Cerebral protective effect of dexmedetomidine in pediatric patients undergoing correction of tetralogy of Fallot with cardiopulmonary bypass

Objective To evaluate the cerebral protective effect of dexmedetomidine in the pediatric patients undergoing correction of tetralogy of Fallot with cardiopulmonary bypass (CPB) . Methods Sixty pediatric patients of both sexes, aged 11 months-14 yr, with body mass index of 9.8-21.4 kg/m2, of ASA physical status Ⅱ or Ⅲ, scheduled for elective correction of tetralogy of Fallot with CPB, were randomly divided into 2 groups (n=30 each) using a random number table: normal saline group (group NS) and dexmedetomidine group (group Dex) . Dexmedetomidine was infused intravenously at a dose of 0.5 μg/kg over 10 min before induction of anesthesia, followed by 0.5 μg·kg-1·h-1 infusion until the end of surgery.The equal volume of normal saline was given instead in group NS.Before induction of anesthesia (baseline, T0) , and at 10 min after induction (T1) , after re-warming to 36 ℃ (T2) , and at 1, 6, 24, 48 and 72 h after termination of CPB (T3-7) , blood samples were obtained from the radial artery and jugular venous bulb for blood gas analysis, jugular venous oxygen saturation (SjvO2) and jugular venous oxygen partial pressure (PjvO2) were recorded, and cerebral O2 extraction rate (CERO2) and arteriovenous blood O2 content difference (Da-jvO2) were calculated.The concentrations of S-100β protein and neuron-specific enzyme (NSE) in serum were determined by enzyme-linked immunosorbent assay at T0 and T3-7.The time for mechanical ventilation, duration of intensive care unit stay, and development of postoperative complications were recorded. Results Compared with the baseline value at T0, the serum concentrations of S-100β and NSE were significantly increased at T3-7, and SjvO2 and PjvO2 were increased, and CERO2 and Da-jvO2 were decreased at T2 in both groups.Compared with group NS, the serum concentrations of S-100β and NSE were significantly decreased at T3-7, and no significant changes were found in the time for mechanical ventilation, duration of intensive care unit stay, and incidence of sinus bradycardia, hypotension, and re-intubation in group Dex.The parameters of cerebral oxygen metabolism were all within the normal range in both groups, and there was no significant difference between the two groups. Conclusion Dexmedetomidine infused intravenously at a dose of 0.5 μg/kg before induction of anesthesia, followed by 0.5 μg·kg-1·h-1 infusion until the end of surgery, provides cerebral protection in the pediatric patients undergoing correction of tetralogy of Fallot with CPB. Key words: Dexmedetomidine; Tetralogy of Fallot; Cardiopulmonary bypass; Brain; Child