Determination of significant differences in performance of the Bentley BOS-CM 40 hollow fibre membrane oxygenator and the Polystan VT5000 venotherm bubble oxygenator

Ten mongrel dogs were connected to cardiopulmonary bypass by cavoaortic cannulation, classic roller pump and either Bentley BOS-CM 40 hollow fibre membrane oxygenator or Polystan VT5000 Venotherm bubble oxygenator for eight hours, with mean flow rate of 100 ml/kg min. Platelet counts (all values corrected by prebypass haematocrit) were significantly lower in the bubble oxygenator group after two hours of cardiopulmonary bypass (p < 0·01). Plasma haemoglobin production was significantly higher after two hours of cardiopulmonary bypass in the bubble oxygenator group (p < 0·01). Venous oxygen saturation (SvO 2 ) was above 65% during the eight hours perfusion in the membrane oxygenator group. In the bubble oxygenator group, however, SvO 2 was below 60% after six hours of cardiopulmonary bypass. After eight hours perfusion the difference in SvO 2 between the two groups was significant (p < 0·05). Thus membrane oxygenators such as the Bentley BOS-CM 40 appear to be indicated in cardiopulmonary bypass of more than two hours duration.