Kasic
Simulated descent breathing hyperbaric air is as effective as oxygen admininstration in the treatment of mild acute mountain sickness.
Clinical Bottom Line: 1. Hyperbaric air was as effective as oxygen in resolving symptoms of acute mountain sickness. 2. Arterial oxygen saturations were higher in the oxygen treated group. Appraised by: Mike Bennett, Dept of Diving and Hyperbaric Medicine, Prince of Wales Hospital Sydney; Tuesday, 16 February, 1999
Clinical Scenario: A 35-year-old man suffering with acute mountain sickness. We wondered if simulated descent in a hyperbaric chamber would be an effective treatment. Three-part Question: In patients suffering acute mountain sickness, does the application of pressure in a hyperbaric chamber, compared to the administration of oxygen given by facemask, result in any comparable relief of symptoms? Search Terms: hyperbaric oxygenation, mountain sickness
The Study: Non-blinded randomised controlled trial with intention-to-treat. Patients presenting with acute mountain sickness (headache and/or nausea) or early high altitude pulmonary oedema (X-Ray changes and/or clinical exam). Control group (N = 14; 11 analysed): Oxygen administration through a rebreather facemask at 4l/min for two hours. Experimental group (N = 15; 13 analysed): Hyperbaric air at 120mmHg above ambient in a portable fabric chamber for two hours.
The Evidence:
| Outcome | Time to Outcome | Oxygen group | Hyperbaric group | Relative risk reduction | Absolute risk reduction | NNT |
| Did not respond | 2hrs | 0.09 | 0.08 | 15% | 0.014 | 71 |
| 95% CI: | -100% to 100% | -0.21 to 0.24 | NNT4 to INF NNH=5 to INF |
Non-Event Outcomes Time to outcome Oxygen group Hyperbaric group P-value
Oxygen saturation 1hr 96% 91% <0.05
Symptom resolution score 3hrs 0.9 0.8 >0.05
Comments: 1. Less than 80% of data set available for analysis in oxygen group. 2. No longer-term follow-up. 3. More severe presentations were excluded from the study
Expiry date:April 2003 References: 1. Kasic J, Yaron M, Nicholas R, Lickteig J, Roach R. Treatment of acute mountain sickness: hyperbaric versus oxygen therapy. Annals of Emergency Medicine 1991; 20:1109-1112.
