High altitude, continuous positive airway pressure, and obstructive sleep apnea: subjective observations and objective data.

We report observations made by one of the authors who ascended to the Thorang La pass (5416 m) in the Nepal Himalaya in October 2010, despite moderate-severe obstructive sleep apnea. We report the first recorded use of nasal CPAP to treat high altitude pulmonary edema (progressively severe dyspnea at rest and severe orthopnea, with tachycardia and tachypnea) that occurred at 4400 meters, when snow and darkness made safe evacuation difficult. We also present objective longitudinal data of the effects of altitude on auto-adjusting CPAP delivered via a portable nasal CPAP device, and on the apnea hypopnea index measured during sleep while using the device. OSA may be a risk factor for the development of high altitude pulmonary edema and we suggest that a nasal CPAP device located in high altitude trekking stations may provide an additional or alternative treatment option for managing high altitude pulmonary edema until evacuation is possible.