Pre-acclimatization Benefits in Occupational Travelers with Repeated High-Altitude Exposure: A Case Series of Thai Engineers at Argentina’s 4,000-meter Salt Pans

Abstract

OBJECTIVES: To evaluate cumulative acclimatization and pharmacological prophylaxis trends in occupational travelers undergoing repeated, cyclical high-altitude exposure.

MATERIALS AND METHODS: This retrospective case series involved Thai engineers completing cyclical work assignments at a 4,000-meter mining facility in Argentina between July 2023 and June 2025. The schedule comprised 7–16 days at altitude followed by 3–6 rest days at a moderate altitude (1,200 m). Acclimatization status was assessed using the 2018 Lake Louise Score (LLS) for the diagnosis of acute mountain sickness (AMS), while prophylactic acetazolamide use was tracked through clinical records.

RESULTS: Five healthy Thai engineers (four males and one female, aged 29–55 years) completed six separate assignments. One participant met the criteria for moderate-to-severe AMS during the initial cycle (1/5 participants, 20%; 1/6 trips, 16.7%). By the third cycle, symptoms at 24 hours had resolved in 4/5 participants (80%) across 5/6 assignments (83.3%). One participant (Case 3) continued to exhibit mild AMS at 24 hours during cycles 2–6; however, from cycle 3 onward, the 48-hour scores consistently improved to a non-diagnostic level. Additionally, acetazolamide prophylaxis was ceased entirely by the third cycle in 3/5 participants, 60%; 3/6 trips, 50%. Wearable-derived SpO₂ data from one participant showed improved SpO₂ stability and higher minimum saturation values during later cycles.

CONCLUSION: Occupational travelers on a cyclical schedule with short rest periods at a moderate altitude can achieve cumulative acclimatization, resulting in decreased symptom severity and a trend toward pharmacological de-escalation. These findings suggest that adaptation is sufficiently preserved over short breaks to mitigate the burden of subsequent ascents.