[Cervical epidural anesthesia].

Abstract

Cervical epidural anaesthesia (CEA) results in an effective sensory blockade of the superficial cervical (C1/C4) and brachial plexus (C5/T1-T2). It is used both intraoperatively and in the treatment of postoperative or chronic pain. The approach to the epidural space at the C7-T1 interspace is not technically difficult. Patients are placed in the sitting position, increasing the negative pressure in the epidural space, with the head flexed on the thorax, in order to open the lowest cervical interspace. A 18-gauge Tuohy needle is inserted by a midline approach into the C6-C7 or C7-T1 interspace. A catheter may be inserted and left in place for postoperative analgesia. Local anaesthetics are administered either alone, or in combination with opiates. The CEA blocks the cardiac sympathetic fibers and consequently decreases heart rate, cardiac output and contractility. The mean blood pressure is unchanged or decreased, depending on peripheral systemic vascular resistance changes. The baroreflex activity is also partly impaired. Sympathetic blockade also decreases myocardial ischaemia. The cardiovascular changes induced by CEA are also partly due to the systemic effect of the local anaesthetic. The respiratory effects are minimal and depend on the extent of the blockade and the concentration of the local anaesthetic. A moderate restrictive syndrome occurs. Since the phrenic nerves originate from C3 to C5, ventilation may be impaired by CEA. Extension of the block may also impair intercostal muscle function, with a risk of respiratory failure when a CEA is used in patients with compromised respiratory function. The potential specific complications, mainly cardiovascular and respiratory, are the exacerbation of the effects of CEA. Side effects such as bradycardia, hypotension and acute ventilatory failure in relation to respiratory muscle paralysis, may be observed. Close monitoring of haemodynamics, respiratory rate and level blockade is required. Cervical epidural anaesthesia may be used either alone, or in combination with general anaesthesia depending on the surgical procedure. This technique seems to be effective in carotid artery surgery since sensitive and reliable information on cerebral function may be obtained. It is also for shoulder and upper limb surgery as well as for pharyngolaryngeal surgery, providing efficient operative anaesthesia and postoperative analgesia. CEA is used for relief of chronic pain in the head and neck or cancer pain due to Pancoast-Tobias syndrome. It seems to be effective for treating pain in patients with unstable angina pectoris or acute myocardial infarction.