Incidence of postoperative sore throat after using a new technique of insertion of a second generation Laryngeal Mask Airway: A randomised controlled trial

Abstract

Background: Sore throat is a common complication after Laryngeal Mask Airway Supreme (SLMA) insertion.

Objective: The aim of this study was to determine whether a new SLMA insertion technique (not removing the pilot tube blocker before insertion) lowers the incidence of sore throat in the postanaesthesia care unit (PACU).

Design: A prospective, single-centre, parallel randomised controlled trial.

Setting: Operating room and PACU at a hospital in China from June to September 2019.

Patients: Four hundred and eight patients aged 18 to 65 years with American Society of Anaesthesiologists physical status class I or II who were scheduled for elective surgery requiring anaesthesia and SLMA insertion.

Interventions: Leaving the blocker at the end of the pilot tube in situ (this blocker keeps the valve open and the balloon remains partially inflated but will deflate with pressure) or removing the blocker and actively deflating the cuff before SLMA insertion.

Main outcome measures: The primary outcome was the incidence of postoperative sore throat in the PACU. The secondary outcomes included sore throat severity (Prince Henry Hospital Pain Score), first-attempt success rate, ease of insertion, time to successful SLMA insertion, oropharyngeal leak pressure, grade of view on fibreoptic bronchoscopy (indicating the accuracy of SLMA positioning) and adverse events.

Results: The incidence of sore throat was 33/204 (16.2%) in the nonremoval group, and 65/204 (31.9%) in the removal group (P < 0.001). The first-attempt success rate was 174/204 (85.3%) in the nonremoval group and 150/204 (73.76%) in the removal group (P = 0.003; relative risk 1.160, 95% CI 1.049 to 1.282). The Kaplan--Meier curves showed that the insertion time in the nonremoval group was shorter (log-rank P = 0.01).

Conclusion: The new insertion technique, leaving the blocker attached to the end of the pilot balloon, resulted in a reduced incidence and severity of postoperative sore throat in the PACU, and an improved first-attempt success rate and the accuracy of SLMA positioning.

Trial registration: Chinese Clinical Trial Registry identifier: ChiCTR1900023022.

Fig. 1

The nonremoval group (a), and the removal group (b).

Fig. 2

CONSORT flow diagram.

Fig. 3

Insertion time of successful attempts to successful insertions.

Fig. 4

Forest plot of the insertion time by residency class. CA, Clinical anaesthesia year is the year of clinical training in anaesthesia after the completion of a year of internship training; SMD, standardized mean difference.