Insertion of the ProSeal™ laryngeal mask airway with the 90° rotation technique

Abstract

To the Editor, We were greatly interested in the recent article by Jeon et al. that described insertion of the ProSeal laryngeal mask airway (PLMA) with the 90 rotation technique. In this study, an extension of their previous work, the authors provided a simple and useful insertion technique for the PLMA that has a high success rate and a low incidence of pharyngeal mucosal trauma. However, several design aspects of this study should be clarified. The evaluation criteria for an effective airway differ from the previous study. In the former article, they evaluated gas leakage and the lowest limitation of peak airway pressure during manual ventilation. In their most recent study, the authors considered normal thoracoabdominal movement and capnography to indicate proper placement, with the possibility that obvious gas leakage was present. Also, a failed insertion attempt was not defined clearly. A three-point ventilation score that Keller et al. described is a useful method to assess the quality of ventilation through the PLMA. Using this score, inadequate quality of ventilation with minimal chest expansion and considerable gas leakage is often considered as the failed insertion attempt. The orogastric tube placement through the PLMA drainage tube was not performed. In fact, the presence of a drainage tube to provide a channel for regurgitated fluid and placement of an orogastric tube is one of the important design modifications of this device. Also, passage of a lubricated orogastric tube via the drainage tube and aspiration of gastric fluid is an essential test to determine correct placement. Difficult placement of the orogastric tube often suggests obstruction of the drainage tube caused, for example, by the device folding over. This situation may put the patient at increased risk of gastric insufflation and aspiration during airway maintenance with the PLMA. In this study, the postoperative sore throat was assessed as a side effect of the two insertion methods. However, the authors did not compare the use of opioid drugs between groups during anesthesia maintenance. Also, standardization of postoperative analgesia should be a crucial component of study design. The type and dose of analgesia and the timing of its administration in relation to the assessment of sore throat should have been described. In the absence of a comparison of opioid dosages during anesthesia and a postoperative analgesic protocol, the secondary outcome findings and their subsequent conclusions should be interpreted with caution, as they may have been determined using incomplete methodology.