EVALUATION OF TWO DIFFERENT DOSES OF NEBULISED DEXMEDETOMIDINE ON ATTENUATING HEMODYNAMIC STRESS RESPONSE TO LARYNGOSCOPY AND INTUBATION IN PATIENTS UNDERGOING SURGERY UNDER GENERAL ANAESTHESIA:A DOUBLE BLINDED RANDOMISED CONTROLLED STUDY

The larynx is a richly innervated structure with abundant neurovascular supply. Laryngoscopy and tracheal intubation are generally associated with pressure on the larynx, which results in the activation of somatovisceral reflexes. Sympathoadrenal activation leads to the release of catecholamines, which results in a rise in hemodynamics. The duration of the intubation and the force exerted during the procedure directly affect the catecholamine response.It starts within 5–10 seconds, peaking at 1–2 minutes, and finally returning to its baseline readings in the next 5 minutes. Although this is a transient response with an average rise in systolic blood pressure (SBP) of 25–30 mmHg, and most healthy patients tolerate it without any untoward effect, it may prove to be extremely deleterious in patients with cerebrovascular or cardiovascular diseases.

It has been associated with the precipitation of cardiac ischemia, cerebral stroke ,pulmonary edema. various preemptive measures are used to attenuate this response ,mainly addressed by intravenous or local agents. Most commonly employed alfa -2 agonist agonist ,opioids, beta blockers and local anesthetics .All of them are associated with various systemic side effects such as opioids with reduced respiratory drive, sedation, and postoperative nausea and vomiting and selective alfa 2 agonists such as dexmedetomidine with hypotension and bradycardia. Most of these are used preemptively but very few are administered through the nebulisation route. Direct instillation through nebulisation is new area with lesser systemic effects, which needs to be explored.

Dexmedetomidine, an alpha 2 agonist, had been widely studied through the intravenous route where it has repeatedly proven itself to suppress the hemodynamic stress response, but systemic side effects such as hypotension and bradycardia are commonly associated, which may be troublesome. However, the recent literature has stated that the nebulization route has better bioavailability: nasal mucosa—65% and buccal mucosa—82%.

Nebulised dexmeditomidine has been reported with a very short distribution half life (6minutes) and elimination half-life(2hours) withoit being associated with systemic side effects.It has reported in literature that dexmedetomidine when administered through the nebulisation route had reduced stress response to laryngoscopy and intubation also reported that nebulised dexmeditomidine can attenuate the postoperative sore throat in patients.