Inclusion Criteria:

• Age ≥ 18 years old.
• TIA with ABCD2 ≥ 4 or ischemic stroke within the prior 14 days.

Exclusion Criteria:

• Individuals < 18 years old.
• Pre-event inability to perform all of own basic ADLs.
• Unable to obtain informed consent from subject or legally authorized representative.
• Incarcerated.
• Known pregnancy.
• Current mechanical ventilation (can enroll later if this resolves) or tracheostomy.
• Current use of positive airway pressure, or use within one month prior to stroke.
• Anatomical or dermatologic anomaly that makes use of CPAP interface unfeasible.
• Severe bullous lung disease.
• History of prior spontaneous pneumothorax or current pneumothorax.
• Hypotension requiring current treatment with pressors (can enroll later if this resolves).
• Other specific medical circumstances that conceivably, in the opinion of the site PI, could render the patient at risk of harm from use of CPAP.
• Massive epistaxis or previous history of massive epistaxis.
• Cranial surgery or head trauma within the past 6 months, with known or possible CSF leak or pneumocephalus.
• Recent hemicraniectomy or suboccipital craniectomy (i.e., those whose bone has not yet been replaced), or any other recent bone removal procedure for relief of intracranial pressure.
• Current receipt of oxygen supplementation > 4 liters per minute.
• Current contact, droplet, or respiratory/airborne precautions.

Eligibility last updated 8/30/21. Questions regarding updates should be directed to the study team contact.