1224 
MONITORING 
0 PAT N0=102 
n ni V— Z7 
1 DEV N0=26 
1 CAT TMC— QA7 
SET CHANNEL NO 
2 DYE=5 
3 12.5 MGM=2S 
3 CONT 
4 STORE CAL 
5**NUMB OF SEC=10-40 
6 CCS OF DYE=0-10 
7 CALC CURVE 
8 REVIEW 
9 END 
(a) 
(b) 
0 BLK=37 
CO=1560 8 CALC 
1 SALINE=967 
AT=12 9 STORE 
2 0 DYE CAL=11846 
BT=6 
3 12.5 MGM=28 
MC=21 
4 STORE CAL 
CV=526 
5 NUMB OF SEC=40 
6 CCS OF DYE=2 
7**CALC CURVE 
8 REVIEW 
9 END 
(c) 
(d) 
Figure 5. — Messages displayed on the remote terminal 
when running the Dye Curve program, (a) Identifi- 
cation message, (b) Calibrations have been entered; 
the number of seconds the curve is to be sampled is 
to be keyed in. (c) The curve is being sampled for 
the forty-second period, (d) The results are dis- 
played and may be stored by pressing '9' on the key- 
board. 
At the end of the sample period, an extrapo- 
lation is performed on the return limb of the 
dye curve to return the concentration to zero 
and remove the error introduced by the recircu- 
lation of dye. The extrapolation is exponential 
and the value of the exponent is determined by 
a constant which is the logarithmic slope of the 
descending limb of the curve prior to any recir- 
culation. When the dye curve analysis is com- 
plete, the sampled dye curve and the extrapo- 
lated dye curve are displayed to be sure that the 
extrapolation is correct. The calculated values 
are also displayed at this time and may be 
stored. Subsequent dilution curves can be run 
using all the constants which were previously 
entered. Button '8' is merely pressed at the mo- 
ment of the next dye injection. As the data is 
stored, the time-of-day clock is sampled and the 
value is stored with the data. 
Oxygen Saturation 
This program calculates and displays the oxy- 
gen saturation as percent saturation from the 
signals which come from the infrared (IR) and 
red (R) photosensitive devices in a cuvette oxi- 
meter. Since this method of measuring oxygen 
saturation uses the transmission of light, the 
relationships are logarithmic, and oxygen satu- 
ration is calculated by obtaining the ratio of the 
logs of the intensity of light detected by the IR 
and R cells. This program uses the same instru- 
mentation as is used for recording dye dilution 
curves. It provides for frequent on-line readout 
of oxygen saturation without having to transfer 
the blood sample to a laboratory instrument for 
measurement. 
Pressure 
This program calculates the maximum, the 
mean, and the minimum of any physiological 
pressure. Because it is difficult to do a pattern 
recognition on many of the pressure wave- 
forms, a trigger is used to indicate the begin- 
ning and end of each heart cycle. This trigger is 
a pulse which is generated with each "R" wave 
of the ECG. The maximum and minimum dur- 
ing each cycle is determined and the mean is 
found over the same period. The values for 
eight beats are obtained and then averaged, and 
the averaged result is displayed on the oscillo- 
scope for observation. Since the time of day is 
recorded with each averaged value and the 
measured pressure is identified with a number 
code, any number of pressure measurements 
can be made and stored for later trend and/or 
statistical analysis. The tedious process of man- 
ual recording and plotting pressure values from 
analog preprocessors and digital displays or 
measuring values from oscillographic record- 
ings is eliminated. 
Flow 
This program also uses the trigger pulse and 
can calculate the maximum, minimum and mean 
of any physiological flow. It also has the capa- 
bility to calculate stroke volume and thus car- 
diac output from a flowmeter which is placed on 
the ascending aorta. While many flowmeters 
give a calibrated mean flow reading, the use of 
