Supplemental Oxygen in Pulmonary Embolism (SO-PE)

Inclusion Criteria:

* Adults ≥18 years old
* Confirmed Pulmonary Embolism (PE) on imaging \<24 hours prior to enrollment
* New symptom onset and / or worsening symptoms \<72 hours
* Confirmation of right ventricular dysfunction (RVD) by clinician
* Oxygen saturation ≥90% while breathing room air

Exclusion Criteria:

* Hemodynamic instability
* Use of vasopressors or mechanical circulatory support
* Planned use of thrombolytics or plan for embolectomy
* Oxygen saturation \<90% while breathing room air
* New onset arrhythmia
* History of pulmonary hypertension, severe chronic obstructive pulmonary disease (COPD) requiring home oxygen or chronic steroid use, hypoventilation syndrome requiring continuous positive airway pressure (CPAP) or bilevel positive airway pressure (BiPAP), or congestive heart failure (CHF) with LV ejection fraction \< 40% or chronic oxygen therapy
* Known pregnancy
* Vasodilator medication used in the past 24 hours
* Symptom onset ≥72 hours
* Inability to wear a face mask
* Inability to obtain adequate baseline echocardiogram