STUDY OBJECTIVE: To compare the mechanical properties of classic, reusable Laryngeal Mask Airways (LMAs) that have been used more than 100 times with one unused LMA. DESIGN: Laboratory testing of devices used clinically. SETTING: Metropolitan university hospital. MEASUREMENTS: Cuff and tube specimens from LMAs that had been used at least 100 times were tested for elongation, tensile strength, stiffness, and tear strength using standard American Society of Testing and Materials protocols. Samples from an unused LMA were analyzed in the same manner for comparison. MAIN RESULTS: Tensile strength of the cuff samples was found to increase by approximately 25%. There was an increase in cuff stiffness and decreased tear strength similar to the manufacturer-reported trends. Cuff elongation decreased by 30%. Results for the LMA tube differed depending on whether the samples were taken in the machine direction or transverse direction. Tensile strength decreased by 30% in machine direction and, on average, very little in transverse direction. CONCLUSIONS: The material in reusable classic LMAs does not lose its strength after 100 uses to the extent that its manufacturer claims. At least 100 uses may be considered safe for these devices.
STUDY OBJECTIVE: To compare the mechanical properties of classic, reusable Laryngeal Mask Airways (LMAs) that have been used more than 100 times with one unused LMA. DESIGN: Laboratory testing of devices used clinically. SETTING: Metropolitan university hospital. MEASUREMENTS: Cuff and tube specimens from LMAs that had been used at least 100 times were tested for elongation, tensile strength, stiffness, and tear strength using standard American Society of Testing and Materials protocols. Samples from an unused LMA were analyzed in the same manner for comparison. MAIN RESULTS: Tensile strength of the cuff samples was found to increase by approximately 25%. There was an increase in cuff stiffness and decreased tear strength similar to the manufacturer-reported trends. Cuff elongation decreased by 30%. Results for the LMA tube differed depending on whether the samples were taken in the machine direction or transverse direction. Tensile strength decreased by 30% in machine direction and, on average, very little in transverse direction. CONCLUSIONS: The material in reusable classic LMAs does not lose its strength after 100 uses to the extent that its manufacturer claims. At least 100 uses may be considered safe for these devices.