Treatment of acute mountain sickness: Hyperbaric versus oxygen therapy

To compare the benefits of simulated descent in a hyperbaric chamber with those of supplementary oxygen for the treatment of acute mountain sickness. A prospective study. The Snake River Health Clinic in Keystone, Colorado, which has an altitude of 2,850 m (9,300 ft). Twenty-four patients who presented with acute mountain sickness. A simulated descent of 1,432 m (4,600 ft) was attained by placing the patients in a fabric hyperbaric chamber and pressurizing the chamber to 120 mm Hg (2.3 PSI) above ambient pressure. Patients were randomly assigned to either the hyperbaric treatment or treatment with 4 L of oxygen given by facemask; both treatments lasted for two hours. Mean arterial oxygen saturation (Sao 2) increased 7% (84 ± 2% to 91 ± 1%) with pressurization and 14% (83 ± 4% to 96 ± 1%) with oxygen during treatment over pretreatment levels. Symptoms of acute mountain sickness decreased as rapidly with pressurization as with oxygen treatment, despite significantly higher Sao 2 in the oxygen-treated group during treatment. Symptomatic improvement was retained in both groups at least one hour after treatment. Simulated descent in a fabric hyperbaric chamber is as effective as oxygen therapy for the immediate relief of acute mountain sickness.