Extreme Physiology & Medicine

, 4:A158 | Cite as

The cardiovascular reserve index (CVRI) - a surrogate index in predicting heat tolerance

  • Yoram Epstein
  • Savyon Mazgaoker
  • Danit Atias
  • Ran Yanovich
  • Uri Gabbay
  • Yuval Heled
Open Access
Meeting abstract

Keywords

Arterial Blood Pressure Body Surface Area Central Venous Pressure Heat Tolerant Climatic Chamber 

Introduction

Cardiovascular Reserve Index (CVRI) was developed as a diagnostic method for estimating quantitatively cardiovascular performance reserve [1]. It has been also been suggested in previous studies as a predictor of cardiovascular related morbidities (e.g. shock or heart failure). We aimed to investigate the CVRI ability to distinguish between heat tolerant (HT) and heat intolerant (HI) individuals during exertional heat stress.

Methods

A modified version of the index was used in the present study as follows:
CVRI = 100 MAP - CVP ( H R 2 - BSA ) Open image in new window

Where: MAP=mean arterial blood pressure (mmHg), HR=heart rate (bpm), CVP=central venous pressure (estimated as 10% of MAP) (mmHg), BSA= body surface area (m2). Double-blind evaluation of momentary CVRI of 15 subjects (5 HI, 10 HT) at time points 0, 60 and 120 min during a standard heat tolerance test (HTT), which consists of a moderate excise on treadmill (5 km·h-1, 2 % slop) in a climatic chamber (40 ºC, 40 % rh) has been performed.

Results

Reduction in CVRI during exertional heat stress was observed in comparison to resting conditions in a comfortable climate (Figure 1). A significantly lower CVRI was found for the HI vis-à-vis the HT subjects (p < 0.0004).

Discussion

Exercise-heat stress challenges the cardiovascular system, which is depicted by lower CVRI values. It follows that the efficiency of the subject's thermoregulatory mechanism can be characterized by the cardiovascular reserve. Thus, CVRI allows HT and HI individuals to be distinguished.

Conclusion

The results suggest that CVRI, assessed from non-invasive measurements, can be used as a surrogate index in HTT for determining tolerance to heat even at an early stage of the test.

Figure 1

References

  1. 1.
    Gabbay U, Bobrovsky BZ: Method and system for estimating momentary cardiovascular performance reserve. U.S. Patent No. 20,150,005,647. 2015Google Scholar

Copyright information

© Epstein et al.; 2015

This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.

Authors and Affiliations

  • Yoram Epstein
    • 1
  • Savyon Mazgaoker
    • 1
  • Danit Atias
    • 1
  • Ran Yanovich
    • 1
  • Uri Gabbay
    • 1
  • Yuval Heled
    • 1
  1. 1.Heller Institute of Medical Research, Sheba Medical Center, Tel Hashomer, Israel. Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel. Department of EpidemiologyBeilinson Medical CentrePetah TiqvaIsrael

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