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Pro & con debate

Local anaesthesia for carotid endarterectomy

Pro

protect the brain

Cedergreen, Pernille; Swiatek, Frans; Nielsen, Henning Bay

Author Information
European Journal of Anaesthesiology: April 2016 - Volume 33 - Issue 4 - p 236-237
doi: 10.1097/EJA.0000000000000370
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This Editorial is part of a Pro and Con debate and is accompanied by the following articles:

  • Licker M. Regional or general anaesthesia for carotid endarterectomy. Does it matter? Eur J Anaesthesiol 2016; 33:241–243
  • Unic-Stojanovic D, Jovic M. Local anaesthesia for carotid endarterectomy. Con: decrease the stress for all. Eur J Anaesthesiol 2016; 33:238–240

Carotid endarterectomy (CEA) removes plaque inside the artery in symptomatic patients.1 Symptoms include transient ischaemic attacks, and cerebral hypoperfusion can provoke syncope. Surgery can be performed with either general anaesthesia or local anaesthesia. Retrospective studies suggest a reduction in postoperative complications with local anaesthesia for CEA,2,3 but information from prospective clinical trials is limited.4–6 In this Editorial, we extend the arguments in favour of regional anaesthesia as the best option for CEA when the key interest is to follow cerebral integrity during surgery.

Advantages of local anaesthesia

Local anaesthesia for CEA is achieved by cervical plexus blockade. Superficial blockade is subcutaneous infiltration along the expected incision line or along the posterior border of the sternocleidomastoid muscle. The roots of C2, C3 and C4 spinal nerves are blocked by deep cervical plexus blockade using a ‘blind’ technique. Ultrasonography-guided local anaesthesia for CEA may be the gold standard.7 A technique has been described,8 and when local anaesthesia is used, re-operation can be performed without additional anaesthetic.

During internal carotid artery clamping, the anaesthetist may be unaware of limitations in the flow through other vessels serving the circle of Willis. Arteries originating from circle of Willis could also be subject to stenosis and about 10% of patients face neurologic changes after clamping of the internal carotid artery.9 The use of noninvasive monitoring such as transcranial Doppler sonography to determine changes in cerebral perfusion10 may help to detect the status of cerebral blood flow during CEA. Neurological deterioration relates to cerebral O2 desaturation9 and this can be monitored with near-infrared spectroscopy.11 It is able to predict neurologic deficit during CEA 5 to10 s before clinical signs of cerebral hypoperfusion become apparent.10

When local rather than general anaesthesia is used, the awake testing procedure is a superior way to demonstrate when cerebral blood supply becomes critical.11 Awake testing includes the ability to squeeze a hand or respond to visual or audio stimuli. With CEA under general anaesthesia, neurological deterioration is usually first diagnosed when the patient is expected to wake up after surgery. When CEA affects cerebral blood flow to an extent that brain integrity is compromised, the best approach is to ask the patient to confirm well-being. This is difficult under general anaesthesia.

Disadvantages of local anaesthesia

Patients with claustrophobia may find their anxiety levels rise when they are placed under surgical drapes. The patient needs to lie still during the delicate manoeuvre required to remove the clot from the artery. A protocol to manage unexpected patient reaction needs to be prepared. Nurses and doctors involved in the operating theatre should be trained in awake testing procedures. An unconscious patient requires easy access to equipment for rapid-sequence intubation.

With local anaesthesia, patients may experience discomfort when the skin of the neck is punctured. Antithrombotic medication challenges the use of deep cervical plexus blockade. Skills in ultrasonography are recommended. Ultrasound devices with high-definition screens are costly but cheap to run in daily practice. Local anaesthesia has the potential to block the phrenic nerve and patients may develop a hoarse voice probably from its action on the recurrent laryngeal nerve. Clinical experience predicts that injection of local anaesthetic close to the bifurcation of the carotid artery may produce an increase in blood pressure. Surgery in the proximity of the arterial sheath may provoke a pain reaction and supplemental local anaesthesia may be necessary.8

Outcome after local anaesthesia

Manipulation of carotid tissue may produce bradycardia and hypotension probably mediated via the glossopharyngeal and vagal nerves. A reduction in mean arterial pressure below 60 mmHg can reduce cerebral blood flow in accordance with the cerebral autoregulation curve. In patients with atherosclerosis, diabetes and hypertension, the curve may be shifted to the right. Interventions to increase mean arterial pressure by administration of vasoactive medication can be guided by near-infrared spectroscopy.12 During CEA, a rapid drop in cerebral oxygenation by more than 20% suggests postoperative neurological complications.11

The postoperative cerebral hyperperfusion syndrome relates to impaired cerebral autoregulation. After declamping, a significant rise in cerebral oxygenation points to cerebral hyperperfusion11 and near-infrared spectroscopy offers a small window to changes in global cerebral blood flow. The best approach to detect whether reperfusion following CEA provokes discomfort is to ask for patient well-being.

A Cochrane review suggests that the choice of anaesthesia for CEA depends on the clinical situation and the preferences of the individual patients and their surgeon.5 The GALA trial was underpowered to detect an effect on mortality4,13 and the quality of randomised studies is a concern.5 Local anaesthesia is the favoured treatment if cost-effectiveness is to be considered.14 Incidences of new neurologic deficit, stroke, death and myocardial infarction are likely to decrease when patients are operated under regional anaesthesia.2 Performing local anaesthesia in patients undergoing CEA positively influences postoperative neurocognitive outcome.15

Experience in authors’ hospital with local anaesthesia

In our department, local anaesthesia is the first choice for patients planned for CEA. A small group of anaesthetists are responsible for the patients. This gives the involved staff a high degree of experience in procedures. The staff involved do not leave the operating theatre during CEA that is performed in a quiet and relaxed atmosphere. When a dedicated group treats vascular surgical patients outcome improves.16

Conclusion

The scientific evidence from randomised trials is insufficient to support the use of local anaesthesia over general anaesthesia for patients undergoing CEA. For the anaesthetist concerned about cost-effectiveness and anxious to maintain sound cerebral physiology, the choice of anaesthesia should be clear. We conclude local anaesthesia is the best option for patients undergoing CEA.

Acknowledgements related to this article

Assistance with the Editorial: none.

Financial support and sponsorship: none.

Conflicts of interest: none.

Comment from the Editor: This Editorial is part of a Pro and Con debate. It was checked and accepted by the editors but was not sent for external peer review.

References

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