Change in pulmonary artery pressure upon acute exposure to high altitude: a systematic review and meta-analysis

We investigated the increase in pulmonary artery pressure (PAP) with altitude gain in healthy low-altitude residents travelling to high altitude, analysing reported measures including systolic (sPAP) and mean pulmonary artery pressure (mPAP) and tricuspid regurgitation pressure gradient (TRPG).

A systematic literature search was performed in PubMed and Embase from database inception to 12 December 2024. Studies including healthy adults residing at <1000 m and reporting sPAP, mPAP or TRPG measured by echocardiography or right heart catheterisation at both low altitude and >1000 m within 30 days were included. Random effects meta-analyses and meta-regression assessed the increase in sPAP, mPAP and TRPG per 1000 m altitude gain.

60 articles with 1220 participants (75% males, age 34±4 years) were eligible; 54 were included into the meta-analysis. sPAP was reported in 38 studies, mPAP in nine and TRPG in 11. At high altitude, absolute sPAP ranged from 24 to 50 mmHg and mPAP from 20 to 26 mmHg. Meta-regression showed a linear increase per 1000 m: sPAP 3.4±0.5 mmHg, mPAP 2.5±0.7 mmHg and TRPG 3.3±1.0 mmHg. The estimated upper limit of normal for the increase per 1000 m was 4.5 mmHg for all three measures.

This systematic review and meta-analysis of healthy low-altitude residents travelling to high altitudes demonstrates a linear increase in PAP with altitude gain, based predominantly on data from elevations >2500 m and younger male populations. It defines upper reference limits for the increase in sPAP, mPAP and TRPG per 1000 m. These population-derived reference ranges may assist in the interpretation of PAP measurements and in counselling individuals evaluated at high altitude, but should be applied with consideration of the underlying population and exposure characteristics.