The acute effect of high-dose supplemental oxygen on haemodynamics assessed by echocardiography in patients with pulmonary vascular disease living in Quito at 2850 m: a randomized, single-blind, placebo-controlled crossover trial

Julian Müller; Mona Lichtblau; Stéphanie Saxer; Mirjam Schmucki; Michael Furian; Simon R Schneider; Joël J Herzig; Meret Bauer; Diego Saragoni; Esther I Schwarz; Elizabeth Cajamarca; Rodrigo Hoyos; Silvia Ulrich

doi:10.1093/ehjopen/oeae097

The acute effect of high-dose supplemental oxygen on haemodynamics assessed by echocardiography in patients with pulmonary vascular disease living in Quito at 2850 m: a randomized, single-blind, placebo-controlled crossover trial

Eur Heart J Open. 2024 Dec 2;4(6):oeae097. doi: 10.1093/ehjopen/oeae097. eCollection 2024 Nov.

Authors

Julian Müller^{1

2}, Mona Lichtblau^{1

2}, Stéphanie Saxer^{1

3}, Mirjam Schmucki^{1

2}, Michael Furian¹, Simon R Schneider¹, Joël J Herzig¹, Meret Bauer¹, Diego Saragoni^{1

2}, Esther I Schwarz^{1

2}, Elizabeth Cajamarca⁴, Rodrigo Hoyos⁴, Silvia Ulrich^{1

2}

Affiliations

¹ Department of Pulmonology, University Hospital Zurich, Rämistrasse 100, 8091 Zurich, Switzerland.
² Faculty of Medicine, University of Zurich, Pestalozzistrasse 3, 8032 Zurich, Switzerland.
³ Department of Health, Eastern Swiss University of Applied Sciences, Rosenbergstrasse 59, 9000 St. Gallen, Switzerland.
⁴ Pneumology Unit, Carlos Andrade Marín Hospital, Av. Universitaria, 170103 Quito, Ecuador.

Abstract

Aims: More than 220 Mio people live at altitudes above 2000 m, many of whom have pre-existing chronic diseases, including pulmonary vascular diseases (PVDs) such as pulmonary arterial hypertension (PAH) or chronic thromboembolic pulmonary hypertension (CTEPH). We investigated the acute effects of high-dose supplemental oxygen on pulmonary haemodynamics assessed by echocardiography in patients with PVD permanently living at 2850 m.

Methods and results: In a randomized, single-blind, placebo-controlled crossover trial, patients with PVD diagnosed with PAH or CTEPH were allocated to receive 10 L/min supplemental oxygen (FiO₂ ≈ 95%) and placebo air administered via a facial mask with reservoir near their living altitude in Quito at 2850 m (FiO₂0.21, PiO₂ ≈ 60% of sea level) in random order with a washout period of >2 h. After >15 min of breathing the respective FiO₂, systolic pulmonary artery pressure (sPAP), cardiac output (CO), and other parameters were assessed by echocardiography. Furthermore, radial arterial blood gases were analysed. Twenty-eight patients with PVD (24 females, 26 PAH, age 45 ± 12 years) treated with phosphodiesterase-5 inhibitors (n = 28) and endothelin receptor antagonists (n = 9) were included. With oxygen vs. placebo air, sPAP was 57 ± 23 vs. 68 ± 24 mmHg, mean difference -11 mmHg (-15 to -6 mmHg, P < 0.001), CO was 3.2 ± 0.9 vs. 3.9 ± 1.1 L/min; -0.7 L/min (-0.9 to -0.4 L/min, P < 0.001), while sPAP/CO was unchanged, and the right ventriculo-arterial coupling was increased. PaO₂ was 22.5 ± 9.7 vs. 7.6 ± 1.5 kPa; 14.9 kPa (11.4-18.4 kPa, P < 0.001).

Conclusion: High-dose oxygen therapy in prevalent patients with PVD living near 2850 m significantly lowered sPAP but also CO by a reduced heart rate, resulting in an unchanged pulmonary resistance. Whether longer-term oxygen therapy would improve pulmonary vascular resistance requires further investigation.

Registration: NCT06084559 URL: https://clinicaltrials.gov/study/NCT06084559.

Keywords: High altitude; Oxygen therapy; PVD; Pulmonary hypertension; Pulmonary vascular disease.

Associated data

ClinicalTrials.gov/NCT06084559