Heart Rate Variability and Spontaneous Baroreflex Sequences: Implications for Autonomic Monitoring During Hemorrhage

Abstract

Background: Noninvasive procedures for predicting progression to hemodynamic instability during induced central hypovolemia in humans were evaluated. The purpose of this study was twofold: (1) to track changes in autonomic function induced by a model of hemorrhage, and (2) to determine whether measures of autonomic function are reliable without strict control of breathing. Methods: Electrocardiogram, respiratory frequency, and arterial pressure during progressive lower body negative pressure were recorded for 10 subjects, and for a separate sample of 20 subjects during 5-minute periods of spontaneous breathing or controlled-frequency breathing at 15 breaths per minute. Heart rate variability was calculated in both time and frequency domains. Up and down baroreflex sequences were calculated with linear regression analysis between sequential changes in systolic pressures and accompanying parallel changes in R-R intervals. Results: Heart rate variability (r2 = 0.92) and up (r2 = 0.90) and down (r2 = 0.96) sequences changed in direct inverse relation to decreased central volume as produced by progressive increases in lower body negative pressure, whereas mean arterial pressures remained constant (r2 = 0.26). Neither heart rate variability nor up and down baroreflex sequences were affected by the mode of breathing. Conclusions: Analysis of heart rate variability and baroreflex sequences in hemorrhaging patients may provide advance recognition of those at risk for progression to shock. In conjunction with more traditional modes of assessing volume status, tracking early changes in autonomic function may improve resuscitation efforts for the hemodynamic compromised patient.

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Document Details

Document Type
Technical Report
Publication Date
Apr 01, 2005
Accession Number
ADA628183

Entities

People

  • Victor A Convertino
  • William H. Cooke

Organizations

  • United States Army Institute of Surgical Research

Tags

Communities of Interest

  • Biomedical

DTIC Thesaurus Topics

  • Blood
  • Blood Volume
  • Cardiovascular Physiological Phenomena
  • Data Analysis
  • Electrocardiography
  • Frequency
  • Frequency Domain
  • Health Services
  • Heart Rate
  • Hemorrhage
  • Hemorrhagic Shock
  • Hypovolemia
  • Information Science
  • Monitoring
  • Patient Care
  • Regression Analysis
  • Sequences

Fields of Study

  • Medicine

Readers

  • Brain and Cognitive Science; Experimental Psychology; Cognitive Neuroscience
  • Cardiovascular Physiology