RecruitingEarly Phase 1Drug trialSupplemental Oxygen in Pulmonary Embolism (SO-PE)A study of how supplemental oxygen helps patients with acute pulmonary embolism (PE). Hypothesis: Oxygen affects right ventricular dysfunction (RVD) in patients with acute pulmonary embolism (PE) primarily by relieving hypoxic pulmonary vasoconstriction and reducing pulmonary pressure (PA) pressure, and that this process is metabolically driven.