Complement and anaphylatoxin responses to cross-clamping of the aorta. Studies during general anaesthesia with or without extradural blockade.

Complement activation and anaphylatoxin formation were studied in 28 patients undergoing aortic reconstructive surgery under general anaesthesia. In 12 of the patients an extradural catheter was placed in the L1-2 space and 2% mepivacaine was injected until blockade reached the T4 level. The remaining 16 patients were operated upon under general anaesthesia alone. Complement activation was not obvious until aortic cross-clamping. The release of anaphylatoxin was less pronounced during cross-clamping in the extradural group.