DEXMEDETOMIDINE FOR ATTENUATION OF PRESSOR RESPONSE OF LARYNGOSCOPY AND INTUBATION

: BACKGROUND: Laryngoscopy and tracheal intubation causes intense autonomic reflex responses consisting of increased circulating catacholamines, tachycardia, hypertension, myocardial oxygen demand, and dysarrythmias. To obtund haemodynamic response lignocaine, opiods, nitroprusside, nitroglycerine, vearpamil, nifedipine, esmolol, clonidine and recently, dexmedetomidine have been studied. AIMS AND OBJECTIVES: We investigated whether dexmedetomidine a α2 agonist could attenuate sympathoadrenal response (Heart rate and MAP) to laryngoscopy and intubation. MATERIALS AND METHODS: Eighty patients, ASA grade I/II, undergoing routine general anesthesia were randomly premedicated by i. v. dexmedetomidine 0. 6µg or saline. Heart rate (HR), mean arterial pressure (MAP), were measured before, after the premedication, after thiopental, after succinylcholine at laryngoscopy, immediately after intubation and then 1 min. 3 min. and 5 min after intubation. STATISTICAL ANALYSIS: Descriptive and inferential statistics using chi-square test, z-test and wilcoxon sign rank test was done. Software used in the analysis was SPSS 17.0 version and Graph Pad Prism 5.0. Data was reported as mean value ± SD & p-value <0.05 is considered as level of significance. RESULTS: The demographic profile was comparable . After intubation the MAP in the control group (z=.5.35, p=<0.05 at laryngoscopy and z=9.95, p<0.05 after intubation) was higher than that in the dexmedetomidine group (z=8, p=0.000) and exceeded the baseline value(p<0.05) The heart rate also showed less fluctuation in the dexmedetomidine group than in the control group. Though there was rise in both the groups, it was more in control group than dexmedetomidine group (z=7.73, p<0.05 at laryngoscopy and z=9.22, p<0.05 after intubation). Thus the pressor response to laryngoscopy and intubation were effectively decreased by dexmedetomidine and were highly significant on comparison (p<0.05). CONCLUSION: i v dexmedetomidine 0. 6µg premedication is advantageous as it is found to be effective and beneficial in attenuating the haemodynamic response of laryngoscopy and intubation to prevent its consequences. Studies suggest that perioperative use of dexmedetomidine may result in a decreased risk of adverse cardiac events, including myocardial ischemia. 21 α adrenoreceptors stimulation can beneficially modulate coronary blood flow during myocardial ischemia by preventing transmural redistribution of blood flow away from the ischemic endocardium, by specific epicardial vasoconstrictive effects, leading to improvement in endocardial perfusion (the reverse steal effect) and by decreasing heart rate. This property along with hemodynamic stability and attenuation of intubation response makes dexmedetomidine an ideal anesthetic adjuvant, particularly for patients undergoing coronary bypass grafting. Dexmedetomidine has been also administered in infant following open heart surgery 22 with a decrease in heart rate during the immediate postoperative time together with an effective and safe sedation. A biphasic cardiovascular response has been described after the of A bolus of 1 mcg/kg results in a transient increase in arterial blood pressure and reflex decrease in heart rate in young healthy patients. Initial response is due to α 2 receptor stimulation of vascular smooth muscle. This response can be markedly decreased by slow infusion over 10 min. In our study, this effect was not noticed due to the slow infusion of the drug over 10 min.