RAPID ASCENT PROTOCOL FOR UNACCLIMATIZED

#### Rapid Ascent Protocol

- Rapid ascents to 2500M or less do not require prophylaxis.
- Rapid ascents to 2500M to 3500M in less than 24 hours should utilize acetazolamide 125mg po BID starting at least 8 hours and ideally 24 hours prior to ascent.48
- Rapid ascents to 3500M or higher will result in a 70-100% incidence of AMS. Prophylaxis with dexamethasone 4mg q6h and acetazolamide 125mg PO BID should be utilized starting 24 hours prior to ascent.49-50

Operational requirements may dictate the need for unacclimatized individuals to rapidly ascend over the course of just a few hours to high altitude. A combination of acetazolamide and/or dexamethasone to decrease the risk of HAI and allow the service member to perform better physically and mentally is recommended. Several prophylaxis protocols for this situation have been studied both in chamber and field settings.

Studies utilizing the protocols that include dexamethasone have been of short duration, usually less than 48 hours. Therefore we recommend when utilizing rapid ascent protocols that include dexamethasone the individuals should complete the mission and return to lower elevation in 48 hours or less. If dexamethasone is discontinued while individuals are at these altitudes AMS symptoms may occur.51-55