Comparison of dexmedetomidine and clonidine for attenuation of sympathoadrenal responses and anesthetic requirements to laryngoscopy and endotracheal intubation

Background: Laryngoscopy and tracheal intubation after the induction of anesthesia are nearly always associated with a sympathetic hyperactivity. To attenuate the pressor response, various drugs have been tried, but studies to compare the effects of dexmedetomidine or clonidine on the hemodynamic response during laryngoscopy and tracheal intubation are anecdotal and sparse. This study aims to find the drug, which was best suited for this purpose and to compare their effects on sedation and anesthetic requirements. Methods: This was a prospective study, which involved three groups of patients. Each group had 20 patients who presented for elective, non-cardiovascular surgeries. The patients in group I (control) were given normal saline and the groups II and III were given dexmedetomidine and clonidine, respectively. Heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP), and Ramsay sedation score were recorded at 1 and 2 min after completion of administration of study drug. Induction was done with propofol and required dose is noted. HR, SBP, and DBP were again assessed during intubation and at 1, 3, 5, and 10 min after intubation. The obtained clinical data were analyzed statistically with analysis of variance. Results: In our study, HR, SBP, and DBP all increased during intubation and thereafter in all three groups. Pretreatment with dexmedetomidine 1 μg/kg and clonidine 2 μg/kg significantly attenuated the cardiovascular and catecholamine responses to tracheal intubation. However, attenuation was significantly more with the dexmedetomidine group with a quicker return to baseline. Dexmedetomidine also fared in terms of anesthetic requirement (propofol) and sedative action. Conclusion: Preoperative administration of a single dose of dexmedetomidine blunted the hemodynamic responses more than clonidine or placebo during laryngoscopy, and reduced anesthetic requirements.