
retrieved and visually displayed at the command of the
attendant.
Thi6 apparatus comprises a measuring chamber having
a predetermined volume, for example,10 millilitres. This
chamber is adapted to be connected to the catheter, and
has a valve near its lower end that moves between a
closed position, at which urine is collected within the
chamber and, an open po6ition, at which the urine flow
from the chamber into a collection bag. The level
sensing device of the invention is located near the upper
end of the chamber and it senses when the urine level in
the chamber reaches the level sensing device, and then
provides an electronic signal indlcating that this
condition is pre6ent. Mechanical means are connected to
the valve and they are driven by an electrical actuator
which responds to the electronic signal to open the
valve. The urine in the chamber thus flows from the
chamber and into the collection bag or the like.
This combination of chamber, valve means, and
sensing device provides a way of measuring the amount of
~2~9~)~7
-- 6 --
urine being expelled by the patient. Every time the
patient excretes a preselected quantity of urine, for
example, 10 millilitres, it is collected in the chamber.
The 10 millilitres of urine fills the chamber with the
urine until the urine level is opposite the 8 ensing
means, which then responds to open the valve and drain
the urine from the chamber. Therefore, the electronic
signal not only serves to open the valve, but also is an
accurate indication that exactly 10 millilitres of urine
has been expelled by the patient. Thus, for example, if
the valve i6 opened three times in a pre-selected
collection period, for example, an hour, this corresponds
to a urine output of 30 millilitres of urine per hour.
Recording means record the number of times the
chamber is filled in the pre-selected collection period.
This recording means visually displays the volume data
on, for example, a dot matrix display readily observable
by an attendant. This panel may optionally be
illuminated. The recording means is designed so that
over a given period of time, for example, 24 hours, the
volume data is stored in the memory circuitry of the
apparatus as a series of numbers corresponding to the
different amounts of urine collected during each
collection period of a serie6 of sequential collection
periods occurring during the 24 hour period. For
example, during the first three hours the patient may
have expelled 50 millilitres of urine during each hour
and then stopped urinating so that the reading is zero
during the fourth hour. The apparatus is designed so
that for each hour interval the attendant could scan the
memory and obtain a reading of the amount of urine
expelled for each hour over the 24 hour period, thus
being able to chart the urine production during each
hour over the twenty-four hour period. The apparatus is
also designed 80 that during any given hour of time the
~269~7
-- 7
attendant may obtain on command an in6tantaneous reading
of the urine production for that portion of an hour time
interval.
Another important feature of this invention ls that
the apparatus is powered by conventional batteries. This
makes it highly convenient for the apparatus to be used
in a hospital, avoldlng the necessity of plugging the
apparatus into a source of alternating current. this is
not only more convenient, but i8 also safer. In srder to
minimize the drainage of power from the batteries, the
apparatus is adapted to operate between a high power mode
and a low power mode. During the high power mode, the
apparatus i6 enable to carry out all its functions.
During the low power mode only a limited number of
functions are operable. The apparatus cycles
automatically between the high and low power mode~.
~rief Description of the Drawings
Some preferred embodiments of the invention are
illustrated in and by the following drawings in which
like reference numerals indicate like parts and in which:
; FIGURE 1 18 a pergpective view of an apparatus of
this invention, 6howing a liguid flow measuring module in
place on a control unit and connected to a liquid
¦ collection bag;
i 25 FIGURE 2 is a cross-sectional view of the measuring
module;
FIGURE 3 is a rear view of the whole of a measuring
module of the type shown in Figure 2, taken in the
direction of arrow 3 in Figure 2;
FIGURE 4 is a top view of the whole of a module of
the type shown in Figure 2, taken in the direction of
arrows 4 in Figure 2;
FIGURE 5 is a bottom view of the whole of a module
of the type shown in Figure 2, taken in the direction of
' ~
~LZ6g~
arrows 5 in Figure 2;
FIGURE 6 ia a cross-sectional view, partly broken
away, of a module of the type shown in Figure 2-in place
on the control unit, as shown in Figure 1, and showing
the liquid level 6ensor of the invention;
FIGURE 7 is a schematic illu~tration showing the
operation of the liquid level sensor of Figure 6 in the
absence of liquid;
FIGURE 8 i 8 a B chematic illustration showing the
operation of the liquid level sensor of Figure 6 in the
pre~ence of liquid;
FIGURE 9 is a schematic illustration of an
alternative liquid level sensor of the invention, showing
its operation in the absence of liquid;
FIGURE 10 i6 a schematic illustration of the
operation of another liquid level æensor according to
this invention, showing its operation in the absence of
liquid;
FIGURE 11 is a plan view of the top of the control
unit showing the control panel and display scxeen where
data related to the flow of liquid can be displayed;
FIGURE 12 is a list of messages which can be
displayed on the display screen shown on the panel in
Figure 11;
FIGURE 13 i8 a schematic drawing showing the
control circuitry in the central unit;
FIGURES 14A and 14B are flow charts illustrating the
sequential operation of the control unit in the apparatus
of this invention.
Detailed Descri~tion of the Dxawi~
Referring to Figure 1, there is shown an apparatus
according to the invention for monitoring the flow of
urine from a patient on a catheter. The apparatus
compri6es a removable liquid measuring module 1 which
1269~1~7
incorporates the liquid level sensing system of the
invention, as will be explained in more detail below.
Measuring module 1 is sandwiohed between two plates
2 and 3 to form a liquid monitoring unit 4 attached to
the side of the housing 5 of an electronic control unit
6. Measuring module 1 is provided with an inlet tube 7
for connection to a catheter (not shown) and an outlet
tube 8 connected to a collection bag 9. Bag 9 is fitted
with a drain tube 10 upon which is mounted a tube clamp
11 which normally keeps drain tube 10 closed. The end of
tube 10 i6 normally 6tored in a pocket 12 on the face of
bag 9 until it is de6ired to empty the bag 9.
Measuring module 1 is kept in place between plates 2
and 3 by a gate 13 61idably mounted on one plate 2 so
that it can either slide over module 1 to prevent it from
falling out from between the plates or be withdrawn over
plate 2 to allow module 1 to be removed. Each plate hac
a window 14 through it (one of which i6 6hown in Figure
1) 80 that an attendant can observe the contents of the
measuring module 1. A scale 15 alongside window 14
provides an approximate indication of the volume of urine
in module 1.
Control unit 6 is provided with a number of keys 16
on it6 top 6urface 17 to operate control unit 6 and
electronically monitor the flow of urine from the
patient. Data relating to the flow of urine and
condition of the equipment are displayed in panel 18,
which is conveniently located on the top 17 of control
unit 6. Batteries (not shown) for providing power to the
electric circuitry are contained within housing 5. The
operation of the control unit 6 will be described in
further detail below.
Control unit 6 may conveniently be provided with
hook6 19 and 20 on its rear face to attach the apparatus
to a patient's bed. Additional hook6 underneath control
~269~-7
-- 10 --
unit 6, one of which i8 shown at 21 in Figure 1, are used
to carry collection bag 9 by engagement through holes
through the top of the bag, one of which i8 shown at 22
in Figure 1.
Turning to Figure 2, there is shown a side cross-
sectional view of measuring module 1 of this invention.
Module 1 comprises a measuring chamber 23 having a
predetermined volume such as 5 or 10 ml. Preferably
chamber 23 has a volume of 10 ml. Measuring chamber 23
has at its upper end an inlet pasæage 24 for connection
to inlet tube 7 a6 shown in Figure 1. Chamber 23 has at
its lower end an outlet pas6age 25 which is in
communlcation with a drain port 26 for attachment to
outlet tube 8 as shown in Figure 1. Another passage 27
leads from the upper end of chamber 23 past a liquid
level 6ensing device 28 into an overflow chamber 29 whose
lower end is also in communication with outlet port 26.
Overflow chamber 29 i8 vented to the atmosphere by means
of a hydrophobic bacterial filter 30 at its upper end. A
valve 31 i8 located at the bottom of measuring chamber 23
for closing outlet 25 from chamber 23. As can be seen in
Pigure 2, outlet 25 sweeps in a continuous, gradual bend
32 from the bottom of measuring chamber 23 into a
generally cylindrical valve compartment 33 whiah is in
communication through port 34 to the outlet 26. The
valve 31 comprises a flexible, circular diaphragm 35
between the walls of valve compartment 32. Diaphragm 35
can be deformed by pressure from a piston (not
shown)from the open position shown in Figure 2 to flex
and bear against outlet 25 to seal that outlet and allow
mea6uring chamber 23 to be filled. To achieve a more
positive closure, diaphragm 35 is provided with a raised
central portlon 35a which will plug outlet 25 whe~ the
valve is clo~ed. Dlaphragm 35 is preferably made of a
rubbery material which flexes in response to pressure
6~3(~7
from the piston and yet will rapidly withdraw without
deformation from outlet 25 when the piston is withdrawn.
It has be~n found that naturai rubber has the desired
characteristics for diaphragm 35.
In operation, urine from the patient enters
measuring chamber 23 via inlet 24 and, with valve 31
- closed, begins to collect in chamber 23 until that
chamber is filled and the rising liquid level enters
passage 27 to activate the liquid level sensor 28. The
sensor 28 then generates an electronic signal which
causes valve 31 to open and rapidly dump the contents of
measuring chamber 23 through outlet 25 and port 34 to
the main outlet 26 and into the collection bag 9, as
shown in Figure 1. The smooth gradual bend 32 in outlet
25 from measuring chamber 23 contributes to sweep out any
solid material and also to rapidly and completely empty
measuring chamber 23. When a predetermined time passes
which is sufficient to allow chamber 23 to empty, valve
31 is closed again to allow chamber 23 to refill.
Overflow chamber 29 acts as a plenum chamber to encourage
rapid emptying of measuring chamber 23 and therefore more
accurate measurement since the chamber will be emptied
i guickly enough before a significant further amount of
urine enters it. Overflow chamber 29 also acts to
conduct excess urine through outlet 26 to collection bag
9 in the unlikely event that valve 31 fails in the closed
position and does not open. Under these circumstances,
measuring chamber 23 will fill and excess urine will flow
through passage 27 to spill over into overflow chamber
29. Preferably, there is no valve in the apparatus
upstream of measuring chamber 23, thus ensuring that
there will always be an unrestricted passage between the
patient and the oollection bag 9. If overflow chamber 29
is used and it becomes full of urine, the hydrophobic
nature of filter 30 will prevent the outward flow of
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126~7
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urine through the filter.
Figure 3 shows the rear of measuring module 1. A
locating rib 36 on an exterior side wall of module 1 is
for engagement with a corresponding channel (not shown)
in the face of plate 3 shown in Figure 1 to orient the
module 1 for correct alignment between plates 2 and 3, as
shown in Figure 1. Figure 3 also illustrates a preferred
construction of the liquid level sensing device 28 of the
invention which comprises two prism elements 37 and 38
disposed opposite each other across channel 27 with gap
39 between them. Prism elementæ 37 and 38 are made of a
light- transmi6sive material and can conveniently be
fabricated from a clear plastic material such as
polystyrene, polycarbonate or an acrylic plastic.
Preferably, with the exception of diaphragm 35, module 1
is entirely made from such a material, typically in two
halves by in~ection molding which are then glued together
to form module 1. Such a construction allows the module
¦ 1 to be made inexpensively and therefore it can be
¦ 20 disposed of after use. ~his has the advantage of making
the unit relatively inexpensive and avoiding
contamination. Indeed, module 1 with its inlet and
outlet tubes 7 and 8, respectively, and the collection
bag 9 can be sold as a single, disposable, sterilizable
unit which provides a greater convenience in the
operation of the equipment of this invention.
The liquid level sensing system 28 of this lnvention
is shown in greater detail in Figure 6 which shows, in
partial cross-section, the level sensing system 28 in
memory module 1 when in place between plates 2 and 3.
Prism element 38 is a solid, radiation transmissive,
substantially cylindrical shaped body in axial alignment
with a source of radiation 40a located in a chamber 40
inside plate 2. ~he source of radiation is preferably a
light-emitting diode which emits a beam of infrared
~:
~Z6'3~7
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light through a collimating channel 41 in plate 2 along
the axis of that channel to impinge upon an input face 42
of prism element 38 which lies in a plane ~ubstantially
perpendicular to the axis. ~he light then travel~ down
element 38 to an output face 43 which lies in a plane at
an acute angle ~ to the axis of that element, as is shown
in Fi gure 7. Across the gap 39 in channel 27 betwsen
elements 38 and 37 is an input face 44 of element 37.
Input face 44 i6 for receiving light from element 38 and
transmitting it down elemen~ 37 to exit face 45 of prism
element 37 which lies in a plane substantially
perpendicular to an axis in alignment with a collimating
channel 46 in plate 3 which leads to a chamber 47 in that
plate containing a photodetector 47a. Usually, the
light-emitting diode, elements 38 and 37 and the
photodetector will be aligned along a common optical axis
shown by the broken line XX in Figure 6. To improve
optical transmi66ion and minimize entry of stray light
into elements 37 and 38, the external ends of these
elements 42 and 45, respectively, at the outer walls of
module 1 are preferably surrounded by annular air spaces
48 and 49, respectively, around the terminal portions of
elements 37 and 38 at ends 42 and 45 and cut into the
body of module 1. These annular areas exposed to the air
and endæ 42 and 45 are polished to an optical finish for
that improvement. Elements 37 and 38 can either be
insert6 into the body of mea6uring module 1 or, more
preferably, can be formed integral therewith.
The operation of level detector 28 can be understood
more readily by reference to Figures 7 to 10. Figure 7
show6 the pa66age of a light beam A through element 38
and into 6pace 39 in channel 27 when liquid has not
ri6en into that space. Under the6e circumstances, the
light beam is refracted at output face 43 of element 38
at the interface between the body of that element and the
`
~26~3(~7
- 14 -
air gap so as be directed away from receiving element 37
in the direction of arrow A. This refraction occurs due
to the difference in the refractive index between air and
prism element 38. Consequently, the light beam does not
reach the photodetector which remains inactive.
Referring to Figure 8, when liquid 50 rises into the
space 39 between elements 37 and 38 the light beam
remains substantially unrefraoted at the interface of the
liquid 50 and element 38, and this impinges upon element
lC 37, to pass along it in the direction of arrow B to be
received by the photodector 46a. This occurs because the
refractive indices of the urine and prism element 38 are
substantially equal. This activates the photodetector to
indicate that the predetermined volume of liquid has been
collected by the measuring chamber. Preferably, the
receiving face 44 of element 37 is parallel to that of
element 38 as shown in Figures 7 and 8. However, the
receiving face 44 can be substantially perpendicular to
the axis of that element as shown in Figure 9. In a
similar manner to Figure 7, when there is no liquid
between the prisms 37 and 38 the light beam from first
prism 38 in Figure 9 will be refracted away from second
prism 37, as shown by arrow C. A further alternative
¦ construction is shown in Figure 10, where elements 37 and
38 have conical faces 51 and 52 acros6 space 39. Under
these circumstances, elements 37 and 38 are preferably
slightly axially offset since deposits can form on the
tips of the cones which tend to transmit light directly
from transmitting element 38 to transmitting element 37
even when there is no body of liquid between the two
elements. Again, Figure 10 shows the light beam D being
refracted away from second prism element 37.
As is shown, in Figure 7, the output face 43 of
first prism element 38 lies in a plane at an aaute angle
~ to the axis of that element. It has been found that if
- 15 -
this angle i6 less than about 30 light tends to leak
from the prism to pass into the other prism element 37
and also tends to allow wetting of face 43 which can make
that face act as a lens to conduct light to the other
prism element. On the other hand, if angle a is much
more than about 60 , the separation required between the
two prism elements becomes ~o large that the accuracy
sensing device deteriorates. Therefore, angle a is
preferably form about 35-to about 60-, more preferably
from about 45- to about 50 and most preferably about 50
since thi~ angle represents the best compromise of low
leakage versus minimum separation.
The preferred keyboard arrangement for the control
unit in the apparatus of this invention is shown in
Figure 11. Eight keys are shown but, of course, a
different number with different functions could be used
as will be apparent to one skilled in the art.
Preferably, the software in the apparatus is
con6tructed 80 that data useful to the attendant and
display messages which are to be amended can be scanned
in a cyclic manner using the read data keys nos. 1 and 2
¦ (Figures 1 and 11). These keys access messages nos. 8, 9
¦ and 10, listed in Figure 12 which respectively relate to
the current collection period, the amount collected in
j 25 that period and the time and date; a showing of the low
volume alarm set; and the total collected for the last
number of hours set in the equipment.
As can be seen in Figure 12, the possible display
includes a number of warning messages nos. 1 to 7 and 12
to 14. No-1 warns that no measuring module is in place,
no. 2 th~t the measuring chamber is being emptied, no. 3
that the measuring chamber is not emptying properly, no.
4 that there is an electrical problem in the system, no.
5 that the e~uipment is conducting a self-test, no. 6
that the volume collected in the last collection period
~ 26 ~ & ~ ~
- 16 -
is less than that set as a minimum in the equipment, no.
7 that the collection bag iB full, no. 12 i8 the first
message displayed when the equipment is turned on, which
calls for the attendant to set the time and date, no. 13
indicates that the batteries are running low, and no. 14
is indication that the self-testing has been selected.
This self-testing can only be conducted by a technician
manipulating the internal circuit of the apparatus.
Key no. 3, shown in Figure 11, moves a cursor tnot
shown) along under the message displayed in panel 18 to
the point where it is desired to adjust the message. The
meS6age i8 then adjusted to increase numerically using
key no. 4 or to decrease using adjustment key no. 5. In
this manner the alarm levels, time, and date, etc. can be
ad~usted. Key no. 6, shown in Figure 11 cancels the
alarms. Key no. 7 illuminates panel 18 and key no. 8 is
a general cancel key.
Referring to Figure 13, there is shown the schematic
control circuitry 53 for the control unit 6. The central
processing unit CPU 54 of the circuitry 53 controls the
functions of the apparatus. This is a conventional
microproce6sor sold by OKI-Data, Item No. 80C39. This is
a CMOS microproaessor with an EPROM memory. Thi6
microprocessor i8 connected through a data bu6 to the
display panel 18, which has on its underside an
electroluminescent light 55 which may be turned on at the
command of the attendant. Panel 18 can be a liquid
crystal display or, more preferably to accommodate more
characters, a dot matrix display. The apparatus 6 has
associated with it an operating keyboard 516, including
keys No. 1, No. 2, No. 3, No. 4, No. 5, No. 6, No. 7 and
No. 8 (as 6hown in Figure 11). The attendant provides
various command inputs to the CPU 54 by depressing one
or more of the keys. ~his will be discussed in greater
detail in connection with the flow chart shown in Figures
~r:,
~26~7
- 17 -
14A and 14B. A real time clock 56 is connected to the
CPU 54 and it functions to cycle the control circuitry 53
between a lower power and high power mode of operation.
~he control circuitry 53 is provided with an alarm
system for providing both an audio and vi6ual alarm when
the rate of urine flow is too low, the collection bag is
full, or both. This alarm system includes an electronic
~witch 57 and a light 58 which is carried on the housing
5 at a position that is readily observable by the
attendant. A buzzer enable switch 59 permits the
attendant to disable the buzzer 60 if desired.
The CPU 54 is driPen by four standard D size
alkaline batteries 61. These batteries 61 are connected
to the CPU 54 through a control switch 62 and voltage
regulator 63 to adjust the voltage so that it is
constant. There is also provided a low battery detect
aircuit 64 which will give a signal to the CPU 54 to when
the batteries need to be replaced. The CPU 54 is
electronically coupled to the optical sensor 28 and has
an output coupled to the actuator circuitry 65 for the
actuator 66 which operates the valve 31. Any suitable
mechanical device will serve as an activator for the
valve 31. The CPU 54 is programmed to open and close the
valve 31 in response to the signal from the optical
sensor 28.
The CPU 54 is programmed in accordance with
conventional practices. A programmer, by following the
flow charts set forth in Figures 14A and 14B, will be
able to program the OKI-Data processor to provide the
control functions indicated by the flow diagrams. It
will be appreciated however, that one skilled in the art
can devise different software to achieve the desire
results for the equipment of this invention.
~26~3~7
- 18 -
OPERATION
The operation of the apparatus of this invention
will now be discussed in connection with the flow
diagrams shown in Figures 14A and 14B, the control
circuitry 53 shown in Figure 13, the control panel shown
in Figure 11 and the panel mes6age6 shown in Figure 12.
The attendant initially turns on the power by closing
6witch 62. Message No. 12 (Figure 12) appears on the
display panel and he next sets the clock 56 if the clock
is not correctly telling the time of day. This is
accomplished by depressing key No. 3 for adjustment to
move a cursor to the part of the mes 8 age to be changed
and depressing either key No. 4 or key No. 5 to increase
or decrease the numbers d.isplayed. By setting the time,
all stored urine output data is erased form the memory of
the CPU 54.
The valve 31 is initially in the closed position as
shown in Figure 2, thus enabling the measuring chamber 23
to fill with urine. Typically, most patients will expel
urine at a rate in excess of 40 millilitres per hour. If
the patient does not urinate at this rate, a dangerous
condition exists and the buzzer alarm 60 iB actuated,
indicating to the attendant that this dangerous condition
exists. This alarm rate can be changed to another level,
if desired by calling up the level message No. 9 using
read data keys Nos. 1 or 2 and then changing the valve
using the select key No. 3 and adjust keys Nos. 4 and 5.
Whenever it is in the high power mode, the CPU 54
checks the inputs from the optical sensor 28 to determine
if the level of urine has reached the sensor. If it has
not, indicating that the chamber is not full, it then
checks to see if the collection period has ended. In
this case the collection period has been set for one
hour. If the hour has not changed, going from the first
to the second collection period in a series of, for
~26g~C'7
-- 19 --
example, 24 hours, the CPU 54 then checks to see if any
of the keys have been depressed. If they have, then the
function of the depressed key or keys will be performed.
Assuming none of these keys have been depre6sed by the
attendant, the CPU 54 then automatically switches to the
idle mode.
Assume that when the CPU 54 comes out of the ldle
mode it detects that the chamber 23 is full. When this
event occurs, the CPU 54 then activates the valve
actuator 66 and opens the valve 31. It automatically
then closes the valve 31 after a æufficient time is
paæsed to permit the chamber 23 to drain the ten
millilitres of urine collected. At this point, the CPU
54 then adds 10 millilitres to the count of urine
collected for the collection period in question. In
other words, if the first ten millilitres were collected
during this hour, the number ten (10) is added to the
memory of the CPU 54, indicating that the first ten
millilitres had been collected. This is the first lO
millilitres for that hour and no urine output data has
been previously stored in the memory for this first hour.
If it was the third reading in the hour, the data stored
in the memory would indicate that 30 millilitres had been
collected for the hour. This proce6s of monitoring the
level of urine in the chamber 23, emptying the chamber 23
when ten millilitre6 has been collected, and then adding
ten millilitre6 to the memory of the CPU 54, is continued
throughout the course of the collection period, in this
case, one hour. this collection process is continuous.
The CPU 54 i8 programmed (1) to count the number of
times the chamber i8 filled with 10 millilitres of urine
during the one hour collection period, (2) to store this
number in the memory, and (3) then, during the next hour,
repeat this operation storing the number of times the
chamber is filled in separate storage in the ~emory for
~26900~
- 20 -
the next hour in the 6eries of 24 hour collection
periods. This is accomplished by the CPU 53 being
programmed to check to determine if the hour has changed.
I ~ the hour has changed, t~e measurement corresponding to
the volume of urine is then placed in a separate storage
register which may be accessed at any time during the 24
hour cycle by the attendant. This is accomplished by
simply depressing the No. 1 or 2 keys to cycle the
available mes6ages on the display screen until the
desired message i8 diBplayed.
At the end of each hour, the program checks to
determine if during that hour less than 40 millilitres of
urine was produced, or whatever minimum has been entered.
If the urine production is less than that minimum per
hour, then the CPU 54 will display a low volume message
No. 6 (Figure 12) and actuate the audio and visual alarm
indicating to the operator that a dangerous condition
exists. In addition to checking for the rate of urine
production, the CPU 54 is also programmed to check the
level of urine in the bag. For example, if the bag being
used i6 capable of holding 1800 millilitres of urine, the
CPU 54 is programmed to check when 1800 millilitres of
urine has been collected, indicating the bag is full. If
this i6 the case, then the bag full indicator is actuated
to sound the buzzer 60 alarm and the bag full message No.
7 will be displayed. Pressing the No. 6 key on the panel
will cancel the low volume or the bag full alarm. In
many instances it will be desirable to illuminate the
display panel 18. This is accomplished by actuating a
switch by depressing the No. 7 key.
