Biomaterial development for cardiopulmonary bypass

Cardiopulmonary bypass (CPB) is dependent on materials foreign to the patient for its successful application. When blood comes into contact with these so-called biomaterials, an inappropriate inflammatory response, which can be life-threatening in some patients, may develop. The reason for this inappropriate activation of host defence mechanisms is not entirely clear, however a number of strategies have evolved over the years to minimize this unwanted sequelae of CPB. These strategies include surface coating of the materials of the circuit, using new materials thought to improve biocompatibility, and using a number of pharmacological interventions designed to suppress the inflammatory response. Recently, there has been some evidence which indicates that the plasticizer employed in the polyvinyl chloride (PVC) tubing of the CPB circuit may play a part in the development of the inflammatory response. The work described in this paper tends to support this thesis. These studies showed that by washing the plasticizer from the surface of the PVC tubing, the biocompatibility, as reflected in the upregulation of CD11b on the surface of neutrophils, was enhanced. Furthermore, the use of non-plasticized substitutes for PVC had a similar effect. The benefit from removing the plasticizer was similar to that gained from surface coating with heparin, one of the conventional approaches to reducing the inflammatory response to CPB.