Evaluation of Preventive Effect of Zinc Lozenge on Sore Throat after Placement of ProSeal Laryngeal Mask Airway: A Randomised Controlled Study

Introduction: Postoperative Sore Throat (POST) is a known complication after general anaesthesia with an endotracheal tube (14.4% to 50%) and less so with Supraglottic Airway (SGA) devices (5.8% to 34%). Various modalities and drugs can decrease POST. Zinc possesses anti-inflammatory and antioxidant properties and is utilised in oral mucositis and xerostomia. Aim: To evaluate the effect of preoperative administration of a zinc lozenge on POST after the removal of the Proseal Laryngeal Mask Airway (PLMA). Materials and Methods: In this randomised, double-blinded controlled study was conducted at the Department of Anaesthesia at Pt. BD Sharma PGIMS, Rohtak, Haryana, India, over a period of five months from August 2020 to December 2020. 100 patients aged 18-60 years of either sex belonging to American Association of Anesthesiologists (ASA) I and II undergoing elective surgery under general anaesthesia with PLMA placement were randomly allocated into two groups to receive a 40 mg zinc lozenge (Group-I) or placebo (Group-II) and were asked to chew it 30 minutes preoperatively. Patients with upper respiratory tract infections, at risk of aspiration, or with anticipated difficult intubation were excluded from the study. The incidence and severity of POST were assessed on a 4-point scale (0-3) at 30 minutes, 2, 4, and 24 hours postoperatively. The primary outcome of the study was the incidence of POST at four hours postoperatively, and the secondary outcome was the severity of POST at 30 minutes, two hours, and 24 hours postoperatively. Statistical analysis was conducted using Statistical Package for Social Sciences (SPSS) version 20.0 (IBM SPSS Statistics Inc., Chicago, Illinois, USA) Windows software programme. The Chi-square test and unpaired t-test were used for statistical analysis. Results: The mean age in Group-I was 38.6 +/- 12.32 years and in Group-II was 37.90 +/- 14.84 years (p-value 0.79). Data regarding the distribution of patients according to sex were comparable with a p-value of 0.31. There was a significantly lower incidence of POST in Group-I (zinc group) than in Group-II (placebo group) at four hours with a p-value of 0.004. Conclusion: The present study has shown that the preoperative administration of a 40 mg zinc lozenge effectively reduces the incidence and severity of POST in the postoperative period, peaking at four hours after general anaesthesia. Zinc lozenges are easy, convenient, non invasive, and successfully prevent POST.