Prior altitude experience of climbers attempting to summit Aconcagua.

Aconcagua (6962 m) is one of the seven summits and the highest mountain outside of Asia. Climbers of varying experience are drawn to its nontechnical route. Our objective was to detail the prior altitude experience of climbers attempting to summit Aconcagua. We asked all climbers on the normal route of Aconcagua to complete questionnaires with demographics and prior high altitude experience while acclimatizing at Plaza de Mulas base camp during 9 nonconsecutive days in January 2009. 127 volunteers from 22 countries were enrolled. Mean age was 39.8 years and 88.2% were male. Median altitude at place of residence was 200 m (IQR: 30, 700). Median previous maximum altitude reached was 5895 m (IQR: 5365, 6150). 7.1% of climbers had never been above 4000 m. Median previous maximum sleeping altitude was 4800 m (IQR: 4300, 5486). 12.6% of climbers had never slept above 4000 m. Climbers who performed acclimatization treks spent a mean of 3.6 (2.5, 4.7) days at>3000 m in the previous 2 months. However, 50.4% of climbers performed no acclimatization treks. Although the majority of mountaineers who attempt Aconcagua have prior high altitude experience, a substantial minority has never been above 4000 m.

Visual analog scale (VAS) for assessment of acute mountain sickness (AMS) on Aconcagua.

OBJECTIVE: The Lake Louise AMS Self-Report Score (LLSelf) is a commonly used, validated assessment of acute mountain sickness (AMS). We compared LLSelf and visual analog scales (VAS) to quantify AMS on Aconcagua (6962 m). METHODS: Prospective observational cohort study at Plaza de Mulas base camp (4365 m), Aconcagua Provincial Park, Argentina. Volunteers climbing in January 2009 were enrolled at base camp and ascended at their own pace. They completed the LLSelf, an overall VAS [VAS(o)], and 5 individual VAS [VAS(i)] corresponding to the items of the LLSelf when symptoms were maximal. Composite VAS [VAS(c)] was calculated as the sum of the 5 VAS(i). RESULTS: A total of 127 volunteers consented to the study. Response rate was 52.0%. AMS occurred in 77.3% of volunteers, while 48.5% developed severe AMS. Median (interquartile range, IQR) LLSelf was 4 (3-7). Median (IQR) VAS(o) was 36 mm (23-59). VAS(o) was linear and correlated with LLSelf: slope = 6.7 (95% CI: 4.4-9.0), intercept = 3.0 (95% CI: -10.0-16.1), ρ = 0.71, τ = 0.55, R(2) = 0.45, p < 0.001. Median (IQR) VAS(c) was 29 (13-44). VAS(c) was also linear and correlated with LLSelf: slope = 5.9 (95% CI: 4.9-6.9), intercept = -0.6 (95% CI: -6.3-5.1), ρ = 0.83, τ = 0.68, R(2) = 0.73, p < 0.001. The relationship between the 5 VAS(i) and LLSelf(i) was less significant and less linear than that between VAS(o), VAS(c), and LLSelf. CONCLUSIONS: While both VAS(o) and VAS(c) for assessment of AMS appear to be linear with respect to LLSelf, the amount of scatter within the VAS is considerable. The LLSelf remains the gold standard for the diagnosis of AMS.

Postexercise peripheral oxygen saturation after completion of the 6-minute walk test predicts successfully reaching the summit of Aconcagua.

OBJECTIVE: 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). METHODS: 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). RESULTS: 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. CONCLUSIONS: 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.