Airway management of a huge thyroid swelling with retrosternal extension by awake intubation using loco-sedative technique.

To the Editor,

The anesthesiologist approaching the patient with a difficult airway has got many techniques and instruments that can be applied for securing and maintaining oxygenation and ventilation.[1234] We report here the airway management of a patient with massive thyroid swelling accompanied by tracheal narrowing, deviation and retrosternal extension. The patient was posted for total thyroidectomy.

A 43-year-old female patient presented with a history of the diffuse neck swelling since 5 years with recent onset of dyspnea. There was no suggestive history of hyper or hypothyroidism. On examination, her vital parameters were normal, and she was neither in distress nor sweating. Neck examination showed a huge swelling of around 8 cm × 4 cm on the right side and 6 cm × 4 cm on the left side. It was moving with swallowing, firm in consistency but not tender. Getting below the swelling was not possible. Cardiovascular system examination revealed no added sounds or murmurs. Chest examination showed bilateral good air entry. Laboratory investigation including thyroid function tests were within normal ranges. Radiological examination including Chest X-ray and magnetic resonance imaging (MRI) revealed diffusely enlarged thyroid gland with left lobe measuring 11.2 × 7.5 × 5.5 cms in size with retrosternal extension and right lobe measuring 8.5 × 6.2 × 4.5 cms in size with inferior margin of right lobe just above sternum associated with superior mediastinal widening, significant compression and displacement of trachea to right side. Carotid artery and jugular vein were displaced laterally on both sides of neck. There was no tracheal erosion or infiltration [Figure 1]. On IDL, larynx was not seen and with 70 degree scope, larynx was pushed to right with normal and mobile bilateral vocal cords. Fine-needle aspiration cytology showed possibility of benign follicular lesion. Airway assessment revealed adequate mouth opening with Mallampati Grade II, but limited neck movement. The plan was to perform awake endotracheal intubation through direct laryngoscopy.

Figure 1

Magnetic resonance imaging plate showing huge swelling with retrosternal extension

Premedication was achieved with injection glycopyrrolate 0.2 mg intramuscular and injection midazolam 1 mg intravenous (iv) followed by nebulization with lignocaine (2%) solution and lignocaine (2%) viscus gargles. In the operation theater, the difficult airway cart was arranged and noninvasive blood pressure cuff, SpO2 and electrocardiogram were attached to the patient. Injection dexmedetomidine bolus was started at 1 mcg/kg over 10 min, followed by infusion at 0.6 mcg/kg/h along with which preoxygenation was done with 100% oxygen. When the sedation score was Ramsay score 3, direct laryngoscopy was performed and lignocaine (5%) spray was puffed and after 5 min trachea was intubated successfully with 7.5 mm size armored tube with external manipulation of larynx. Intubation was confirmed by attaching EtCO2 monitor, which was followed by IV injection of propofol and injection vecuronium. Anesthesia was maintained with incremental doses of vecuronium and sevoflurane. Total thyroidectomy was uneventful. On completion of surgery, neuromuscular blockade was reversed and trachea was extubated after performing leak test to rule out any possibility of tracheomalacia.

The problems anticipated during induction were difficult mask ventilation after induction of general anesthesia and muscle relaxation secondary to partial or complete airway collapse by huge thyroid swelling, which can cause severe hypoxia and warrants urgent tracheal intubation which may be difficult and time consuming due to distorted anatomy.[234]

In this situation, it was prudent to secure the airway before induction of anesthesia. Awake fiberoptic intubation is ideal gold standard technique in such situation where intubation is done under direct visualization of the glottis.[1] Fiberoptic bronchoscope was not available in our institute so awake oral intubation with direct laryngoscopy was planned.

Dexmedetomidine is selective ά2 agonist with pharmacological actions like analgesia, anxiolysis, sedation, reduction in the secretion, sympatholytic action, minimal respiratory depression, decreased stress response to intubation and attenuation of airway reflexes making it promising agent in this situation.[5] Hence dexmedetomidine in bolus and infusion was used during induction to enhance patient comfort and cooperation, which is essential for the success of awake intubation using direct laryngoscopy.

In conclusion, awake intubation using topical anesthesia and sedation with dexmedetomidine infusion is a viable option in case of huge thyroid swelling.