Clinical evaluation of six hollow-fibre membrane oxygenators

In a clinical evaluation to study the performance of hollow-fibre membrane oxygenators, we compared the gas exchange characteristics and the production of plasma free haemoglobin for different oxygenators. In this study, the data of the Univox, Cobe-Optima, Capiox-SX, Affinity, Safe II and Sarns Turbo 440 oxygenators were evaluated during cardiac surgery in comparable patient groups. Thirteen patients scheduled for elective surgery were enrolled in each group. In all groups, cardiopulmonary bypass (CPB) was conducted using pulsatile blood flow during fibrillation and the period in which the aorta was crossclamped. Arterial and venous blood gases were determined from which oxygen transfer, carbon dioxide transfer, oxygen gradient, shunt fraction and diffusing capacity were calculated. Blood samples were taken 5, 30, 60 and 90 min after beginning CPB. As a result of our measurements we found that the gas exchange capacities of all six oxygenators are within clinically acceptable limits, although the data considering oxygen and carbon dioxide transfer showed a significantly higher capacity for the Sarns Turbo 440 oxygenator (p < 0.05) in comparison with the other oxygenators. Plasma free haemoglobin was, however, significantly higher in the Univox and Sarns Turbo 440 groups (p < 0.005). This difference was already present after 30 min of bypass and increased with time, and is considered as a negative aspect, in relation to optimal patient care.