Effects of a sea level stay on pulmonary hemodynamics in patients with pulmonary arterial hypertension living in Quito near 2850m.

Ulrich, Silvia; Müller, Julian; Furian, Michael; Saxer, Stéphanie; Schneider, Simon R; Herzig, Joel; Bauer, Meret; Schmucki, Mirjam et al. · Chest · 2026

case_series · Level IV

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Abstract

Amongst the >80 Mio people living >2500m are patients with pulmonary arterial hypertension (PAH). How does descent to sea level (SL) affect pulmonary hemodynamics and 6-minute walk distance (6MWD) in patients with PAH living at high altitude (HA)? HA-residents with PAH were transported to SL. Vital signs including heart rate (HR), arterial oxygen saturation (SaO<sub>2</sub>), 6MWD, systolic pulmonary artery pressure (sPAP), cardiac output (CO) and other measures were assessed at 2850m and after the first (day2) and second night (day3) at SL. 28 patients (24 female, age 46±12yrs), treated with phosphodiesterase-5-inhibitors (N=28) and endothelin-receptor antagonists (N=9) were included. SaO<sub>2</sub>, sPAP, HR, CO and 6MWD at HA were 90±5%, 68±24mmHg, 74±14 bpm, 3.9±1.1 l/min and 462±100 m. At SL day2, SaO<sub>2</sub> was higher (+5.5 (3.9 to 7.1)%, sPAP and HR were lower (-11 (-16 to -5) mmHg, -7 (-12 to -3) bpm, all p<0.001), resulting in an unchanged sPAP/CO and oxygen delivery. HR and CO further decreased on day3, resulting in unchanged sPAP/CO vs. HA. 6MWD was higher at SL vs. HA at day2 (+41 (16 to 67)m, p<0.001) but not day3. No adverse events occurred including after re-ascent. Typical PAH-patients living at 2850m reveal improved blood oxygenation after decent to SL along with decreased sPAP, but also HR, resulting in unchanged pulmonary resistance and oxygen delivery. While 6MWD initially increased at SL, it returned to high-altitude-baseline after the 2<sup>nd</sup> night along with further HR and CO decrease.