588 
HEMODYNAMICS 
was then put in the oxygenator with the same 
prime solution described for Study 3. The oxy- 
genator had 132 discs; these were rotated at 
100 RPM. Oxygen and CO2 entering the oxy- 
genator were filtered through a 0.22 [x Millipore 
filter. Plasma pH was controlled by changing 
the CO2 flow into the oxygenator. The plasma 
was circulated through the oxygenator at 2,300 
± 575 cc/min. It was kept at 37°C. After 20 
hours, the red cells were returned to the plasma 
and mixed with it in the pump oxygenator cir- 
cuit. Calcium chloride, 10% solution, 30 cc was 
added. 
Each calf was healthy as judged by observa- 
tion. Each received penicillin (500,000 units) 
and streptomycin (1 gram) 24 hours before 
operation and the morning of operation. Anes- 
thesia was induced with 4% halothane, given 
through a plastic bag fitted over the nose. An 
endotrachael tube was inserted. Anesthesia was 
maintained with 0.5 to 1.5% halothane and 50% 
oxygen — 50% nitrous oxide gas flow. A Bird 
mechanical ventilator was used with the anes- 
thesia machine. The left external jugular vein 
and left common carotid artery were exposed. 
Heparin, 150 units/kg, was given 5 minutes 
before insertion of a cannula through the ex- 
ternal jugular vein into the right atrium. The 
left carotid artery was occluded with a vascular 
clamp and a #12-#16 arterial perfusion cannula 
was inserted in the proximal portion. Right 
atrial pressure was measured through a central 
venous catheter. Arterial pressure was meas- 
ured through a second small catheter placed, 
using the Seldinger technique, through the left 
common carotid artery well into the aorta. 
Strain gage transducers were used. 
Venous flow to the pump oxygenator was 
controlled initially to keep the right atrial pres- 
sure at the level existing prior to bypass. If 
arterial blood pressure fell to less than 90 mm 
Hg, the calf's blood volume was increased until 
venous pressure reached 12 mm Hg, or until 
systolic pressure was above 90. If right atrial 
pressure were 12 mm Hg and systolic pressure 
remained less than 90, epinephrine in 1/500,000 
concentration was given intravenously at a rate 
adequate to restore the systolic pressure to 90 
within five minutes. 
Oxygenated blood flow from the pump to the 
calf was 0.5 to 2.1 L/min/M^. It was continued 
for 16-30 minutes, until 95% or more calculated 
mixing of the blood in the pump oxygenator 
and in the animal had occurred. The perfusion 
cannulas were then withdrawn and the carotid 
artery cannulation site was accurately repaired 
with 5-0 synthetic vascular suture. The neck 
wound was closed and the calf was held upright 
in a sling while recovering from anesthesia. 
Respiratory assistance with a ventilator and 
endotrachael tube was continued when neces- 
sary. Surviving calves were later returned to 
pens for continued periodic observation. 
During the procedures, cultures for bacterial 
growth were obtained from donor whole blood, 
plasma, plasma and prime solutions mixed, 
blood after the red cells had been returned, 
blood in the oxygenator at the end of bypass, 
and blood from the calf at the end of the pro- 
cedure. Samples for determination of pH, PCO2, 
PO2, hematocrit and hemoglobin oxygen satura- 
tion were taken periodically. 
In 8 of the 16 procedures described, Pluronic 
F-68 was added at the time the plasma was put 
in the oxygenator, to produce a concentration 
of 0.6 mg/ml. No Pluronic was used in the other 
eight procedures. 
Two control procedures were carried out ini- 
tially. In one, the left common carotid artery of 
a heparinized calf was clamped for 12 minutes. 
In the other the entire procedure as described 
above was done except that the 20-hour period 
of oxygenation was omitted. 
Results, Study 4 
Immediately before bypass, in the non-Plu- 
ronic and Pluronic groups respectively, systolic 
pressures were 129 ± 27 and 133 ± 25 mm Hg, 
diastolic pressures were 93 ±: 22 and 98 ± 24 
mm Hg, and right atrial pressures were 4 ± 4 
and 2 ± 5 mm Hg. None of these differences 
were significant. 
A significant decrease in blood pressure oc- 
curred after 16 minutes of partial bypass in the 
non-Pluronic group compared to the Pluronic 
group. Systolic pressure was 54 ± 8 in the 
former compared to 97 ± 15 in the latter (p < 
0.05). Diastolic pressures were 38 ± 7 and 77 ± 
14, respectively (p < 0.05). At this time, right 
atrial pressures were 4 ± 6 mm Hg in the non- 
