Human cardiovascular responses to passive heat stress

Craig G. Crandall, Thad E. Wilson

Research output: Contribution to journalArticle

42 Citations (Scopus)

Abstract

Heat stress increases human morbidity and mortality compared to normothermic conditions. Many occupations, disease states, as well as stages of life are especially vulnerable to the stress imposed on the cardiovascular system during exposure to hot ambient conditions. This review focuses on the cardiovascular responses to heat stress that are necessary for heat dissipation. To accomplish this regulatory feat requires complex autonomic nervous system control of the heart and various vascular beds. For example, during heat stress cardiac output increases up to twofold, by increases in heart rate and an active maintenance of stroke volume via increases in inotropy in the presence of decreases in cardiac preload. Baroreflexes retain the ability to regulate blood pressure in many, but not all, heat stress conditions. Central hypovolemia is another cardiovascular challenge brought about by heat stress, which if added to a subsequent central volumetric stress, such as hemorrhage, can be problematic and potentially dangerous, as syncope and cardiovascular collapse may ensue. These combined stresses can compromise blood flow and oxygenation to important tissues such as the brain. It is notable that this compromised condition can occur at cardiac outputs that are adequate during normothermic conditions but are inadequate in heat because of the increased systemic vascular conductance associated with cutaneous vasodilation. Understanding the mechanisms within this complex regulatory system will allow for the development of treatment recommendations and countermeasures to reduce risks during the ever-increasing frequency of severe heat events that are predicted to occur.

Original languageEnglish (US)
Pages (from-to)17-43
Number of pages27
JournalComprehensive Physiology
Volume5
Issue number1
DOIs
StatePublished - Jan 1 2015

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Hot Temperature
Cardiac Output
Blood Vessels
Heat-Shock Response
Hypovolemia
Baroreflex
Autonomic Nervous System
Syncope
Cardiovascular System
Occupations
Vasodilation
Stroke Volume
Heart Rate
Maintenance
Hemorrhage
Blood Pressure
Morbidity
Skin
Mortality
Brain

ASJC Scopus subject areas

  • Medicine(all)

Cite this

Human cardiovascular responses to passive heat stress. / Crandall, Craig G.; Wilson, Thad E.

In: Comprehensive Physiology, Vol. 5, No. 1, 01.01.2015, p. 17-43.

Research output: Contribution to journalArticle

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