COMPARISON OF EFFICACY OF INTRAVENOUS VERSUS INTRAMUSCULAR DEXMEDETOMIDINE ON ATTENUATION OF HEMODYNAMIC RESPONSES TO LARYNGOSCOPY AND ENDOTRACHEAL INTUBATION: A PROSPECTIVE RANDOMISED STUDY

Abstract

Objectives: Laryngoscopy and endotracheal intubation provoke significant hemodynamic stress responses, which may be detrimental in high-risk patients. Dexmedetomidine, a selective alpha-2 adrenergic agonist, effectively attenuates these responses, although the intravenous (IV) route is often associated with rapid hemodynamic shifts. The intramuscular (IM) route, with slower absorption, may yield more sustained drug levels and improved hemodynamic stability. The present study was undertaken to compare the efficacy of IV versus IM dexmedetomidine (1.5 mcg/kg) in attenuating hemodynamic responses to laryngoscopy and intubation. Methods: After Institutional Ethics Committee approval, 64 American Society of Anesthesiologists physical Status I–II patients aged 18–60 years undergoing elective surgery under general anesthesia were randomised into two groups of 32. Group DIV received IV dexmedetomidine 1.5 mcg/kg over 20 min, with the infusion commenced 45 min before induction (i.e., starting at 45 min pre-induction and completing at 25 min pre-induction), and Group DIM received IM dexmedetomidine 1.5 mcg/kg, 45 min before induction. Heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP) and mean arterial pressure (MAP) were recorded at baseline, after drug administration, after induction, during laryngoscopy and intubation, and at 1, 3, 5 and 7 min post-intubation. Unpaired t-test and Chi-square test were used; Bonferroni correction was applied for multiple comparisons, and repeated measures analysis of variance was used for analysis of hemodynamic parameters across multiple time points. p<0.05 was considered significant. Results: Both groups were demographically comparable except for body mass index, which was significantly different between the groups (p=0.024). Group DIM showed significantly lower HR, SBP, DBP and MAP at all-time points compared to Group DIV (p<0.05). When analyzing change from baseline values, Group DIM demonstrated significantly smaller increases in HR, SBP, DBP, and MAP during laryngoscopy and intubation compared to Group DIV (p<0.05). At laryngoscopy, HR was 75.4±4.0 bpm in Group DIM versus 89.2±6.0 bpm in Group DIV (p<0.001); MAP was 92.4±4.0 mmHg versus 104.4±6.2 mmHg (p<0.001). The HR at laryngoscopy was significantly higher than baseline in Group DIV (p<0.05), whereas in Group DIM it remained significantly lower than baseline (p<0.05), confirming effective sympatholysis. The IM route provided superior attenuation with more stable perioperative hemodynamics. Conclusion: IM dexmedetomidine 1.5 mcg/kg, administered 45 min before induction, provided more effective attenuation of the hemodynamic response to laryngoscopy and endotracheal intubation than the IV route, maintaining HR and MAP within a clinically acceptable range (±20% of baseline) without excessive suppression below baseline.