The effects of cardiopulmonary bypass temperature on inflammatory responsefollowing cardiopulmonary bypass

Objectives: The inflammatory response to cardiopulmonary bypass is believed to play an important role in end organ dysfunction after open heart surger y and may be more profound after normothermic systemic perfusion. The aim o f the present study was to investigate the effects of cardiopulmonary bypas s temperature on the production of markers of inflammatory activity after c oronary artery surgery. Methods: Forty-five low risk patients undergoing el ective coronary artery surgery were prospectively randomized into three gro ups: hypothermia (28 degrees C, n = 15), moderate hypothermia (32 degrees C , n = 15), and normothermia (37 degrees C, n = 15). All patients received c old antegrade crystalloid cardioplegia and topical myocardial cooling with saline at. 4 degrees C. Serum samples were collected for the estimation of neutrophil elastase, interleukin 8, C3d, and IgG under ice preoperatively, 5 min after heparinisation, 30 min following start of CPB, at the end of CP B, 5 min after protamine administration, and 4, 12 and 24 h postoperatively . Results: Patients were similar with regard to preoperative and intraopera tive characteristics (age, sex, severity of symptoms, number of grafts perf ormed, aortic cross clamp time, cardiopulmonary bypass time). Neutrophil el astase concentration increased markedly as early as 30 min after the onset of cardiopulmonary bypass and peaked 5 min after protamine administration. Levels were not significantly different between the three groups. A similar finding was apparent for C3d release. Interleukin 8 concentrations also de monstrated a considerable increase related to cardiopulmonary bypass in all groups, but there was a significantly more rapid decline in interleukin 8 concentrations in the normothermic group in the postoperative period. Elute d IgG fraction showed a much earlier peak concentration than the other mark ers, occurring within 30 min of the start of cardiopulmonary bypass. Levels reached a plateau, before declining soon after the end of bypass and remai ned higher than preoperative values at 24 h. There was no difference betwee n the three groups. The cumulative release of ail markers was calculated fr om the concentration-rime curves, and was not statistically different betwe en groups. Conclusion: Normothermic systemic perfusion was not shown to pro duce a more profound inflammatory response compared to hypothermic and mode rately hypothermic cardiopulmonary bypass. (C) 1999 Elsevier Science B.V. A ll rights reserved.