Hypoxia awareness and symptom dynamics under aviation-related simulated exposure

Hypoxia poses a significant risk in aviation and other safety-critical domains, yet individual awareness and perception of hypoxic states remain highly variable. This study investigated subjective symptom perception, continuous self-assessment, hypoxia recognition, objective performance, and physiological responses during experimentally induced hypoxia.

Twenty-three participants completed two experimental sessions in a within-subject design: a control condition and a hypoxia condition. Subjective symptoms were assessed using a post-exposure questionnaire, complemented by continuous ratings of overall feeling, concentration, and breathing. Objective performance was evaluated using a Stroop test and a mental rotation task, while physiological response was quantified via peripheral oxygen saturation (SpO₂).

Hypoxia induction was robust across all participants, with significant reductions in SpO₂ metrics under hypoxia. While no individual symptoms reached statistical significance after correction for multiple comparisons, several hypoxia-related symptoms showed consistent directional trends and approached statistical significance. Continuous subjective ratings were significantly lower under hypoxia, with breathing demonstrating a pronounced temporal deterioration. Hypoxia recognition occurred more often during hypoxia than during control. No significant effects were observed in objective performance measures.

These findings suggest that hypoxia primarily affects physiological state and subjective experience, with breathing-related sensations showing the clearest temporal changes among the subjective measures and potentially contributing to hypoxia awareness within the present experimental paradigm.