Numerical investigation of the effect of tracheostomy on flow and particle transport characteristics in human airways

Abstract

Tracheostomy is a typical surgical procedure that has been widely practiced to address airway-related difficulties, such as airway obstruction or chronic conditions, that require long-term supportive ventilation. However, it may result in symptoms that detrimental to respiratory system. Computational fluid dynamics (CFD) is a noninvasive and efficient approach for observing the effects of tracheostomy. In this study, we introduced a CFD framework that can reveal the effects of tracheostomy tube insertion based on a comparison with the airflow of a normal airways. An automatic transformation method was developed using a patient's anatomical information to combine subject-specific airways with an artificial tracheostomy tube geometry and an idealized upper airway geometry for later comparison of characteristics of airflow and particle transport. The CFD scheme used for flow simulation in lungs was employed to achieve the behaviors of airflow. The tracheostomy tube generates a jet flow, resulting in twice greater wall shear stress (WSS) and 30 times greater viscous dissipation in the trachea compared to normal airway. The tracheostomized airway induces an intense turbulent jet, which enhances chaotic motion of the particles therein and allows particles to deposit more frequently on the surface. Subsequently, an increase in particle deposition is observed on the central airway's surface. The variation of pressure between inspiration and expiration phase was twice greater and the airflow resistance was also significantly higher compared to normal airway, implying the greater work of breathing. The novel framework could evaluate the efficiency and potential complications in performing tracheostomy beforehand by observing airflow behaviors.