Randomized comparison of the classic Laryngeal Mask Airway with the Airway Management Device during anaesthesia

We compared the modified Airway Management Device (AMD) with the classic Laryngeal Mask Airway (cLMA) in a randomized comparative trial.

Primary outcome was success of airway placement. Secondary outcomes included time to achieve an airway, airway manipulations required, complications during use and fibre-optic assessment of airway positioning.

We planned to study 300 patients but interim analysis demonstrated the study should be stopped after 100 patients. The AMD was inserted on the first attempt less frequently than the cLMA (P=0.04). Eight AMDs and one cLMA could not be placed within three attempts (P=0.03). The AMD required more attempts (P=0.03) and more manipulations (P=0.02) and caused more complications (P=0.01) during insertion. During maintenance of anaesthesia, three AMDs and no cLMAs had to be removed as a result of complications. Seal pressure was better with the AMD than with the cLMA (AMD 25 cm H2O, cLMA 20 cm H2O, P=0.001). Efficacy of ventilation was better with the cLMA than with the AMD (P=0.005). On fibre-optic examination, positioning over the larynx was better with the cLMA than with the AMD (P=0.005). Two of 32 attempts to pass an orogastric tube via the AMD were successful. During recovery, two AMDs and no cLMAs required premature removal. Tolerance during emergence, the incidence of blood on the devices and the incidence of postoperative complications were equivalent between devices. Overall failure rate of the AMD was greater than that of the cLMA (P=0.001).

Successful insertion of the cLMA is more likely than that of the AMD. Insertion of the AMD required more attempts and caused a greater number of complications. Fibre-optic position was poorer than with the cLMA. When an airway is established, the AMD caused a greater number of complications during anaesthesia and failed more frequently than the cLMA. During recovery from anaesthesia, more complications occurred with the AMD. Overall performance of the AMD was poorer than with the classic LMA.