Although the negative impact of sleep apnea on the clinical course of acute ischemic stroke (AIS) is well known, data regarding non-invasive ventilation in acute patients are scarce. Several studies showed its tolerability, safety and signals-of-efficacy, yet no controlled randomized sequential phase studies currently exist that aim to establish the efficacy of early non-invasive ventilation in AIS patients. The main hypothesis for this study is that early non-invasive ventilation with automated bilevel positive airway pressure (auto-BPAP) positively affects short-term clinical outcomes in AIS patients. This is a multicenter, prospective, randomized, controlled, third rater-blinded, parallel-group trial. Patients with AIS with proximal arterial obstruction and clinically suspected sleep apnea will be randomized to standard or standard stroke care plus auto-BPAP. Auto-BPAP will be initiated within 24 hours from stroke onset and performed for a maximum of 48 hours during diurnal and nocturnal sleep. Patients will undergo cardiorespiratory polygraphy between day 3 and 5 to assess sleep apnea. The primary endpoint is any early neurological improvement on the NIHSS at 72 hours from randomization. Safety, tolerability, short-term and 3 months functional outcomes are assessed as secondary endpoints by un-blinded and blinded observers respectively. This study will provide data to power a subsequent phase III study.

Inclusion Criteria:

• Male and female patients 18 - 80 years;
• Clinical suspicion of an AIS (measurable or fluctuating neurological deficit with a National Institutes of Health Stroke Scale [NIHSS] ≥ 4 points) within 24 hours from symptom-onset;
• Extracranial (internal carotid artery) or intracranial (internal carotid artery; middle/anterior/posterior cerebral arteries) ≥ 50% stenosis, near-occlusion or occlusion diagnosed by ultrasound, computed tomography angiography (CTA) or magnetic resonance angiography (MRA), corresponding to acute neurological deficit;
• High-risk of having sleep apnea (classified by the Berlin sleep apnea questionnaire); or history of known sleep apnea; or witnessed repetitive apnea episodes during sleep or somnolence during hospitalization;
• Written informed consent by participants; alternatively by proxy or two physicians when not obtainable by patient or proxy (according to local regulations).

Exclusion Criteria:

• Perceived course towards the malignant middle cerebral artery infarction;
• Immediate or perceived need for intubation;
• Known sleep apnea currently on non-invasive ventilatory treatment;
• Standard contraindications for non-invasive ventilatory treatment;
• Pre-morbid modified Rankin scale (mRS) score ≥ 3;
• Severe comorbidities (i.e., severe heart failure, severe obstructive lung disease, active malignant disease, severe dementia);
• Pregnant and breast feeding women;
• Participation in another clinical trial other than standard-of-care registry.