Running on Empty? The Compensatory Reserve Index

Abstract

BACKGROUND: Hemorrhage is a leading cause of traumatic death. We hypothesized that state-of-the-art feature extraction and machine learning techniques could be used to discover, detect, and continuously trend beat-to-beat changes in arterial pulse waveforms associated with the progression to hemodynamic decompensation. METHODS: We exposed 184 healthy humans to progressive central hypovolemia using lower-body negative pressure to the point of hemodynamic decompensation (systolic blood pressure 9 80 mm Hg with or without bradycardia). Initial models were developed using continuous noninvasive blood pressure waveform data. The resulting algorithm calculates a compensatory reserve index (CRI), where 1 represents supine normovolemia and 0 represents the circulatory volume at which hemodynamic decompensation occurs (i.e., running on empty ). Values between 1 and 0 indicate the proportion of reserve remaining before hemodynamic decompendecompensation-- muche fuel gauge of a car indicates the amount of fuel remaining in the tank. A CRI estimate is produced after the first 30 heart beats, followed by a new CRI estimate after each subsequent beat. RESULTS: The CRI model with a 30-beat windowhas an absolute difference between actual and expected time to decompensation of 0.1, with a SD of 0.09. The model distinguishes individuals with low tolerance to reduced central blood volume (i.e., those most likely to develop early shock) from those with high tolerance and are able to estimate how near or far an individual may be from hemodynamic decompensation. CONCLUSION: Machine modeling can quickly and accurately detect and trend central blood volume reduction in real time during the compensatory phase of hemorrhage as well as estimate when an individual is running on empty and will decompensate (CRI, 0), well in advance of meaningful changes in traditional vital signs.

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Document Details

Document Type
Technical Report
Publication Date
Dec 01, 2013
Accession Number
ADA616659

Entities

People

  • Greg Z. Grudic
  • Jane Mulligan
  • Steven L. Moulton
  • Victor A Convertino

Organizations

  • United States Army Institute of Surgical Research

Tags

Communities of Interest

  • Biomedical

DTIC Thesaurus Topics

  • Autonomous Navigation
  • Blood
  • Blood Volume
  • Cardiovascular Physiological Phenomena
  • Data Analysis
  • Feature Extraction
  • Health Care
  • Health Services
  • Hemorrhage
  • Hemorrhagic Shock
  • Machine Learning
  • Medical Personnel
  • Physiological Monitoring
  • Robots
  • Unsupervised Machine Learning
  • Vital Signs
  • Waveforms

Fields of Study

  • Medicine

Readers

  • Cardiovascular Physiology
  • Computational Modeling and Simulation
  • Neural Network Machine Learning.

Technology Areas

  • AI & ML
  • AI & ML - Bayesian Inference