M. P. KAYE AND J. B. PACE 
359 
Table II. — Summary of Blood Gases, Oxygen Transfer 
and Blood Flow of 10 Animals Subjected to Perfusion 
with Membrane Oxygenator 
Average Values (10 Animals) 
1 Hr. 
4 Hr. 
Ven. 
28 
35 
37 
Art. 
354 
286 
304 
Sat. % 
Ven. 
52 
68 
67 
Art. 
99 
99 
99 
PCO3 
Ven. 
44 
45 
43 
Art. 
30 
38 
36 
PH 
Ven. 
7.44 
7.29 
7.36 
Art. 
7.55 
7.36 
7.44 
Flow (cc/min) 
3907 
4048 
Trans, (cc/min) 
223 
207 
ranging from 58 to 67% at flows of 3,900 to 
4,200 cc/min. 
These results substantiate the clinical impres- 
sion that perfusion was adequate in all animals. 
When compared to the results obtained from 
perfusion of the group III animals (bubble oxy- 
genator), it is apparent that oxygen transfer 
was comparable over a similar range of flow 
rates and inlet (venous) saturations. Table III. 
Four of the animals in group III died during 
perfusion as a consequence of air embolism. Air 
embolism occurred in these animals because of 
inability of the bubble oxygenator to defoam ad- 
equately. In spite of the filters in the arterial 
line, considerable air was noted in the coronary 
arteries of these animals. 
Hematological studies of the animals involved 
in this study revealed a decrease in hemoglobin 
consequent to perfusion (11.15 gm% pre-op. — 
9.98 gm% post-op.) as well as a decrease from 
the immediate post-operative value through day 
seven (9.51 gm% 1 day post-op. — 7.0 gm% 7 
days post-op). This decrease, however, was sim- 
Table III. — Summary of Blood Gases, Oxygen Transfer 
and Blood Flow of 6 Animals Surviving Perfusion with 
Bubble Oxygenator 
Average Values (6 Animals) 
Pre-bypass 
1 Hr. 
4 Hr. 
pOj 
Ven. 
21 
37 
36 
Art. 
355 
336 
435 
Sat. % 
Ven. 
43 
60 
62 
Art. 
99 
99 
99 
pco. 
Ven. 
35 
47 
46 
Art. 
28 
38 
41 
pH 
Ven. 
7.43 
7.28 
7.31 
Art. 
7.45 
7.34 
7.35 
Flow (cc/min) 
3592 
3463 
Oj Trans, (cc/min) 
188 
220 
ilar in both membrane and bubble oxygenator 
groups (Figure 4). 
Platelet counts were decreased slightly in the 
immediate post-operative period but rapidly re- 
turned to normal for animals perfused with the 
membrane oxygenator. A similar directional 
change in platelet count was seen for animals 
perfused with the bubble oxygenator, but the 
decrease noted immediately following surgery 
was greater (Figure 5) . 
Changes in plasma hemoglobin levels were 
minimal following perfusion with the mem- 
brane oxygenator and compare favorably to lev- 
els noted following perfusion with the bubble 
oxygenator (Figure 6). 
Studies of white blood cell counts, serum elec- 
trolytes, liver function, creatinine and serum 
enzymes revealed no changes not anticipated as 
a consequence of anesthesia, thoracotomy, car- 
diotomy and four hours of perfusion. Compari- 
son of the results of these studies between 
group II and group III animals revealed no sig- 
nificant differences. 
Post-mortem examination of animals surviv- 
ing the ten-day experimental period revealed no 
significant findings other than those attributa- 
ble to the surgical procedure. 
CONCLUSIONS 
The data presented indicate that two 3-liter 
Dow capillary membrane oxygenator units 
when used in parallel are capable of supporting 
a calf on total cardiopulmonary bypass for peri- 
ods up to at least four hours. To permit a satis- 
factory perfusion, it is necessary that a filter be 
placed in the line on the inlet side of the oxy- 
genator. Use of this oxygenator without a filter 
results in deposition of platelet aggregates on 
the oxygenator inlet tubesheet with consequent 
decrease in the number of functioning capillar- 
ies and hence effective surface area for gas 
transfer. 
Oxygen transfer rates at flows ranging from 
2,500 cc to 5,000 cc per minute were comparable 
for Dow units with filters and the bubble oxy- 
genator. Because of low arterial PCO2 noted in 
initial studies with one liter units, all experi- 
ments in this report were carried out using a 
mixture of 95 % oxygen and 5 % carbon dioxide 
