Finite element analysis of soft tissue pressure at different fixation positions of tracheal catheter in oral cavity (Preprint)
Authors: wang zhiwei , Dong Zhenghui , He Xiaoyan , Tao ZhenZhen , QI Jinfang , Zhang Yatian , Ma Xian 
Published: December 2024

BACKGROUND

The primary method of respiratory support for critically ill patients in the ICU is oral tube intubation, which ensures airway patency, increases ventilation volume, and enhances lung function. However, the use of oral tube intubation may lead to Oral Mucosal Pressure Injury (OMPI) due to excessive or prolonged pressure, friction, and shear forces [1]. OMPI can increase patient pain, elevate the risk of infection, impose a financial burden on healthcare, increase staff workload, and even result in medical disputes. Studies indicate that the incidence of OMPI in ICU patients ranges from 2.95% to 49.2%, with different fixation positions and methods of tracheal catheterization influencing its occurrence [2]. While numerous factors contribute to OMPI, including patient-related factors, physiological conditions, the use of specific medications, and nursing-related aspects, there are limited reports addressing the mechanical factors that cause OMPI [3-5]. The International Guidelines for the Clinical Prevention and Treatment of Stress Injuries (2019) suggest that finite element models can be employed to evaluate mechanical factors by assessing stress distribution characteristics within tissue structures and predicting the risk of cellular and tissue damage [6]. This study utilizes a finite element theory contact algorithm to simulate the compression process of oral soft tissue when the tracheal catheter is fixed in various positions within the oral cavity. It aims to analyze the stress distribution characteristics under this action to more accurately evaluate the actual stress state within the oral soft tissue structure, thereby preventing the occurrence of OMPI.

OBJECTIVE

This study aimed to establish finite element models for different fixation positions of tracheal catheters in the oral cavity to identify the optimal fixation position that minimizes the risk of oral mucosal pressure injury.

METHODS

CT data of the head and face from healthy male subjects were selected, and a 3D finite element model was created using Mimics 21 and Geomagic Wrap 2021 software. A pressure sensor was utilized to measure the actual pressure exerted by the oral soft tissue on the upper and lower lips, as well as the left and right oral angles of the tracheal catheter. The generated model was imported into Ansys Workbench 21.0 software, where all materials were assigned appropriate values, and boundary conditions were established. Vertical loads of 2.6 N and 3.43 N were applied to the upper and lower lips, while horizontal loads of 1.76 N and 1.82 N were applied to the left and right corners of the mouth, respectively, to observe the stress distribution characteristics of the skin, mucosa, and muscle tissue in four fixation areas.

RESULTS

The equivalent stress of the skin mucosa was ranked as follows: left oral angle < right oral angle < upper lip < lower lip, with values of [(28.42±0.65) kPa, (30.72±0.98) kPa, (35.20±0.99) kPa, (41.79±0.48) kPa] (P<0.001). The equivalent stress of muscle tissue, from smallest to largest, was: right oral angle < left oral angle < upper lip < lower lip, with values of [(34.35±0.52) kPa, (35.64±1.18) kPa, (43.17±0.58) kPa, (43.17±0.58) kPa]（P<0.001）. The shear stress of the skin mucosa tissue also followed the same order: left oral angle < right oral angle < upper lip < lower lip, with values of [(6.58±0.16) kPa, (7.05±0.32) kPa, (7.70±0.17) kPa, (10.02±0.44) kPa] (P<0.001). The shear stress of muscle tissue increased in the following order: right oral angle < left oral angle < upper lip < lower lip, with values of [(5.69±0.29) kPa, (5.74±0.30) kPa, (8.91±0.55) kPa, (11.96±0.50) kPa] (P<0.001). The equivalent and shear stresses of muscle tissue were significantly higher than those of the skin mucosal tissue across all four fixation positions, with statistical significance (P<0.05).

CONCLUSIONS

Fixation of the tracheal catheter at the left and right oral corners results in the lowest equivalent and shear stresses, while the lower lip exhibits the highest stresses. It is recommended to minimize the contact time and area of the lower lip during tracheal catheter fixation, and to alternately replace the contact area at the left and right oral corners to prevent oral mucosal pressure injuries.