The assessment of an individual's degree of acclimatization to altitude is difficult. This is particularly applicable to military operations that have to be performed at altitude. This study describes a new and simple test that allows for the determination of an individual's risk for high-altitude illness at higher altitudes. The prediction is based on the lowest oxygen saturation (SaO2) found during an uphill run at high altitude (11,060 ft [3,371 m]), combined with the time needed to complete the run. The test results were compared against the severity of high-altitude symptomatology on the summit of Mont Blanc (15,762 ft [4,808 m]). The main outcome was the significant correlation between time as well as SaO2 and the severity of high-altitude symptomatology on the summit of Mont Blanc. The newly developed performance test allows, at a "safe" altitude, the prediction of an individual's risk of developing high altitude illness if they continue to ascend. It allows the determination of the best acclimatized subjects within a group, for example, before a military mission at greater altitude.
[Show abstract][Hide abstract] ABSTRACT: Expanding athlete participation in high-altitude environments highlights the importance for a sports physician to have a good understanding of the high-altitude illness (HAI) syndromes: acute mountain sickness (AMS), high-altitude cerebral edema (HACE), and high-altitude pulmonary edema (HAPE). All may occur in the setting of acute altitude exposure higher than 2500 m; incidence and severity increases as altitudes or ascent rates increase. Once HAI is recognized, proven therapies should be instituted to alleviate symptoms and avert the possibility of critical illness. Allowing for acclimatization is the best strategy for preventing HAI. Acetazolamide and dexamethasone are additional preventive measures for AMS/HACE; nifedipine, salmeterol, and phosphodiesterase inhibitors are useful in preventing HAPE. Along with the immediate hazards of HAI with altitude exposure, the sport physician also should be familiar with altitude/hypoxic training practices used by athletes to enhance fitness and performance.
Current Sports Medicine Reports 01/2010; 9(2):79-85. DOI:10.1249/JSR.0b013e3181d404ac · 1.55 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The 6-minute walk test (6MWT) is a single measurement of functional status in patients with cardiovascular disease. It has not been studied at high altitude. We investigate the screening value of 6-minute walk distance (6MWD) and postexercise vital sign (VS) measurements as predictors of successfully reaching the summit or development of acute mountain sickness (AMS) on Aconcagua (6962 m).
Prospective observational cohort in Aconcagua Provincial Park, Argentina. Adults climbing the normal route who registered with base camp physicians were included. There were no exclusion criteria. VSs were measured before (resting) and after (postexercise) completion of 6MWT while volunteers acclimatized at Plaza de Mulas base camp (4365 m). Volunteers proceeded towards the summit at their own pace and upon descent returned a questionnaire with maximum altitude reached and Lake Louise AMS Self-report Score (LLSelf).
One hundred twenty-four volunteers completed the 6MWT. Sixty-four volunteers (51.6%) completed questionnaires; 56% summited. Median LLSelf was 4 (IQR: 3.0-6.5). There was no association between any resting or postexercise VS measurements and AMS. However, mean postexercise SpO(2) was 80.8% in summiters and 76.4% in nonsummiters, a difference of -4.4% (95% CI: -6.7 to -2.0, p = 0.0005). Postexercise SpO(2) < 75% had 97.2% sensitivity and negative likelihood ratio of 0.086 in predicting the outcome of successfully reaching the summit: only one climber with SpO(2) < 75% successfully reached the summit.
This study provides the first published data on 6MWD recorded in the field at high altitude. Postexercise SpO(2) < 75% may be a useful screening test for predicting the outcome of successfully reaching the summit of Aconcagua.
Wilderness and Environmental Medicine 12/2010; 21(4):309-17. DOI:10.1016/j.wem.2010.09.003 · 1.20 Impact Factor
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