Fibreoptic nasotracheal intubation is an effective technique for the management of patients with difficult airways. Obtaining optimal intubating conditions when providing patient comfort and safety are the major goals while preparing the patient for fibreoptic intubation. One challenge associated with this procedure is to provide adequate sedation while maintaining a patent airway and ensuring ventilation. An ideal sedation regimen would provide patient comfort, blunting of airway reflexes, patient cooperation, haemodynamic stability, amnesia and the maintenance of a patent airway with spontaneous ventilation. Conventional sedatives like the benzodiazepines, propofol, or opiates have respiratory-depressant properties that may be detrimental in tenuous airway situations.

Dexmedetomidine is a drug whose clinical profile makes it especially well suited for sedation during awake fibreoptic intubation. It is a highly specific α2-agonist that can produce sedation, anxiolysis, analgesia, and profound levels of sedation in the absence of respiratory depression. The latter property is of special interest in difficult airway cases because during dexmedetomidine administration a stable respiratory pattern is usually seen, with little or no deterioration in respiratory pattern or change in oxygenation.

This study is specifically conducted to determine whether a loading dose of i.v. dexmedetomidine before awake fibre-optic intubation for patients with difficult airway undergoing General Anaesthesia will provide greater ease of intubation and better patient tolerability,  adequate sedation without respiratory depression and upper airway obstruction and reduced haemodynamic responses as compared to placebo. Rescue sedation will be given in both groups in case of anxiety, agitation or discomfort.