Bicarbonate buffered ultrafiltration leads to a physiologic priming solution in pediatric cardiac surgery

Abstract

Pediatric cardiopulmonary bypass (CPB) involves a high ratio of priming blood volume to patient blood volume. The composition of packed red blood cells (RBCs) is very unphysiological in terms of acid-base, electrolyte and metabolite values. Therefore, we tested the hypothesis whether ultrafiltration of the prime and replacement with bicarbonate buffered hemofiltration solution (BB-HS) is sufficient for reducing the metabolic load and reaching a physiologic state. For planned surgery of congenital heart defects with cardiopulmonary bypass, 20 CPB circuits were primed with BB-HS, gelatin and 1 unit of RBCs. The fluid was hemofiltrated using an ultrahemofilter at 300 ml/min until approximately 1000 ml of ultrafiltrate was restored with BB-HS. Blood gas analyses were obtained from the priming blood, once before and once after bicarbonate buffered ultrafiltration (BBUF). The measured substrates decreased significantly (P < 0.001) after BBUF (glucose from 13.0 ± 2.6 to 6.3 ± 1.0 and lactate from 3.8 ± 1.5 to 2.3 ± 1.0 mmol/l). Acid-base parameters increased (P < 0.001) to normal or high normal values (pH from 7.01 ± 0.09 to 7.68 ± 0.12; HCO3 from 12.1 ± 2.4 to 25.4 ± 3.6 mmol/l and BE from -15.4 ± 3.6 to 3 -0.8 ± 3.7 mmol/l). Even the electrolytes sodium, potassium and calcium changed significantly (P < 0.001) toward the physiologic range. BBUF is an efficient method of reducing the metabolic load of priming. After BBUF, even the electrolyte and acid-base balance reached a physiologic state, which is important for minimizing electrolyte and acid-base disturbances after initiation of CPB. © 2008 Published by European Association for Cardio-Thoracic Surgery. All rights reserved.