Zero Degree Head Positioning in Hyperacute Large Artery Ischemic Stroke

Inclusion Criteria: * Ischemic stroke symptoms consistent with large artery occlusion * Baseline standard of care non-contrast head CT (or MRI) negative for hemorrhage or mass-effect * Evidence of arterial occlusion on standard of care CT angiography or MR angiography * Favorable neuroimaging (Alberta Stroke Program Early Computed Tomography Score \[ASPECTS\] \> 6 in anterior circulation stroke; not applicable in posterior circulation stroke) * Ordered treatment with mechanical thrombectomy * Pre-stroke baseline modified Rankin Score (mRS) \< 1 * Ability to enroll, randomize and begin the intervention within the Emergency Department Exclusion Criteria: * Non-English speaking subjects will be excluded due to use of English language instruments (modified Rankin Scale \[mRS\] \& NIHSS) and English speaking investigators * Pregnancy or suspicion of pregnancy * Evidence or suspicion of vomiting any time prior to consent which could predispose to aspiration pneumonia and therefore confound determination of protocol safety * Anticipated palliative care referral * Evidence of evolving malignant infarction on admission noncontrast CT (or MRI) * Need for intubation with mechanical ventilation, or non-invasive ventilatory support with either bi-level positive airway pressure (BiPAP) or continuous positive airway pressure (CPAP) * Inability to tolerate zero-degree positioning due to congestive heart failure, preexisting pneumonia, chronic obstructive pulmonary disease, or other medica…