Proof of concept study – alternative pharmacoprophylaxis for high-altitude pulmonary edema: A hospital-based randomized controlled trial

Background

High-altitude pulmonary edema (HAPE) is noncardiogenic pulmonary edema caused by exaggerated hypoxic pulmonary vasoconstriction and abnormally high pulmonary artery pressure. Some patients who develop HAPE have more chances to develop HAPE again on reinduction to high altitude (HA). This was a pilot project to look for a suitable drug (acetazolamide, nifedipine, or tadalafil) that could be used prophylactically in HAPE patients on reinduction to HA. The study incorporated a randomized, double-blind, placebo-controlled trial.

Method

One hundred and twenty serving personnel/previously healthy lowlanders, inducted to HA, thirty in each group, with history of one episode of clinically and radiologically diagnosed mild-to-moderate HAPE, were randomly distributed in the nifedipine, acetazolamide, tadalafil, and placebo groups. On discharge, all the patients were sent on leave for 4 weeks, after descent, to their homes, and they had to report to transit camp before reascent, where they were given either of the three medications or the placebo, then they were inducted to HA.

Result

HAPE, on reascent, did not develop in patients, given any of the three medications but developed in four patients in the placebo group.

Conclusion

Hence, a fully conscious person with mild-to-moderate HAPE could be effectively managed at altitude if the appropriate expertise and facilities are available and may be reinducted with any of the three drugs, if exigency exists. Trial Registry No.: CTRI/2022/03/041543.