Serial oxygen uptake determination were done in 39 patients and 24 mongrel dogs during 20% hemodilutional cardiopulmonary bypass at normothermia. In patients, the time of the bypass ranged from 37 to 161 minutes. In dogs, the bypass time was standardized at 120 minutes.
In patients, average of the mean perfusion index was 2.03 l/M
2/min in the group I (BSA 1.2M
2, n=13), 2.47 l/M
2/min in the group II (0.8 BSA<1.2M
2, n=6) and 2.72 l/M
2/min in the group III (BSA<0.8M
2, n=20). During total perfusion, the average of the mean arterial blood pressure was 75.7mmHg in group I, 53.6mmHg in group II, and 44.1mmHg in group III. The average of the mean oxygen saturation during perfusion were 60.5%, 64.2%, 56.7% and the average of the O
2 consumption were 72.5ml/M
2/min, 94.7ml/M
2/min and 112.6ml/M
2/min respectively. O
2 consumption (during perfusion)/O
2 consumption (predicted) ranged 0.22 to 0.96 in all patients and 0.52, 0.62, 0.63 respectively. The average of the O
2 extraction rate during perfusion were 32.9%, 42.8% and 36.0% respectively. The average of hematocrit during perfusion was 24.4% in patients and 23.5% in dogs. In dogs, classified into 5 groups, group A perfused at rate 25ml/Kg/min had an average mean arterial blood pressure of 20.6mmHg, group B perfused at rate 50ml/Kg/min had 38.3mmHg, group C perfused at rate 75ml/Kg/min had 58.7mmHg, group D at rate 100ml/Kg/min had 67.7mmHg, group E at rate 125ml/Kg/min had 58.4mmHg. The average of the O
2 consumption were 1.66ml/Kg/min (group A), 2.87 ml/Kg/min (group B), 4.10ml/Kg/min (group C), 3.62ml/Kg/min (group D), 5.91ml/Kg/min (group, E ).
1) Mean arterial blood pressure varied directly with flow rate in dogs, but not in patients. During perfusion mean arterial blood pressure was maintained at a lower level and mean central venous pressure at a higher level than at pre-perfusion value.
2) There is a linear relationship between flow rate and oxygen consumption both in patients and dogs. Oxygen consumption during perfusion were considerably lower than normal oxygen consumption.
3) Venous oxygen saturation during perfusion was lower than pre-perfusion value. There is a linear relationship between flow rate and venous oxygen saturation in dogs, but not in patients.
4) In patients, relationship between perfusion index and O
2 consumption indicates that the perfusion index over than 2.7 l/M
2/min will be desirable, and in dogs splanchnic pooling during perfusion suggested the flow rate 75-100ml/Kg/min will be desirable.
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