Serial changes in spirometry during an ascent to 5,300 m in the Nepalese Himalayas

Area of Science:

• Physiology
• Environmental Medicine
• Pulmonary Medicine

Background:

• High-altitude environments present physiological challenges.
• Understanding lung function changes at extreme altitudes is crucial for climber safety and health.
• Acute mountain sickness (AMS) is a common concern during rapid ascent.

Purpose of the Study:

• To assess changes in forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), and peak expiratory flow (PEF) during ascent to 5,300 m.
• To correlate these pulmonary function changes with arterial oxygen saturation (SpO2) and AMS symptoms.

Main Methods:

• Forty-six subjects were monitored during a 10–16 day ascent from 2,800 m to 5,300 m in the Nepalese Himalayas.
• Pulmonary function tests (FVC, FEV1, PEF), SpO2, and AMS scores were recorded twice daily.
• AMS was evaluated using a standardized scoring system.

Main Results:

• Forced vital capacity (FVC) significantly decreased with altitude.
• Peak expiratory flow (PEF) significantly increased with altitude.
• Forced expiratory volume in 1 second (FEV1) remained unchanged.
• No significant correlation was found between spirometric changes, SpO2, or AMS scores.

Conclusions:

• Hypobaric hypoxia causes a progressive fall in FVC and an increase in PEF, while FEV1 is unaffected.
• The observed pulmonary function changes may be linked to inspiratory force, pulmonary edema, or airway dynamics.
• Current spirometric measures may not be sensitive enough to detect altitude-related pulmonary dysfunction or correlate with AMS severity.