CIRCULATING CYTOKINES IN PATIENTS UNDERGOING NORMOTHERMIC CARDIOPULMONARY BYPASS

To determine the cytokine release during normothermic cardiopulmonary bypass, we have measured plasmatic levels of tumor necrosis factor-alp ha and interleukins-1 beta, 6, and 8 in 10 patients during the first 2 4 hours after the start of bypass. Arterial blood samples were collect ed at intervals before, during, and after bypass. Interleukin-1 beta w as not detectable in the plasma, and traces of tumor necrosis factor-a lpha were detected in only three patients at times independent of the cardiopulmonary bypass procedure. Circulating endotoxin remained undet ectable. Plasma interleukin-6 and interleukin-8 rose significantly fro m 2 until 24 hours after the start of bypass (p < 0.05) and peaked res pectively at 4 and 2 hours after the beginning of bypass (interleukin- 6, 268.1 +/- 131.43 pg/ml; interleukin-8, 370 +/- 420 pg/ml; mean peak +/- standard deviation). Peak values of interleukin-6 and interleukin -8 were correlated neither with the duration of aortic crossclamping o r the bypass procedure nor with the hemodynamic parameters recorded at the same times. This study shows that normothermic cardiopulmonary by pass does not induce systemic release of tumor necrosis factor-alpha a nd interleukin-1 beta. A local production of these cytokines cannot be excluded, because interleukin-6 and interleukin-8 are produced by sti mulated macrophages and monocytes in response to tumor necrosis factor -alpha and interleukin-1 beta. Our results, at normothermia, show a si milar pattern of interleukin-6 and interleukin-8 release when compared with release during hypothermic cardiopulmonary bypass. Interleukin-8 , an important chemotactic neutrophil factor, might play a role in rep erfusion injuries observed in lungs and heart after cardiopulmonary by pass.