PROJECT SUMMARY/ABSTRACT Children with Down syndrome (DS) often experience dangerously low heart rates on induction of anesthesia for routine procedures and this occurs at 10 times the rate of non-DS patients. Given that the cardiac output of children is heart rate dependent, bradycardia is especially perilous in this population. Historically, individuals with DS were not expected to survive beyond childhood; consequently, correction of congenital anomalies, e.g. cardiac defects, was not frequently offered. Fortunately, today individuals with DS live into adulthood and surgical correction of anomalies is universally offered. Thus, increasing numbers of children with DS are exposed to anesthesia and at risk for this hemodynamic catastrophe. It is medically unacceptable and requires more study. This project seeks to address the problem of induction bradycardia by studying its mechanism. We plan to quantify nervous system determinants of heart rate during these bradycardic events and eventually develop protocols to identify and mitigate the risk. Specifically, we aim to: 1) Quantify the autonomic nervous system behavior during induction using multi-parameter monitoring to potentially unveil their root cause. 2) Test the feasibility of that autonomic nervous system monitor using both ambulatory and perioperative monitoring protocols to detect which patients are at risk. Successful completion of this project will provide the physiologic information required to reduce the risk of morbid bradycardic events on induction of anesthesia in children with DS.