A Retrospective Analysis of Altitude Illness at the Himalayan Rescue Association Aid Post Manang (2018-2023).

Abstract

Shrestha, Suraj, Sanjeev Kharel, Suman Acharya, Gobi Basyal, and Sanjeeb S. Bhandari. A Retrospective Analysis of Altitude Illness at the Himalayan Rescue Association Aid Post Manang (2018-2023). High Alt Med Biol. 00:00-00, 2025. Introduction: The Himalayan Rescue Association (HRA) in Nepal has been operating high-altitude aid posts in the Himalayas to alleviate illnesses in hikers and locals with a focus on acute mountain sickness (AMS), high-altitude pulmonary edema (HAPE), and high-altitude cerebral edema (HACE), as well as other common medical problems. This study examines the altitude-related illnesses occurring between 2018 and 2023 at the HRA Manang aid post. Materials and Methods: A retrospective study analyzing the medical records of HRA Manang from 2018 to 2023 was conducted. Demographics and diagnoses were documented, and the Lake Louise Score (LLS) was calculated for AMS cases. The frequency of altitude-related illness was compared among trekkers with/without a good ascent profile. Results: During the study period, a total of 2,904 people visited the aid post, with 337 (11.6%) suffering from altitude-related illnesses, including 274 AMS, 40 HAPE, 11 HACE, and 12 concurrent HAPE with HACE, with 58.8% of cases seen in the fall season. Most were adults, non-Nepali (70.3%), of which only 4.5% comprised the pediatric population. The majority of AMS cases were mild (70.6%) (LLS ≤5), while 17.2% had moderate to severe AMS. Almost one-third (28.2%) of cases had rapid ascent (elevation >500/day above 2,500 m), with a majority of 67.4% being Nepali compared to non-Nepali (p < 0.05). The proportion of HACE and concurrent HAPE with HACE was significantly higher among those with rapid ascent profiles. About 36.20% of cases with altitude-related illness had taken prophylactic acetazolamide, which was considerably lower among Nepali patients (p < 0.001). Motor vehicle evacuation (86.7%), followed by helicopter evacuation (13.3%), was used for those requiring immediate descent. Conclusion: Altitude illness is a common problem among trekkers in the Annapurna region of Nepal. More effort should be focused on educating high-altitude travelers to reduce the risk of these problems.