Modified Ultrafiltration in Children

Abstract

Pediatric cardiopulmonary bypass (CPB) results in increased total body water and capillary permeability. Ultrafiltration has been effective in removing this excess water. The con ventional method of ultrafiltration is restricted by the vol ume in the venous reservoir and therefore is inefficient in smaller children and neonates, whose blood volume is dis proportionately smaller than the circuit volume. Modified ultrafiltration, performed in the immediate post-CPB period, is more effective in these patients. Blood from the aorta is pumped through the ultrafilter, and warm concentrated blood is returned to the right atrium. This removes excess water from the patient and provides a method of salvaging volume from the circuit. Modified ultrafiltration results in consistent improvements in systolic blood pressure, cardiac index, and lung compliance, as well as a reduction in pul monary vascular resistance. Removal of various inflamma tory mediators, such as tumor necrosis factor a, interleu kin-6, and interieukin-8, has been reported after modified ultrafiltration. Other advantages include an increase in he matocrit, colloid osmotic pressure, and coagulation factors, resulting in decreased bleeding and a decreased need for transfusions. In the animal model, improvement in cerebral recovery after deep hypothermic circulatory arrest has been reported. The disadvantages of this technique include the risk of air entrapment, delay in heparin reversal, and poten tial for cooling.