Pharyngolaryngeal morbidity with the laryngeal mask airway in spontaneously breathing patients: does size matter?

BACKGROUND: Currently, the manufacturer of the laryngeal mask airway (LMA; Laryngeal Mask Company, Ltd., Northfield End, Henley on Thames, Oxon, United Kingdom) recommends using as large a mask size as possible. The aim of this study was to compare the incidence of pharyngolaryngeal morbidity after the use of a large (size 5 in males and size 4 in females) or small (size 4 in males and size 3 in females) LMA in spontaneously breathing patients.

METHODS: A total of 258 male and female patients were randomly assigned to insertion of a large or small LMA while breathing spontaneously during general anesthesia. After insertion of the LMA, a "just-seal" cuff pressure was obtained, and intracuff pressure was measured at 10-min intervals until just before removal of the LMA. The 2- and 24-h incidence of postoperative sore throat, pain, hoarseness, dysphagia, and nausea and vomiting was assessed. Complications after LMA removal, including body movement, coughing, retching, regurgitation, vomiting, biting on the LMA, bronchospasm, laryngospasm, or the presence of blood on the LMA, were recorded.

RESULTS: The use of a large LMA was associated with a higher incidence of sore throat in both sexes (20% vs. 7% in men, 21% vs. 5% in women; P < 0.05) and a higher incidence of hoarseness in male patients at 2 h postoperatively (21% vs. 9%, P < 0.05). There was a higher incidence of sore throat in male patients at 24 h postoperatively with the use of a large LMA (26% vs. 12%, P < 0.05). There was no difference in the incidence of complications of LMA removal orother pharyngolaryngeal morbidity, such as difficulty swallowing, drinking, and eating, or nausea and vomiting, between male or female groups at any time period with the use of a large LMA.

CONCLUSIONS: Selection of a small laryngeal mask airway (size 4) in spontaneously breathing male patients may be more appropriate to limit the occurrence of sore throat on the first postoperative day. All patients had a fourfold increased risk of developing sore throat when a large LMA was used.