Attenuation of sympathoadrenal responses and anesthetic requirement by dexmedetomidine

CONTEXT: During induction of general anesthesia hypertension and tachycardia caused by tracheal intubation may lead to cardiac ischemia and arrhythmias. Dexmedetomidine attenuates the hemodynamic response to endotracheal intubation and reduces anesthetic requirement. AIMS: The purpose of this study was to evaluate the effect of a single pre-induction intravenous dose of dexmedetomidine 1 μg/kg on cardiovascular response resulting from laryngoscopy and endotracheal intubation and need for anesthetic agent. MATERIALS AND METHODS: Fifty patients scheduled for elective major surgery were randomized into two groups each having twenty five patients-dexmedetomidine group (Group 1) and control group (Group 2). Heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP) and Ramsay sedation score were recorded at 1, 2 and 5 min after completion of administration of study drug. Fentanyl 2 μg/kg was administered to all patients and propofol was given until loss of verbal contact. Intubation was facilitated with vecuronium 0.1 mg/kg i.v. Anesthesia was maintained with oxygen (O2) and nitrous oxide (N2O) 33%: 67% and isoflurane. Heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP) was noted at 1 min, 2 min and 5 min after intubation. STATISTICAL ANALYSIS USED: For statistical analysis of the clinical data obtained, the analysis of variances (ANOVA) with paired t-test was used. RESULTS: Pretreatment with dexmedetomidine 1 ug/kg attenuated, but did not totally abolish the cardiovascular and catecholamine responses to tracheal intubation after induction of anesthesia. In our present study, HR, SBP, DBP all increased after intubation at 1, 2, 3 and 5 min in both the groups, but the rise was significantly less in the dexmedetomidine group. Requirement of propofol was significantly less in the dexmedetomidine group. CONCLUSIONS: Preoperative administration of a single dose of dexmedetomidine blunted the hemodynamic responses during laryngoscopy, and reduced anesthetic requirements.