Background: Chronic obstructive pulmonary disease (COPD) may predispose to symptomatic pulmonary hypertension at high altitude. We investigated hemodynamic changes in lowlanders with COPD ascending rapidly to 3100 m and evaluated whether preventive dexamethasone treatment would mitigate the altitude-induced increase in pulmonary artery pressure.
Methods: In this placebo-controlled, double-blind trial, non-hypercapnic COPD patients living <800 m, were randomized to receive either dexamethasone (8 mg/day) or placebo tablets one day before ascent from 760 m and during a 3-day-stay at 3100 m. Echocardiography was performed at 760 m and after the first night at 3100 m. The trans-tricuspid pressure gradient (RV/RA, main outcome), cardiac output (Q) by velocity-time integral of left ventricular outflow, indices of right and left heart function, blood gases and pulse-oximetry (SpO2) were compared between groups.
Results: 95 patients, 79 men, mean ± SD age 57 ± 8y FEV1 89 ± 21% pred, SpO2 95 ± 2% were included in the analysis. In 52 patients receiving dexamethasone, RV/RA, Q and SpO2 at 760 and 3100 m were 19 ± 5 mm Hg and 26 ± 7 mm Hg, 4.9 ± 0.7 and 5.7 ± 1.1 l/min, SpO2 95 ± 2% and 90 ± 3% (P < 0.05 all changes). In 43 patients receiving placebo the corresponding values were 20 ± 4 mm Hg and 31 ± 9 mm Hg, 4.7 ± 0.9 l/min and 95 ± 3% and 89 ± 3% (P < 0.05 all changes) between group differences of altitude-induced changes were (mean, 95% CI): RV/RA -4.8 (-7.7 to -1.8) mm Hg, Q 0.13 (-0.3 to 0.6) l/min and SpO2 1 (-1 to 2) %.
Conclusions: In lowlanders with COPD travelling to 3100 m preventive dexamethasone treatment mitigates the altitude-induced rise in RV/RA potentially along with a reduced pulmonary vascular resistance and improved oxygenation.
Keywords: Altitude; COPD; Dexamethasone; Hemodynamics; Hypobaric hypoxia; Pulmonary artery pressure.
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