Comparison of different methods in determining the laryngeal mask airway (LMA) size in adult patients

Background and objective: In this study, we aimed to compare the effects of different LMA size selection methods on successful LMA application, perioperative ventilation parameters and postoperative airway complications in determining the appropriate size of LMA used for elective surgery in adult patients in our operating room. Material and Method: This study is a retrospective analysis of case files that contain the patients ASA I-II group, according to the American Society of Anesthesiologists (ASA) Physical State Classification, aged between 18-70 and LMA used for elective surgery in Dokuz Eylül University Faculty of Medicine between the dates January 2017 and January 2018. Patients with insufficient data were excluded from the study. Results: A total of 190 patients were included in our study grouped in 5 different ways. For the 51 cases, the LMA size was chosen according to the body weight of the patients in LMA size selection guided weight according to the body weight of the manufacturer. For the thirty-three cases, the size of the LMA, approximately equal to the width of the external auditory canal auricula, was used. The size of the LMA selected for thirty-eight cases was the LMA dimensions corresponding to the language width of the cases. In thirty-six cases, the size of the LMA that corresponds to the width of the fingers, while the thumb, and the small finger were opened to the outside, and the second, third and fourth fingers were adjacent, were preferred. In thirty-two cases, it was found that the appropriate LMA was chosen to correspond to this distance by looking at the thyromental distances of the cases. The best score in terms of LMA placement score was determined to be in Group Ear. The best group in terms of the number of attempts to place the LMA in the cases was determined as Group Ear. Group Ear was the best group for the complications of sore throat in terms of postoperative complications. Conclusion: In our study, successful placement rates for adequate and appropriate ventilation in Group Ear were found to be comparable with the success rates reported in other studies. The results of our study showed that the ear size measurement method was one of the effective methods to decide the appropriate LMA size. Therefore, it can be said that the ear size can be used as a guide for the selection of the appropriate LMA size. This method may be an addition to the methods currently in use and can save users from remembering formulas and tables based on body weight / gender. As a result, considering all these reasons and the data we obtained from our study, it is an effective and fast method to decide the appropriate LMA size according to the ear size, but there is still a need for prospective randomized controlled studies for the use and investigation of different methods. Keywords: Laryngeal mask airway, LMA size selection, elective surgery, LMA placement parameters, ventilation parameters, postoperative airway complication