Comparing Acute Mountain Sickness Definitions to Examine Differences in Systemic Inflammation

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Date

2021

Authors

Shah, Karina

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Publisher

University of Oregon

Abstract

Acute mountain sickness (AMS) occurs when individuals rapidly ascend to high altitudes, but its exact cause remains unknown. Additionally, AMS is assessed using a subjective questionnaire with a variety of criteria used for diagnosis so there is no precise, objective method for determining if a subject has AMS. Hypoxia, or low oxygen, at altitude results in a proinflammatory state and AMS is associated with systemic inflammation as determined by elevated plasma levels of some cytokines. Thus, we wanted to determine if the association between AMS and inflammation was altered based on how AMS was defined. To examine this, 17 women and 17 men were exposed to 10 hours of normobaric hypoxia (11.5% O2) simulating 15600 feet. Blood samples taken before and at 10 hours of hypoxia were assayed for 13 inflammatory cytokines. AMS was defined by the following definitions: 1) Lake Louise Questionnaire (LLQ) score ≥3 and a headache score ≥1 at the 10-hour time point, 2) maximum LLQ score ≥3 and a maximum headache score of ≥1, 3) maximum LLQ score ≥3 and a maximum Environmental Symptoms Questionnaire (ESQ) score of 0.7 or maximum LLQ score ≥3, a maximum headache score ≥2, and a maximum ESQ score ≥0.4, 4) maximum LLQ score ≥3, 5) LLQ score ≥3 at the 10-hour time point. RESULTS: We found that Interleukin (IL) 8 significantly increased in AMS- but not AMS+ participants regardless of AMS definition. Additionally, AMS- but not AMS+ participants significantly increased IL-33 concentration from baseline to 10 hours of hypoxia only under definitions 3, 4, and 5. Furthermore, all subjects significantly increased IL-1β concentration except AMS+ subjects for definitions 1, 3, and 5. These data suggest that how AMS is defined may influence whether there are differences in circulating inflammatory cytokines between those with and without AMS. Therefore, the relationship between systemic inflammation and AMS may be more complex than previously thought.

Description

1 page.

Keywords

acute mountain sickness, inflammation, altitude, hypoxia

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