Heart rate, blood pressure, and SpO2 responses to simulated 5000 m hypobaric exposure in healthy male Vietnamese pilots.

This study was motivated by the limited high-altitude physiology data available for Asian military aviators, especially in Vietnam. To characterize acute heart rate (HR), blood pressure (BP), and oxygen saturation (SpO2) responses in healthy Vietnamese pilots during simulated 5000 m hypobaric exposure. Seventy-five healthy male military pilots underwent 30-min exposure in a hypobaric chamber simulating 5000 m altitude. HR, systolic/diastolic BP (SBP/DBP), and SpO2 were recorded at baseline (0 m), peak altitude, and post-exposure. HR increased from 80.0 ± 9.0 to 91.9 ± 11.0 bpm, SBP/DBP rose by 10.4/6.5 mmHg, and SpO2 decreased from 98.4 ± 1.0% to 77.7 ± 6.0% (all p < 0.001). All changes were transient, returning to baseline within 5 min after exposure, and no adverse events occurred. Higher baseline HR and older age predicted smaller HR increases. Acute 5000 m hypobaric hypoxia caused transient tachycardia, hypertension, and hypoxemia. Response variability correlated with baseline hemodynamic status and age. This safe, reproducible model can serve as a noninvasive cardiovascular stress test in clinical and aerospace medicine.