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 |
NNT=4
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.
