Cerebral oxygenation and hemodynamic changes during infant cardiac surgery: measurements by near infrared spectroscopy

Abstract

Despite dramatic advances in the survival rate amongst infants undergoing cardiac surgery for congenital heart disease, the incidence of brain injury suffered by survivors remains unacceptably high. This is largely due to our limited understanding of the complex changes in cerebral oxygen utilization and supply occurring during the intraoperative period as a result of hypothermia, neuroactive drugs, and profound circulatory changes. Current techniques for monitoring the adequacy of cerebral oxygen supply and utilization during hypothermic cardiac surgery are inadequate to address this complex problem and consequently to identify the infant at risk for such brain injury. Furthermore, this inability to detect imminent hypoxic-ischemic brain injury is likely to become all the more conspicuous as new neuroprotective strategies, capable of salvaging ‘‘insulted’’ neuronal tissue from cell death, enter the clinical arena. Near infrared spectroscopy is a relatively new, noninvasive, and portable technique capable of interrogating the oxygenation and hemodynamics of tissue in vivo. These characteristics of the technique have generated enormous interest amongst clinicians in the ability of near infrared spectroscopy to elucidate the mechanisms of intraoperative brain injury and ultimately to identify infants at risk for such injury. This paper reviews the experience with this technique to date during infant cardiac surgery.