A smaller endotracheal tube combined with intravenous lidocaine decreases post-operative sore throat - a randomized controlled trial

Background Post‐operative sore throat (POST) has increasingly been a common clinical complication particularly in thyroid surgery. We conducted a trial to evaluate the effect of non‐pharmacological [smaller‐sized endotracheal tube (ETT)] combined with pharmacological intervention [lidocaine intravenous (i.v.)] on POST in women undergoing thyroid surgery. Methods Two hundred and forty patients scheduled for thyroid surgery were randomly divided into four groups: Group A, ETT size 7.0 with saline; Group B, ETT size 6.0 with saline; Group C, ETT size 7.0 with lidocaine; Group D, ETT size 6.0 with lidocaine. Patients in Groups C and D received i.v. 1.5 mg/kg lidocaine that was filled in syringe up to 10 ml 5 min before induction of anaesthesia; whereas patients in Groups A and B received an equal volume of saline. The incidence and severity of POST were evaluated at 1, 6 and 24 h after tracheal extubation. Results The highest incidence of POST occurred at 6 h after extubation in all groups. The incidence of POST was significantly lower in Group D compared with Groups A (23% vs. 62%, P