Bicarbonate-Buffered Ultrafiltration During Pediatric Cardiac Surgery Prevents Electrolyte and Acid-Base Balance Disturbances

Pediatric cardiopulmonary bypass is still a challenge because of electrolyte disturbances and inflammation. Many investigations deal with different types of hemofiltration to reduce these potentially harmful side effects. We tested the hypothesis of whether bicarbonate-buffered hemofiltration of the priming solution minimizes electrolyte and acid-base disturbances during the initiation of cardiopulmonary bypass and whether bicarbonate-buffered hemofiltration performed during cardiopulmonary bypass could reduce cytokine levels. Twenty children younger than 2 years of age (mean age 166 +/- 191 days; mean weight 6.42 +/- 3.22 kg) scheduled for pediatric cardiac surgery with cardiopulmonary bypass were enrolled in this prospective clinical study. Cardiopulmonary bypass circuits were primed with a bicarbonate-buffered hemofiltration solution, gelatin and 1 unit of packed red blood cells. The priming was hemofiltered using an ultrahemofilter until approximately 1000 mL of ultrafiltrate was restored with the buffered solution. Further hemofiltration was performed throughout the whole bypass time, especially during rewarming. Blood gas analyses and inflammatory mediators were monitored during the operation. Blood gas analysis results after initiation of cardiopulmonary bypass and throughout the entire study remained within the physiologic ranges. Even potassium decreased from 4.0 +/- 0.3 to 3.4 +/- 0.4 mmol.l(-1) after initiation of cardiopulmonary bypass. Plasma levels of tumor necrosis factor alpha decreased significantly (47 +/- 44 vs. 24 +/- 21 pg.mL(-1)) whereas complement factor C3a (5.0 +/- 2.9 vs. 16.8 +/- 6.6 ng.mL(-1)) and interleukin-6 (7.3 +/- 15.2 vs. 110 +/- 173 pg.mL(-1)) increased despite hemofiltration. In conclusion, this study shows that bicarbonate-buffered ultrafiltration is an efficient, simple and safe method for performing hemofiltration, both of the priming solution and during the entire bypass time. The use of a physiological restitution solution prevents electrolyte and acid-base balance disturbances. The elimination of inflammatory mediators seems to be as effective as other ultrafiltration methods.