Low-Dose Dexmedetomidine (0.5 µg/Kg) With 1 MAC Sevoflurane for Attenuation of the Haemodynamic Response to Laryngoscopy and Tracheal Intubation: A Randomised, Double-Blind, Placebo-Controlled Trial

Background: Laryngoscopy and tracheal intubation provoke a sympathetic pressor response that can harm patients with limited cardiovascular reserve. Higher doses of dexmedetomidine attenuate this response but cause bradycardia and hypotension. We evaluated a low dose of dexmedetomidine combined with 1 MAC sevoflurane. Material and Methods: In this randomized, double-blind, placebo-controlled trial, 50 ASA I adults (18–60 years) scheduled for elective surgery under general Anesthesia received either dexmedetomidine 0.5 µg/kg in 100 mL normal saline (group DEX, n = 25) or 100 mL normal saline (group NS, n = 25) over 10 minutes before induction. Anesthesia was induced with morphine and thiopentone, and maintained with 2% sevoflurane (1 MAC) in 66% nitrous oxide. Heart rate (HR), systolic (SBP), diastolic (DBP) and mean arterial pressure (MAP) were recorded up to 45 minutes after intubation and for 3 hours postoperatively. Results: Groups were comparable at baseline. One minute after intubation, group NS showed significant rises in SBP (133.52 ± 13.54 vs 110.32 ± 17.36 mmHg), DBP (88.44 ± 13.89 vs 70.00 ± 15.64 mmHg) and MAP (104.96 ± 11.78 vs 85.08 ± 15.60 mmHg) compared with group DEX (all p < 0.001). HR was significantly lower in group DEX at 3 minutes (78.92 ± 14.04 vs 92.40 ± 13.09 bpm; p < 0.001). Bradycardia (36% vs 4%; p = 0.005) and hypotension (60% vs 28%; p = 0.023) were more frequent in group DEX; all episodes responded to standard treatment. Conclusion: Dexmedetomidine 0.5 µg/kg with 1 MAC sevoflurane effectively attenuates the hemodynamic response to laryngoscopy and intubation, at the cost of manageable bradycardia and hypotension.

Keywords: Dexmedetomidine, Sevoflurane, Laryngoscopy, Intubation, Intratracheal, Hemodynamics, Blood Pressure, Heart Rate.