ACUTE-PHASE RESPONSES TO CARDIOPULMONARY BYPASS IN CHILDREN WEIGHING LESS-THAN 10 KILOGRAMS

Background. Cardiopulmonary bypass induces a systemic inflammatory res ponse. This study investigated, in a pediatric population, cytokine-in duced responses and their potential modification by intraoperative ste roid administration. Methods. Markers of the acute-phase response were measured perioperatively in 24 children weighing less than 10 kg unde rgoing cardiac operations. Those having operations with cardiopulmonar y bypass were randomized to receive either no steroid (group I, n = 8) or 10 mg/kg methylprednisolone in the pump prime (group II, n = 10); patients undergoing nonbypass procedures were controls (group III, n = 6). Results. In all groups, plasma interleukin-6 level was elevated ( p < 0.01) above baseline throughout the postoperative period, peaking earlier in group I. Levels of C-reactive protein peaked at 48 hours, a nd postoperative core temperature was raised in all groups. Levels of interleukin-6 from 2 to 6 hours and C-reactive protein at 24 hours pos toperatively were greater (p < 0.05) in group I than in group II. Maxi mum interleukin-6 level, C-reactive protein level, and temperature wer e all significantly greater in group I than in group III. Maximum inte rleukin-6 level correlated with maximum C-reactive protein level in gr oup I only (r(s) = 0.76; p < 0.05) and showed no association with temp erature, Duration of bypass did not correlate with levels of interleuk in-6. Conclusions. This study demonstrated a marked acute-phase respon se to operation; the greater response to procedures with cardiopulmona ry bypass was abrogated by intraoperative steroid administration. The importance of interleukin-6 as an inducer of acute phase proteins afte r bypass is supported by its association with C-reactive protein level s, but other factors must be important in the induction of pyrexia.