Fluid monitoring apparatus

Apparatus for accurately and more safely monitoring blood and bodily fluids in a patient. In one embodiment, at least one load cell supports a container for receiving various sizes of sponges that hold such fluids. The sponges may be sorted into the container utilizing a sorting grip located above or forming a part of the container, and photoelectric or other sensors detect the number of sponges placed into the container via each opening in the grid. The load cells and sensors are connected to controller circuitry which counts, tracks and displays the number of each size of sponges in the container and the weight of fluid in the sponges. The weighing apparatus may be connected to a computer that is programed to read information from the weighing apparatus and from its own keyboard to calculate, update, store, display and print values corresponding to amounts of suction products, urine, crystalloids, irrigation, miscellaneous blood products including whole blood, fresh frozen plasma, packed red blood cells, platelets, cryoprecipitates and stimates introduced to or removed from the patient. The processor of the weighing apparatus may be adapted to perform the computer's functions in order to reduce the size of the apparatus. Alternatively, a computer without a weighing apparatus may be used to account for the values mentioned above, in which case the operator manually enters information relating to numbers and weights of sponges.

This invention relates to monitoring weight and quantity of fluids in a 
patient during surgery. 
BACKGROUND OF INVENTION 
Loss of blood and bodily fluids during surgery is presently accounted for 
by antiquated methods. Sponges of uniform size are used to absorb the 
blood and fluids and the sponges are laid out on a fabric or plastic sheet 
or otherwise arranged where they can be easily inspected and counted. This 
task typically falls on the anesthesiologist who visually estimates the 
quantity of blood and fluids contained in the sponges. 
Estimating loss of blood and fluids by examining sponges is an art. 
Conventional wisdom holds, for instance, that surgeons tend to 
underestimate blood loss while anesthesiologists overestimate it. Further, 
fluid may evaporate as sponges lie waiting to be counted and thus cause 
estimations to vary. Surrounding material, such as fabric on which the 
sponges are placed, can also absorb fluid and affect the estimate. 
Blood and other body fluids have also recently begun to be thought of as 
biocontaminants which require careful handling, management and control. 
Earlier techniques such as laying sponges out on sheets to account for 
blood loss are thus more frequently thought of as unacceptable. The need 
arises for a way to account for body fluids from the patient while at the 
same time ensuring minimum risk of contamination from such fluids. 
SUMMARY OF THE INVENTION 
The present invention allows efficient, effective and safer accounting for 
blood and other fluids which are introduced into or lost from the patient. 
A first embodiment of the invention allows for accounting of sponges that 
contain fluids removed from the patient. This weighing apparatus includes 
a container for receiving such sponges. A sorting grid located above the 
container forms two or more openings which correspond in size to 
predetermined sizes of sponges. At least one photoelectric cell or other 
sensor is mounted to monitor the space below each opening and above the 
container for detecting when a sponge is placed in the opening and falls 
into the container. The sponge container is supported by a platform which 
is in turn supported by a load cell. The grid may alternatively form the 
top of the container, and the container may include transparent portions 
on its side surfaces which allow the photoelectric cells to count sponges. 
The load cell and sensors are connected via conventional input/output means 
to a processor which is programmed to read signals from the load cell and 
sensors, calculate values relating to numbers of each type of sponge and 
weight of fluids in the container, and to update and display those value. 
The weighing apparatus may include rocker or other switches for manually 
altering information relating to numbers of sponges and it also is capable 
of receiving other control information such as tare, span, zero and other 
commands. 
The weighting apparatus may be connected to a processor or computer whose 
keyboard is used to enter other information that relates to other fluids 
introduced to or taken from the patient, such as suction fluids, urine, 
crystalloids, irrigation solution, miscellaneous blood products, fresh 
frozen plasma, packed red blood cells, platelets, cryoprecipitate and 
stimate. A preferred embodiment of the invention allows real-time 
updating, storage, display and printout of information relating to 
quantities of such fluids. The computer may be a customized unit with 
adequate processing and memory capabilities together with an appropriate 
display and a membrane keyboard such as those found in fast-food 
restaurants. 
The weighting apparatus may alternatively include computing means to give 
it the manual data entry, updating, storage, display and pringitn 
capabilities of the weighting apparatus with computer mentioned above. A 
computer may also be used without the weighing apparatus; in that event, 
the operator manually enters information into the computer relating to 
sponge counts and weight of fluid in the sponges. 
It is thus an object of the present invention to provide apparatus for 
accurate and automated tracking of fluids removed from a patient. 
It is an additional object of the present invention to provide a device for 
accounting for and weighing sponges that contain body fluids of a patient 
in surgery, and to allow those sponges to be controlled in order to reduce 
risk of contamination. 
It is an additional object of the present invention to provide apparatus 
for weighing and accounting for sponges that contain fluid removed from a 
patient, receiving information manually entered on a keyboard relating to 
weight or volume of fluid introduced into or removed from the patient, and 
updating, storing, displaying and presenting such information on a 
real-time basis and in an attractive and convenient format. 
It is an additional object of the present invention to provide apparatus 
for documenting weight and volume of fluids in a patient during the course 
of surgery. 
It is an additional object of the present invention to provide apparatus 
for accurately quantifying weight and volume of blood and other body 
fluids in a patient during the course of surgery to allow for more 
effective and efficient management of those fluids. 
Other objects, features and advantages of the present invention will become 
apparent with reference to the remainder of the specification, claims and 
drawings contained in this document.

DETAILED DESCRIPTION OF THE DRAWINGS 
FIG. 1 shows an embodiment of a fluid monitoring apparatus 10 according to 
the present invention. Device 10 comprises a weighing apparatus 12 and an 
accounting apparatus 14 which can be connected to weighing apparatus 12. 
Weighing apparatus 12 holds a container 16 for receiving sponges 18 (not 
shown) that have absorbed fluids from the patient whose fluids are being 
monitored. Container 16 may be a plastic basket or other receptacle of 
desired size, shape, weight and material. Container 16 can contain a 
protective bag 20 whose opening can be twist-tied or otherwise sealed when 
sponges 18 are disposed of in order to minimize possibility of 
contamination of the surgical suite or other areas by sponges 18. 
Container 16 may alternatively be a cardboard foldable box 17 as shown, for 
instance in FIGS. 4-6. Such a container 16 allows sponges to be disposed 
of in box 17 while they are counted and weighed at the same time by device 
10. This configuration reduces possibility of biocontamination from fluids 
in the sponges. 
Container 16 is supported by a platform 22 which may be of stainless steel 
or other desirable material. Platform 22 is supported in turn in part by 
one or more load cells 24 (not shown). Load cells 24 contain piezoelectric 
crystals or other devices which generate an electrical signal proportional 
to the degree of their deformation and thus proportional to the load 
placed upon them. 
The container 16, platform 22 and load cells 24 may be surrounded by a 
housing 26 which may be of any desired shape and material. It may contain 
casters or wheels 28 for mobility and one or more doors 30 (not shown) for 
closing off housing 26 once container 16 is in place. 
Located above container 16 and mounted on or connected to housing 26 is a 
sorting grid 32 which forms one or more openings 34 that correspond to 
predetermined sizes of sponges 18. For instance, a first opening 34 may 
correspond to small sponges, a second to medium sponges and a third to 
large sponges as shown in FIG. 1. Various sorting grids 32 may be utilized 
in connection with weighing apparatus 12 depending upon sizes and types of 
sponges utilized in the surgical suite. Openings 34 are useful, in 
connection with sponge counters discussed below, in allowing the 
anesthesiologist or other person utilizing the apparatus to ensure that 
the number of sponges utilized during surgery matches the number disposed 
of so that no sponges are inadvertently misplaced or left in the surgical 
suite or the patient. 
A photoelectric or other desirable sensor 36 is mounted in housing 26 so 
that its optical path 38 intersects the space 40 below an opening 34 and 
above container 16. A reflector 42 may be mounted across the space 40 for 
reflection of optical signals from the sensor 36 so that it generates an 
electrical signal every time a sponge 18 is dropped through its 
corresponding opening 34 and into container 16. In the embodiment shown in 
FIG. 1, three sensors 36 are used, each corresponding to an opening 34. 
More sensors 36 may also be used, or fewer sensors 36 which are configured 
to operate with split photoelectric screens. 
Load cells 24 and sensors 36 are connected to electronic controller 44, as 
shown schematically in FIG. 15, which is in turn connected to switches and 
displays on control panel 46 of weighing apparatus 12. 
FIG. 2 shows a partial cross-section side elevational view of the weighing 
apparatus 12 of FIG. 1. The intersection of optical path 38 of 
photoelectric sensor 36 with space 40 below opening 34 and above container 
16 is apparent in this figure. 
Container 16 formed as a box 17 as shown in FIGS. 4, 5 and 6 includes 
sorting grid 32 as its top surface. Box 17 may be formed of coated 
corrugated material, plastics or other appropriate material. As shown in 
FIGS. 4-6, such a unitary container 16 may fold accordion-style for 
shipping and disposal. Top surface of box 17 forming grid 32 and openings 
34 may be formed of plastic or other appropriate material which is bonded, 
glued or otherwise connected to the remainder of box 17. Alternatively, 
grid 32 may simply be part of the cardboard or other material forming the 
box 17, and openings 34 may simply be holes cut in the top surface. 
Unitary container 16 as shown in FIGS. 4-6 contains windows 19 and mirrors 
21 for cooperating with sensors 36 to count sponges 18. Windows 19 may be 
formed of plastic film bonded, glued or otherwise attached to sidewalls of 
box 17, or they may simply be portions of a plastic liner of box 17. 
Mirrors 21 may be reflective tape attached to the interior surface of box 
17 sidewalls. 
Box 17 also preferably has a cover 23 which may be secured into place with 
snaps, hook and loop fastener or other appropriate fasteners to seal box 
17 for disposal. A unitary container 16 as described in these three 
paragraphs can thus be supplied in compact form, used in its unfolded 
state and then sealed and secured for disposal in order to reduce the 
likelihood of contamination from fluid in sponges 18. 
Controller 44 of weighing apparatus 12 comprises a processor means 48, a 
storage means 50 connected to processor means 48, and an input/output 
means 52 connected to processor means 48. In the embodiment shown in FIGS. 
1 and 15 processor means 48 and storage means 50 are found on a processor 
board manufactured by Computer Dynamics of South Carolina having product 
number CPU-9-4-R-32-DB. The board contains a Z80 microprocessor, 32K 
random access memory ("RAM"), 32K read only memory ("ROM"), 2 RS232 serial 
ports, 2 timers and a battery operated clock. An analog input board, 
having product number DAD-48, also supplied by Computer Dynamics, forms a 
portion of input/output means 52 to allow controller 44 to communicate 
with load cells 24. Input/output means 52 also comprises a PIO-64 digital 
interface board and a PIO-16 digital interface board to allow controller 
44 to communicate with display means 54 and switches on control panel 46 
respectively. These boards are also supplied by the Computer Dynamics 
Company. 
The controller 44 of weighing apparatus 12 of FIG. 1 is powered by a 
Computer Dynamics QMB10.5PS8T/P/S powered STD rack which can be connected 
to a 105-125 V 60 Hz power source. 
Display means 54 on control panel 46 as shown in FIG. 2 comprises an 
Industrial Electronic Engineers 03700-02-012 twelve digit fluorescent 
display and an Industrial Electronic Engineers 03700-060020 twenty digit 
fluorescent display for displaying weight of fluid contained in sponges 
18, number of sponges 18 which have passed through each sorting grid 
opening 34 and other information. Display means 54 may just as readily 
comprise a liquid crystal display, light emitting diodes, a cathode-ray 
tube or other desirable visual display. 
Sensors 36 in the embodiment shown in FIG. 1 each comprise a Micro Switch 
PK 9091 2 photoelectric modulated infrared sensor head with PK 9093 2 
sensor base and PK 9094 0 multi-function timer/logic card. Other desirable 
sensors may also be used. 
Switches shown on control panel 46 in FIG. 3 comprise three single pole 
double throw momentary paddle switches 56 for incrementing and 
decrementing sponge counts corresponding to each sorting grid opening 34, 
and five single pole single throw momentary push button switches for span 
switch 58, tare switch 60, zero switch 62, hold switch 64 and clear switch 
66 shown on control panel 46 in FIG. 3. A single pole single throw keylock 
switch 68 controls access to operation of weighing apparatus 12 and allows 
it to be actuated. A block diagram of processor means 48, storage means 
50, and input/output means 52 of controller 44 of weighing apparatus 12 is 
shown in FIG. 15. 
The following are field wiring diagrams for the PIO-64 digital interface 
board and the PIO-16 digital interface board. 
__________________________________________________________________________ 
PIO-64 Destination 
Conn. 
Pin 
Chan. 
Bit 
Signal Name Connector 
Pin 
__________________________________________________________________________ 
P1 7 50 3 Display, Upper, TO 
Upper Display 
l 
P1 9 50 4 Display, Upper, CS 
Upper Display 
3 
P1 11 50 5 Display, Upper, RD 
Upper Display 
5 
P1 13 50 6 Display, Upper, AO 
Upper Display 
7 
P1 15 50 7 Display, Upper, WR 
Upper Display 
9 
P1 17 51 0 Display, Upper, Data-0 
Upper Display 
25 
P1 19 51 1 Display, Upper, Data-1 
Upper Display 
23 
P1 21 51 2 Display, Upper, Data-2 
Upper Display 
21 
P1 23 51 3 Display, Upper, Data-3 
Upper Display 
19 
P1 25 51 4 Display, Upper, Data-4 
Upper Display 
17 
P1 27 51 5 Display, Upper, Data-5 
Upper Display 
15 
P1 29 51 6 Display, Upper, Data-6 
Upper Display 
13 
P1 31 51 7 Display, Upper, Data-7 
Upper Display 
11 
P2 7 54 3 Display, Lower, TO 
Lower Display 
1 
P2 9 54 4 Display, Lower, CS 
Lower Display 
3 
P2 11 54 5 Display, Lower, RD 
Lower Display 
5 
P2 13 54 6 Display, Lower, AO 
Lower Display 
7 
P2 15 54 7 Display, Lower, WR 
Lower Display 
9 
P2 17 55 0 Display, Lower, Data-0 
Lower Display 
25 
P2 19 55 1 Display, Lower, Data-1 
Lower Display 
23 
P2 21 55 2 Display, Lower, Data-2 
Lower Display 
21 
P2 23 55 3 Display, Lower, Data-3 
Lower Display 
19 
P2 25 55 4 Display, Lower, Data-4 
Lower Display 
17 
P2 27 55 5 Display, Lower, Data-5 
Lower Display 
15 
P2 29 55 6 Display, Lower, Data-6 
Lower Display 
13 
P2 31 55 7 Display, Lower, Data-7 
Lower Display 
11 
__________________________________________________________________________ 
PIO-16 Destination 
Conn. Pin 
Chan. 
Bit 
Signal Name 
Connector 
Pin 
__________________________________________________________________________ 
J1 47 81 7 Switch, Large + 
Panel T1 
4 
J1 45 81 6 Switch, Large - 
Panel T1 
5 
J1 43 81 5 Switch, Medium + 
Panel T1 
6 
J1 41 81 4 Switch, Medium - 
Panel T1 
7 
J1 39 81 3 Switch, Small + 
Panel T1 
8 
J1 37 81 2 Switch, Small - 
Panel T1 
9 
J1 35 81 l Switch, Tare 
Panel Tl 
10 
J1 33 81 0 Switch, Zero 
Panel Tl 
11 
J1 31 80 15 Switch, Span 
Panel T1 
12 
J1 29 80 14 Switch, Clear 
Panel T1 
13 
J1 27 80 13 Switch, Hold 
Panel T1 
14 
J1 25 80 12 Switch, Calibrate 
Panel T1 
15 
__________________________________________________________________________ 
The control program for the controller 44 of weighing apparatus 12 shown in 
FIG. 1 is written in the "C" language to execute on the Z80 processor. The 
program while running reads the weight from the load cells 24, subtracts 
the tare weight of sponges 18 from the load cell weight and multiplies by 
a predetermined factor to obtain blood loss, displays the computed weights 
and displays current counts for different sponge sizes. 
During normal operation, the upper portion of display means 54 indicates 
the approximate fluid contained in the sponges that have been dropped 
through the openings 34 in sorting grid 32. When other functions are 
selected, the upper portion of display means 54 may display the actual 
weight in grams or instructions to the operator if instructions are 
required. The lower portion of display means 54 during normal operation 
indicates the number of sponges which have been counted by sensors 36. 
During other functions the lower portion of display means 54 may show 
messages and data appropriate for those functions. 
The program contains routines utilized for spanning, taring, zeroing, 
holding and clearing in connection with switches 58, 60, 62, 64 and 66. 
When the span button 58 is pushed, controller 44 calibrates the span of 
weighing apparatus 12. The first step of the procedure displays the 
reading from load cell excitation. Excitation is factory set, and in the 
embodiment shown in FIG. 1 it should be 20,000 which represents eight 
volts of excitation. Depressing the span switch 58 enables the second step 
of the procedure which displays the weight in grams in the upper portion 
of display means 54 and the span multiplier in the lower portion. By 
placing a calibrated weight on the scales and adjusting the multiplier 
with the counter switches 56 until the displayed weight is equal to the 
marking on the calibrated weight, the operator can set the span to weigh 
fluid in sponges 18 more accurately. 
The tare switch 60 initiates a procedure to measure and enter the weights 
of dry sponges 18 into the controller 44. As sponges 18 are entered the 
dry weight is subtracted from the wet weight to determine liquid in the 
sponges. The procedure displays instructions to the operator for each 
step. The zero switch 62 removes the difference between load cell 24 zero 
and what the operator would have the weighing apparatus 12 display as zero 
to account for variation in weights of containers 16 and protective bags 
20. When either is replaced, the operator should depress the zero switch 
62 to ensure that weighing apparatus 12 is starting from zero weight when 
weighing the sponges. 
The hold switch 64 enables the operator to process more than one bag 20 of 
sponges 18 without manually recording the count and weight of sponges in 
previously filled bags 20. Depressing the hold switch 64 adds the current 
values of the sponge counters 70 (not shown) in storage means 50 of 
controller 44 and the estimated fluid loss to values (starting at zero) 
held in storage means 50 and it zeros the counters 70. The display will 
remain the same because the sum of memory plus the current value is 
displayed. However, the upper portion of display means 54 will display 
more fluid loss because controller 44 is no longer subtracting the tare 
weight of sponges 18 that are in bags 20 which have been removed from 
apparatus 12. The container 16 in apparatus 12 at the time the hold switch 
64 is depressed should be removed and after a fresh bag 20 has been placed 
in container 16, the zero switch 62 should be depressed to maintain 
maximum accuracy. 
The clear switch 66 enables the operator to reset sponge counters 70 to 
zero. Only the current counters are reset, and any non-zero quantities in 
the "held" registers will be displayed. To zero the quantities in the 
"held" registers the power may be removed from the unit or the clear 
switch 66 may be depressed while keylock switch 68 is positioned in the 
"calibrate" position. 
The counter switches 58 enable the operator to correct the values in sponge 
counters 70. Pressing a switch 56 down increments the count by one and 
lifting up the switch decrements the count by one. While apparatus 12 is 
in the "span" function the counter switches 56 increase or decrease the 
span multiplier in order to adjust the displayed weight to the standard 
weight. The amount of adjustment is greatest with the left-most switch and 
least with the right-most switch. 
The keylock switch 68 enables an operator with a matching key to select 
either the "calibrate" or "run" mode. In the run mode, the span switch 58 
and tare switch 60 are disabled to prevent inadvertent changes to internal 
parameters during an operating session. In the calibrate mode all 
functions available in the run mode are active plus the span and tare 
functions. Additionally, positioning the keylock switch 68 in the 
calibrated position enables the clear switch 66 to clear the "held" sponge 
counter 70. (When keylock switch 68 is in the "run" position, the clear 
switch 66 clears only current sponge counters 70.) 
Pseudo-code for the controller 44 program which accomplishes these 
functions is shown below: 
______________________________________ 
Main Program: 
Initialize variables. 
Initialize communication channels. 
Display program identification messages. 
Wait for scales to warm up. 
Send initialization message to host computer. 
Initialize switch input card (PIO-16) to interrupt to 
Read Switch program below. 
Do forever: 
Wait for a switch to be depressed, a signal from 
host communications device, or time to update the 
screen. 
Case wait condition of 
Time to update the display: 
Read weight from scales. 
Subtract tare weight of sponges from scale 
weight and multiply by factor to get 
estimated blood loss. 
Display weight computed above. 
Display current counts for different size 
sponges. 
Switch depressed: 
Case Switch Depressed of: 
Span: If Calibrate key is on then enter 
span procedure. 
Zero: Adjust scale offset to display 
zero weight. 
Tare: If Calibrate key is on then enter 
tare procedure. 
Hold: Add current weight and counts to 
hold registers. 
Clear: Change current count values to 
zero. 
Small+: Increment small sponge count. 
Small-: Decrement small sponge count. 
Medium+: Increment medium sponge count. 
Medium-: Decrement medium sponge count. 
Large+: Increment large sponge count. 
Large-: Decrement large sponge count. 
Communications Signal: 
If a character has received and is the request 
to send data then Construct message with 
estimated fluid loss and switch counts and 
set "send message" flag. 
If the "send messge" flag is on and the device 
is ready to send a character then send the 
next character of the message. 
If all of the message has been sent then reset 
the "send message" flag. 
End of Program. 
Switch Interrupt Procedure. 
Wait 30 milliseconds. 
Read switches. 
End of Switch Interrupt Procedure. 
______________________________________ 
The weighing apparatus 12 shown in FIG. 1 may be operated as follows: To 
start the process, apparatus 12 should be connected to a standard 105-125 
V 60 hz power source and allowed a minimum of 30 minutes for warmup. 
Displayed weight on display means 54 will stop fluctuating when apparatus 
12 is ready for use. Apparatus 12 should be zeroed by depressing the zero 
switch 62 and following the instructions shown on display means 54. 
Container 16 and bag 20 should be in place at this time. 
Apparatus 12 must be initialized if sponges 18 are not of the type normally 
used with apparatus 12. If different sponges are used, the operator must 
initialize the apparatus 12 by pushing the tare switch 60 and following 
instructions on display means 54 to establish dry or tare weight of 
sponges 18. The operator should then ensure that the upper portion of 
display means 54 reads "zero" plus or minus ten and that the lower portion 
of display means 54 shows zeros corresponding to sponge counts. 
Each sponge taken from the patient should be separated from others and 
dropped through the proper opening 34 in sorting grid 32. The count 
portion of the display means 54 corresponding to sponge count for that 
opening 34 should increment by one for each sponge that is dropped through 
the opening 34. If a sponge is missed by sensor 36, such as when two 
sponges are stuck together, the count may be corrected by pressing the 
appropriate counter switch 56 down. If a sponge is counted twice, such as 
if it sticks in opening 34 and swings back and forth, the count may be 
corrected by lifting the proper counter switch 56 once. 
When a container must be changed, the operator should press the hold button 
64 to hold the current weight and sponge count. The container 16 and bag 
20 should be removed from apparatus 12 and bag 20 replaced with a new bag. 
After container 16 and new bag 20 are in place in apparatus 12, the 
operator should press the zero button 62 to remove any difference in bag 
weights that may exist. The fluid quantity and sponge count shown on 
display means 54 should remain the same as they were before the hold 
button 64 was pressed. The operator then resumes using apparatus 12. 
To span apparatus 12, the operator positions the keylock switch 68 to the 
"calibrate" position and zeros the apparatus 12 to ensure that the read 
out on display means 54 is stable. The operator then presses the span 
switch 58 and records the excitation value from the lower portion of 
display means 54. This value should be 20,000 plus or minus ten percent. 
The operator then presses the span switch 58 once again and display means 
54 instructs him to place a standard weight on platform 22. The operator 
then places the standard weight on platform 22 and depresses the span 
button 58 a third time. He can then adjust the multiplication factor 
displayed on lower portion of display means 54 by pressing counter 
switches 50 until the value on upper portion of display means 54 is the 
same as the weight stamped on the standard weight. The steps beginning 
with zeroing the apparatus 12 are repeated until the value on the upper 
portion of display means 54 is zero plus or minus two while zeroing and 
the standard value while spanning. The operator then positions the keylock 
switch 68 to the run position. 
The tare procedure may be performed at any time during an operation. 
However, the dry weight values established for sponges 28 will be 
subtracted for the quantity of sponges shown in the current display when 
the procedure is complete. The operator positions keylock switch 68 to 
"calibrate" and presses the tare switch 60. Apparatus 12 instructs the 
operator serially to place a number of a certain size of sponge on 
platform 22. The operator does so and then repeats the steps beginning 
with pressing tare switch 60 for each size of sponge to tare sponge 
weights. The quantities of various sponge sizes used for tare calibration 
procedure will be added to the displayed current sponge count and should 
not be removed from container 16 without correcting the sponge quantities 
displayed. 
The weighing apparatus 12 may also be utilized with an accounting apparatus 
14 which allows for entry of information relating to other types of blood 
components and fluids introduced to or taken from the patient. Accounting 
apparatus 14 shown in FIG. 1 is a personal computer 72 comprising a 
processor means 74 (not shown), an input/output means 76 (not shown) and a 
storage means 78 (not shown) which are conventional. A conventional 
keyboard 80 and a display means 82 such as a monochrome, composite or RGB 
video monitor, or a liquid crystal display are connected to input/output 
means 76. In the embodiment shown in FIG. 1, controller 44 of apparatus 12 
is connected to computer 72 via RS232 ports on apparatus 12 and computer 
72. The two could also easily be linked by IR 232 means. Computer 72 may 
also be connected to a printer 84 for printing out information relating to 
weight and volume of fluid in the patient. In the embodiment shown in FIG. 
1, computer 72 is a Compaq portable IBM compatible computer with an 8086 
processor, 640 kilobytes of memory, a 10 megabyte hard disk drive, a 360 
kilobyte floppy disk drive, two asynchronous communications channels, a 
printer and a color monitor. Accounting software with supporting operating 
system and libraries allows computer 72 to read information from keyboard 
80 and from weighing apparatus 12, and update, store and display such 
information. 
Accounting apparatus 14 can also be a smaller, customized unit 73 as shown 
in FIG. 4. Unit 73 once again contains appropriate processor means 74, 
input/output means 76, storage means 78, display means 82 and, if desired, 
an integral printer 84. Unit 73 can include a membrane-type keyboard 81 
similar to those found in fast-food restaurants. The face 83 of keyboard 
81 contains keys that correspond to body fluid components which are 
tracked by apparatus 14. Such a face 83 is shown in FIG. 7. A 
telephone-type keypad has been found to be more convenient than a 
calculator-type keypad because a larger percentage of the population is 
more familiar with the telephone keypad. Other keys on the face 83 include 
function keys such as cursor control, numeric and graph keys. 
The accounting software for the embodiment of accounting apparatus 14 shown 
in FIG. 1 is written in the Pascal language. The program is MS-DOS based 
and utilizes a DOS-hosted "Power System" program supplied by Pecan 
Software Systems, Inc. It also utilizes software libraries "Insight Window 
Designer" and "Pascal Relational Database" also supplied by Pecan Software 
Systems, Inc. The Pascal compiler is a descendent of UCSD Pascal and is 
described by the book "The UCSD Pascal Handbook" which is incorporated 
herein by this reference. 
FIG. 16 shows organization of the software units. (See the UCSD Pascal 
Handbook for definition of a software unit.) The main unit "FluidTrac" 
calls the Initialize unit and initiates the operation of the Timer, the 
Scheduler and the Keyboard units. The Initialize procedure initializes the 
variables in the Global data area and accepts data about the operation 
which will be tracked. The Timer is triggered by the System Clock and 
subdivides the clock interruptions into signals for the Scheduler. The 
Scheduler examines the status of the Keyboard, Display and Scales 
processes and if the conditions are correct permits each process to 
execute. The Keyboard process accepts data entered from the keyboard. The 
Display process writes the data on the screen. The Scales process 
communicates with the weighing apparatus 12 and enters its data into the 
Global area. The following Pseudo-code describes the operation of each 
unit. 
______________________________________ 
FluidTrac program: 
Initialize insight window designer. 
Initialize. 
Draw main display window. 
Start Timer process. 
Start Scheduler process. 
Close opened files. 
Restart FluidTrac. 
End of FluidTrac program. 
Initialize procedure: 
Open necessary files. 
Clear all display variables. 
Read Initialization Data Base from disk. 
Open initialization window. 
Read character from keyboard. 
While the characters is not "Q" do 
Case character of 
P: Read Patient's name from keyboard 
A: Read Patient's age from keyboard. 
Estimate blood volume. 
W: Read Patient's weight from keyboard. 
Estimate blood volume. 
S: Read Patient's sex from keyboard. 
Estimate blood volume. 
H: Enter initial hematocrit. 
B: Enter estimated blood quantity. {overrides 
FluidTrac estimate} 
D: Enter doctor's name. 
U: Enter update period. 
L: Enter whether or not to print the log. 
End of Case 
Read character from keyboard. 
End of While. 
Initialize operational variables. 
Initialize log header. 
Initialize scales. 
Initialize and attach semaphores. 
Attach Timer to system clock. 
End of Initialize procedure. 
Scheduler Process: 
While the termination flag is not set do 
Wait for signal to run from Timer. 
If keyboard is not busy then 
Start Display. 
Start Scales. 
If a character has arrived from the keyboard then 
Set the keyboard busy flag to true. 
Signal Keyboard to continue. 
End While. 
End of Scheduler process. 
Timer Process: 
While not exit do 
If time to run processes signal Scheduler. 
If time to snapshot data for summary report then 
Take snapshot of data. 
Log current readings from Weighing Apparatus. 
End While. 
End Timer. 
Display Process: 
Display current time and time remaining in the current 
period. 
If the graph has been selected then 
If the values to be displayed on the graph do not 
fit on the screen at the current scale, 
increase the scale and display the message 
"Scale Changed." 
Update each bar graph to display current value. 
Else 
Check values for alarm and warning conditions and 
change color attributes to 
Green on Black 
Conditions are not to be checked. 
Black on Green 
Normal operating conditions. 
Black on Yellow 
Value either greater than 
positive warning level or less 
than negative warning level. 
White on Red Value either greater than 
positive alarm level or less than 
negative alarm level. 
Display values on screen. 
End of Display Process. 
Scales Process: 
If a message has arrived from the scales then 
Read message. 
If message includes the weight then put weight into 
display values. 
If message includes the sponge counts put the 
counts into the display values. 
If message includes the sponge tare weights put the 
new tare weights into the tare weight 
registers. 
Update values affected by values read in. 
End of Scales Process. 
Keyboard Process: 
While exit flag is not set do 
Read keyboard. 
Case keyboard of 
Fluids: Begin 
Read keyboard 
Case keyboard 
Suction: Enter suction 
value and update 
display values. 
Urine: Enter urine 
removed and 
update display 
values. 
IV: Enter crystalloid 
quantity infused 
and update 
display values. 
Irrigation: Enter irrigation 
solution used and 
update display 
values. 
End case. 
end{fluids} 
Blood 
Products: Begin 
Read keyboard 
Case keyboard of 
Blood: Enter quantity of 
miscellaneous 
blood products 
used. 
FFP: Enter quantity of 
fresh frozen 
plasma used. 
PRBC: Enter quantity of 
packed red blood 
cells used. 
PLTLTS: Enter quantity of 
platelets used. 
CRYPO: Enter quantity of 
cryoprecipitate 
used. 
STYMT: Enter quantity of 
stimate used. 
End Case 
Update display values. 
End{blood products} 
Sponges: Enter sponge quantity added 
Hematocrit: Enter new hematocrit reading. 
Graph: Change display to graph. 
Numeric: Change display to numeric 
display. 
Quit: Set exit flag to true. 
End while exit flag not set. 
Terminate the log. 
Take last data snapshot. 
Signal scheduler that keyboard process is finished. 
End of Keyboard process. 
______________________________________ 
The program executes in three phases: initialization, tracking and summary. 
In the initialization phase, the operator enters information about the 
patient that will appear on the log or be used to establish initial 
conditions. In the tracking phase, the operator enters information about 
fluids added to or removed from the patient and the program computes blood 
loss and fluid balance and displays the information in the form of 
graphics or tables. For example, fluids treated with a cell saver 
autotransfusion device can be tracked using the "suction," "irrigation" 
and "PRBC" buttons to account for fluid suction amounts removed from the 
patient, and to add the amount of the packed red blood cells scavenged by 
the device and transfused back into the patient. During the summary phase, 
the program prints bar graphs of some of the more important entries 
recorded during the tracking phase. 
The program uses a standard method of selecting functions and entering 
data. The top three lines of the display are reserved as standard 
information lines. The top line, as shown in FIGS. 8, 9 and 10, displays 
the name of the system and the button names which have been selected to 
reach the current menu. The last item on the first line is an expanded 
button description for the highlighted button on the second line. The 
second line is the button line which displays the menu selections 
currently available to the operator. By pressing the number of the button 
on the keyboard, the function named by the button will be executed. The 
third line is used for error messages, prompt messages, normal operator 
messages and data entry by the operator. 
FIGS. 17A and B show the hierarchy of menus to select the various functions 
available in the program. Processing is represented by rectangles, 
hierarchical selections are represented by buttons or ovals, and functions 
selected by buttons are represented by an oval inside a rectangle. Except 
where the "Quit" button has a line leaving to another process, pressing 
the "Quit" button returns to the next highest level in the hierarchy. For 
example, pressing "Quit" in the line of buttons under "Tracking Phase" 
will cause the "Summary Phase" to be entered and pressing "Quit" on the 
"Blood Products" line will cause the selections under "Tracking Phase" to 
be made available. 
Many of the functions require entry of data by the operator. At the proper 
time during the process, the program will request the information from the 
operator on the third line of the display. The operator may enter and edit 
an entry by using the keys, cursor controls and backspace until the entry 
is correct. The information is not processed until the "return" key is 
depressed. 
During the initialization phase the operator enters information which will 
appear on logs produced by the program or be used to set initial values 
used in the tracking phase. The format of the screen used during the 
initialization phase is shown in FIG. 8. Initial blood volume is computed 
utilizing age, weight and sex information entered in the initialization 
phase. That volume may be overridden by entry of initial blood volume 
utilizing the "Volume" button. Name and identification number of the 
patient and doctor may also be entered in the initialization phase. The 
operator presses the "Quit" button to terminate the initialization phase, 
and the program will notify the operator to prepare the weighing apparatus 
12 and the printer. During the tracking phase, the program processes 
interrupts from its clock and schedules other tasks which require 
attention. The "Scale" task processes messages from the weighing apparatus 
12, the "Keyboard" task processes entries from the keyboard 80 and updates 
the values to be displayed on display means 82, and the "Display" task 
updates the data shown on display means 82. FIGS. 9 and 10 illustrate the 
"Numeric" and "Graphic" screens which display the values entered or 
computed. 
The "Display" processor updates the values on display means 82 periodically 
(every 2 to 5 seconds) which have changed during the period. FIG. 11 lists 
the values displayed and the source of the data. 
The functions corresponding to the Tracking Phase buttons are as follows: 
(a) Top Level Menu 
I. Blood--select Blood Products Menu to add blood products infused. 
II. Fluids--select Fluids Menu to add fluids removed or added. 
III. Sponges--select Sponges Menu to account for sponges and fluid in the 
sponges used. 
IV. Hematocrit--select Hematocrit menu to record hematocrit values. 
V. Graph--select the graphics display (See FIG. 6). 
VI. Numeric--select the numeric display (See FIG. 5). 
VII. Quit--terminate fluid tracking. The program will ask the operator if 
he really desires to stop tracking in case he has pressed the "Quit" key 
by mistake. 
(b) Blood Products Menu 
1. Blood--enter the amount of miscellaneous blood products including whole 
blood infused since the last time recorded. 
2. FFP--enter the amount of fresh frozen plasma infused since the last time 
recorded. 
3. PRBC's--enter the amount of packed red blood cells infused since the 
last time recorded. 
4. Platelet--enter the amount of platelets infused since the last time 
recorded. 
5. Cryoprecipitate--enter the amount of cryoprecipitate infused since the 
last time recorded. 
6. Stimate--enter the amount of stimate infused since the last time 
recorded. 
(c) Fluids Menu 
1. Suction--enter the quantity of fluid in the suction container 
accumulated since the last time recorded. 
2. Urine--enter the amount of urine output since the last time recorded. 
3. IV--enter the amount of crystalloid infused since the last time 
recorded. 
4. Irrigation--enter the amount of irrigation used since the last time 
recorded. 
5. Quit--return to the Top Level Menu. 
(d) Sponge Menu 
(This menu is overridden when accounting apparatus 14 is connected to 
weighing apparatus 12.) 
1. Small 10--add 10 sponges to the small sponge count and the weight of the 
fluid in the sponges to fluid in sponges accumulator. 
2. Medium 10--add 10 sponges to the medium sponge count and the weight of 
the fluid in the sponges to fluid in sponges accumulator. 
3. Large 10--add 10 sponges to the large sponge count and the weight of the 
fluid in the sponges to fluid in sponges accumulator. 
4. XSmall--add X sponges to the small sponge count and the weight of the 
fluid in the sponges to fluid in sponges accumulator. 
5. YMedium--add Y sponges to the medium sponge count and the weight of the 
fluid in the sponges to fluid in sponges accumulator. 
6. ZLarge--add Z sponges to the large sponge count and the weight of the 
fluid in the sponges to fluid in sponges accumulator. 
7. Quit--return to Top Level Menu. 
The program during the tracking phase produces a log of entries as shown in 
FIG. 12. Each page has a header which contains the patient identification 
and doctor identification. Each line contains the following columns: 
1. Date--the date the event was entered. 
2. Time--the time using a 24-hour clock that the event was recorded. 
3. Source--a code to designate who recorded the event: F--the program; 
A--anesthesiologist at keyboard; N--nurse's station; and S--weighing 
apparatus 12. 
4. Event--description of the event. 
5. Quantity--if a quantity is associated with the event, e.g. Remove 
Suction, the quantity entered will be displayed in this column. 
6. Delta--the difference between the initial estimated fluid and the 
current estimated fluid. The initial fluid is entered or computed during 
the initialization phase. 
7. Fluid--the current estimated fluid level for the patient. 
During the summary phase, reports such as those shown in FIGS. 9 and 10 are 
produced. When the program is started, the operator is given the 
opportunity to change the period at which snapshots of fluid balance, 
urine output, crystalloid infused, estimated blood loss and blood products 
values are saved. The summary reports are a graphic representations of 
these values. FIG. 13 shows a fluid balance report and FIG. 14 shows the 
format of a urine report. The urine report format is also used for the 
crystalloid, estimated blood loss and blood products graphs. 
Weighing apparatus 12 and accounting apparatus 14 may be combined into a 
single machine whose processing means not only monitors load cells 24, 
sensors 36 and switches on control panel 46, but also a membrane or other 
keyboard connected to the machine to calculate, update, store, display and 
print the values discussed above. The storage means of the machine would 
preferably include mass memory devices such as a hard disk and one or more 
floppy disk drives, and additional RAM for storing the accounting program. 
The input/output means of the machine would connect the processor with the 
storage means, the load cells 24, the sensors 36, the keyboard, the 
printer and a video or liquid crystal display. Sponge switches 56, span 
switch 58, tare switch 60, zero switch 62, hold switch 64, clear switch 66 
and keyboard switch 88 could be eliminated by initiating their 
corresponding functions from the keyboard. A primary disadvantage of such 
a configuration, however, is that different personnel typically operate 
weighing apparatus 12 and accounting apparatus 14; one person handles the 
sponges and the other, typically the anesthesiologist, operates the 
accounting apparatus 14. 
Alternatively, the accounting apparatus 14, as discussed above, can be used 
without a weighing apparatus 12. In this event, the operator manually 
enters sponge counts and weights under the "Sponge" button in the Tracking 
Phase. 
The following are examples of actual use of the weighing apparatus and 
computer shown in FIG. 1. 
I. A known volume of bank blood (455 cc) was placed on three sizes of 
sponges. A known quantity (500 cc) of irrigant (normal saline) was added. 
The sponges were placed in the apparatus, providing an estimated blood 
volume of 449 cc. This was one of many test runs which showed an accuracy 
of plus or minus 10-20 cc's. Experience indicates that the higher the 
volume of measurement even greater the accuracy. 
II. A 19-year-old female underwent orthopedic back surgery. Estimated blood 
loss by the anesthetist was 1300 cc, by the anesthesiologist 1100 cc and 
by the surgeon 1000 cc. The apparatus recorded the estimated blood loss at 
962 cc. 
III. A 78-year-old female underwent implantation of hip prosthesis and had 
poor cardiopulmonary status. The anesthesia team initially estimated blood 
loss to be 400 cc, but then changed the estimation to be 600 cc. The 
apparatus documented estimated blood loss at 806 cc even though several 
sponges were not counted. Estimated fluid balance at the completion of 
surgery was +5575 cc. This example documents the inaccuracy of current 
estimation procedures by anesthesiologists and anesthetists. The greater 
the blood loss and the more precarious the patient's situation, the 
greater the clinical problem becomes. Anesthesia personnel compensate for 
the acknowledged inaccuracy by infusing excess crystalloid, such as 
Ringer's lactate or normal saline; in this case, the fluid excess was 
greater than five liters. This excessive infusion is only partially 
justified by egress of the infused fluid into the extravascular space. The 
excess infused fluid is excreted in time. 
IV. A 19-year-old female underwent spinal fusion. Estimated blood loss was 
1300 cc by the anesthetist, 1000 by the anesthesiologist (present at the 
beginning and the end of surgery) and 1100 by the surgeon. The apparatus 
measured the estimated blood loss at 1462 cc. Fluid administration in this 
patient was conservative, and the patient was hypotensive in recovery. The 
situation was corrected by transfusion when the patient's hematocrit fell 
below 30, associated with decreased urinary output. This clinical problem 
possibly could have been avoided if data from the apparatus were utilized 
for administration of fluids. 
V. A 35-year-old male suffered multiple open facial fractures, associated 
with nasal hemorrhage and bleeding from the lacerations. Fluid irrigation 
was 3000 cc. Estimated blood loss by the anesthesia team was 3000 cc. The 
apparatus measured estimated blood loss at 4182 cc, and postoperation 
fluid balance was positive 5470 cc. High volumes of irrigation fluid can 
present a problem by skewing estimates of blood loss; the irrigant is 
absorbed in the sponges and mixes with blood removed by suction. 
VI. A 59-year-old female underwent hip surgery. Estimated blood loss 
according to the anesthesiologist was 1100 cc. The surgeon did not venture 
a guess as to blood loss. One unit of blood (packed red blood cells) was 
given. The apparatus recorded estimated blood loss at 740 cc. The change 
in hematocrit tended to confirm the apparatus estimate. Such an 
unnecessary administration of blood, which may present unnecessary legal 
and medical (infectious) risk, could perhaps have been avoided. 
The foregoing is provided for purposes of explanation and illustration. 
Modifications and enhancements to the embodiments described above may be 
made without departing from the scope or spirit of the invention.