Nocturnal Cerebral Oxygenation in Low-Altitude Residents With Pulmonary Vascular Disease Staying Overnight at High Altitude. Data From a Randomized, Controlled, Crossover Trial

Carolin Kränzle, Vera Bissig, Simon R. Schneider, Julian Müller, Kay von Gruenigen, Meret Bauer, Laura Mayer, Lea Lüönd, Tanja Ulrich, Aglaia Forrer, Arcangelo Carta, Ester I. Schwarz, Konrad E. Bloch, Mona Lichtblau, Michael Furian, Silvia Ulrich

https://doi.org/10.1002/pul2.70363 

Abstract

Whether hypoxia during popular high-altitude travel negatively affects cerebral oxygenation in vulnerable patients with pulmonary vascular disease (PVD) is unknown. We studied overnight cerebral tissue oxygen saturation (CTO) and desaturation index (cODI) in PVD-patients at 2500 m and effects of supplemental oxygen therapy (SOT). In this randomized-controlled crossover trial, stable PVD-patients diagnosed with pulmonary arterial or distal chronic thromboembolic pulmonary hypertension (PAH/CTEPH) had CTO and cODI (decrease in CTO ≥ 4%) assessed overnight at 470 m and 2500 m along with fingertip pulseoximetry (SpO2) and desaturation index (aODI). For safety, SOT was given if SpO2 dropped < 80% for > 30 min and stratified analysis accordingly. Primary endpoint was the difference in CTO between 470 and 2500 m. 16 PVD-patients (7 women; 13 PAH, 3 CTEPH), (mean ± SD) 56 ± 14 years old, were included per-protocol. At 470 m, the mean nocturnal CTO was 66.3 ± 1.6% and SpO2 90.3 ± 0.8%. At 2500 m on ambient air, CTO was unchanged 65.9 ± 1.6% (mean difference −0.4%; 95% CI −4.0 to 3.2) despite a lower SpO2 of 83.6 ± 0.8; −6.7 (−8.7 to −4.6%). At 2500 vs. 470 m, cODI increased by 3.1 events/hour (−0.3 to 6.6). SOT needed by 50% of PH-patients improved SpO2 by +7.5 (4.9 to 10.0), but not CTO and cODI (+3.6% (−1.0 to 8.2)) and −3.8 events/hour (−8.1 to 0.5). In PVD-patients on ambient air at 2500 m, nocturnal CTO remained unchanged compared to 470 m despite lower SpO2. SOT promptly improved SpO2 without affecting cerebral oxygenation. These findings suggest sufficient nocturnal cerebral protection at 2500 m in PVD.

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