Ultrasound‐guided localisation of the trachea

A 45-year-old woman presented to our Emergency Department with Ludwig's angina. She was obese with a body mass index (BMI) of 35 and was noted to have poor dental hygiene. She had signs and symptoms of airway compromise: dyspnoea, stridor, dysphonia, drooling and inability to close the mouth or swallow. There was obvious swelling, tenderness and erythema in the submandibular region spreading over the pretracheal region. She was transferred to the operating theatre to secure the airway prior to incision and drainage of the submandibular space. As there was concern that bag-mask ventilation might prove difficult after induction of anaesthesia, an awake fibreoptic intubation technique was chosen as the most suitable method of managing the airway. ‘Plan B’ was to place a trans-tracheal catheter and perform an intravenous induction. As it was not possible to identify the trachea by palpation, a portable ultrasound machine was used to locate it 2 cm lateral to the midline. The position of the trachea was marked to facilitate rapid access should it become necessary. The patient underwent successful awake nasal intubation using the fibreoptic bronchoscope and local anaesthetic applied to the airway. Successful location of the trachea plays an important part in managing the difficult airway for both elective and emergency cases. Emergency cricothyrotomy is part of the Difficult Airway Society guidelines for management of the ‘can’t ventilate, can't intubate or can't intubate, can't oxygenate scenario' [1]. In the elective situation, insertion of a trans-tracheal catheter is now an established procedure in the anaesthetic management of complex ENT surgery [2]. Using anatomical landmarks to locate the trachea may not be straightforward, especially in an emergency. A deviated trachea or aberrant vascular anatomy in the pretracheal region may make placement of the needle difficult, and a short neck may make it impossible to identify the tracheal rings. Although the use of ultrasound during percutaneous dilational tracheostomy has been recommended as a tool to improve pre-operative assessment and aid accurate initial placement of the needle in the trachea [3] it has not been widely adopted in the anaesthetic management of the difficult airway. We would suggest that this is a useful technique to identify the trachea prior to both elective trans-tracheal cannulation and emergency cricothyrotomy. Our case demonstrates its value where anatomical landmarks are distorted or aberrant vasculature exists.