Intravenous dexmedetomidine versus magnesium sulphate for attenuation of hemodynamic response to laryngoscopy and endotracheal intubation in adults undergoing cardiac valve replacement surgery at a tertiary care hospital in Udaipur, Rajasthan

Background: Laryngoscopy and endotracheal intubation induce sympathetic activation (increased heart rate, blood pressure), which may be hazardous in patients undergoing cardiac valve replacement. This study aimed to compare intravenous dexmedetomidine (1 mcg/kg) and magnesium sulphate (20 mg/kg) in attenuating the hemodynamic response to laryngoscopy and intubation during elective cardiac valve replacement surgery. Methods: This prospective, randomized, double-blind, parallel-group trial enrolled 66 adult patients (ASA II–III, aged 18–70 years) undergoing elective cardiac valve replacement surgery under general anaesthesia at a tertiary care centre. Patients were allocated to Group D (dexmedetomidine 1 mcg/kg, n =33) or Group M (magnesium sulphate 20 mg/kg, n =33), each infused over 10 minutes in 100 ml normal saline commencing 20 minutes before anticipated intubation. Haemodynamic parameters (heart rate [HR], systolic blood pressure [SBP], diastolic blood pressure [DBP], mean arterial pressure [MAP]) were recorded at baseline, after drug infusion, after induction, and at 1, 3, 5, 8, 10, and 15 minutes following intubation. Results: Following drug infusion, dexmedetomidine reduced HR (84.3 ± 4.5 to 78.2 ± 4.3 bpm), whereas magnesium sulphate was associated with a paradoxical mild increase (85.8 ± 5.3 to 87.4 ± 5.1bpm; p < 0.001 intergroup). At one-minute post-intubation, HR (99.4 ± 4.6 vs 104.5 ± 5.3 bpm), SBP (125.0 ± 5.7 vs 135.5 ± 6.2 mmHg), DBP (81.3 ± 3.9 vs 89.9 ± 4.0 mmHg), and MAP (95.9 ± 4.2 vs 105.1 ± 4.8 mmHg) were all significantly lower in Group D (p < 0.001 for all). These differences were sustained through 15 minutes. Conclusions: Intravenous dexmedetomidine (1 mcg/kg) provides significantly superior attenuation of the haemodynamic response than magnesium sulphate 20 mg/kg in adults undergoing cardiac valve replacement surgery.