Blood cell rheologic deterioration by complement activation during experimental prolonged perfusion with membrane oxygenation

Abstract

In order to understand the microcirculatory disturbances during clinical ECMO, the relation of complement activation to blood cell rheologic parameters during prolonged perfusion with membrane oxygenation was studied in 10 experiments using fresh human donor blood. The perfusion set-up was a standard ECMO circuit without a patient. Blood rheologic parameters reflecting the fluidity of blood in the microcirculation were analysed by a St George's Filtrometer. Changes in complement fractions C3a and C5a were measured by the radio-immunoassay (RIA) technique and the TCC (terminal complement complex) by ELISA technique. Samples for complement activation and blood rheological analysis were taken at 24 hours for correlation. There were strong and significant correlations between red and white cell rheologic parameters with all complement fractions. These observations indicate that complement activation plays a significant role in the deterioration of blood rheology during extracorporeal circulation. Improvements in biocompatibility and blood protection are required if this technology is to be made safer.