Pharmacological Prophylaxis and Supplemental Oxygen for Unacclimatized Rescuers at Very High Altitude: Scoping Review and 2025 Joint Recommendations of the International Commission for Mountain Emergency Medicine and the International Society for Mountain Medicine

McLaughlin, Kyle, Steve Roy, Marika Falla, Giacomo Strapazzon, Andrew M. Luks, Ken Zafren, Hermann Brugger, Martin Musi, Iztok Tomazin, John Ellerton, Ghan Bahadur Thapa, and Peter Paal. Pharmacological prophylaxis and supplemental oxygen for unacclimatized rescuers at very high altitude: scoping review and 2025 joint recommendations of the International Commission for Mountain Emergency Medicine and the International Society for Mountain Medicine. High Alt Med Biol. 00:00-00, 2025. Background: Mountain rescuers and pilots rapidly ascending to altitudes above 3,500 m are exposed to the detrimental effects of hypobaric hypoxia, including cognitive and physical impairment, as well as high-altitude illness (HAI). We conducted a scoping review of oxygen supplementation and pharmacologic measures to improve cognitive and physical performance and prevent HAI in unacclimatized rescuers rapidly ascending above 3,500 m during rescue missions. Methods: Following Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines, 723 articles were screened, 133 reviewed and a total of 50 articles were included for data extraction, based on the intervention: 6 on oxygen, 29 on acetazolamide (AZ), 17 on dexamethasone (DEX), 3 on nifedipine, and 5 on phosphodiesterase-5 inhibitors. Discussion: Supplemental oxygen improves physical and cognitive performance at high altitude and is recommended for rapid ascent rescues >30 minutes between 3,500 and 4,000 m, and for rescues of any duration above 4,000 m. If oxygen is administered, pharmacological prophylaxis is not required. If oxygen is unavailable, AZ or DEX can be used for rapid ascent rescues above 3,500 m for longer than 3 hours to reduce the incidence and severity of acute mountain sickness. At altitudes above 5,000 m or for rescues requiring prolonged physical work, the use of both AZ and DEX is recommended. Conclusions: To enhance the safety and effectiveness of high-altitude rescues, we provide recommendations for the use of supplemental oxygen and pharmacologic prophylaxis to reduce the risk of HAI and improve cognitive and physical performance during rapid ascents to altitudes >3,500 m.