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Hypoxemia and acute mountain sickness: which comes first?
Jack A Loeppky1, Milton V Icenogle, Gerald A Charlton
1Cardiology Section, VA Medical Center, Albuquerque, New Mexico 87108, USA. loeppkyj@telus.net
High Altitude Medicine & Biology
|January 1, 2009
Summary
Early hypoxemia, or low blood oxygen, may predict acute mountain sickness (AMS) in individuals resting at high altitudes. This finding could help identify susceptibility to AMS before symptoms develop.
Area of Science:
- Altitude physiology
- Respiratory medicine
- Environmental health
Background:
- Acute mountain sickness (AMS) is commonly linked to hypoxemia, but previous studies had inconsistent findings due to varying exposure conditions.
- Understanding the early onset of hypoxemia is crucial for predicting AMS development.
Purpose of the Study:
- To investigate whether hypoxemia occurs early in individuals who subsequently develop AMS while resting at simulated high altitude.
- To identify potential predictors of AMS susceptibility.
Main Methods:
- 51 participants underwent 8-12 hour exposures at a simulated altitude of 4880m.
- Acute mountain sickness (AMS) was assessed using Lake Louise (LL) and AMS-C scores.
- Spirometry, gas exchange, and arterial blood gases were measured at various time points.
Main Results:
- Individuals who developed AMS (+AMS group) showed significantly lower PaO2 and SaO2 at 1 and 12 hours compared to the non-AMS group.
- Ventilation responses were similar between groups.
- Pulmonary edema indicators (reduced vital capacity, increased breathing frequency) appeared later in the +AMS group.
Conclusions:
- Early hypoxemia, potentially due to diffusion impairment or venous admixture, is observed in individuals susceptible to AMS.
- Measuring early hypoxemia may serve as a useful predictor for AMS susceptibility.
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