Effects of Endotracheal Tube Prewarming versus Precooling on Postoperative Sore Throat

Postoperative sore throat (POST) is a common complication of general anaesthesia requiring endotracheal intubation. This randomised double-blind study compared the effects of endotracheal tube (ETT) prewarming versus precooling on POST. A total of 122 patients with American Society of Anaesthesiologists physical status I or II undergoing surgery under general anaesthesia requiring ETT were recruited. Following randomisation, patients in Group A and Group B were intubated with ETT immersed in 40°C and 5-10°C saline, respectively. The incidence and severity of POST, hoarseness of voice and cough were assessed at 1-hour and 24-hours postoperatively. No significant differences were observed in terms of sore throat, hoarseness and cough at the first hour, nor in the severity of sore throat and hoarseness. Group B had a significantly lower incidence of hoarseness at 24-hours postoperatively (p = 0.013). No significant difference in terms of sore throat were observed between the two groups at 24-hours postoperatively (p = 0.521). On further analysis, at 1-hour postoperatively, the majority of patients who developed moderate hoarseness were male (p = 0.011), and those intubated with larger sized ETT reported moderate hoarseness and cough (p = 0.027 and p = 0.024, respectively). Cough was reported only at 1-hour postoperatively, which were 18 (30.5%) and 11 (18.6%) of patients in the prewarmed and precooled ETT, respectively (p = 0.134). Although there were no significant differences between prewarmed and precooled ETT in relation to POST, we found a significantly lower incidence of hoarseness at 24-hours postoperatively in the latter group, which would reduce a common postoperative complication.