Oxygen Concentration Target in Stroke Endovascular Treatment

The optimal fraction of inspired oxygen (FiO2) during EVT under general anesthesia is currently uncertain. This is a randomized controlled trial (RCT) designed to assess the impact of normobaric high-concentration oxygen versus low-concentration oxygen on early neurological function following EVT. It is a prospective, open-label, parallel-design RCT planned to be conducted at Beijing Tiantan Hospital, Capital Medical University. It is anticipated that 200 cases of AIS patients undergoing EVT under general anesthesia will be consecutively enrolled from 2024 to 2026. Eligible participants will be randomly assigned in a 1:1 ratio. After general anesthesia induction, patients will receive continuous inhalation of oxygen with either FiO2=80% or FiO2=30% through endotracheal intubation until the end of the procedure, with a gas flow rate set at 4 L/min. The positive end-expiratory pressure (PEEP) is uniformly set to 5 cmH2O to balance its effect on pulmonary oxygen delivery. The primary outcome will be the occurrence of early neurological improvement (NIHSS score of 10 points 24±2 hours after EVT). Safety outcomes include potential adverse events such as site infection, three-month mortality, etc.

Inclusion criteria

• Age ≥18 years.
• Anterior circulation occlusive stroke is confirmed by CT angiography (CTA), magnetic resonance angiography (MRA) or digital subtraction angiography (DSA), and occlusions of intracranial internal carotid artery (ICA) or M1 segment of the middle cerebral artery (MCA) were involved.
• NIHSS score at admission: 6-20.
• Randomization can be completed within 24 hours after stroke onset.

Exclusion criteria

• Stroke onset within 6-24 hours with a CT perfusion imaging (CTP)-assessed mismatched area<15 ml.
• Presence of anemia, defined as hemoglobin levels o below 120 g/L in men and below 110 g/L in women.
• Pre-stroke modified Rankin scale (mRS) score ≥2.
• Complicated by severe agitation and seizures.
• Evidence of intracranial hemorrhage at admission.
• Presence of chronic obstructive pulmonary disease, asthma, or other respiratory conditions, or requirement for daily supplemental oxygen or mechanical ventilation.
• Baseline arterial blood gas analysis indicating impaired gas exchange: PaO2 < 60 mmHg on room air, or oxygenation index (PaO2/FiO2) < 300 mmHg with supplemental oxygen.
• Emergency chest CT reveals significant pulmonary parenchymal infection.
• An oxygen mask or ventilator must be used before anesthesia to maintain a SpO2≥94%.
• Loss of airway protective reflex or vomiting aspiration upon admission.