Medicine & Science in Sports & Exercise:
A-37 Free Communication/Poster - High Altitude Physiology: JUNE 1, 2011 7:30 AM - 12:30 PM: ROOM: Hall B
USARIEM, Natick, MA.
(No relationships reported)
Hypohydration is believed to exacerbate development of acute mountain sickness (AMS) in unacclimatized lowlanders ascending to high altitude.
PURPOSE: We examined the prevalence and severity of AMS and concurrent hydration status in 24 low-altitude residents during a 7 day ascent of Mt. Kilimanjaro (5895 m). Specifically, after 5 days acclimatization up to 4637 m, we assessed the impact of a single day ascent to the summit with overnight at 5731 m on AMS and hydration status.
METHODS: AMS was assessed morning and evening using the Environmental Symptoms Questionnaire to calculate the AMS-Cerebral (AMS-C) severity score. Resting SaO2 was obtained by finger pulse oximetry during AMS assessment. Hydration status was assessed from first morning void urine specific gravity (Usg) measured by Hydra Trend test strips (UriDynamics, Inc., Indianapolis, IN). Usg values ≥1.020 indicated hypohydration. Food and beverages were readily available and participants were encouraged to eat and drink, ad lib.
RESULTS: After acclimatization, upon awaking at 4637 m AMS prevalence (1/24) and AMS-C severity score (0.142±0.194, mean±SD) were low and SaO2 was 85±3%, indicating good acclimatization. Only 3/24 subjects were hypohydrated. All participants reached the summit, and descended to crater camp at 5731 m by 1500 h. That evening, AMS prevalence (10/24) and severity (0.913±0.894) were higher (p<0.05) and SaO2 (70±6%) lower (p<0.01) vs. 4637 m. Next morning AMS prevalence (5/24) and severity (0.482±0.376) decreased (p<0.05) and SaO2 (74±4%) improved (p<0.01) relative to the prior evening values. Upon awakening, 15/24 subjects were hypohydrated, but only 1/5 subjects with AMS was hypohydrated, and individual morning AMS-C scores demonstrated no correlation with individual morning Usg.
CONCLUSION: In acclimatized subjects hypohydration did not increase AMS symptom severity. Funding: USAMRMC. Authors' views; not official U.S. Army or DoD policy.