R. SHEPARD, E. MCGOWAN, J. SCOTT, H. BAKER, D. BO WEN AND K. PRUITT 
591 
hours. One died 48 hours after operation with 
laryngeal edema. Weight gain was 3 pounds. 
The other died 6 hours after bypass was com- 
pleted, the immediate cause being inadequate 
replacement of post-bypass chest tube drainage. 
Both animals were awake. Each moved normally 
and each had greater than 95% arterial blood 
oxygen saturation when breathing room air 
after operation. 
DISCUSSION 
Pluronic F-68 was found to diminish occur- 
rence of systemic fat emboli in cardiopulmonary 
bypass circulation, by Adams and associates, in 
1959.11 A moderate-size literature about its use 
has developed. 12 The pathophysiology of cardio- 
pulmonary bypass circulation has been widely 
studied.i^ 
The data described in this paper indicate that 
during cardiopulmonary bypass circulation, 
pathophysiologic effects occurring due to lack of 
normally pulsatile arterial blood flow, and due 
to protein denaturation, may often be con- 
founded. The data presented, obtained in an 
effort to separate these effects, support the hy- 
potheses proposed in the introduction to this 
paper. 
SUMMARY 
Gamma globulin and albumin put in a disc 
oxygenator produced a precipitate which was a 
species of denatured gamma globulin and al- 
bumin combined. 
Both bovine and human plasma developed 
gross amounts of precipitate during 20 hours in 
a disc oxygenator. The precipitate did contain 
albumin. 
Human plasma from which gamma globulin 
and fibrinogen had been removed did not form 
a precipitate during 20 hours in a disc oxygena- 
tor. 
Neither bovine nor human plasma formed 
gross precipitate when Pluronic F-68 had been 
added to the plasma prior to the 20 hour period 
in the disc oxygenator. 
When 8 calves were subjected to brief veno- 
arterial, partial bypass circulation, with blood 
reconstituted from plasma which had been in 
a disc oxygenator 20 hours, 5 died. All had pro- 
found neurologic damage. 
Under similar circumstances, but with Plu- 
ronic F-68 added to the plasma prior to the 
period of oxygenation, all of 8 calves were long- 
term survivors, without neurologic damage, as 
judged by observation. 
Oxygen consumption in 23 calves maintained 
on cardiopulmonary bypass circulation for 4 
hours was 101 ± 17 cc/min/M^ in 13 animals 
perfused with non-pulsatile flow, and 126 ± 
18 cc/min/M2 in 10 animals perfused with pul- 
satile flow of normal pulsatile energy character- 
istics. 
Two calves have been maintained on complete 
cardiopulmonary bypass for 20 hours. Pluronic 
F-68 was added to the blood in the disc oxygena- 
tor and pulsatile flow was used. Death occurred 
48 and 6 hours after operation, respectively. 
Post-operative technical problems were the im- 
mediate causes of death. 
For comparison of studies involving response 
to pulsatile blood flow, quantitative statement 
of pulsatile energy characteristics of the flow in 
the animal rather than in the pump is necessary. 
ACKNOWLEDGMENTS 
The authors are grateful, for their advice or 
work with these projects, to R. M. Stroud, T. A. 
Noto, J. E. Bearden, E. H. Bell, L. V. Branham, 
M. T. Brooks, J. A. Burdeshaw, G. E. Carpenter, 
G. H. Cassell, C. R. Cooper, F. E. Harrell, L. N. 
Larkin, B. K. Phelps, C. A. Reaves, S. H. Red- 
mond, J. L. Schaeffer, J. F. Sharp, D. C. Simp- 
son, A. F. Spear, E. J. Stephenson, J. L. Ste- 
wart, E. M. Vaughn, M. S. Waits, J. C. Walker, 
C. L. Wallace, J. C. Wells, and H. A. Wingate, 
Jr., over a 10-year period. 
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