M. P. KAYE AND J. B. PACE 
357 
VENOUS 
ARTERIAL 
TRANS. 
STfllURn Fiji 
MVITHUUERIDCK 
cililD FILTER'S 
t si p 2 - I-S 
U?TH 1 
WATER PUMP 
LUCALOUl 
DOW 
DOW 
OXY 
OXY 
TRANS. 
FILTER'S 
DIAGRAM OF CIRCUIT FOR PERFUSION 
WITH DOW OXYGENATOR 
Figure 2. — Res. = Venous Reservoir; Heat Exch. r= 
Disposable Venous Heat Exchanger; Pump = Roller 
Pump; Trans. = Pressure Transducer; Fractions re- 
fer to internal diameter of tubing. 
artery. In all instances, the caval catheters 
ranged between sizes 36 to 40 and the arterial 
cannula was a size 18, 20 or 22. During the 
course of bypass, the lungs were inflated with 
helium and the endotracheal tube was clamped. 
Halothane was administered through the oxy- 
genators with a 95% oxygen, a 5% carbon diox- 
ide mixture and a gas flow rate of 30 1/minute. 
Heparin (2 mg/kg) was given hourly. Prota- 
mine sulfate in a dose approximately one half 
the total heparin dose was administered at the 
termination of the procedure. 
Arterial blood samples for PO2, PCO2 and 
pH were drawn from the arterial pressure mon- 
itoring lines while the animal was under anes- 
thesia and prior to bypass. After bypass was in- 
stituted, samples for pH, PO2 and PCO2 were 
obtained from inlet and outlet sides of the oxy- 
genator immediately and then at hourly inter- 
vals for 4 hours. Additional samples were 
obtained for hematological and biochemical stud- 
ies during the pre-operative period and on 
post-operative days 1, 3, 5 and 7. Table I lists 
the studies performed. 
All animals in this study were subjected to 
complete autopsies at the conclusion of the ex- 
periment. The membrane oxygenators were 
flushed with a glutaraldehyde solution, then 
photographed and disassembled. After inspec- 
tion, the headers and inlet and outlet tubesheets 
were also photographed. 
Table I. — Listing of Biochemical and Hematological 
Tests Performed on All Animals 
Hemoglobin 
Hematocrit 
Red Blood Cell Count 
White Blood Cell Count & Differential 
Platelets 
Plasma Hemoglobin 
Fibrinogen 
Lactate 
Bilirubin — Total and Direct 
Creatinine 
Potassium 
SGOT 
SGPT 
LDH 
RESULTS 
In the initial group (I) of fifteen animals, it 
was noted that during the first 15-20 minutes 
of perfusion, the pressure gradient across the 
oxygenator increased rapidly. During the 
course of the four-hour perfusion, this gradient 
then continued to increase but at a very slow 
rate reaching an average maximum of 160 mm 
Hg at the end of 4 hours. Oxygenation during 
perfusion appeared marginally adequate and 10 
of the 15 animals survived the experimental 
procedure. Examination of the oxygenators at 
the termination of the experiments revealed a 
significant deposition of platelet aggregates on 
the inlet tubesheets (Figure 3b) with occasional 
deposition of aggregates on the outlet tube- 
sheets and both headers. Although it is al- 
most impossible to quantitate the amount of 
platelet aggregate deposition, visual estimates 
of the amount of inlet tubesheet surface area 
covered provided adequate data to show a direct 
