Investigating the Regulation of the Circulatory System during Acute Hypobaric Hypoxia Exposure

Abstract

To support sustainable lunar exploration, future lunar habitats are proposed to utilize hypobaric hypoxic (HH) internal atmospheres, such as 8.2 psia with 34% O₂ or 7.6 psia with 32% O₂, to optimize crew health and extravehicular activity (EVA) efficiency. However, both chronic adaptation and potential acute exposure due to system leaks pose significant physiological risks, particularly concerning cardiovascular compensation and tissue oxygen utilization, which are not yet fully understood.This study investigated the physiological responses to acute HH exposure by monitoring real-time cardiovascular parameters and skeletal muscle oxygenation in healthy participants. Experiments were conducted under three conditions: normobaric normoxia (simulated 40 m altitude) and acute HH at simulated altitudes of 3500 m and 4500 m.HH exposure induced significant decreases in arterial oxygen saturation, triggering compensatory increases in heart rate, respiratory rate, and tidal volume. Cardiovascular dynamics and skeletal muscle oxygen extraction and consumption exhibited distinct altitude-dependent patterns. These findings clarify the immediate physiological trade-offs between oxygen delivery and utilization under acute hypoxia.This study elucidates the key mechanisms of human cardiovascular and muscular metabolic adaptation to acute HH. The results provide critical physiological data for assessing crew health risks during lunar habitat operations and EVAs, informing the development of environmental control systems, safety protocols, and predictive health models for future deep space missions.

Keywords: Hypobaric Hypoxia, Circulatory System, Skeletal Muscle Oxygenation, EVA Safety

DOI: 10.54941/ahfe1007791