Comparative evaluation of the efficacy of Nebulized Dexmedetomidine as an additive to Nebulized lignocaine for difficult awake fibreoptic Intubation

Since the 1960s, awake fibreoptic intubation (AFOI) has been established as the gold standard for anticipated difficult tracheal intubation. AFOI usually requires good sedation, patient cooperation, and preserved spontaneous respiration. The conscious sedation is desirable to make this procedure more tolerable. Adequate airway preparation is essential to minimize patient discomfort, to optimize intubating conditions, and to ensure procedural success. This can be achieved in broadly two ways- topical administration of local anaesthetic and blockade of neural supply to oropharynx and larynx. Topical administration of local anaesthetic in the form of spray or gargle causes less discomfort and trauma to patients as compared to airway nerve blocks. Topical application by nebulization technique is one of the promising techniques used to anesthetize the airway. Various pharmacological methods have been reported to achieve conscious sedation for AFOI including fentanyl, midazolam, ketamine, propofol, remifentanil and dexmedetomidine.

The combination of moderate conscious sedation and regional anaesthesia has been more commonly used to relieve patient anxiety and to suppress the pharyngeal, laryngeal, tracheal, and bronchial reflexes during AFOI. Effect of lignocaine nebulization has been studied extensively.

 Dexmedetomidine is a highly selective and specific alpha 2 adrenoreceptor agonist and has properties making it suitable for AFOI. In addition to hemodynamic stability, anxiolytic and analgesic properties, it results in sedation while maintaining easy reusability, it also causes relaxation of bronchial smooth muscles thus reduces cough reflex and inhibits the salivary gland secretions. Dexmedetomidine demonstrates minimal respiratory depression.

 Nebulized dexmedetomidine administration allows rapid absorption through nasal, respiratory and buccal mucosa. The bioavailability is 65% through nasal mucosa and 82% through buccal mucosa.