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The effects of altitude on human performance and cognition were evaluated in a field study performed on Mount Denali in Alaska during the summer of 1990. Climbers performed a series of perceptual, cognitive, and sensory-motor tasks before, during, and after climbing the West Buttress route on Denali. Relative to a matched control group that performed the tasks at sea level, the climbers showed deficits of learning and retention in perceptual and memory tasks. Furthermore, climbers performed more slowly on most tasks than did the control group, suggesting long-term deficits that may be attributed to repeated forays to high altitudes. [ABSTRACT FROM AUTHOR]

A case of mitral regurgitation due to a stab wound to the heart in a nine-year-old boy is presented. The initial injury did not require operative intervention and was treated with closed tube thoracostomy alone. After six years and the development of progressive mitral insufficiency, a two-centimeter defect in the anterior leaflet of the mitral valve was repaired with a pericardial patch. He had an uneventful recovery and no regurgitation is present five years following the repair.

Mountaineering involves high altitude and cold exposure which are each associated with significant levels of dehydration (via altitude-cold diuresis, high energy expenditures, and poor access to water). The purpose of this study was to identify and validate urine and blood indices of dehydration as compared to changes in total body water (which served as the reference standard). Male subjects (n = 10) were studied during a 14 day mountaineering expedition in the sub-Arctic during which they climbed to an altitude of 5245 +/- 229 m (mean +/- SE). Daily activity consisted of approximately 10-15 hours skiing, hiking, and performing mountaineering tasks with heavy loads (> 30 kg). Various measurements were made immediately before ascending (Pre) and after descending (Post) the mountain: body weight (Bw) and composition (%Fat), urine specific gravity (USG), urine protein (UP), plasma electrolytes (K+, Cl-, Na+), plasma proteins (PP), plasma and urinary osmolality (UOsm), hematocrit (Hct), hemoglobin (Hb), blood urea nitrogen (BUN), plasma aldosterone, and total body water (TBW determined via deuterium oxide). Post the expedition significant (p < 0.05) decreases were observed in Bw, and %Fat, while significant increases were found in Na+, K+, USG, UOsm and UP. TBW was slightly reduced, however, changes were non-significant (Pre = 52.9 +/- 1.2 L vs. Post = 52.6 +/- 1.3 L). USG is often used to monitor hydration status in field settings; however, no significant correlations were found between changes in TBW and USG, nor between changes in TBW and other typical urinary indicators of dehydration.(ABSTRACT TRUNCATED AT 250 WORDS)

The purpose of this study was to examine changes in select anaerobic and aerobic dependent physical performance tasks in U.S. Marines exposured to field operations at moderate altitude. The subjects (N = 16) completed Wingate anaerobic power, submaximal aerobic cycle ergometry, hand grip strength, and push-up tests on three separate occasions. Testing sessions occurred at sea level, at altitude after a 10-day acclimatization period (immediately before field operations), and at altitude immediately after 4.5 days of field operations. Anaerobic power was significantly (p < 0.05) reduced after the field operations at altitude. In contrast, the aerobic cost of doing submaximal exercise was slightly elevated (p < 0.05) after the altitude field operations. No physiologically significant effect was noted for hand grip or push-up results. The findings of this study indicate that field operations at moderate altitude do result in slight, but significant, anaerobic-aerobic performance decrement in U.S. Marines.