Heparin surface treatment does not impair gas and heat transfer of an extracorporeal circuit

Surface treatment of a cardiopulmonary bypass circuit with heparin improves its haemocompatibility. However, potential side effects of this layer of heparin are impairment of O 2 transfer and CO 2 transfer in the oxygenator and heat transfer in the heat exchanger. Therefore we studied these side effects during extracorporeal circulation with moderate hypothermia in 30 patients who underwent elective coronary artery bypass grafting surgery. All patients were heparinized systemically. In 15 patients (Duraflo II-group) we used an extracorporeal circuit (including a Bentley Bos-CM50 membrane oxygenator) which was treated with heparin. The results of this group were compared with those obtained from another group of 15 patients (control-group), who were operated upon with an identical extracorporeal circuit but without heparin surface treatment. We found no significant differences between the two groups in O 2 transfer, CO 2 transfer or heat transfer during normothermia or hypothermia. We concluded that neither O 2 transfer and CO 2 transfer of the oxygenator nor heat transfer of the heat exchanger were impaired by Duraflo II heparin surface treatment during clinical cardiopulmonary bypass with moderate hypothermia.