Effects of Thermal Softening of Double-Lumen Endobronchial Tubes on the Prevention of Postoperative Sore Throat in Smokers: A Randomized Controlled Trial

Tracheal intubation-related complications, such as postoperative sore throat (POST), hoarseness, and vocal cords injuries, are not uncommon. It is well known that thermal softening of double-lumen endobronchial tubes (DLTs) has been used to prevent these events from happening in non-smokers; however, no study has ever assessed the effects of thermal softening of DLTs in smokers undergoing one-lung anesthesia. The authors aimed to investigate whether thermal softening of DLT can achieve a better effect in preventing POST.A total of 258 smokers scheduled for one-lung anesthesia were randomly assigned to 1 of the following 2 groups: (1) group C (non-thermal softening group) and (2) group T (DLTs were placed in 40°C 0.9% saline for 10 minutes). Incidence and severity of POST and hoarseness were assessed until 48 hours after surgery. Vocal cords were examined using laryngoscope before intubation and immediately after extubation. Patients' hemodynamic change at intubation and extubation was recorded. The primary outcomes were the incidence and severity of POST. The secondary outcomes were the incidence and severity of hoarseness, vocal cords injuries, and patients' hemodynamic change at intubation and extubation.Sore throat and vocal cord injuries occurred less frequently in the thermal softening group than in the control group (31/129 v 60/129, p < 0.01; 21/129 v 49/129, p < 0.001; 12/129 v 35/129, p < 0.001 for sore throat; 14/70 v 27/70, risk ratio (95% confidence interval): 0.52 (0.30-0.90), p = 0.025 for sore throat; 5/129 v 52/129, p < 0.05 for vocal cord injuries).Thermal softening of DLTs significantly reduced the incidence and severity of DLTs intubation-related POST within 72 hours after extubation.