LARYNGEAL MASK AIRWAY PERFORMANCE - EFFECT OF CUFF DEFLATION DURING ANESTHESIA

We studied the effect of deflating the laryngeal mask airway (LMA) cuf f in situ on recorded respiratory tidal ventilation in 30 spontaneousl y breathing anaesthetized patients. Another 26 patients were studied i n whom the LMA cuff was undisturbed. Deflation of the cuff to a pressu re of 22 mm Hg (below an estimated arteriolar perfusion pressure of th e pharyngeal mucosa), by removing approximately 50% of the recommended cuff injection volume, had a minimal effect on tidal ventilation (P = 0.9). This manoeuvre may have a role in minimizing transmitted cuff p ressure on the adjacent pharyngeal mucosa. Complete cuff deflation, ho wever, resulted in a 17% decrease in mean tidal ventilation (P < 0.05) , with two patients (6%) demonstrating a substantial leak around the c uff and airway obstruction. The practice of complete cuff deflation du ring the recovery period from anaesthesia cannot be recommended.