Key messages
- Current evidence does not show any clear difference between local anaesthesia (where the patient remains awake) and general anaesthesia for the risk of stroke, death, or other unwanted effects for people having surgery to widen a narrowed carotid artery (carotid endarterectomy).
- Future studies should recruit more people, analyse and publish information from all of them, and make sure that the researchers assessing the outcomes do not know which type of anaesthetic people had.
What is a carotid endarterectomy?
A stroke happens when blood stops flowing to any part of your brain. The carotid artery is the main vessel supplying blood to the brain. This artery can become narrowed due to fatty deposits that build up over time. Around 1 in 5 strokes is caused by narrowing of the carotid artery. Blood clots can form at the point of narrowing. If a blood clot breaks off into the bloodstream, it can be carried into the brain, where it blocks the blood supply and causes a stroke.
A surgical operation – carotid endarterectomy – removes the inner lining, fatty deposits and any blood clots in the carotid artery and can lower the risk of stroke. However, even with very careful surgery, approximately 1 in 20 people will suffer a stroke caused by the operation itself.
Anaesthetics are medicines that prevent people feeling pain. Surgeons can use either a local anaesthetic, where an area of the body is numbed, or general anaesthetic, where a person is put to sleep. The use of a local anaesthetic rather than a general anaesthetic might lower the risk of a stroke during or after carotid endarterectomy surgery.
What did we want to find out?
We wanted to find out if using local anaesthetic for carotid endarterectomy:
- lowers the risk of stroke and death around the time of the operation;
- lowers the rate of other unwanted effects; and
- is more acceptable to individuals and surgeons
when compared to general anaesthetic.
What did we do?
We searched for studies that compared local and general anaesthetics in people who had a carotid endarterectomy. We compared and summarised their results, and rated our confidence in the evidence, based on factors such as study methods and sizes.
What did we find?
We found 16 studies involving 4839 people. The biggest study included 3526 people and the smallest study had 20 people. The studies were conducted around the world. More men than women were included in the studies, and their average age was 67 years.
Main results
Local anaesthetic makes little to no difference in risk of stroke within 30 days of surgery compared to general anaesthetic.
Local anaesthetic may not reduce risk of death within 30 days of surgery compared to general anaesthetic.
Since neither type of anaesthesia has clear benefits over the other, the choice of which to use can be made on the basis of the clinical situation, and the preferences of the surgeon and patient.
Main limitations of the evidence
We have either little, or moderate, confidence in these results. The quality of the evidence was reduced 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, information from some people who were meant to be included in the studies was left out, which also reduces the quality of the evidence.
How up to date is this evidence?
The evidence is current to February 2021.
The incidence of stroke and death were not convincingly different between local and general anaesthesia for people undergoing carotid endarterectomy. The current evidence supports the choice of either approach. Further high-quality studies are still needed as the evidence is of limited reliability.
Carotid endarterectomy may significantly reduce the risk of stroke in people with recently symptomatic, severe carotid artery stenosis. However, there are significant perioperative risks that may be minimised by performing the operation under local rather than general anaesthetics. This is an update of a Cochrane Review first published in 1996, and previously updated in 2004, 2008, and 2013.
To determine whether carotid endarterectomy under local anaesthetic: 1) reduces the risk of perioperative stroke and death compared with general anaesthetic; 2) reduces the complication rate (other than stroke) following carotid endarterectomy; and 3) is acceptable to individuals and surgeons.
We searched CENTRAL, MEDLINE, Embase, and two trials registers (to February 2021). We also reviewed reference lists of articles identified.
Randomised controlled trials (RCTs) comparing the use of local anaesthetics to general anaesthetics for people having carotid endarterectomy were eligible.
Three review authors independently extracted data, assessed risk of bias, and evaluated quality of evidence using the Grading of Recommendations, Assessment, Development, and Evaluations (GRADE) tool. We calculated a pooled Peto odds ratio (OR) and corresponding 95% confidence interval (CI) for the following outcomes that occurred within 30 days of surgery: stroke, death, ipsilateral stroke, stroke or death, myocardial infarction, local haemorrhage, and arteries shunted.
We included 16 RCTs involving 4839 participants, of which 3526 were obtained from the single largest trial (GALA). The main findings from our meta-analysis showed that, within 30 days of operation, neither incidence of stroke nor death were significantly different between local and general anaesthesia. Of these, the incidence of stroke in the local and general anaesthesia groups was 3.2% and 3.5%, respectively (Peto odds ratio (OR) 0.91, 95% confidence interval (CI) 0.66 to 1.26; P = 0.58; 13 studies, 4663 participants; low-quality evidence). The rate of ipsilateral stroke under both types of anaesthesia was 3.1% (Peto OR 1.03, 95% CI 0.71 to 1.48; P = 0.89; 2 studies, 3733 participants; low-quality evidence). The incidence of stroke or death in the local anaesthesia group was 3.5%, while stroke or death incidence was 4.1% in the general anaesthesia group (Peto OR 0.85, 95% CI 0.62 to 1.16; P = 0.31; 11 studies, 4391 participants; low-quality evidence). A lower rate of death was observed in the local anaesthetic group but evidence was of low quality (Peto OR 0.61, 95% CI 0.35 to 1.06; P = 0.08; 12 studies, 4421 participants).