Use of Modified Ultrafiltration After Repair of Congenital Heart Defects

Abstract

The use of cardiopulmonary bypass (CPB) for repair of congenital heart defects exposes children to extremes of hemodilution and hypothermia. Exposure of blood to the foreign surfaces of the oxygenator and bypass circuit initiates a systemic inflammatory response. Adverse effects of CPB include increased capillary permeability and increased total body water (TBW), which often results in tissue edema and multiple organ dysfunction. A variety of techniques have been developed for reversing tissue edema and hemodilution after CPB, including ultrafiltration during CPB, postoperative peritoneal dialysis, postoperative continuous arterial venous hemofiltration, and aggressive use of diuretics. A technique termed modified ultrafiltration (MUF) has been developed at the Hospital for Sick Children in London. Unlike conventional ultrafiltration, MUF is performed in the immediate post-CPB period and removes excess water from the patient as well as provides a method of salvaging blood from the circuit. MUF has been shown to modulate the inflammatory response to CPB by removing inflammatory mediators including interleukin (IL)-6, IL-8, and tumor necrosis factor (TNF). A prospective randomized trial of MUF showed improved hemodynamics with a reduction in TBW and decreased need for blood transfusion when compared with nonfiltered controls. MUF has been shown to improve left ventricular systolic function after CPB, resulting in increased systolic blood pressure and cardiac index. In a recent study, use of MUF significantly reduced the incidence of pleural effusions after cavopulmonary connection and the Fontan procedure. MUF is a useful adjunct to CPB in children and significantly decreases perioperative morbidity. Copyright 1998 by W.B. Saunders Company