The determination of an appropriate time for placement of the classic laryngeal mask airway in patients undergoing general anesthesia

Abstract

Background: The management of the airways is an essential component of anesthesia planning. Laryngeal mask airway (LMA) plays an important role in modern anesthesia, however, intubation by LMA has some complications. It may cause inadequate anesthesia depth, which can lead to adverse events. The aim of this study was to evaluate the optimal time for intubation by LMA under general anesthesia. Methods: This study was conducted on 96 patients, who underwent operation and were appropriate candidates for intubation with appropriate LMA. The participants were divided to four groups, each with 24 cases, based on the time interval between anesthetic agent administration and intubation with LMA; 15 seconds for the first group, 16 to 30 seconds for the second group, 31 to 45 seconds for the third group, and 45 to 60 seconds for the fourth group. The patients involved in these groups were selected based on the following prerequisites, patients’ age, gender, easy intubation, need for additional drug administration, basic blood pressure before drug administration, within the time intervals one, three, and five minutes after placement of LMA, duration of LMA, SaO2 before and after placement of LMA, coughing, patient’s movement, laryngospasm, gag reflex after intubation, allowing appropriate ventilation, presence of sore throat after surgery, number of attempts, extent of mouth opening and leak in peri-LMA space. Results: Overall, 72 males and 24 females participated in this study with a mean age of 40.64. Intubation by LMA was performed easily during the first attempt in 58% of the participants, with minimal resistance in 28.6% and with some problems during the second attempt in 10.5% of the cases. Throat pain after the operation was significantly lower. Systolic and diastolic pressure and heart rate had no statistically significant difference. Conclusions: The results showed that in the first 15 seconds after the drug (e.g. propofol) administration, there were lower complications, rapid placement, and optimized time for the placement of LMA. The rate of success and its quality were reduced during the first attempt of insertion and termination of the effect of propofol.