Impact of Moderate-Altitude Staging on Pulmonary Arterial Hemodynamics after Ascent to High Altitude

摘要

Staged ascent (SA), temporary residence at moderate altitude en route to high altitude, reduces the incidence and severity of noncardiopulmonary altitude illness such as acute mountain sickness. To date, the impact of SA on pulmonary arterial pressure (PAP) is unknown. We tested the hypothesis that SA would attenuate the PAP increase that occurs during rapid, direct ascent (DA). Transthoracic echocardiography was used to estimate mean PAP in 10 healthy males at sea level, after DA to simulated high altitude (hypobaric chamber, PB-460 torr), and at 2 times points (90min and 4 days) during exposure to terrestrial high altitude (PB-460 torr) after SA (7 days, moderate altitude, PB-548 torr). Alveolar oxygen pressure (Pa02) and arterial oxygenation saturation (Sa02) were measured at each time point.