Awake fibreoptic intubation (AFOI) is planned for a morbidly obese patient with a large goitre causing tracheal deviation. Which topical anaesthesia technique provides the best anaesthesia of the supraglottic larynx and vocal cords?
- A Spray-as-you-go (SAYG) technique through the fibreoptic scope suction channel
- B Topical lidocaine nebulisation via facemask only
- C Bilateral superior laryngeal nerve blocks combined with transtracheal injection ✓
- D Viscous lidocaine gel applied to the oropharynx
Explanation
Bilateral superior laryngeal nerve (SLN) blocks anaesthetise the supraglottic mucosa from the epiglottis to the vocal cords (internal branch of SLN), while transtracheal injection of lignocaine through the cricothyroid membrane anaesthetises the subglottic trachea and cough reflex. Combined, these provide the most complete anaesthesia for AFOI. Spray-as-you-go is effective but more technique-dependent. Nebulised lignocaine covers the upper airway broadly but may be less reliable for infraglottic structures. Preparation also includes antisialogogue pre-medication (glycopyrrolate) and judicious sedation (dexmedetomidine or low-dose midazolam) maintaining spontaneous ventilation.
Reference: Morgan & Mikhail's Clinical Anesthesiology, 6th ed.
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Written and medically reviewed by the StethoPrep medical team.