Thyroidectomy

Updated February 3, 2014
Author: VerLee

Description: PreOp Assessment & Management, IntraOp Guidleines for thyroidectomy


Overview

Preoperative Assessment

History

Examination

Investigations

Blood tests: CBC, electrolytes, thyroid function, and corrected calcium levels should all be routinely performed.

Chest X-ray: May show tracheal deviation and narrowing. In complex or suspicious cases, lateral thoracic inlet views may be necessary to exclude retrosternal extension and to detect tracheal compression in the anteroposterior plane.

Computed tomography scan: This is advisable when the patient gives a history indicative of airway encroachment (e.g. positional dyspnea). It is also helpful if there is suspicion of malignancy as it can illustrate tracheal invasion by a carcinoma. If there is >50% narrowing of the trachea on the plain chest film, a CT scan is necessary to accurately delineate the site and degree of airway compromise, in order to predict the tracheal tube diameter and length likely to be required.

Nasal Endoscopy: This may be performed before operation to record any pre-existing vocal cord palsy. It is advisable for medicolegal purposes, as preoperative cord dysfunction because of malignancy or previous surgery may be asymptomatic. Nasendoscopy can also help to delineate laryngeal displacement.

Anesthetic Techniques

Several methods, including combinations of techniques, can be used safely and effectively.

General anesthesia

The majority of cases are straightforward even when imaging suggests significant degrees of tracheal deviation or compression. Full preoxygenation should precede i.v. induction and muscle relaxation with a neuromuscular blocking drug, once manual ventilation has been demonstrated.

If preoperative assessment has increased concerns regarding the airway, the following options should be considered:

Whichever approach is used, all equipment must be checked and the surgeon must be immediately available.

Anesthesia may be maintained via inhalation agents or TIVA.

Other perioperative considerations

Postoperative Complications

Bleeding: This may result in tense swelling in the neck and respiratory difficulty. Clip removers or stitch cutters must be kept at the bedside to evacuate blood and hematoma, if the patient is in extremis. Otherwise, this is done expeditiously in the OR. Early reintubation is recommended in this situation.

Tracheomalacia: Airway obstruction secondary to this very rare complication requires immediate re-intubation.

Recurrent laryngeal nerve (RLN) palsy: This may be unilateral or bilateral and present with respiratory difficulty or stridor. With unilateral palsy or partial cord paralysis, the patient may simply complain of hoarseness of voice or have difficulty in phonation. RLN injury may result from ischaemia, contusion, traction entrapment, and actual transection. Traditionally, anaesthetists were taught to inspect the cords under direct vision immediately post-extubation, but this can be difficult and may be unreliable. The laryngeal mask airway and fibrescope has been used to make this technically easier and also to observe the vocal cords during surgery.

Laryngeal edema: This is a rare cause of airway obstruction post-thyroidectomy, but may result because of a traumatic intubation or with complex surgery. This may require corticosteroid therapy and humidified oxygen.

Hypocalcemia: Temporary hypocalcemia requiring calcium replacement may occur in up to 20% of patients after thyroidectomy for large multinodular goiter, but permanent hypocalcemia is rare. It may present with perioral tingling, twitching, or tetany. If left untreated, it can progress to seizures or ventricular arrhythmias. The diagnosis may be made clinically by precipitating carpopedal spasm through cuff inflation (Trousseau's sign) or facial twitching by tapping over the facial nerve at the parotid gland (Chvostek's sign). The ECG may show prolonged QT intervals. If the serum calcium is > 2 mmol litre− 1, oral calcium supplements are prescribed. If the serum calcium is below this concentration, urgent treatment should be commenced with i.v. calcium (usually 10 ml of 10% calcium gluconate for more than 3 min). A calcium infusion may be necessary.

Pneumothorax: This is a possible complication of retrosternal dissection. For suspected /diagnosed pneumonthorax management go to Crisis Checklist #19