Oropharyngeal leak pressure of the LMA Protector™ vs the LMA Supreme™; a prospective, randomized, controlled clinical trial

BACKGROUND: Clinical characteristics such as oropharyngeal leak pressure (OLP) and ventilation peak pressure are important factors for successful use of supraglottic airway devices in general anaesthesia. We hypothesized that the LMA Protector™ compared to the LMA Supreme™ may develop a higher OLP, which could be of clinical significance. METHODS: Ninety-six patients were randomized to the LMA Protector™ or LMA Supreme™ groups. We measured oropharyngeal leak pressure within 5 minutes after insertion of the supraglottic airway device with a standardized cuff pressure at 60 cm H2 O. Secondary parameters, such as insertion time of the supraglottic airway device, the number of attempts inserting the supraglottic airway device and the gastric tube, volume of gastric contents, and maximum airway pressure, as well as pulse oximetry throughout the operation were measured. Further, blood staining after removal of the supraglottic airway device and postoperative airway morbidity 3 hours after surgery were determined. RESULTS: The mean difference of oropharyngeal leak pressure was 5.2 (95% CI 2.8-7.6), ie, 30.9 (7.4) cmH2 O for the LMA Protector™ vs 25.6 (4.4) cmH2 O for the LMA Supreme™ (P < 0.001; mean(SD)). Similarly, there was a mean difference between OLP and maximal ventilation peak pressure 5.6 (95% CI 3.1-8.2) ie 19.6 (7.7) cmH2 O for the LMA Protector™ vs 14.0 (4.4) cmH2 O for the LMA Supreme™ (P < 0.001). No difference was found between the groups for other secondary parameters, as well as postoperative airway morbidity. CONCLUSION: The LMA Protector™ enabled a higher OLP compared to the LMA Supreme™. This finding may be important for patients requiring a higher peak pressure for sufficient supraglottic airway device ventilation.