[Use of cardiopulmonary bypass decreases leukocyte count and activation of the complement system]

Platelet damage, complement activation and neutropenia during extracorporeal circulation are the result of blood contact with artificial surfaces, mainly in the oxygenator. To evaluate the biocompatibility of the ++auto-oxygenation technique of cardiopulmonary bypass (CPB) 2 techniques of extracorporeal circulation were compared in 40 patients undergoing elective coronary bypass surgery. Patients were studied in 2 groups, 20 patients in each: I (++auto-oxygenation --patients lungs used in CPB) and II (conventional technique of CPB with bubble oxygenator). Several blood samples were taken before, during and after perfusion to estimate pulmonary leukocytes sequestration in all patients and additionally complement C3a and C5a anaphylatoxins + were measured (radioimmunoassays) in 6 patients of each group. During cardiopulmonary bypass the decline in leukocyte number was observed in both groups, but leukocyte count was higher in group I then II, due to the transpulmonary leukocyte sequestration which was higher in group II. The difference between leukocytes count in group II was 1.46 +/- 0.5 x 10(3)/mm3 vs only 0.34 +/- 0.2 x 10(3)/mm3 in group I, p less than 0.001. In postoperative period an increase in circulating white blood cells was observed in both groups when compared to pre-bypass time, but the difference between groups was non significant. The level of C3a increased in group I from 244 +/- 46 ng/ml to 418 +/- 34 ng/ml, in group II from 268 +/- 46 ng/ml to 521 +/- 65 ng/ml, p less than 0.001, but in group I the levels were significantly lower, p less than 0.001. The current study confirms that cardiopulmonary bypass results in significant leukocyte and complement activation and supports the theoreticaly better biocompatibility of CPB with lung over oxygenator.