The effect of modified ultrafiltration on the postoperative course in patients with congenital heart disease.

Improvements in the technology of cardiopulmonary bypass have significantly reduced morbidity following repair of congenital cardiac defects. However, the use of cardiopulmonary bypass exposes infants to extremes of hemodilution and hyperthermia, often in association with tissue ischemia. Exposure of the blood to surfaces of the bypass circuit initiates a systemic inflammatory response that may result in organ dysfunction after cardiopulmonary bypass, especially the heart, lungs, and brain. The technique of modified ultrafiltration (MUF) was introduced by Naik and colleagues at the Hospital for Sick Children in London over 10 years ago. Since that time, multiple studies have evaluated the effects of MUF on organ function and postoperative morbidity following repair of congenital heart defects. Use of MUF after cardiopulmonary bypass reverses hemodilution and decreases tissue edema resulting in improved pulmonary function with decreased duration of postoperative ventilation, improved left ventricular function, decreased postoperative bleeding, and a decrease in the incidence and duration of pleural effusions following the Fontan procedure. Despite the increasing evidence that the use of MUF reduces postoperative morbidity, many important questions remain unresolved. The mechanisms by which MUF results in these beneficial effects requires additional investigation. In addition, further studies are necessary to identify patients most likely to benefit from MUF and to define the optimal protocols for its use. In the future, prospective randomized studies incorporating recent advances in the technology of cardiopulmonary bypass will be necessary to define the optimal utilization of ultrafiltration during and after cardiopulmonary bypass.