Influence of temperature during cardiopulmonary bypass on leukocyte activation, cytokine balance, and post-operative organ damage

This study examined the hypothesis that core temperature (T degrees) during cardiopulmonary bypass (CPB) influences the perioperative systemic inflamm atory response and post-operative organ damage. Twenty-four pigs were assig ned to a T degrees regimen during CPB: normothermia (T degrees 37 degreesC; n = 8), moderate hypothermia (T degrees 28 degreesC; n = 8), or deep hypot hermia (T degrees 20 degreesC; n = 8). Perioperative leukocyte activation, endotoxin release, and production of tumor necrosis factor-alpha (TNF alpha ) and interleukin-10 (IL10) were examined with regard to post-operative org an damage, which was scored at histological examination of tissue probes of heart, lungs, liver, kidney, and ileum, taken 6 h after CPB. Total blood l eukocyte count and TNF alpha plasma levels during CPB were significantly lo wer and IL10 levels were significantly higher in the moderate hypothermic g roup than in both other groups. Elastase activity, leukotriene B4-, and end otoxin levels were not affected by T degrees regimen. Moderate hypothermia was associated with the lowest histological organ damage score and normothe rmia with the highest. In all animals organ damage score for heart, lungs, and kidneys correlated significantly with TNF alpha levels at the end of CP B. Our data demonstrate a clear relationship between TNF alpha production d uring cardiac operations and post-operative multiple-organ damage. Moderate hypothermia, by stimulating IL10 synthesis and suppressing TNF alpha produ ction during CPB, might provide organ protection.