Both Hypoxia and Hypobaria Impair Baroreflex Sensitivity but through
                    Different Mechanisms

Nicolas Bourdillon; Mathias Rolland Aebi; Bengt Kayser; Denis Bron; Gregoire P Millet

doi:10.1055/a-1960-3407

International Journal of Sports Medicine, Inhaltsverzeichnis

CC BY-NC-ND 4.0 · Int J Sports Med 2023; 44(03): 177-183
DOI: 10.1055/a-1960-3407

Physiology & Biochemistry

Both Hypoxia and Hypobaria Impair Baroreflex Sensitivity but through Different Mechanisms

Nicolas Bourdillon

¹ISSUL, institute of sports sciences, Université de Lausanne, Lausanne, Switzerland

,

Mathias Rolland Aebi

¹ISSUL, institute of sports sciences, Université de Lausanne, Lausanne, Switzerland

²Wissenschaft & Technologie, armasuisse, Thun, Switzerland

,

Bengt Kayser

¹ISSUL, institute of sports sciences, Université de Lausanne, Lausanne, Switzerland

,

Denis Bron

¹ISSUL, institute of sports sciences, Université de Lausanne, Lausanne, Switzerland

,

Gregoire P Millet

³ISSUL, University of Lausanne, Lausanne, Switzerland

› Institutsangaben

Abstract

Baroreflex sensitivity (BRS) is a measure of cardiovagal baroreflex and is lower in normobaric and hypobaric hypoxia compared to normobaric normoxia. The aim of this study was to assess the effects of hypobaria on BRS in normoxia and hypoxia. Continuous blood pressure and ventilation were recorded in eighteen seated participants in normobaric normoxia (NNx), hypobaric normoxia (HNx), normobaric hypoxia (NHx) and hypobaric hypoxia (HHx). Barometric pressure was matched between NNx vs. NHx (723±4 mmHg) and HNx vs. HHx (406±4 vs. 403±5 mmHg). Inspired oxygen pressure (PiO₂) was matched between NNx vs. HNx (141.2±0.8 vs. 141.5±1.5 mmHg) and NHx vs. HHx (75.7±0.4 vs. 74.3±1.0 mmHg). BRS was assessed using the sequence method. BRS significantly decreased in HNx, NHx and HHx compared to NNx. Heart rate, mean systolic and diastolic blood pressures did not differ between conditions. There was the specific effect of hypobaria on BRS in normoxia (BRS was lower in HNx than in NNx). The hypoxic and hypobaric effects do not add to each other resulting in comparable BRS decreases in HNx, NHx and HHx. BRS decrease under low barometric pressure requires future studies independently controlling O₂ and CO₂ to identify central and peripheral chemoreceptors’ roles.

Key words

baroreflex sensitivity - blood pressure - heart rate - hypobaria - hypoxia - hypocapnia

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Referenzen

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