Effect of preanaesthetic dexmedetomidine nebulization in hemodynamic responses following laryngoscopy and intubation

Direct laryngoscopy and intubation are noxious stimuli and are associated with transient but unpredictable and variable haemodynamic changes. This response occurs within 30 seconds after intubation and lasts less than 10 minutes. The consequences of laryngoscopy and intubation may precipitate ischemia, arrhythmias, cerebrovascular stroke, pulmonary oedema, increase in intracranial pressure in vulnerable group. Till date, numerous drugs and various routes have been tried to attenuate this stress response such as opioids, vasodilators, beta blockers, calcium channel blockers, intravenous lignocaine but none of the agents proved to be ideal.

Dexmedetomidine is a highly selective alpha 2 adrenoreceptor agonist. It is a short acting drug having sympatholytic, sedative, hypnotic, anxiolytic, analgesic and anti-sialogogue properties. Its pleiotropic effect have led to its increasing use for reducing anaesthesia and analgesic requirements in the perioperative period.

The efficacy of dexmedetomidine in attenuating the hemodynamic response to laryngoscopy and intubation has been studied through intravenous, intranasal and intramuscular routes. However, it is noted that intravenous administration causes bradycardia, hypotension and even cardiac arrest [2] and intranasal administration may be associated with nasal irritation, cough, vocal cord irritation or laryngospasm.

Inhalation of nebulized drug is an alternative method of administration that is relatively easy to set up, does not require venipuncture, and is associated with high bioavailability of the administered drug.

Nebulised dexmedetomidine has been used as an effective premedication in paediatric patients in the doses of 1 and 2mcg/kg. Few studies are available which have evaluated either 1 or 2 mcg/kg dexmedetomidine in attenuating stress response to intubation. Hence, our study and we hypothesize that dexmedetomidine nebulisation at 1 mcg/kg provides good haemodynamic stability and sedation.