Ren 2020.

Study characteristics
Methods	Setting: single‐centre, China Design: RCT, 2 arms, open‐label, blind endpoint Start date: August 2017 Completion date: December 2018
Participants	90 men and women randomised: experimental GA = 48, comparator CSA = 42; procedure interrupted in GA = 8 and CSA = 7; 0 lost to follow‐up, 90 analysed Mean age: CSA = 69.19 (SD 6.46) years and GA = 69.21 (SD 5.78) years Gender (men/women): 50/40 Mean NIHSS score: 14 (score range: 11–16) Mean ASPECTS: 9 (score range: 8–10) ASA I/II/III: CSA = 5/15/22 and GA = 4/19/25 Mean BMI (kg/m²): CSA = 24.91 (SD 2.59) and GA = 23.84 (SD 2.02) 4 (9.52%) participants converted from CSA to GA 71 (78.8%) participants received IV r‐tPA before EVT Diagnostic criteria: AIS with LVO in anterior cerebral circulation Inclusion criteria ASA grades I–III (reported in trial, but at the protocol was reported as ASA grades II–III) Glasgow Outcome Score ≥ 13 (reported only in protocol) NIHSS score < 20 (reported only in trial) AIS ≤ 6.5 hours of symptom onset (reported only in trial) Aged ≥ 60 years (reported in trial, but at protocol was reported as 45–60 years) Intracranial proximal arterial occlusion in the anterior cerebral circulation (carotid artery, M1 or M2 segments of the middle cerebral artery) demonstrated by CTA, MRA, or DSA (reported only in trial) Exclusion criteria People with prestroke mRS score > 2 Haemorrhage demonstrated by CT Obvious or known difficult airway; cognitive impairment; disturbance of consciousness; hypoxaemia (SpO2 < 90%) occlusion in the posterior circulation History of craniotomy (reported only in protocol) Heart disease (heart rate 50 beats/minute) (reported only in protocol) Severe hypertension (SBP ≥ 180 mmHg or DBP ≥ 110 mmHg) (reported only in protocol) BMI > 30 kg/m² (reported in protocol as bodyweight beyond ± 15% of the standard bodyweight) History of liver or kidney dysfunction (reported only in protocol) Hypersensitivity (allergic) or intolerance to dexmedetomidine or remifentanil (reported only in protocol) Study termination by the researchers from a medical perspective (reported only in protocol) Refusal to participate (reported only in protocol)
Interventions	Experimental: GA Induced with propofol 1.5 mg/kg, fentanyl 2 µg/kg, and cisatracurium 0.2 mg/kg after preoxygenation, and anaesthesia maintained with propofol 4–6 mg/kg per hour, remifentanil 0.05–0.1 µg/kg per hour, dexmedetomidine 0.2–0.4 µg/kg per hour, and cisatracurium 0.1 mg/kg per hour. Comparator: CSA During the procedure, supplemental oxygen (4 L/minute) was delivered via a facemask; the drug performed was 1–1.5 mg/kg propofol as the loading dose followed by a maintenance dose of 2–4 mg/kg per hour propofol and 0.4–0.7 µg/kg per hour dexmedetomidine titrated according to Richmond Agitation–Sedation Scale score of –2 to –3; additionally, fentanyl 1 µg/kg or midazolam 0.04 mg/kg was used as a supplement Blood pressure was routinely recorded non‐invasively at 3‐minute intervals The anaesthesiologist performed GA if the procedure was not possible due to the restlessness of participants in the CSA group At the end of the surgery, recanalisation was classified by the neuroradiologist according to the mTICI perfusion grade. After removal of the tracheal intubation, all participants were transferred to the SU or ICU for ≥ 24 hours and cared for by an expert neurologist Vasoactive drugs such as phenylephrine, ephedrine, atropine, urapidil, and nimodipine were used to keep blood pressure and heart rate fluctuation stable at the target values. Phenylephrine was the most commonly used vasopressor, and nimodipine was the most commonly used agent for hypotension Excluded medications: not reported
Outcomes	Primary outcome (specified) Vital signs Vasoactive drugs Primary outcome (collected) Favourable neurological outcome at 90 days (favourable defined as mRS score 0–2 and unfavourable as mRS score 3–6; 0–1, complete recovery; 2, mild disability; 3, moderate disability and transfer for rehabilitation; 4, transfer to the nursing home with a severe disability; 5–6, transfer to hospice/withdrawal of care) Secondary outcomes (specified) Pain scores Ramsay score ICU residence time Adverse reactions Secondary outcomes (collected) Baseline characteristics Intraprocedural haemodynamics (recorded at arrival at catheterisation laboratory (T0); before puncture (T1); after angiography (T2); 3 minutes (T3), 6 minutes (T4), 9 minutes (T5), 12 minutes (T6), 15 minutes (T7), 30 minutes (T8), and 45 minutes (T9) during the procedure) Successful recanalisation (mTICI 2b; 0, no reperfusion; 1, penetration of affected vascular territory with minimal reperfusion; 2a, reperfusion of < 50% of territory of occluded vessel; 2b, reperfusion 50% but slower than expected filling of territory of occluded vessel; 3, complete reperfusion) Time metrics (time interval from stroke onset to catheterisation laboratory, catheterisation laboratory to groin puncture, and groin puncture to recanalisation), vasopressor use, satisfaction score of the neurointerventionalist (10‐point scale: 0, poor; 10, excellent) Complications (pneumonia, other infections, vessel perforation, vessel dissection, distal thrombus, and symptomatic intracerebral haemorrhage, defined as worsening involving NIHSS score 1 within 7 days after haemorrhage Conversion rate from CSA to GA, ASPECTS, and NIHSS score (0, no deficit; 42, most severe deficit) before and 48 hours after intervention Mortality at discharge and 3 months after stroke Time points reported: at discharge and 90 days after the procedure
Notes	Conflicts of interest: quote: "The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest". Funding: quote: "self' (describe at ChiCTR‐IPR‐16008494) Protocol: ChiCTR‐IPR‐16008494
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "a computer‐generated randomisation table was used by an independent anaesthesia assistant to allocate patients into two groups: the CSA group (n = 42) and the GA group (n = 48)".
Allocation concealment (selection bias)	Unclear risk	Details not fully described. Quote: "a computer‐generated randomisation table was used by an independent anaesthesia assistant to allocate patients into two groups: the CSA group (n = 42) and the GA group (n = 48)".
Blinding of participants and personnel (performance bias)	High risk	Although the authors described that personnel were blinded, we judged it as a high risk of bias due to the nature of the intervention. Quote: "our anaesthesia team included an attending anaesthesiologist and an anaesthesiologist assistant who were both blinded to group allocation".
Blinding of outcome assessment (detection bias)	Low risk	Quote: "all of the investigators who assessed primary and secondary outcomes were blinded to group allocation".
Incomplete outcome data (attrition bias)	Low risk	0 losses and crossovers occurred in 4 (9.52%) participants from CSA to GA, but they were analysed as ITT.
Selective reporting (reporting bias)	High risk	We noted several changes from what was reported in the protocol against the trial publication for the inclusion and exclusion criteria, and primary and secondary outcomes.
Other bias	High risk	Authors changed study objective. Protocol stated the objective was to observe the effect of different concentrations and ways of giving dexmedetomidine with remifentanil for people with craniocerebral disease interventional therapy under GA; however, the trial published results regarding the effect of CSA vs GA on outcomes in people undergoing mechanical thrombectomy for AIS.