Clinical evaluation of a novel LMA with a color-coded pressure gauge

Abstract

BackgroundUnintended hyperinflation of the cuff of a laryngeal mask airway (LMA) may be associated with increased airway morbidity and postoperative pain. While the manufacturers recommend a cuff pressure of ≤60cmH2O, in usual clinical practice, there is no method used to determine the intracuff pressure. The purpose of this prospective study was to evaluate the accuracy of a newly designed LMA with a built in pressure gauge intended to alert the clinician to elevated intracuff pressures. The pressure gauge has a color code system intended to reflect the intracuff pressure with green being 40–60cmH2O. MethodsThere was no change dictated in clinical practice for these patients. Per our usual practice, the LMA was removed from the package and inserted with the cuff partially inflated. Additional air was added to the cuff using a syringe as needed to ensure a seal during positive pressure ventilation to a peak inflating pressure (peak ventilating pressure) of 20–25cmH2O. The clinicians placing the LMA did not use the pressure gauge for clinical feedback during cuff inflation. Immediately after LMA placement, the pressure in the cuff of the LMA was measured using a hand held manometer by an independent reviewer not part of the patient's anesthetic management. The color indicated on the pressure gauge (yellow, green or red) was recorded prior to pressure sampling. Additional data collected included the patient's demographic data (age, weight, and gender), the size of the LMA, and whether air was added to the cuff. ResultsThe study cohort included 100 children, ranging in age from 3 months to 19 years and in weight from 5.4 to 80.1kg. One patient was excluded due to malfunction of the pressure gauge and pilot balloon of the LMA. The intracuff pressure as measured by manometer correlated appropriately with the color coding of the pressure gauge in 94 of the 99 (95%) of the LMA's tested. ConclusionsGiven the potential association of excessive intracuff pressures with postoperative sore throat and the inability to ensure acceptable intracuff pressures using clinical judgment, this new LMA may allow a simple means of achieving this goal without the use of costly devices (manometers) in every operating room. In 95% of the LMA's tested, the color reading correlated appropriately with the intracuff pressure.