Laryngo-pharyngeal complaints after use of the laryngeal mask airway

PURPOSE: To compare the incidence of dysphagia, dysphonia and sore throat following anesthesia, using the laryngeal mask airway (LMA), among patients receiving intermittent positive-pressure ventilation (IPPV) and those breathing spontaneously (SV) and with two different concentrations of nitrous oxide (N2O) in oxygen.

METHODS: In a prospective trial, 120 patients (ASA I-III, 16-70 yr, > 60 kg) undergoing minor peripheral surgery were randomised into four groups with respect to type of ventilation and N2O concentration (50% or 66%) received. Cuff pressure measurements were monitored continuously. Twenty-four hours after surgery, patients were questioned for sore throat, dysphagia and dysphonia.

RESULTS: At 30 min post-LMA insertion, increases in cuff pressure were 35.2+/-17.1 mmHg (22.8%) vs 50.1+/-16.3 mmHg (32.7%) in patients breathing 50 and 66% N2O, respectively (P < 0.01). There were no differences in cuff pressure increment between patients in the SV and IPPV groups. Cuff pressure values at the end of surgery depended on the duration of surgery and on the concentrations of N2O. The overall incidence of postoperative discomfort at 24 hr was dysphagia 11%, dysphonia 11% and sore throat 28.8%. Only two patients reported sore throat as more than mild. There was no relationship between cuff pressure and laryngo-pharyngeal complaints. The incidence of dysphonia in the groups receiving IPPV was higher than that in the groups with spontaneous ventilation (17.2 vs 5%, P < 0.05).

CONCLUSION: Post-operative discomfort is related to the type of ventilation but not to variation in LMA cuff pressure.