Conscious sedation compared to general anesthesia for intracranial mechanical thrombectomy: A meta‐analysis

Abstract Introduction Endovascular therapy is the standard of care for severe acute ischemic stroke caused by large‐vessel occlusion in the anterior circulation, but there is a debate on the optimal anesthetic approach during this therapy. Meta‐analyses of observational studies suggest that general anesthesia increases disability and death compared with conscious sedation However, their results are conflicting. This meta‐analysis study was performed to assess the relationship between the effects of general anesthesia compared to conscious sedation during endovascular therapy for acute ischemic stroke. Methods Through a systematic literature search up to August 2020, 18 studies included 4,802 subjects at baseline with endovascular therapy for acute ischemic stroke and reported a total of 1,711 subjects using general anesthesia and 1,961 subjects using conscious sedation were found. They recorded relationships between the effects of general anesthesia compared to conscious sedation during endovascular therapy for acute ischemic stroke. Odds ratio (OR) or Mean differences (MD) with 95% confidence intervals (CIs) were calculated between the effect of general anesthesia compared to conscious sedation during endovascular therapy for acute ischemic stroke using the dichotomous or contentious methods with a random or fixed‐effect model. Results No significant difference were found between general anesthesia and conscious sedation during the endovascular therapy for acute ischemic stroke in functional independence at 90 days (OR, 0.78; 95% CI, 0.44–1.40, p = 40); successful recanalization at 24 hr (OR, 1.23; 95% CI, 0.62–2.41, p = 55); mortality at 90 days (OR, 1.36; 95% CI, 0.83–2.24, p = .22); interventional complication (OR, 1.24; 95% CI, 0.76–2.02, p = .40); symptomatic intracranial hemorrhage (OR, 0.64; 95% CI, 0.41–0.99, p = .05); aspiration pneumonia (OR, 0.96; 95% CI, 0.58–1.58, p = .87); and National Institute of Health Stroke Scale score after 24 hr (MD, 0.38; 95% CI, −1.15–1.91, p = .62); with relative relationship favoring general anesthesia only in decreasing the symptomatic intracranial hemorrhage. Conclusions General anesthesia has no independent relationship compared to conscious sedation during the endovascular therapy for acute ischemic stroke with a relative relationship favoring general anesthesia only in decreasing the symptomatic intracranial hemorrhage. This relationship encouraged us to recommend either anesthetic strategy during the endovascular therapy for acute ischemic stroke with no possible fear of higher complication.

| 3 of 9 SHEN Et al. functional independence at 90 days, successful recanalization at 24 hr, mortality at 90 days, interventional complication, symptomatic intracranial hemorrhage, aspiration pneumonia, National Institute of Health Stroke Scale score after 24 hr, and symptomatic intracranial hemorrhage; and S (study design): no restriction.
First, we conducted a systematic search of OVID, Embase, Cochrane Library, PubMed, and Google scholar till June 2020, using a combination of keywords and similar words for anesthetic strategy, conscious sedation, general anesthesia, endovascular therapy, and acute ischemic stroke as shown in Table 1. All identified studies were combined in an EndNote file, duplicates were discarded, and the title and abstracts were reviewed to exclude studies that did not report a relationship between the effect of general anesthesia compared to conscious sedation during endovascular therapy for acute ischemic stroke, based on the previously mentioned inclusion and exclusion criteria. The remaining articles were examined for correlated information.

| Screening
Data were abridged based on study-associated and subjectassociated features onto a consistent form. the last name of the primary author, period of study, year of publication, country, region of the studies, and study design; population type, the total number and the number of subjects used conscious sedation, or general anesthesia, demographic data, and clinical and treatment characteristics; and method of assessment; result assessment; and tool, which evaluates validity and bias in studies of prognostic factors across six domains: participation, attrition, prognostic factor measurement, confounding measurement, and account, outcome measurement, and analysis and reporting. (Hayden et al., 2013) Any inconsistencies were addressed by a re-evaluation of the original article.

| Eligibility
The primary result concentrated on the effect of general anesthesia compared to conscious sedation during endovascular therapy for acute ischemic stroke. A comparison between the effect of conscious sedation and general anesthesia was extracted to form a summary.

| Inclusion
Sensitivity analyses were limited only to studies reporting the relationship between the effects of general anesthesia compared to conscious sedation during endovascular therapy for acute ischemic stroke. For subgroup and sensitivity analysis, we used comparisons between conscious sedation and general anesthesia as references.

| Statistical analysis
The dichotomous or contentious methods with a random or fixedeffect model were used to calculate odds ratio (OR) or mean differences (MD) and 95% CI. We calculated the I 2 index; the I 2 index is between 0% and 100%. Values of approximately 0%, 25%, 50%, and 75% indicate no, low, moderate, and high heterogeneity, respectively. (Sheikhbahaei et al., 2016) When I 2 was higher than 50%, we chose the random effect model; when it was lower than 50%, we used the fixed-effect model. A subgroup analysis was performed by stratifying the original evaluation per outcome categories as described before. In this analysis, a p-value for differences between subgroups of < 0.05 was considered statistically significant.
Publication bias was evaluated quantitatively using the Egger regression test (publication bias considered present if p ≥ .05), and qualitatively, by visual examination of funnel plots of the logarithm of ORs or MDs versus their standard error (SE). (Higgins, 2003) All p-values were two tailed. All calculations and graphs were performed using reviewer manager version 5.3 (The Nordic Cochrane Centre, The Cochrane Collaboration, Copenhagen, Denmark).  Table 2.

| RE SULTS
The 18 studies included 4,802 subjects at baseline with endovascular therapy for acute ischemic stroke and reported a total of 1,711 subjects using general anesthesia and 1,961 subjects using conscious sedation. Those studies had subjects using general anesthesia compared to conscious sedation during endovascular therapy for acute ischemic stroke. 11 studies reported data stratified by the anesthetic strategy related to the functional inde- The study size ranged from 44 to 1,376 subjects at the start of the study with subjects using general anesthesia ranged from 19 to 426, and subjects using conscious sedation ranged from 15 to 554. A stratified analysis of studies that did and did not adjust for age and gender was not performed because not enough studies reported were adjusted for this factor.
Based on the visual inspection of the funnel plot as well as on quantitative measurement using the Egger regression test, there was no evidence of publication bias (p = .87).

| D ISCUSS I ON
The 18 studies included 4,802 subjects at baseline with endovascular therapy for acute ischemic stroke and reported a total of 1,711 subjects using general anesthesia and 1,961 TA B L E 2 Characteristics of the selected studies for the meta-analysis F I G U R E 2 Forest plot of the general anesthesia versus conscious sedation during the endovascular therapy for acute ischemic stroke related to functional independence at 90 days subjects using conscious sedation. (Abou-Chebl, 2010Berkhemer, 2016;Davis, 2012;Goldhoorn, 2020;Hassan, 2012;Jumaa, 2010;Just, 2016;Langner,;Li, 2014;Löwhagen Hendén, 2017;Mundiyanapurath, 2015;Nichols, 2018;Ren, 2020;Schönenberger, 2016;Simonsen, 2018;Sørensen, 2019;Zussman et al., 2018) No significant difference was found between general anesthesia and conscious sedation during the endovascular therapy for acute ischemic stroke. All the relationships had high reported general anesthesia did not have inferior tissue or clinical F I G U R E 6 Forest plot of the general anesthesia versus conscious sedation during the endovascular therapy for acute ischemic stroke related to symptomatic intracranial hemorrhage F I G U R E 7 Forest plot of the general anesthesia versus conscious sedation during the endovascular therapy for acute ischemic stroke related to aspiration pneumonia F I G U R E 8 Forest plot of the general anesthesia versus conscious sedation during the endovascular therapy for acute ischemic stroke related to National Institute of Health Stroke Scale score after 24 hr