Effect of Hemodilution on Fluctuation of Cerebral Oxygen Saturation during Cardiopulmonary Bypass in Children with Cyanotic Congenital Heart Disease

Abstract

Background: In patients with cyanotic congenital heart disease (CHD), cerebral oxygenation may be maintained by elevations in hematocrit (Hct). Hemodilution accompanying cardiopulmonary bypass (CPB), however, can disrupt cerebral oxygen balance, leading to fluctuations in cerebral oxygen saturation (ScO2). The present study investigated the effects of Hct changes on the fluctuation of ScO2 during CPB in cyanotic CHD using performance measurement (PM). Methods: Children with CHD (51 acyanotic and 46 cyanotic) who had undergone cardiac surgery using CPB were enrolled. Median performance error (MDPE), median absolute performance error (MDAPE), and wobble parameters of ScO2 were calculated before (reference value), during, and after CPB. Correlations of PM parameters with Hct and reductions in Hct (ΔHct) were also evaluated. Results: Before CPB, patients with cyanotic CHD had lower MDPE and larger wobble than those with acyanotic CHD, although mean ScO2 did not differ significantly between the two groups. During CPB, ScO2 of acyanotic CHD increased as ΔHct increased, but PM variables were not associated with ΔHct. In cyanotic CHD, MDPE (r = −0.324, p = 0.032) and MDAPE (r = 0.339, p = 0.024) correlated significantly with ΔHct during CPB. After CPB, MDPE (r = 0.574, p = 0.025) and MDAPE (r = −0.543, p = 0.036) were significantly correlated with Hct in children with cyanotic CHD who underwent palliative surgery. Conclusion: Therefore, ScO2 fluctuation during CPB in children with cyanotic CHD may be affected by the decrease in Hct, suggesting that excessive hemodilution can negatively influence the maintenance of cerebral oxygenation in these patients.