Oral Melatonin VS Nebulized Dexmedetomidine Premedication on Attenuation of Hemodynamic Response to Direct Laryngoscopy and Tracheal Intubation in Hypertensive Patients

Laryngoscopy and endotracheal intubation are associated with sympathetic stimulation and induce hemodynamic changes with consequent increase in heart rate (HR) and blood pressure (BP) which may lead to myocardial infarction, cardiac arrhythmias, cardiac failure and cerebrovascular accidents in patients with underlying cardiovascular or cerebrovascular diseases. Dexmedetomidine is a centrally acting α-2 adrenergic agonist with sedative, hypnotic, analgesic, anxiolytic, anti-sialagogue, antinociceptive and sympatholytic action. Premedication with dexmedetomidine through intravenous, intramuscular and intranasal route has been shown to effectively attenuate hemodynamic response to laryngoscopy and endotracheal intubation. Nebulization provides an alternative route of dexmedetomidine premedication with high bioavailability through both nasal (65%) and oral mucosa (82%) and avoids a venipuncture as a prerequisite. Recent studies have shown nebulization as a novel route of dexmedetomidine administration for attenuation of hemodynamic response to endotracheal intubation. Melatonin is a natural substance produced mainly in the pineal gland of all mammals and vertebrates. It is rapidly distributed and eliminated after intravenous administration. After oral administration, plasma concentration peaks after 60 min and is then eliminated. It exerts its hypnotic effects through the activation of the Melatonin receptors type I and II (MT1, MT2). It has shown potent analgesic effects in a dose dependent manner in experimental studies. It may induce relaxation of the arterial wall smooth muscle by increasing nitric oxide levels. Therefore, premedication with sublingual/oral Melatonin is associated with pre-operative anxiolysis and sedation without impairment of orientation, psychomotor skills, or impact on quality of recovery, moreover, it attenuates the hemodynamic stress response to laryngoscopy and tracheal intubation.