A Comparative study between the effects of two doses of nebulized Dexmedetomidine as a premedication in attenuating the hemodynamic response to laryngoscopy and endotracheal intubation

Endotracheal intubation is one of the methods of securing airway before performing surgical procedure requiring General Anaesthesia. The most commonly used equipment to aid endotracheal intubation is a laryngoscope, and the procedure performed is known as laryngoscopy.   Laryngoscopy and endotracheal intubation are noxious stimuli, associated with transient but significant hemodynamic changes, termed as pressor/hemodynamic response. Hemodynamic changes Starts within 1 minute lasting upto 10 minutes. Cardiovascular changes occur primarily through reflex response.  In Adults most  common response to Airway manipulation is hypertension and tachycardia mediated by  the cardioaccelerator nerves and sympathetic chain ganglia.

Various agents in the form of opioid analgesics, benzodiazepines, beta blockers, calcium channel blockers, and vasodilators  have been tried till now to attenuate the hemodynamic respone to Laryngoscopy and Endotracheal Intubation but none of them proved to be Ideal

Dexmedetomidine is Dextro isomer and pharmacologically active component of Medetomidine , It an Alpha 2 Adrenergic agonist which inhibits Pontine ceruleus, an important noradrenergic nucleus mediating Sympathetic nervous system function, vigilance, memory, analgesia , arousal. Dexmedetomidine is used as an adjuvant for premedication, especially in patients susceptible to preoperative and perioperative stress because of its sedative, anxiolytic, analgesic, sympatholytic, and stable hemodynamic profile. Dexmedetomidine decreases oxygen consumption in intraoperative period (up to 8%) and in postoperative period (up to 17%), reduces the extent of myocardial ischemia during cardiac surgery. It also has respiratory-sparing effects.  Dexmedetomidine has been shown to provide good perioperative haemodynamic stability with decreased intraoperative opioid requirements. Dexmedetomidine  reduces sympathetic response to surgery by activating peripheral presynaptic α2- AR which reduces the release of catecholamines.

Most common route of administration of Dexmedetomidine is Intravenous route but is associated with adverse effects such as Bradycardia and Hypotension, Other routes of administration include Intramuscular and Intranasal.  Nebulised Dexmedetomidine is a non invasive method, with good bioavailability ( nasal  mucosa accounts for 65 % and buccal mucosa accounts for  82% )and rapid absorption. Recent studies using nebulised Dexmedetomidine  suggested it to be a novel route of  Dexmedetomidine administration . Nebulised dexmedetomidine have been used in various studies to attenuate the intubation  stress  response. To the best of our knowledge limited studies are available comparing the  effects of  different  doses of  nebulised dexmedetomidine in attenuation of  haemodynamic stress response