The significance of baseline cerebral oxygen saturation in children undergoing congenital heart surgery

Objectives Despite recent significant improvement in outcome, children undergoing surgery for correction of congenital heart defects have a persistent and troublesome mortality rate and incidence of neurologic complications. Recent data suggest that some congenital heart defects are associated with abnormal brain development and with low cerebral blood flow. We hypothesized that some children with congenital heart disease have an abnormally low baseline (preoperative) cerebral oxygen saturation (ScO2). Methods ScO2 was continuously recorded intraoperatively in 143 infants and children (age <18 years) undergoing repair of congenital heart defects on cardiopulmonary bypass. Baseline saturation was obtained prior to induction of anesthesia. Preoperative and postoperative saturations were correlated with the patient’s physiology (cyanotic vs. acyanotic, presence of ventricular- or arterial-level left-to-right shunts) and outcome. Results Patient age ranged from 2 days to 17 years (median 8 months). Mean baseline ScO2 was 64%. Preoperative ScO2 was lower in infants with left to right shunt physiology (P < .01), but not in cyanotic infants without left-to-right shunts. Perioperative death was associated with baseline saturation less than 50%. Conclusions Baseline ScO2 is lower in patients with left-to-right shunt physiology. Postoperative saturation is lower in patients with left-to-right shunt physiology and in cyanotic patients. Low baseline ScO2 predicts perioperative mortality in children with congenital heart disease. Measurement of ScO2 preoperatively will provide additional information for parent counseling, and preoperative optimization of ScO2 may improve outcome.