The current measures to prevent acute mountain sickness (AMS) mainly include drug prevention and non-drug prevention. Acetazolamide is a drug approved by the U.S. FDA for the prevention and treatment of AMS. Remote limb ischemic preconditioning (RIPC) can also reduce the incidence of AMS as a non-durg method, with a strategy of 2 times/day training for 1 week reducing the incidence of AMS in 6 hours from 40% to 30%. The objective of this study is to determine whether rapid RIPC training combined with acetazolamide can further reduce the incidence of AMS. In this study, subjects will be divided into 5 groups: medicine group (acetazolamid 125mg bid, 2 days before entering the hypoxic room), RIPC group (RIPC training twice daily, 6 days before entering the hypoxic room), rapid RIPC group (RIPC training forth daily, 3 days before entering the hypoxic room), combined group (rapid RIPC training plus acetazolamide) and controlled group. RIPC training, completed by Renqiao Remote Ischemic Conditioning Device (Doctormate®), will be comprised of 5 cycles of bilateral upper limb ischemia and reperfusion, which will be induced by 2 cuffs placed around the upper arms respectively and inflated to 200mmHg for 5 minutes followed by 5 minutes of reperfusion by cuff deflation. After the intervention, subjects will be exposed to 4500m altitude in a normobaric hypoxic chamber for 6 hours. The incidence of AMS and other data will be compared between groups.
The primary objective of the study will be to determine whether rapid remote limb ischemic preconditioning (RIPC) combined with acetazolamide can further reduce the incidence of acute mountain sickness (AMS) during the 6-hour hypoxic chamber.