What was the review about?
Acute ischaemic stroke is a sudden loss of blood circulation in a specific brain area, caused by a blockage in one of the blood vessels, promoting neurological damage. Urgent (recanalisation) treatment to remove the blockage can be beneficial. We wanted to know whether the type of anaesthesia used for this procedure influences treatment to restore blood flow after blood vessels are blocked (recanalisation therapies).
What are recanalisation therapies and anaesthesia types?
Recanalisation therapies use different approaches to restore blood flow. This can be done by using different devices to remove the blockage from the large arteries that supply the brain. The procedure can be performed under different types of anaesthesia. General anaesthesia – complete medicine-induced anaesthesia followed by supporting breathing (where the person is 'put to sleep'); local anaesthesia – the medicine is directly applied only to a small specific area, providing pain relief; conscious sedation anaesthesia – medicines are given to make the person feel drowsy and relaxed and then carefully monitored, and monitored anaesthesia care – a specific type of anaesthesia service requested by the anaesthesiologist for the care of a patient undergoing a procedure that may fluctuate between the different levels of sedation anaesthesia (i.e. minimal, moderate, and deep).
What did we want to find out?
We wanted to know what type of anaesthesia approach promotes better patient outcomes during recanalisation therapies for acute ischaemic stroke.
What did we do?
We searched for studies that compared different types of anaesthesia for endovascular interventions (where catheters are inserted in small incisions in the groin or arms, and are guided through the blood vessels) in people with acute ischaemic stroke. We compared and summarised their results, and rated our confidence in the evidence, based on factors such as study methods and group size. We included trials that compared general anaesthesia with any other anaesthesia type in people who received recanalisation therapies in acute ischaemic stroke. Studies could have taken place anywhere in the world and participants could have been of any age as long as they received an endovascular recanalisation therapy for acute ischaemic stroke under any anaesthesia type.
Search date: 21 March 2022
What we found?
We found six trials, involving 982 people, in hospitals in high-income countries including China (three), Denmark (one), France (one), Germany (one), and Sweden (one). We pooled the results when appropriate.
People treated with general anaesthesia had more artery recanalisation compared to non-general anaesthesia in the short term. General anaesthesia did not change functional wellness and death compared to non-general anaesthesia in the long term.
Reliability of evidence
We have either little or moderate confidence in these results because, in most studies, it was possible that researchers collecting information about the outcomes of surgery knew which type of anaesthetic people had been given. This could have influenced their assessments. Also, a small number of trials were included with a small population. Furthermore, the variability between included studies, management and anaesthetic type, type of recanalisation therapy, and the experience of the healthcare provider involved in the procedure may have had a significant influence on outcomes.
What happens next?
Our search found eight ongoing studies with 2578 participants. We plan to add the results of these studies to update the review.
In early outcomes, general anaesthesia improves target artery revascularisation compared to non-general anaesthesia with moderate-certainty evidence. General anaesthesia may improve adverse events (haemodynamic instability) compared to non-general anaesthesia with low-certainty evidence. We found no evidence of a difference in neurological impairment, stroke-related mortality, all intracranial haemorrhage and haemodynamic instability adverse events between groups with low-certainty evidence. We are uncertain whether general anaesthesia improves functional outcomes and time to revascularisation because the certainty of the evidence is very low.
However, regarding long-term outcomes, general anaesthesia makes no difference to functional outcomes compared to non-general anaesthesia with low-certainty evidence. General anaesthesia did not change stroke-related mortality when compared to non-general anaesthesia with low-certainty evidence. There were no reported data for other outcomes.
In view of the limited evidence of effect, more randomised controlled trials with a large number of participants and good protocol design with a low risk of bias should be performed to reduce our uncertainty and to aid decision-making in the choice of anaesthesia.
The use of mechanical thrombectomy to restore intracranial blood flow after proximal large artery occlusion by a thrombus has increased over time and led to better outcomes than intravenous thrombolytic therapy alone. Currently, the type of anaesthetic technique during mechanical thrombectomy is under debate as having a relevant impact on neurological outcomes.
To assess the effects of different types of anaesthesia for endovascular interventions in people with acute ischaemic stroke.
We searched the Cochrane Stroke Group Specialised Register of Trials on 5 July 2022, and CENTRAL, MEDLINE, and seven other databases on 21 March 2022. We performed searches of reference lists of included trials, grey literature sources, and other systematic reviews.
We included all randomised controlled trials with a parallel design that compared general anaesthesia versus local anaesthesia, conscious sedation anaesthesia, or monitored care anaesthesia for mechanical thrombectomy in acute ischaemic stroke. We also included studies reported as full-text, those published as abstract only, and unpublished data. We excluded quasi-randomised trials, studies without a comparator group, and studies with a retrospective design.
Two review authors independently applied the inclusion criteria, extracted data, and assessed the risk of bias and the certainty of the evidence using the GRADE approach. The outcomes were assessed at different time periods, ranging from the onset of the stroke symptoms to 90 days after the start of the intervention. The main outcomes were functional outcome, neurological impairment, stroke-related mortality, all intracranial haemorrhage, target artery revascularisation status, time to revascularisation, adverse events, and quality of life. All included studies reported data for early (up to 30 days) and long-term (above 30 days) time points.
We included seven trials with 982 participants, which investigated the type of anaesthesia for endovascular treatment in large vessel occlusion in the intracranial circulation. The outcomes were assessed at different time periods, ranging from the onset of stroke symptoms to 90 days after the procedure. Therefore, all included studies reported data for early (up to 30 days) and long-term (above 30 up to 90 days) time points.
General anaesthesia versus non-general anaesthesia(early)
We are uncertain about the effect of general anaesthesia on functional outcomes compared to non-general anaesthesia (mean difference (MD) 0, 95% confidence interval (CI) –0.31 to 0.31; P = 1.0; 1 study, 90 participants; very low-certainty evidence) and in time to revascularisation from groin puncture until the arterial reperfusion (MD 2.91 minutes, 95% CI –5.11 to 10.92; P = 0.48; I² = 48%; 5 studies, 498 participants; very low-certainty evidence). General anaesthesia may lead to no difference in neurological impairment up to 48 hours after the procedure (MD –0.29, 95% CI –1.18 to 0.59; P = 0.52; I² = 0%; 7 studies, 982 participants; low-certainty evidence), and in stroke-related mortality (risk ratio (RR) 0.98, 95% CI 0.52 to 1.84; P = 0.94; I² = 0%; 3 studies, 330 participants; low-certainty evidence), all intracranial haemorrhages (RR 0.92, 95% CI 0.65 to 1.29; P = 0.63; I² = 0%; 5 studies, 693 participants; low-certainty evidence) compared to non-general anaesthesia. General anaesthesia may improve adverse events (haemodynamic instability) compared to non-general anaesthesia (RR 0.21, 95% CI 0.05 to 0.79; P = 0.02; I² = 71%; 2 studies, 229 participants; low-certainty evidence). General anaesthesia improves target artery revascularisation compared to non-general anaesthesia (RR 1.10, 95% CI 1.02 to 1.18; P = 0.02; I² = 29%; 7 studies, 982 participants; moderate-certainty evidence). There were no available data for quality of life.
General anaesthesia versus non-general anaesthesia (long-term)
There is no difference in general anaesthesia compared to non-general anaesthesia for dichotomous and continuous functional outcomes (dichotomous: RR 1.21, 95% CI 0.93 to 1.58; P = 0.16; I² = 29%; 4 studies, 625 participants; low-certainty evidence; continuous: MD –0.14, 95% CI –0.34 to 0.06; P = 0.17; I² = 0%; 7 studies, 978 participants; low-certainty evidence). General anaesthesia showed no changes in stroke-related mortality compared to non-general anaesthesia (RR 0.88, 95% CI 0.64 to 1.22; P = 0.44; I² = 12%; 6 studies, 843 participants; low-certainty evidence). There were no available data for neurological impairment, all intracranial haemorrhages, target artery revascularisation status, time to revascularisation from groin puncture until the arterial reperfusion, adverse events (haemodynamic instability), or quality of life.
Ongoing studies
We identified eight ongoing studies. Five studies compared general anaesthesia versus conscious sedation anaesthesia, one study compared general anaesthesia versus conscious sedation anaesthesia plus local anaesthesia, and two studies compared general anaesthesia versus local anaesthesia. Of these studies, seven plan to report data on functional outcomes using the modified Rankin Scale, five studies on neurological impairment, six studies on stroke-related mortality, two studies on all intracranial haemorrhage, five studies on target artery revascularisation status, four studies on time to revascularisation, and four studies on adverse events. One ongoing study plans to report data on quality of life. One study did not plan to report any outcome of interest for this review.