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Carotid endarterectomy

2007; Elsevier BV; Volume: 99; Issue: 1 Linguagem: Inglês

10.1093/bja/aem137

1471-6771

Simon Howell,

Intracranial Aneurysms: Treatment and Complications

Carotid endarterectomy (CEA) is performed to prevent embolic stroke in patients with atheromatous disease at the carotid bifurcation. There is now substantial evidence to support early operation in symptomatic patients, ideally within 2 weeks of the last neurological symptoms. Thus, the anaesthetist may be faced with a high risk patient in whom there has been limited time for preoperative preparation. The operation may be performed under local or general anaesthesia. The advantages and disadvantages of both are explored in this review. Carotid shunting may offer a degree of cerebral protection, but carries its own risks and has not been proved to reduce morbidity and mortality. The use of carotid shunts is based on clinical judgement, awake neurological monitoring, and the use of monitors of cerebral perfusion. There is no ideal monitor of cerebral perfusion in the patient receiving general anaesthesia. Both the intraoperative and postoperative periods may be witness to dramatic haemodynamic changes that may compromise the cerebral or myocardial circulations. In particular, postoperative hypotension may compromise both myocardial and cerebral perfusion, and severe hypertension can cause cerebral hyperperfusion. There is as yet limited evidence to guide the management of these problems. In summary, CEA can yield significant benefit, but those with the most to gain from the operation also present the greatest challenge to the anaesthetist. Carotid endarterectomy (CEA) is performed to prevent embolic stroke in patients with atheromatous disease at the carotid bifurcation. There is now substantial evidence to support early operation in symptomatic patients, ideally within 2 weeks of the last neurological symptoms. Thus, the anaesthetist may be faced with a high risk patient in whom there has been limited time for preoperative preparation. The operation may be performed under local or general anaesthesia. The advantages and disadvantages of both are explored in this review. Carotid shunting may offer a degree of cerebral protection, but carries its own risks and has not been proved to reduce morbidity and mortality. The use of carotid shunts is based on clinical judgement, awake neurological monitoring, and the use of monitors of cerebral perfusion. There is no ideal monitor of cerebral perfusion in the patient receiving general anaesthesia. Both the intraoperative and postoperative periods may be witness to dramatic haemodynamic changes that may compromise the cerebral or myocardial circulations. In particular, postoperative hypotension may compromise both myocardial and cerebral perfusion, and severe hypertension can cause cerebral hyperperfusion. There is as yet limited evidence to guide the management of these problems. In summary, CEA can yield significant benefit, but those with the most to gain from the operation also present the greatest challenge to the anaesthetist. Carotid endarterectomy (CEA) is a prophylactic operation. It is performed in patients who are at risk of stroke from emboli arising from atheromatous plaque at the carotid bifurcation. Although atheroma at this site can cause marked carotid stenosis, CEA is not performed to relieve stenosis, but is undertaken in patients. Timely CEA can substantially reduce the risk of disabling or fatal stroke, but if this benefit is to be realized it is essential that the risks of surgery do not outweigh the subsequent reduction in the risk of stroke. This article reviews the perioperative management of patients undergoing CEA. The indications for CEA in various circumstances were recently reviewed by the American Academy of Neurology.11Chaturvedi S Bruno A Feasby T et al.Carotid endarterectomy–an evidence-based review: report of the Therapeutics and Technology Assessment Subcommittee of the American Academy of Neurology.Neurology. 2005; 65: 794-801Crossref PubMed Scopus (353) Google Scholar There are two groups of patients to consider: symptomatic patients who have active plaque giving rise to emboli that enter the cerebral circulation and cause transient ischaemic attacks (TIAs) and reversible ischaemic neurological deficits, and asymptomatic patients who have demonstrable disease at the carotid bifurcation but no history of a recent neurological event attributable to this lesion. There is unequivocal evidence to support CEA in symptomatic patients with >70% carotid stenosis in the relevant carotid territory. This is based particularly on two large studies, the North American Symptomatic Endarterectomy Trial (NASCET) and the European Carotid Surgery Trial (ECST), both of which compared surgery with best medical treatment.19European Carotid Surgery Trialists’ Collaborative GroupRandomised trial of endarterectomy for recently symptomatic carotid stenosis: final results of the MRC European Carotid Surgery Trial (ECST).Lancet. 1998; 351: 1379-1387Abstract Full Text Full Text PDF PubMed Scopus (2369) Google Scholar 69North American Symptomatic Carotid Endarterectomy Trial CollaboratorsBeneficial effect of carotid endarterectomy in symptomatic patients with high-grade carotid stenosis.N Engl J Med. 1991; 325: 445-453Crossref PubMed Google Scholar The data from these and the smaller Veteran’s Affairs Trial were combined in a meta-analysis by Rothwell and colleagues.80Rothwell PM Eliasziw M Gutnikov SA et al.Analysis of pooled data from the randomised controlled trials of endarterectomy for symptomatic carotid stenosis.Lancet. 2003; 361: 107-116Abstract Full Text Full Text PDF PubMed Scopus (995) Google Scholar For patients with a carotid stenosis of 70% or more there was absolute risk reduction for the combined outcome of perioperative death or subsequent stroke more than 5 yr of 16% yielding a number needed to treat of 6.3. The benefit in patients with 50–69% stenosis was less marked with an absolute risk reduction of 4.6% more than 5 yr and a number needed to treat of 22. CEA was not beneficial to symptomatic patients with 30–49% stenosis or near carotid occlusion, and was harmful in symptomatic patients with 50% stenosis are a different population to patients with ‘active’ plaque that is discharging emboli into the cerebral circulation. There are data to support CEA in asymptomatic patients but they are less robust than those supporting the operation for patients with symptoms. The asymptomatic carotid artery stenosis (ACAS) study was halted after a 2.7 yr median follow-up because of a projected 5.9% absolute reduction in the risk of ipsilateral stroke at 5 yr.20Executive Committee for the Asymptomatic Carotid Atherosclerosis StudyEndarterectomy for asymptomatic carotid artery stenosis.JAMA. 1995; 273: 1421-1428Crossref PubMed Google Scholar Although the results of this study were encouraging, the very low perioperative stroke and death rate of 2.3% was not supported by more recent studies. The asymptomatic carotid surgery trial (ACST) recruited patients with a carotid artery diameter reduction of at least 60% on ultrasound and no symptoms in the previous 6 months. This study showed a net reduction of 5.4% in the combined outcome of stroke within 5 yr and death within 30 days of surgery.65Mohammed N Anand SS Prevention of disabling and fatal strokes by successful carotid endarterectomy in patients without recent neurological symptoms: randomized controlled trial. MRC asymptomatic carotid surgery trial (ACST) collaborative group.Lancet. 2004; 363: 1491-1502Abstract Full Text Full Text PDF PubMed Scopus (0) Google Scholar The benefits were mainly seen in younger patients and were uncertain for patients older than 75 yr. The American Academy of Neurology document makes the point that there is a significant difference between the primary endpoint of the ACAS and ACST studies.11Chaturvedi S Bruno A Feasby T et al.Carotid endarterectomy–an evidence-based review: report of the Therapeutics and Technology Assessment Subcommittee of the American Academy of Neurology.Neurology. 2005; 65: 794-801Crossref PubMed Scopus (353) Google Scholar ACAS took ipsilateral stroke as the primary endpoint, whereas ACST included contra-lateral and vertebrobasilar strokes. If ACST analysis was limited to ipsilateral stroke, the absolute benefit would be reduced. CEA should be performed sooner rather than later in symptomatic patients. A pooled analysis of data from NASCET and ESCT demonstrated that the greatest absolute risk reduction for ipsilateral stroke, any stroke, and death within 30 days of surgery was found in patients who underwent surgery within 2 weeks of their last event.81Rothwell PM Eliasziw M Gutnikov SA Warlow CP Barnett HJ Endarterectomy for symptomatic carotid stenosis in relation to clinical subgroups and timing of surgery.Lancet. 2004; 363: 915-924Abstract Full Text Full Text PDF PubMed Scopus (958) Google Scholar This decrease in benefit from surgery was significantly more rapid in women than in men. The benefit of early surgery is explained by the natural history of carotid plaque in symptomatic patients. In a study conducted by Harrison and Marshall,35Harrison M Marshall J The finding of thrombus at carotid endarterectomy and its relationship to the timing of surgery.Br J Surg. 1977; 64: 511-512Crossref PubMed Google Scholar 66% of patients undergoing CEA within 4 weeks of their most recent event had thrombus overlying the carotid stenosis compared with 21% of patients waiting for a longer period. Plaque morphology studies have shown that patients with recent symptoms are more likely to have acute plaque disruption, spontaneous embolization, overlying thrombus formation, and abnormal levels of metalloproteinases within the plaque.68Naylor R Time is brain!.Surgeon. 2007; 5: 23-30Abstract Full Text PDF PubMed Google Scholar Ideally, patients presenting with a suspected TIA should have undergone investigation and, if appropriate, surgery within 2 weeks of presentation. At present, this goal is far from being achieved in the UK. The 2004 Royal College of Physicians Sentinel Stroke Audit found that only 50% of patients had undergone a duplex scan within 12 weeks of presentation, let alone surgery.68Naylor R Time is brain!.Surgeon. 2007; 5: 23-30Abstract Full Text PDF PubMed Google Scholar 83Royal College of Physicians of LondonRoyal College of Physicians National Sentinal Stroke Audit.Available from: www.rcplondon.ac.uk/pubsbrochures/pub_print_natsenastr.htmDate: 2004Google Scholar The best care of a patient with a progressing stroke of less than 24 h duration is less clear. The American Academy of Neurology review identified four studies that examined this issue.11Chaturvedi S Bruno A Feasby T et al.Carotid endarterectomy–an evidence-based review: report of the Therapeutics and Technology Assessment Subcommittee of the American Academy of Neurology.Neurology. 2005; 65: 794-801Crossref PubMed Scopus (353) Google Scholar Three of the studies found benefit from surgery, but one reported a postoperative stroke and death rate of 20%. The best management of this difficult clinical problem remains unclear. The brain receives its blood supply from four major arteries. Eighty-to-ninety per cent of the cerebral blood supply is delivered via the two internal carotid arteries with the majority of the remainder coming from the vertebrobasilar system. The carotid arteries and basilar artery unite to form the Circle of Willis at the base of the brain. This ring of arteries offers the brain considerable protection against the occlusion of one or another vessel, but its presence should not lead to clinical complacency. The Circle of Willis is incomplete in 15% of normal people and in patients with cerebrovascular disease one or more of the vessels within the circle maybe occluded by atheromatous plaque. After careful surgical exposure, the external, internal, and common carotid arteries are cross-clamped so that the carotid bifurcation is isolated from the circulation. The artery is opened and the plaque removed. Most often this is done through a longitudinal incision and the artery is patched upon closure as this reduces the incidence of re-stenosis. The operation of eversion CEA in which the internal carotid artery is transected and turned inside out to remove the plaque is used by some surgeons. Whichever technique is used care must be taken to remove all of the debris from the intimal surface of the artery to prevent postoperative emboli occurring. During the course of the operation, a shunt may be inserted. There are a number of different types of carotid shunt but all are essentially a length of plastic tubing to carry the blood from the common carotid to the internal carotid artery, so maintaining blood flow during the course of surgery. Although at first sight this may seem to be a useful technique to maintain cerebral blood flow in those patients who have a contralateral carotid stenosis or a compromised Circle of Willis, it is not an entirely benign intervention. Acute complications of shunt insertion include air or plaque embolization, intimal tears, and carotid dissection. There is an associated risk of local complications including haematoma, nerve injury, infection, and late carotid restenosis. For all these risks, flow through the shunt may be inadequate to meet cerebral oxygen requirements. Practice varies widely between surgeons; some routinely insert shunts in all patients, whereas others eschew their use altogether. A middle way is a policy of selective shunting based on one or another monitor of cerebral function or blood flow. The technologies used to monitor for cerebral ischaemia are discussed below. There are limited high quality data to guide practice. The issue is made complex by the number of different options to be compared. Studies may compare a policy of shunting vs not shunting, shunting vs selective shunting based on the use of a cerebral monitor, or selective shunting vs not shunting. Bond and colleagues6Bond R Rerkasem K Counsell C et al.Routine or selective carotid artery shunting for carotid endarterectomy (and different methods of monitoring in selective shunting).Cochrane Database Syst Rev. 2002; (CD000190)PubMed Google Scholar systematically reviewed the evidence for and against shunting. They found only three studies that were sufficiently rigorous for inclusion in a systematic review. In two studies comparing routine shunting with no shunting there was no significant difference in the rate of all strokes, ipsilateral stroke, or death up to 30 days after surgery.28Gumerlock MK Neuwelt EA Carotid endarterectomy: to shunt or not to shunt.Stroke. 1988; 19: 1485-1490Crossref PubMed Google Scholar 88Sandmann W Kolvenbach R Willeke F Risks and benefits of shunting in carotid endarterectomy.Stroke. 1993; 24: 1098-1099Crossref PubMed Scopus (0) Google Scholar However, these studies suffered from flaws of methodology and reporting. A third trial compared shunting on the basis of EEG monitoring and carotid pressure measurement with pressure measurement alone.23Fletcher JP Morris JG Little JM Kershaw LZ EEG monitoring during carotid endarterectomy.Aust N Z J Surg. 1988; 58: 285-288Crossref PubMed Google Scholar There was no significant difference between the risk of ipsilateral stroke between the two groups. Bond and colleagues suggest that further trials of various methods of monitoring are not justified until the efficacy of shunting is established. This is perhaps too simplistic a statement. They do concede that a systematic review of the sensitivity and specificity of the various forms of monitoring would be appropriate to inform any trial of selective shunting. The two most feared major perioperative complications of CEA are cerebrovascular accident and myocardial infarction. The pooled data from the NASCET, ESCT, and Veteran’s Administration Trial provide an insight into the incidence of cerebrovascular accident after CEA.80Rothwell PM Eliasziw M Gutnikov SA et al.Analysis of pooled data from the randomised controlled trials of endarterectomy for symptomatic carotid stenosis.Lancet. 2003; 361: 107-116Abstract Full Text Full Text PDF PubMed Scopus (995) Google Scholar Data are presented on 3248 patients who underwent surgery. Of 35 deaths (1.1%) within 30 days of surgery, 20 deaths were from operative strokes. Two hundred and twenty-nine patients suffered the combined outcome stroke or death within 30 days of surgery. The data from the Cochrane Collaboration meta-analysis of regional vs general anaesthesia for CEA also provide valuable information on the overall incidence of adverse events. In this analysis, there were 195 deaths within 30 days of surgery among 17 703 patients, a death rate of 1.1%. There were 564 strokes within 30 days of surgery among 16 835 patients, an incidence of any stroke of 3.4%. Twenty-six studies including 13 547 patients reported on the combined outcome of any stroke or death within 30 days of surgery. There were 604 events in the pooled data giving an event rate of 4.5%. Twenty-two studies reported on the occurrence of myocardial infarction within 30 days of surgery. There 323 postoperative myocardial infarctions were reported in a total of 14 773 patients, a myocardial infarction rate of 2.2%. It is not clear what proportion of these myocardial infarctions was fatal.78Rerkasem K Bond R Rothwell PM Local versus general anaesthesia for carotid endarterectomy.Cochrane Database Syst Rev. 2004; (CD000126.)Crossref Google Scholar Although carotid cross-clamping is a major haemodynamic challenge to the cerebral circulation, the majority of strokes after surgery are due to embolization or thrombosis. In a review of 38 neurological events that occurred in 2024 patients who had undergone CEA, the causes of neurological events included intraoperative clamping ischaemia in 5 patients (13.2%); thromboembolic events in 24 (63.2%); intracerebral haemorrhage in 5 (13.2%); and deficits unrelated to the operated artery in 4 (10.5%).79Rockman CB Jacobowitz GR Lamparello PJ et al.Immediate reexploration for the perioperative neurologic event after carotid endarterectomy: is it worthwhile?.J Vasc Surg. 2000; 32: 1062-1070Abstract Full Text Full Text PDF PubMed Scopus (41) Google Scholar The majority of perioperative events become manifest within 8 h of surgery. In a retrospective review of 771 CEAs, 26 patients developed a neurological deficit after surgery. Nineteen of the neurological deficits were diagnosed in the operating theatre or recovery room and a further five within 8 h of surgery.92Sheehan MK Baker WH Littooy FN Mansour MA Kang SS Timing of postcarotid complications: a guide to safe discharge planning.J Vasc Surg. 2001; 34: 13-16Abstract Full Text Full Text PDF PubMed Scopus (0) Google Scholar Patients with carotid artery disease have a high incidence of severe coronary artery disease. Hertzer and colleagues39Hertzer NR Beven EG Young JR et al.Coronary artery disease in peripheral vascular patients. A classification of 1000 coronary angiograms and results of surgical management.Ann Surg. 1984; 199: 223-233Crossref PubMed Google Scholar reported coronary angiography data on 1000 patients being considered for major vascular surgery, including 295 patients presenting with cerebral vascular disease. Twenty-six per cent of the patients with cerebrovascular disease had coronary artery disease sufficiently severe that they were considered to be potential candidates for coronary artery surgery.39Hertzer NR Beven EG Young JR et al.Coronary artery disease in peripheral vascular patients. A classification of 1000 coronary angiograms and results of surgical management.Ann Surg. 1984; 199: 223-233Crossref PubMed Google Scholar It is unsurprising that patients undergoing CEA are at risk of preoperative myocardial injury. The pooled meta-analysis data discussed earlier rank myocardial infarction second to stroke as a complication of endarterectomy with rates of 3.4 and 2.2%, respectively. Data on perioperative cardiac troponin release indicate that considerably more patients suffer asymptomatic perioperative myocardial injury. In a study comparing CEA with carotid stenting, 13% of patients undergoing CEA had detectable cardiac troponin I release into the circulation.66Motamed C Motamed-Kazerounian G Merle JC et al.Cardiac troponin I assessment and late cardiac complications after carotid stenting or endarterectomy.J Vasc Surg. 2005; 41: 769-774Abstract Full Text Full Text PDF PubMed Scopus (0) Google Scholar This silent cardiac troponin release cannot be regarded as clinically irrelevant. The association between asymptomatic perioperative troponin release after major vascular surgery and a worsened intermediate and long-term prognosis is well established.48Kim LJ Martinez EA Faraday N et al.Cardiac troponin I predicts short-term mortality in vascular surgery patients.Circulation. 2002; 106: 2366-2371Crossref PubMed Scopus (219) Google Scholar 51Landesberg G Shatz V Akopnik I et al.Association of cardiac troponin, CK-MB, and postoperative myocardial ischemia with long-term survival after major vascular surgery.J Am Coll Cardiol. 2003; 42: 1547-1554Crossref PubMed Scopus (324) Google Scholar CEA may also be associated with cranial nerve injury, bleeding and airway swelling and oedema. Ballotta and colleagues reported cranial nerve deficits in 25 out of 200 patients who underwent CEA. There were 11 hypoglossal, 8 recurrent laryngeal, 2 superior laryngeal, 2 marginal mandibular, and 2 greater auricular nerve injuries. Many, if not all of these injuries, can be attributed to surgical traction. All nerve dysfunctions were transient, with all but four nerves recovering completely within 6 months.5Ballotta E Da Giau G Renon L et al.Cranial and cervical nerve injuries after carotid endarterectomy: a prospective study.Surgery. 1999; 125: 85-91Abstract Full Text Full Text PDF PubMed Scopus (84) Google Scholar The operation is performed on an artery imbedded among vascular tissues, and postoperative bleeding, leading to a neck haematoma, airway compression, and respiratory compromise are possible. Patients should be monitored for this in the immediate postoperative period. If there is evidence of respiratory compromise, the clips should be removed from the neck wound to decompress the airway and the patient taken back to theatre immediately. This is a setting in which the use of local anaesthesia has the benefit that surgery can proceed at once. CEA may be carried out under regional or general anaesthesia. The impact of the choice of anaesthesia on the outcome of this operation has been extensively studied. A systematic review by Tangkanakul and colleagues102Tangkanakul C Counsell C Warlow C Local versus general anaesthesia for carotid endarterectomy.Cochrane Database Syst Rev. 2000; (CD000126)PubMed Google Scholar of the impact of the type of anaesthesia on outcome from CEA was published in 2000 and was updated by Rerkasem and colleagues78Rerkasem K Bond R Rothwell PM Local versus general anaesthesia for carotid endarterectomy.Cochrane Database Syst Rev. 2004; (CD000126.)Crossref Google Scholar in 2004. Data were reported from seven randomized trials involving 554 operations and 41 nonrandomized studies involving 25 622 operations. The authors of the review had significant concerns about the quality of several of the nonrandomized studies. A meta-analysis of the nonrandomized studies showed that the use of local anaesthetic was associated with significant reductions in the odds of death from all causes (OR 0.67, 95% CI 0.46–0.97), stroke (OR 0.56, 95% CI 0.4–0.70), stroke or death (OR 0.61, 95% CI 0.48–0.77), myocardial infarction (OR 0.55, 95% CI 0.39–0.79), and pulmonary embolism within 30 days of surgery (OR 0.31, 95% CI 0.15–0.63). A meta-analysis of the randomized studies showed that the use of local anaesthetic was associated with a reduction in the risk of local haemorrhage within 30 days of surgery, but there was no evidence of a reduction in the odds of operative stroke.78Rerkasem K Bond R Rothwell PM Local versus general anaesthesia for carotid endarterectomy.Cochrane Database Syst Rev. 2004; (CD000126.)Crossref Google Scholar 102Tangkanakul C Counsell C Warlow C Local versus general anaesthesia for carotid endarterectomy.Cochrane Database Syst Rev. 2000; (CD000126)PubMed Google Scholar However, the trials were small and in some studies intention-to-treat analyses were not possible. A large-scale study of general anaesthesia vs local anaesthesia (GALA) is currently in progress. CEA may be performed under either a superficial cervical plexus block or combined deep and superficial cervical plexus block. The techniques for performing these blocks have been described elsewhere.96Stoneham MD Knighton JD Regional anaesthesia for carotid endarterectomy.Br J Anaesth. 1999; 82: 910-919Crossref PubMed Google Scholar Many practitioners use both blocks together while others choose to use a superficial block alone. Patients should be told to report any discomfort because the surgeon can supplement the block with local anaesthetic infiltration. Stoneham and colleagues95Stoneham MD Doyle AR Knighton JD Dorje P Stanley JC Prospective, randomized comparison of deep or superficial cervical plexus block for carotid endarterectomy surgery.Anesthesiology. 1998; 89: 907-912Crossref PubMed Scopus (0) Google Scholar compared superficial cervical plexus block alone with combined deep and superficial block in a randomized controlled trial and found them to be comparable with regard to the amount of local anaesthetic supplementation given by the surgeon. However, patients in whom paraesthesia was elicited during placement of the deep block required less lidocaine supplementation and those in the deep block group were less likely to require analgesia during the first 24 h after the operation. Anatomical considerations suggest that a superficial block alone might not be expected to block all the relevant nerves for CEA. Dye injection studies performed in cadavers suggest a communication between the deep and superficial cervical spaces such that local anaesthetic may be able to spread from a superficial cervical plexus block to the deep structures so long as the injection is made beneath the investing fascia of the neck and is not only s.c.74Pandit JJ Dutta D Morris JF Spread of injectate with superficial cervical plexus block in humans: an anatomical study.Br J Anaesth. 2003; 91: 733-735Crossref PubMed Scopus (0) Google Scholar The hazards of deep cervical plexus block include injection into the CSF with consequent brainstem anaesthesia, arterial injury and intra-arterial injection, and phrenic nerve paralysis resulting in respiratory distress.10Carling A Simmonds M Complications from regional anaesthesia for carotid endarterectomy.Br J Anaesth. 2000; 84: 797-800Crossref PubMed Scopus (44) Google Scholar The deep block should not be performed in anticoagulated patients. CEA under cervical epidural anaesthesia is well described and does provide good operating conditions. However, it is associated with a significant risk of major anaesthetic complications. In a series of 394 patients who underwent endarterectomy under cervical epidural anaesthesia, serious complications included dural puncture in two patients, epidural venepuncture in six patients, and respiratory muscle paralysis in three patients.7Bonnet F Derosier JP Pluskwa F Abhay K Gaillard A Cervical epidural anaesthesia for carotid artery surgery.Can J Anaesth. 1990; 37: 353-358Crossref PubMed Google Scholar While the use of local anaesthesia has the merit that it allows direct neurological monitoring of the conscious patient, general anaesthesia also has laudable qualities. Patients can find CEA under regional anaesthesia stressful. They must lie still with their head turned to one side for 90 min or more and the positioning of the drapes may be profoundly unpleasant for a claustrophobic patient. The operation may be performed with a laryngeal mask airway and a laryngeal mask may be inserted if there is a need to convert from regional to general anaesthesia as described in what follows. However, access to the airway during surgery can be difficult and, with the head turned to one side, it is the view of this author that the definitive airway control offered by endotracheal intubation is to be preferred. There are no data to favour any particular general anaesthetic technique. It may be argued that sevoflurane is the volatile agent of choice for neuroanaesthesia.17Engelhard K Werner C Inhalational or intravenous anesthetics for craniotomies? Pro inhalational.Curr Opin Anaesthesiol. 2006; 19: 504-508Crossref PubMed Scopus (60) Google Scholar Desflurane has been shown in an animal model to cause marked vasodilation, increasing cerebral blood volume, and thence intracranial pressure.40Holmstrom A Akeson J Desflurane increases intracranial pressure more and sevoflurane less than isoflurane in pigs subjected to intracranial hypertension.J Neurosurg Anesthesiol. 2004; 16: 136-143Crossref PubMed Scopus (30) Google Scholar Although both sevoflurane and isoflurane can provide rapid recovery, sevoflurane produces less vasodilation than isoflurane at the same depth of anaesthesia.41Holmstrom A Akeson J Sevoflurane induces less cerebral vasodilation than isoflurane at the same A-line autoregressive index level.Acta Anaesthesiol Scand. 2005; 49: 16-22Crossref PubMed Scopus (21) Google Scholar However, these considerations regarding intracranial pressure are of more importance in the setting of intracranial surgery than in an extracranial operation such as CEA. The effect of anaesthetic agents on cerebral blood flow and metabolism are perhaps more important. At concentrations of up to 1.0 MAC, sevoflurane produces concomitant reductions in cerebral metabolic blood flow and cerebral metabolic rate. At concentrations above this there is evidence of increases in regional ce