Comparing performance of ProSeal laryngeal mask airway and I-gel in anesthetized adult patients

With great interest, we read the recent article by Ekinci et al1 comparing the performance of ProSeal laryngeal mask airway (PLMA) and I-gel in anesthetized adult patients. They showed that insertion was easier, insertion time was shorter, success rate of nasogastric tube insertion was higher, and complications were fewer with the I-gel compared to the PLMA. However, we note other issues of this study making interpretation of their findings questionable. First, insertion of the 2-supraglottic airway devices was carried out by an investigator. The authors did not state experience of this investigator on clinical use of the 2-supraglottic airway devices before the initiation of the study, and whether this investigator had the same proficiency with the uses of the 2 devices. Actually, experience and competence with any of the new airway devices are critical for their successful use. Thus, we cannot exclude the possibility that different experiences and proficiency levels of the investigator with the 2 devices tested in this study attributed to their findings. Here, we would like to echo the viewpoint of Behringer and Kristensen2 that for the results of a comparative study to be valid, participants must be equally proficient with each tested device in order to avoid bias. Second, the authors did not specify the insertion method of PLMA. Actually, there are several methods recommended for the PLMA insertion, such as classical digital insertion technique, introducer tool placement, laryngoscope aided insertion technique, stylet technique and gum elastic bougie-aided placement, and so forth. It has been shown that the insertion techniques can significantly change the ease and success rate of PLMA insertion, time required for effective airway, airway leakage pressure, success rate of nasogastric tube insertion, and incidence of complications.2,3 We believe that addressing this issue would further clarify the transparency of this study. Third, in this study, the airway leakage pressure was measured by increasing peak inspiratory pressures until the leakage sound was heard. This may not be the standard method measuring the airway leakage pressure of supraglottic airway devices. It is generally recommended that the airway leakage pressure of supraglottic airway device should be determined by setting the pop-off valve to limit peak airway pressure to 40 cm H2O, and allowing airway pressure to increase at a fresh gas flow of 3 L/min until no further increase in airway pressure is observed. Moreover, when a stable airway pressure is reached, the locations of gas leak should also be determined as the drainage tube (bubbling of soap solution), mouth (audible), or stomach (epigastric auscultation).4 Finally, the rate of sore throat was significantly higher in the PLMA group than in the I-gel group. However, the authors did not indicate the time of evaluating postoperative sore throat. It is reported that in adult patients, incidence and severity of sore throat associated with the laryngeal mask airway change with time in the early postoperative period. Furthermore, the authors did not specify the postoperative analgesic protocol. When postoperative sore throat is used as a variable to evaluate the performance of the airway devices and is compared between different devices, standardization of postoperative analgesia should be a crucial component of study design. Also, the type and dose of analgesia, and the timing of its administration in relation to the assessment of postoperative sore throat should have been described in the methods.5 In the absence of comparison of 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.