Heart Rate Variability as a Predictor of Hypotension

by Boone, Louvonia Rose

HEART RATE VARIABILITY AS A PREDICTOR OF HYPOTENSION. Louvonia R. Boone, Aymen Alian Awad, Nicholas Galante, Lisbeysi Calo, Kirk Shelley, David Silverman, Department of Anesthesiology, Yale University, School of Medicine, New Haven, CT. Heart rate variability describes beat to beat variance. This physiologic phenomenon is a marker of a healthy and responsive neuro-cardiovascular system. Indeed, there is a substantive body of research examining the decreased and otherwise altered profiles of older individuals, those with diabetic neuropathy, patients after infarctions. A new area of interest lies in the use of heart rate variability as a predictor of acute adverse outcomes, one critical area of interest includes hypotension. Several researchers have reviewed the effects of spinal anesthesia with its resultant sympathectomy in obstetrical patients utilizing an array of heart rate variability tools. Hanss et al performed retrospective analysis and identified an LF/HF ratio greater than 2.5 as a significant benchmark for parturients who would develop hypotension after spinal anesthesia. In our institution we studied a smaller cohort of 26 women and did not find this number or the general trend of greater sympathetic tone in hypotensive women. We subsequently studied the heart rate variability in controlled research settings using lower body negative pressure to simulate central hypovolemia. We found clear, albeit not statistically significant, separation between subjects who are responders and those who are non-responders. These separations were noted before inter group differences in heart rate. Our studies show promising if not significant separation in a controlled research setting. Considering the great inter group variability and challenges encountered in obtaining appropriate short term ECG recordings, we present cautious hope for clinical application.