BIOCOMPATIBILITY OF EXTRACORPOREAL-CIRCULATION WITH AUTOOXYGENATION

Platelet damage, complement activation and neutropenia during cardiopulmonary bypass are the result of blood contact with artificial surfaces, mainly in the oxygenator. To evaluate biocompatibility of this kind of bypass we compared two techniques of extracorporeal circulation in 40 patients undergoing elective coronary bypass operations. In 20, a standard technique with a bubble oxygenator was used (group 1), and in the remaining 20 patients with autooxygenation, the patients' own lungs were included in the perfusion circuit (group 2). Several blood samples were taken before, during and after perfusion to estimate the corrected platelet numbers and pulmonary leucocyte sequestration in all patients, and additionally in 6 patients from each group, complement C3a and C5a anaphylatoxins were measured (radioimmunoassay). At the end of cardiopulmonary bypass, the decline of platelet number corrected to haematocrit platelet number in group 1 was significantly higher than in group 2 (P < 0.01). There was a significant increase in circulating white blood cells when compared to pre-bypass time in both groups (P < 0.05). However, comparison of differences between leucocyte counts in the blood of the patients' right and left atria showed enhanced leucocyte sequestration in group 1, 1.46 +/- 0.5 x 10(3)/mm3 vs only 0.34 +/- 0.2 x 10(3)/mm3 in group 2. The C3a rose progressively during extracorporeal circulation: in group 1 from 268 +/- 46 ng/l to 521 +/- 65 ng/l, and in group 2 from 244 +/- 46 ng/l to 418 +/- 34 ng/l (P < 0.05). No characteristic changes in C5a activation were observed in either group. The current study confirms the theoretically better biocompatibility of extracorporeal circulation with the use of the patients' lungs as compared to an oxygenator.