Supplemental oxygen for pulmonary embolism (SO-PE): study protocol for a mechanistic, randomised, blinded, cross-over study.

backgroundAcute pulmonary embolism (PE) mortality is linked to abrupt rises in pulmonary artery (PA) pressure due to mechanical obstruction and pulmonary vasoconstriction, leading to right ventricular (RV) dilation, increased RV wall tension and oxygen demand, but compromised right coronary artery oxygen supply. Oxygen is a known pulmonary vasodilator, and in preclinical animal models of PE, supplemental oxygen reduces PA pressures and improves RV function. However, the mechanisms driving these interactions, especially in humans, remain poorly understood. The overall objective of the supplemental oxygen in pulmonary embolism (SO-PE) study is to investigate the mechanisms of supplemental oxygen in patients with acute PE. METHODS AND ANALYSIS: This randomised, double-blind, cross-over trial at Massachusetts General Hospital will include adult patients with acute PE and evidence of RV dysfunction but without hypoxaemia (SaO ETHICS AND DISSEMINATION: The SO-PE study is funded by the NHLBI and has been approved by the Institutional Review Board of Mass General Brigham (no. 2023P000252). The study will comply with the Helsinki Declaration on medical research involving human subjects. All participants will provide prospective, written informed consent. TRIAL REGISTRATION NUMBER: NCT05891886.