Emergency bypass system: analysis of gas transfer

A portable emergency bypass system using a membrane oxygenator device (CPS) was evaluated. The ability of the CPS to supply the oxygen transfer needs of five anesthetized dogs consistently over six hours and the system's effects on hemoglobin concentration, platelet count, and degree of hemolysis were assessed. The animals maintained spontaneous heart beats, pump flows averaged 100 ml/kg/min; mean arterial pressures were maintained at from 114 to 144 mm Hg. Immediate dilution of hemoglobin and platelet levels occurred in the first 30 minutes. Further hemodilution was limited during the first two hours, although three of the animals required transfusions during the six-hour period to maintain their hematocrits. Plasma free hemoglobin did not significantly increase during the six hours. Baseline oxygen consumption data obtained in three animals ranged from 44.5 to 96 (ml oxygen/min/m2). Oxygen and carbon dioxide transfer measurements during the first hour of bypass were not significantly different from measurements during the last hour of perfusion. The study suggests that optimal use of the CPS could supply much if not all of a patient's basal oxygen transfer requirements for at least six hours.