- Procedure may vary from excision of a simple nodule to removal of retrosternal goiter to relieve tracheal compression.
- The latter can be excised through a standard collar incision, but it may be necessary to split the sternum to access the inferior pole of the enlarged gland.
- Although blood loss is usually minimal, there is potential for major haemorrhage from large blood vessels closely related to the gland, particularly if the thyroid extends retrosternally.
- The duration of the goiter is important. Long-standing compression of the trachea may be associated with tracheomalacia.
- A rapid increase in size suggests the possibility of malignancy.
- Look for Symptoms of
- positional breathlessness,
- stridor, and
- voice change
- These give an indication of the extent of the goiter and possible problems in lying the patient flat for induction of anesthesia.
- The patient should be clinically euthyroid before surgery.
- Tachycardia and atrial fibrillation are common manifestations of hyperthyroidism.
- Assessment of the airway and neck
- Mallampati score
- mandible protrusion
- Neck exam to assess:
- the size of the goiter and its consistency; a hard goiter suggests malignancy. If it is possible to feel below the gland, then retrosternal spread is unlikely.
- tracheal deviation
- listen for stridor
- range of movement of the neck
- Superior vena caval (SVC) obstruction is indicated by the presence of distended neck veins that do not change with respiration.
- Pemberton's sign of SVC obstruction may be elicited by asking the patient to raise his arms straight up; if obstruction is present, the patient's face will become blue and engorged.
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.
Several methods, including combinations of techniques, can be used safely and effectively.
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:
- Induction in the semi-supine or sitting position
- Inhalation induction with sevoflurane: the patient should be premedicated to dry secretions, and airway adjuncts such as a nasopharyngeal airway of correct size should be immediately available in case the patient obstructs their airway as they lose consciousness. Sevoflurane in Heliox may be useful in cases when preoperative stridor is severe.
- Fiberoptic intubation:
- care should be taken in patients with marked stridor in whom complete obstruction may result from insertion of the bronchoscope.
- This technique is useful when there may be severe laryngeal displacement or a co-existing airway problem (e.g. ankylosing spondylitis).
- Ventilation through a rigid bronchoscope can be performed if attempts to pass an endotracheal tube (ETT) fail because of a mid-lower tracheal obstruction.
- Tracheostomy under local anaesthetic may be performed by the surgeon. Obviously this can be difficult with a neck mass.
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
- Eyes should be taped and padded, especially, if exophthalmos is present.
- Reinforced flexible ETTs are commonly used and taped into position.
- Some MMC surgeons (MacGillvray) use electromyographic monitoring via a NIM Endotracheal Tube
- If a NIM tube is used, short-term relaxants are indicated so that EMG monitoring is successful.
- NIM Tube placement is critical, and videolaryngoscopy is often used to assure proper placement.
- The patient is positioned slightly head-up to prevent venous engorgement, with the head extended and stabilized using a head ring and sandbag between the scapulae. Arms are extended and tucked, thus, a long i.v. extension line is required to maintain adequate access.
- Muscle relaxation, if used, should be monitored.
- If surgery is likely to be complex or extensive it may be appropriate to administer i.v. steroid (e.g. dexamethasone 8 mg) to decrease the likelihood of postoperative edema and subsequent respiratory difficulty. Dexamethasone also contributes to antiemesis after operation.
- Extubation is most safely performed with the patient fully awake and breathing spontaneously.
- You may be asked to maintain the patient's intrathoracic pressure positive for 10–20 s (effectively performing a Valsalva maneuver) with the patient in the head-down position, in order to assess hemostasis before wound closure.
- If the goiter was large and long-standing, there may be a risk of tracheomalacia (erosion of the tracheal cartilages) that can lead to postoperative stridor and even complete airway obstruction with tracheal collapse.
- Some surgeons examine the trachea under direct vision or ask for partial withdrawal of the tracheal tube, so that the tip is just proximal to the site of the goiter. If there is concern, the anesthetist should deflate the cuff of the ETT to ensure that there is a leak before extubation.
- Patient should be recovered sitting upright as much as possible to avoid venous congestion and edema.
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