SEACOAST 1- SEdAtion With COllAteral Support in Endovascular Therapy for Acute Ischemic Stroke

Study design: SEACOAST 1 is a prospective, randomized, blinded endpoint trial comparing collateral vigor and clinical outcomes, focusing on two distinct sedation strategies: 1. General anesthesia with mild hypercarbia (GAH) during the sedation up until full revascularization versus 2. General anesthesia with normocarbia (GAN) during the sedation up until full revascularization Neuroanesthesia protocol, focused on maintenance of baseline BP, avoidance of hypotension during induction, and targeted partial pressure of carbon monoxide (PCO2) levels (normocarbia or mild hypercarbia): * Anesthesia must not delay target initiation of procedure (groin puncture) of 90 min from ED arrival * Standard American Society of Anesthesiologists (ASA) monitoring: 5 lead ECG, end-tidal CO2 (ETCO2), Pulse oximeter, BP monitor, Body temperature per esophageal probe, ET gas analyser * Neuromuscular block (NMB) monitor for depth of neuromuscular blockade * Arterial line placement is encouraged if it can be inserted within 5 min. Otherwise noninvasive BP per cuff. If arterial line has not been placed prior to induction monitor noninvasive blood pressure (NIBP) every 1 min per cuff until arterial line becomes available. * BP goals - keep at baseline with goal of no more than 10% drop (last recorded BP prior to induction) and cannot exceed 185/105 if patients received intravenous tissue plasminogen activator (IV TPA). \*BP can be lowered to desired goal only after revascularization as deemed necessary by the neurointerventional physician * Induction with propofol or etomidate and rocuronium 1.2 mg/kg or succinylcholine * Short acting vasoactive drugs (Phenylephrine, Ephedrine, Esmolol, Clevidipine) should be readily available to maintain BP in the predefined range throughout procedure. Phenylephrine drip recommended to maintain BP * Anesthesia maintenance with volatile anesthetic and fentanyl; doses to be titrated to BP per anesthesiologist * Qualitative end-tidal CO2 (ETCO2) measurement * Immediately upon groin puncture interventionalist will provide blood gas sample to test arterial C02 A. Normocarbia arm: Controlled ventilation with PCO2 levels 40 (±5%) B. Mild hypercarbia arm: Controlled ventilation with PCO2 levels 50 (±5%) * Normalize PCO2 levels to 40 (±5%) immediately after adequate revascularization (TICI 2B) * Baseline arterial blood gas values for correlation/correction with PCO2 level detected on ETCO2 measurements * Mandatory extubation attempt within 60 minutes after procedure completion. Reasons for failed extubation should be documented