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Acute mountain sickness: predictors of climbers’ performance at high altitudes
Seoane L, Nervi R, Seoane M, Gorraiz Rico F, Torres S, RodrÃguez Cerrillo M
Hospital Universitario Austral, Pilar, Provincia de Buenos Aires. Argentina. Hospital Regional de RÃo Gallegos, RÃo Gallegos, Provincia de Santa Cruz, Argentina. ANMAT. Administración Nacional de Medicamentos, Alimentos y TecnologÃa Médica, Argentina.
Objective: To determine the relationship between climber variables (lactic acid levels,
blood pressure, heart rate, respiratory frequency, and peripheral oxygen saturation
[SaO2] and their physical performance and development of acute mountain sickness
(AMS) on the Llullaillaco volcano (6739 m) in Argentina.
Material and methods: As 8 climbers ascended the mountain, we measured lactic acid
and other clinical variables, including SaO2. We also assessed visual acuity (Pelli-Robson
chart), AMS (Lake Louise scoring). SaO2 and heart rate were assessed at rest and on a 6-
minute walk test.
Results: Lactic acid levels of 2 mmol/L or more at 5000 m predicted worsening of a
climber’s condition at higher altitudes, progression to AMS, and declining performance
(positive predictive value, 66.7%; negative predictive value, 100%; precision, 87.5%).
Values on performance of the 6-minute walk test at 5000 m showed that a change of 20
beats/min in heart rate and a 10% change in SaO2 predicted worsening condition at
higher altitudes (specificity, 100%). Likewise, a Lake Louise score of 4 or more at 5000 m
also predicted worsening climber condition and AMS.
Conclusions: Clinical variables and laboratory findings for mountain climbers in base
camps can predict their performance at higher altitudes. A lactic acid level of 2 mmol/L
or more, a change in SaO2 of more than 10% after the walk test and a Lake Louise score
of 4 or more predicted worsening of clinical signs.