Study of the Cardiorespirator System Response to Normobaric Hypoxia

Abstract

Research into cardiorespiratory responses to prolonged hypoxia (more than 60 minutes) is of particular interest in terms of elucidating adaptive mechanisms under the conditions of oxygen deficiency. Aim: to identify the parameters of the cardiorespiratory system under relative rest most sensitive to hypoxia and to determine the most optimal time interval for a hypoxic test. Experiments were carried out in a normobaric hypoxic complex, in which hypoxic respiratory gas conditions were created corresponding to the partial oxygen pressure at altitudes of 3500 and 4500 m. Cardiorespiratory responses were evaluated using a MetaLyzer 3B ergospirometric system (Cortex, Germany). Indicators sensitive to moderate normobaric hypoxia under relative rest include hemoglobin oxygen saturation (the most sensitive indicator), oxygen and carbon dioxide ventilation efficiency (VE/VO₂ and VE/VCO₂), respiratory rate and respiratory coefficient (VCO₂/ VO₂). A significant change in the indicators of the cardiorespiratory system at an altitude of 4500 m was noted within 5 minutes following hypoxic exposure; therefore, normobaric hypoxic tests should be carried out at this height under the hypoxic exposure of 30 minutes.