Sealing mechanism study of laryngeal mask airways via 3D modelling and finite element analysis

Proper sealing of laryngeal mask airways (LMAs) is critical for airway management in clinical use. Understanding the sealing mechanism can significantly help front-line anaesthetists to reduce the incidence of adverse events. However, anaesthetists, who may not have the most substantial engineering backgrounds, lack intuitive ways to develop an understanding of the LMA sealing mechanism effectively. The paper aims to study the LMA-pharynx sealing mechanisms from the perspective of front-line anaesthetists. We use a computer-aided 3D modelling technique to visualise the LMA—pharynx interactions, which helps anaesthetists identify the critical areas of complications. Furthermore, we conduct a quantitative pressure distribution analysis of the LMA-pharynx contacting surface using the finite element analysis technique, which helps further understand the sealing mechanics in those areas. We present two cases studies based on one male volunteer, aged 50, inserted with a ProSeal LMA. In the first case, a relatively low cuff pressure (CP) was applied to simulate the clinical circumstances in which complications related to air leakage are most likely to happen; in the second case, we increase the CP to a relatively high value to simulate the scenarios with an increased risk of complications related to high mucosal pressure. The experiments suggest the follows: (1) Sore throat complications related to high mucosal pressure is most likely to occur in the hypopharynx with a high CP setting, particularly in the areas where the cricoid cartilage presses the mucosa. (2) The narrow hyoid bone super horn width likely causes LMA insertion difficulties. (3) Insufficient CP will significantly increase the risk of air leakage in the oropharynx. A complete sealing pressure line in the contacting surface will be formed with sufficient CP, thereby preventing the air leakage into the oral.