The following is a summary of “High altitudes and partial pressure of arterial oxygen in patients with chronic obstructive pulmonary disease – A systematic review and meta-analysis,” published in the July 2024 issue of Pulmonology by Sevik et al.

Prior research in healthy individuals has documented a decrease in partial pressure of arterial oxygen (PaO₂) of approximately -1.60 kPa per kilometer of altitude gain. However, the impact of altitude-induced changes in PaO₂ on altitude-related adverse health effects (ARAHE) among patients with chronic obstructive pulmonary disease (COPD) has not been thoroughly explored. This study aims to estimate the effect size of PaO₂ decline per kilometer of altitude increase and to identify the prevalence of ARAHE in patients with chronic obstructive pulmonary disease exposed to high altitudes. A systematic review was conducted using PubMed and Embase databases until May 30, 2023. Inclusion criteria focused on peer-reviewed, prospective studies involving patients with chronic obstructive pulmonary disease at altitudes exceeding 1,500 meters, with arterial blood gas measurements taken within the first three days of altitude exposure. 

Data extraction included aggregate and individual patient data (IPD), which were analyzed using a random-effects meta-analysis approach. The primary outcome measures were the relative risk estimates and 95% confidence intervals for the relationship between PaO₂ and altitude among patients with chronic obstructive pulmonary disease. Thirteen studies were incorporated into the aggregate data analysis, with six studies (222 patients, 45.2% female) contributing individual patient data for quantitative analysis. The estimated effect size of PaO₂ decline was -0.84 kPa per 1000 meters of altitude gain (95% CI: -0.92 to -0.76; I² = 65.0%, P < 0.001). Multivariable regression analysis identified COPD severity, baseline PaO₂, age, and duration of altitude exposure as significant predictors of PaO₂ levels at high altitude. ARAHE occurred in 37.8% of patients with chronic obstructive pulmonary disease, with older age, female sex, COPD severity, baseline PaO₂, and target altitude being significant predictors of ARAHE incidence (area under ROC curve: 0.9275, P < 0.001). 

This meta-analysis indicates that patients with chronic obstructive pulmonary disease experience a less pronounced decrease in PaO₂ with altitude compared to healthy individuals. These findings underscore the need for enhanced patient management strategies, including the potential use of supplemental oxygen or acetazolamide, to mitigate hypoxemia and ARAHE in patients with chronic obstructive pulmonary disease planning to travel to high altitudes or undertake long-haul flights.

Source: sciencedirect.com/science/article/pii/S2531043724000953