Clinical evaluation of a new hollow fibre membrane oxygenator

Twelve consecutive patients undergoing elective cardiac surgery were perfused with the Cobe Optima hollow fibre oxygenator. Gas transfer characteristics and blood handling were studied. The device had a maximum oxygen transfer of 315 ml/minute. The average shunt fraction was 4.5%, and was not influenced by blood-flow rate. Mean platelet count declined slightly to 91% of the baseline at the end of the study period. Haemolysis was evaluated by monitoring serum-free haemoglobin, serum haptoglobin and serum haemopexin. The evolution was as follows: free haemoglobin increased from 14 +/- 5 mg/100 ml to 85 +/- 0.8/100 ml (p = 0.01) at the end of bypass; haptoglobin decreased from 1.33 +/- 0.90 g/l to 0.89 +/- 0.15 g/l (p = 0.01); and haemopexin decreased from 0.84 +/- 0.13 g/l to 0.74 +/- 0.15 g/l (p = nonsignificant). In all patients the residual capacity of serum haptoglobin to protect against haemolysis was satisfactory. All patients had an uneventful postoperative course.