Plasma fibronectin levels during cardiopulmonary bypass.

Plasma fibronectin, also called cold-insoluble globulin, is a cryoprecipitable glycoprotein with both opsonic and adhesive activities. It binds to collagen, actin, and heparin and can form soluble as well as cryoprecipitable complexes in the cold. Fibronectin augments particulate phagocytosis by the reticuloendothelial system and can influence lung vascular permeability. Plasma fibronectin deficiency is temporally associated with respiratory failure in septic surgical, trauma, and burn patients. We measured plasma fibronectin and albumin levels in nine adults undergoing elective cardiopulmonary bypass to determine whether dilution alone could account for the changes in plasma fibronectin. Plasma fibronectin concentration decreased 17% with the surgical trauma of opening of the chest and placement of the vascular cannulas. On heparinization and initiation of cardiopulmonary bypass, plasma fibronectin fell an additional 48% (P less than 0.001), whereas albumin concentration (corrected for albumin in the pump prime) fell only 25% (P less than 0.001), emphasizing that dilution was not the only mechanism contributing to the decline in plasma fibronectin. Fibronectin levels began to increase after discontinuation of cardiopulmonary bypass and in association with diuresis, but unexpectedly they remained subnormal until 4 days postoperation. Thus the decline in fibronectin concentration with cardiopulmonary bypass may be due to dilution as well as opsonic consumption and possible complexing with heparin in the cold.