Complement and neutrophil activation during cardiopulmonary bypassA randomized comparison of hypothermic and normothermic circulation

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Abstract
OBJECTIVE: Activation of both complement and neutrophils has beendemonstrated to be involved in many pathological reactions followingcardiopulmonary bypass (CPB). The aim of the present study is to evaluatethe effect of normothermic and hypothermic CPB on both complement andneutrophil activation. METHODS: Two groups of patients (n = 20 each)scheduled for elective coronary artery bypass grafting, underwent CPB withintermittent warm or cold blood cardioplegia. Plasma concentration of C3a,C5a and C5b-9, as well as nitro-blu tetrazolium (NBT) scores of circulatingneutrophils were measured before anesthesia, 10 and 30 min after thebeginning of CPB, and 8, 16 and 24 h, postoperatively. RESULTS: In bothgroups, CPB determined a significant complement activation, evidenced as asignificant increase in plasma concentration of C3a, C5a and C5b-9. This inturn triggered the neutrophil activation, documented as a significantincrease of NTB scores in circulating neutrophils at the end of CPB and inthe early postoperative period. Interestingly, in the warm group the extentof both complement and neutrophil activation was significantly highercompared with the cold group during the whole sampling period. CONCLUSION:In conclusion, our study clearly demonstrates that warm CPB is associatedwith an increased ability to activate complement and neutrophils inpatients undergoing coronary surgery.