BIOCOMPATIBILITY OF CARDIOPULMONARY BYPASS - INFLUENCE ON BLOOD COMPATIBILITY OF DEVICE TYPE, MODE OF BLOOD-FLOW AND DURATION OF APPLICATION

The biocompatibility of artificial organs is recognised as an area pre senting difficulties in terms of the complexity of the situation. The nature of the blood response involving interactions of systems, patter n and extent of change, patient status and the influence of the whole device contribute to the complexity. Recognising these, the profile of the blood response to cardiopulmonary bypass (CPB), with respect to t ype of device, mode of blood flow, duration of the procedure and patie nt status, has been evaluated by monitoring contact phase activation [ Factor XII-like activity (FXIIA)], fibrinolytic activity [Fibrin degra dation products (X-FDP's)], complement activation (C3a, C5a), leucocyt e activation [Granulocyte elastase (GE)] and platelet and white cell i maging. FXIIA, X-FDP's, and GE rose gradually during CPB, with levels remaining elevated post-operatively for up to 48 h. In contrast, C3a l evels rose sharply with no significant elevation in the post-operative period, while C5a did not show significant changes during bypass. The use of pulsatile perfusion resulted, in lesser activation of the para meters, although these were significantly less only for GE. The altera tions in FXIIA, X-FDP's, C3a and GE correlated positively with the dur ation of CPB, with this effect pronounced in the post-operative period for FXIIA, X-FDP's and GE. However, these changes had no apparent inf luence on clinical outcome and the majority of patients had uncomplica ted post-operative recoveries. With respect to the use of bubble/membr ane oxygenators, platelet and white cell deposition and the patterns o f change for FXIIA and C3a were similar in the two groups. The investi gation has enabled a broad perspective of biocompatibility in CPB rele vant to the clinical application of biomaterials.