Regional Anaesthesia for Carotid Endarterectomy
Regional Anaesthesia for Carotid Endarterectomy
Preoperative hypertension is a risk factor for postoperative stroke and death, so patients with uncontrolled hypertension require close attention to perioperative arterial pressure control. Specific figures for preoperative arterial pressure targets have not been defined from controlled trials, but a sensible target is that systolic and diastolic arterial pressures are ≤180 and ≤100 mm Hg, respectively.
The 2012 National Guidelines for Stroke recommend that carotid intervention for recently symptomatic severe carotid stenosis should be regarded as an emergency procedure in patients who are neurologically stable, and should ideally be performed within 48 h of a transient ischaemic attack or minor stroke and definitely within 1 week, as the benefits of carotid surgery decrease rapidly after this. Implementation of these recommendations means that there is less time for preoperative patient preparation, including arterial pressure control, which could predispose to arterial pressure lability.
An estimation of the patient's 'normal' arterial pressure should be obtained from several sources including the clinic visit, the preoperative assessment clinic, and the anaesthetic room—this is the minimum arterial pressure accepted during the period of carotid cross-clamping. Arterial pressure should be measured in both arms using the correct techniques described by the British Hypertension Society.
The patient's neurological status should be assessed before operation, and neurological deficit(s) documented, as differences detected in the postoperative period potentially require surgical re-exploration. It is worthwhile noting the patient's presenting neurological complaint, for example, amaurosis fugax, dysphasia, etc. If the patient develops a neurological deficit when the carotid cross-clamp is applied, they commonly present with the same symptoms that they first presented with (M.D.S., unpublished observations).
Anti-hypertensive medications should usually be continued except for angiotensin-converting enzyme inhibitors and angiotensin II receptor antagonists, but reductions in arterial pressure should be avoided in patients with neurological symptoms. β-Blockers protect against perioperative cardiac complications in patients with a history of myocardial ischaemia, but this is offset by an increased risk of stroke in higher dose regimes and in patients who become acutely anaemic (although acute anaemia is rare in patients undergoing CEA). The American College of Cardiology recommendations for perioperative β-block include continuation if already taking but not to start unless specifically indicated. Metoprolol is associated with increased risk of stroke in patients undergoing non-cardiac surgery compared with other selective drugs such as atenolol or esmolol and should probably be avoided. Statins should be continued as there is evidence of up to a 3% reduction in the incidence of stroke after CEA.
Antiplatelet therapy has a theoretical, therapeutic benefit both at the thrombogenic endarterectomy site and in the coronary circulation in high-risk vascular patients. Aspirin is recommended for all vascular patients in the perioperative period, but the situation regarding clopidogrel is less clear. There is certainly evidence in patients undergoing CEA of the benefits of dual antiplatelet therapy (aspirin combined with low-dose clopidogrel) to reduce the rate of micro-embolization after operation, and a Cochrane review of randomized trials found significant protection against stroke in patients receiving clopidogrel.
Neither the incidence of clinically important neck haematoma nor the morbidity rate from haemorrhagic complications increases in patients undergoing CEA taking clopidogrel with or without aspirin. Surgery may take longer; however, careful consideration should be given to the risks and benefits of performing regional anaesthesia in these patients. There is no evidence available in the literature on the safety of performing CEA under GA or regional anaesthesia techniques in patients receiving newer, faster onset and offset antiplatelet drugs such as ticagrelor or prasugrel or any other of the newer oral anticoagulants.
Preoperative Assessment
Preoperative hypertension is a risk factor for postoperative stroke and death, so patients with uncontrolled hypertension require close attention to perioperative arterial pressure control. Specific figures for preoperative arterial pressure targets have not been defined from controlled trials, but a sensible target is that systolic and diastolic arterial pressures are ≤180 and ≤100 mm Hg, respectively.
The 2012 National Guidelines for Stroke recommend that carotid intervention for recently symptomatic severe carotid stenosis should be regarded as an emergency procedure in patients who are neurologically stable, and should ideally be performed within 48 h of a transient ischaemic attack or minor stroke and definitely within 1 week, as the benefits of carotid surgery decrease rapidly after this. Implementation of these recommendations means that there is less time for preoperative patient preparation, including arterial pressure control, which could predispose to arterial pressure lability.
An estimation of the patient's 'normal' arterial pressure should be obtained from several sources including the clinic visit, the preoperative assessment clinic, and the anaesthetic room—this is the minimum arterial pressure accepted during the period of carotid cross-clamping. Arterial pressure should be measured in both arms using the correct techniques described by the British Hypertension Society.
The patient's neurological status should be assessed before operation, and neurological deficit(s) documented, as differences detected in the postoperative period potentially require surgical re-exploration. It is worthwhile noting the patient's presenting neurological complaint, for example, amaurosis fugax, dysphasia, etc. If the patient develops a neurological deficit when the carotid cross-clamp is applied, they commonly present with the same symptoms that they first presented with (M.D.S., unpublished observations).
Anti-hypertensive medications should usually be continued except for angiotensin-converting enzyme inhibitors and angiotensin II receptor antagonists, but reductions in arterial pressure should be avoided in patients with neurological symptoms. β-Blockers protect against perioperative cardiac complications in patients with a history of myocardial ischaemia, but this is offset by an increased risk of stroke in higher dose regimes and in patients who become acutely anaemic (although acute anaemia is rare in patients undergoing CEA). The American College of Cardiology recommendations for perioperative β-block include continuation if already taking but not to start unless specifically indicated. Metoprolol is associated with increased risk of stroke in patients undergoing non-cardiac surgery compared with other selective drugs such as atenolol or esmolol and should probably be avoided. Statins should be continued as there is evidence of up to a 3% reduction in the incidence of stroke after CEA.
Antiplatelet therapy has a theoretical, therapeutic benefit both at the thrombogenic endarterectomy site and in the coronary circulation in high-risk vascular patients. Aspirin is recommended for all vascular patients in the perioperative period, but the situation regarding clopidogrel is less clear. There is certainly evidence in patients undergoing CEA of the benefits of dual antiplatelet therapy (aspirin combined with low-dose clopidogrel) to reduce the rate of micro-embolization after operation, and a Cochrane review of randomized trials found significant protection against stroke in patients receiving clopidogrel.
Neither the incidence of clinically important neck haematoma nor the morbidity rate from haemorrhagic complications increases in patients undergoing CEA taking clopidogrel with or without aspirin. Surgery may take longer; however, careful consideration should be given to the risks and benefits of performing regional anaesthesia in these patients. There is no evidence available in the literature on the safety of performing CEA under GA or regional anaesthesia techniques in patients receiving newer, faster onset and offset antiplatelet drugs such as ticagrelor or prasugrel or any other of the newer oral anticoagulants.
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