Abstract
Introduction
A growing number of climbers attempts mountains over 5,500 meters each year. The rescue of climbers from these elevations is dangerous and expensive, with each rescue on Denali averaging over $20,000. The 6-minute walk test (6MWT), previously tested on Aconcagua, is an inexpensive and easily reproducible screening test for summit success that may provide early detection for those requiring rescue.
Objective
The purpose of this study was to validate the 6MWT at 14,000 ft (4,267 m) on Denali, Alaska.
Methods
This was a prospective observational cohort study of healthy adults between the ages of 18 and 65 who had been at 14,000 ft for less than 24 hours in June, 2013. Vital signs (VS) were measured before and after the 6MWT. Subjects attempted to summit at their own pace and, at the time of descent, returned to the study tent and completed a Lake Louise AMS Questionnaire (LLQ) and reported maximum elevation reached.
Results
One hundred and twenty-one participants enrolled in the study. Complete data was collected on 100 subjects (86% response rate) of whom 62% summited. Univariate analysis revealed that there was no association between any resting or post-exercise VS and summit success. Specifically, there was no significant difference between the post-exercise oxygen saturation in summiters (S, 74.6%) and non-summiters (NS, 74.05%), which differed by –0.54% (95% CI: –0.93% to –0.13%, P = .53). The 6-minute walk test distance (6MWTD) revealed marginal significance with 2025 ft (S) and 1855 ft (NS) for a difference of –170 feet (95% CI: –247.6 ft to –91.39 ft, P = .048; OR: 1.000; 95% CI: 1.000 to 1.002).
Conclusions
This study showed that the post-exercise oxygen saturation does not correlate with summit success. The distance a subject covered in 6 minutes, however, may be a better measure of functional status at altitude.