A Comparative Study Between the Efficacy of Magnesium Sulphate and Dexmedetomidine for Cough Suppression During Anesthetic Emergence in Smokers Undergoing Elective Abdominal Surgery: A Randomized Double-Blind Controlled Trial

Abstract

Background: Emergence coughing following general anesthesia (GA) is common in smokers and may result in severe complications, including hemodynamic instability, bronchospasm, wound dehiscence, increased intracranial pressure (ICP), and raised intraocular pressure. Dexmedetomidine (DEX) and magnesium sulfate (MgSO4) have demonstrated antitussive properties through distinct pharmacological mechanisms, but direct comparisons in smokers undergoing abdominal surgery remain limited. Objectives: The present study aimed to compare their efficacy in suppressing emergence cough in active smokers and assess their effects on hemodynamics and sedation. Methods: This double-blind, randomized controlled clinical trial enrolled 165 active smokers classified as American Society of Anesthesiologists (ASA) I-II, scheduled for elective abdominal surgeries under GA, who were evenly stratified into three groups: Dexmedetomidine (0.5 µg/kg), MgSO4 (30 mg/kg), and placebo. Study drugs were infused over 10 minutes during wound closure. Cough severity and incidence were recorded from cessation of anesthesia to 10 minutes post-extubation. Hemodynamic parameters and sedation (Ramsay Sedation Score) were monitored for 30 minutes post-extubation. Results: Both DEX and MgSO4 significantly reduced coughing incidence (30.9% and 60.0% vs. 87.3% in controls, P < 0.001 and P = 0.002, respectively) and severity (median scores: 0 vs. 2, P < 0.001). Dexmedetomidine was superior to MgSO4 in both outcomes (P = 0.002). Dexmedetomidine induced early and sustained reductions in heart rate (HR) and mean arterial pressure (MAP; P < 0.001), while MgSO4 showed delayed hemodynamic effects post-extubation. Sedation was deeper with DEX (median Ramsay score: 2 vs. 1; P < 0.001) but did not delay recovery. Conclusions: Both DEX and MgSO4 effectively reduce emergence coughing in smokers. Dexmedetomidine offers superior cough suppression and hemodynamic stability but with deeper sedation.