One night at 1,900 m prompts ventilatory acclimatization without altering cardiac autonomic regulation at 3,000 m in males with coronary artery disease.
Level 2 - randomized trial
Individual randomized crossover trial
PubMed 41455100 · doi:10.1152/japplphysiol.00416.2025
What was done
Ten males with coronary artery disease (CAD) participated in a randomized placebo-controlled crossover trial conducted in a hypobaric chamber. Participants slept for one night either at simulated moderate altitude (1,900 m) or control conditions (250 m, placebo) before decompression to simulated high altitude (3,000 m) the following morning. Overnight respiratory polygraphy was performed. Wakeful resting measurements before overnight stay and after ascent to 3,000 m included peripheral oxygen saturation (SpO2), end-tidal partial pressure of CO2 (PETCO2), cerebral tissue oxygen saturation index (cTSI), baroreflex sensitivity (BRS), heart rate variability (HRV), and pulmonary artery systolic pressure (PASP).
What was found
The overnight stay at 1,900 m had more apneas/hypopneas (33 [9, 51] h-1) than placebo (6 [3, 13] h-1, P = 0.02). Subsequent wakeful rest at 3,000 m showed: - SpO2: 88 ± 2% vs. 87 ± 2% (placebo), P = 0.03 - PETCO2: 34 ± 3 mmHg vs. 36 ± 3 mmHg (placebo), P = 0.002 - cTSI decrease: -3.6 ± 2.2% vs. -6.5 ± 3.1% (placebo), P = 0.02 - PASP: 30 ± 8 mmHg vs. 28 ± 7 mmHg (placebo), P = 0.04 - BRS and HRV: No significant differences between conditions.
Why it matters
A single night at moderate altitude induces ventilatory acclimatization and reduces cerebral deoxygenation upon further ascent to 3,000 m in men with CAD without perturbing resting cardiac autonomic tone, despite causing nocturnal breathing events and mildly higher pulmonary pressure.
Limits
The trial had a very small sample size (n = 10) and only included male participants. It was conducted in an artificial hypobaric chamber during short-term resting conditions, leaving exercise tolerance, longer-term altitude stays, and clinical cardiovascular outcomes unmeasured.
Cited by
- supports At 10,000 feet of elevation, there is a notable physiological effect on the body.