Cerebral function monitors during pediatric cardiac surgery: Can they make a difference?

Abstract

m ECAUSE OF THE ADVANCES in surgical and perfusion techniques in the past three decades, the majority of conenital heart defects can now be repaired at a younger age than n the past. The most commonly used bypass techniques during ediatric cardiac surgery are low-flow cardiopulmonary bypass CPB) or high-flow deep hypothermic CPB, with or without irculatory arrest (dhCA).1 These methods allow a relatively loodless field and improve surgical conditions and ease of epair, but can have marked impacts on cerebral physiology and otential deleterious effects on cerebral function, leading to eurologic complications in the postoperative period. Clinical neurologic deficits after CPB in adults have been eported to occur in 1% to 5% of patients.2,3 In contrast, the ncidence of subclinical postoperative neurologic dysfunction s 50% to 70%.4,5 In a recent study, the incidence of cognitive ecline after CABG surgery was 53% in the immediate postperative period, 36% at 6 weeks, 24% at 6 months, and 42% t 5 years’ follow-up.6 As a consequence of advanced surgical and bypass technolgy, the mortality after pediatric cardiac surgery has decreased, lthough the incidence of acute and chronic neurologic seuelae remains a disturbing concern and has become the focus f recent research. In a multicenter study conducted between 988 and 1989, the incidence of acute neurologic morbidity in hildren ranged from 2% to 25%,7 with seizures and choreothetosis the most common complications reported. In the same tudy, other reported neurologic deficits were prolonged coma, troke, and hemiparesis. In 1998, a retrospective review reorted an incidence of acute neurologic complications of 2.3%, ith seizures, again, the most common finding (1.3%) espeially after heart transplantation.8 Other neurologic complicaions were coma after cardiac arrest, choreoathetosis, facial alsy, and bilateral subdural hematomas. Seizures have been ocumented in up to 36% of patients undergoing heart translantation9 and are likely related to cyclosporin A toxicity. otor disorders like chorea,12-14 paraplegia,15 Tourette’s synrome,16 neurodevelopmental delay,10,11,17 and language and ehavioral problems9,10 have been documented after pediatric ardiac surgery. Long-term neurologic sequelae are difficult to tudy, but perioperative deficits are now recognized as an ndependent risk factor for poor neurodevelopmental outcome t 1 and 4 years after CPB in children.9,10 The incidence and risk of cerebral injury during cardiac urgery in children are influenced by many factors including he underlying congenital heart defect, type of surgery, perfus