Complement activation during cardiopulmonary bypass

We researched complement activation of fifteen patients who had open heart surgery and on ten patients who had closed heart surgery. Our results showed that the complement system was partially activated by the anaesthesia and partially by tissue damage. This activation was aggravated when plasma contacted the pump-oxygenator system, continued in the intensive-care unit and became normal in the 24th hour after the operation. Complement activation occurred both via the alternative and classical pathways but the alternative pathway was activated more than the classical with increase in bypass time. Pulmonary sequestration of leucocytes which occurred due to the complement activation and the complement derived inflammatory mediators could have contributed to the pathogenesis of the post-pump syndrome.