A Pilot Study to Assess the Feasibility and Safety of Targeting Mean Arterial Pressure to Reduce Intra-operative Hypotension

Congenital heart disease (CHD) is the most common birth defect.1 Surgery to treat CHD is complicated by white matter injury (WMI) on brain magnetic resonance imaging (MRI) and neurodevelopmental (ND) deficits in 50% to 75% of neonates after CHD surgery.2-6 Cerebral hypoperfusion is a major mechanism of brain injury during both cardiopulmonary bypass (CPB) and the perioperative period in the intensive care unit (ICU).7-10 Investigators lack diagnostic and therapeutic means to reduce cerebral hypoperfusion-associated white matter injury (WMI) and improve long-term ND outcomes.11 Our long-term goal is to use real-time measurement of the cerebral lower limit of autoregulation (LLA) to manage arterial blood pressure, reduce cerebral hypoperfusion-associated brain injury, and improve long-term ND outcomes in children at risk for brain hypoperfusion. In a prospective, single blind, randomized clinical trial (RCT) in adults undergoing cardiac surgery, investigators previously showed that targeted LLA arterial blood pressure management to maintain mean arterial pressure (MAP) above the LLA decreased the incidence of postoperative delirium by 45%.12 Our preliminary data indicate that neonates are exposed to significantly more cerebral hypotension than adult patients undergoing CPB. Our central hypothesis is that a strategy of targeting mean arterial pressure (MAP) to a level above an individual's LLA will reduce the risk for WMI and neurodevelopmental impairment in neonates undergoing congenital heart surgery. Our team has validated methodology to delineate the LLA and demonstrated the important role of cerebral autoregulation monitoring on short-term outcomes in CHD subjects who have undergone CPB.13 We can rigorously measure cerebral autoregulation in real time and the amount of cerebral hypotension (duration and magnitude) through the integration of near infrared spectroscopy (NIRS) and the arterial blood pressure.14,15 The efficacy of an LLA targeted MAP strategy to minimize WMI and improve ND outcomes can only be demonstrated by a prospective, single-blind, multi-center randomized RCT. To obtain funding for this large multi-center RCT will require the demonstration of feasibility and safety, as well as, an estimation of the sample size needed to show efficacy.