Pre-Intubation Topical Magnesium Sulfate Spray for Prevention of Postoperative Sore Throat after Double-Lumen Endobronchial Intubation: A Randomized Placebo-Controlled Trial

Abstract

Background: Postoperative sore throat (POST) frequently occurs following endotracheal intubation and may be particularly relevant when a double-lumen endobronchial tube (DLT) is used. This study evaluated whether topical 20% magnesium sulfate spray administered before DLT intubation reduces POST severity and postoperative hoarseness in patients undergoing thoracotomy.
Methods: The trial enrolled adults aged 18–65 years scheduled for thoracotomy with DLT intubation; participants were randomly assigned, under double-blind conditions, to receive either five puffs of topical 20% magnesium sulfate spray or normal saline before intubation. POST severity was assessed using a 0–10 numeric rating scale at 1, 24, and 48 hours after surgery. Postoperative hoarseness was assessed as a secondary outcome.
Results: Sixty-three patients contributed to the study, including 32 in the magnesium sulfate group and 31 in the control group. Baseline characteristics were comparable between groups. Median POST scores were significantly lower in the magnesium sulfate group at 1 hour [3.00 (2.00–3.75) vs. 4.00 (4.00–5.00)], 24 hours [1.00 (1.00–2.00) vs. 2.00 (1.00–3.00)], and 48 hours [1.00 (1.00–1.00) vs. 1.00 (1.00–2.00)] (all p<0.001). Mixed-model analysis showed a significant group-by-time interaction (p<0.001), with an overall adjusted mean difference of −0.94 (95% CI: −1.23 to −0.65). Moderate hoarseness was less frequent in the magnesium group, but the difference was not statistically significant (12.5% vs. 29.0%; p=0.129).
Conclusion: Topical 20% magnesium sulfate spray before DLT intubation reduced POST severity during the first 48 hours after thoracotomy, with the greatest benefit in the early postoperative period. However, postoperative hoarseness was not significantly reduced.