Tracheal compliance and limit flow rate changes in a murine model of asthma

Creation of an in vitro biomechanical model of the trachea using rapid prototyping

Previous in vitro models of the airways are either rigid or, if flexible, have not matched in vivo compliance characteristics. Rapid prototyping provides a quickly evolving approach that can be used to directly produce in vitro airway models using either rigid or flexible polymers. The objective of this study was to use rapid prototyping to directly produce a flexible hollow model that matches the biomechanical compliance of the trachea. The airway model consisted of a previously developed characteristic mouth-throat region, the trachea, and a portion of the main bronchi. Compliance of the tracheal region was known from a previous in vivo imaging study that reported cross-sectional areas over a range of internal pressures. The compliance of the tracheal region was matched to the in vivo data for a specific flexible resin by iteratively selecting the thicknesses and other dimensions of tracheal wall components. Seven iterative models were produced and illustrated highly non-linear expansion consisting of initial rapid size increase, a transition region, and continued slower size increase as pressure was increased. Thickness of the esophageal interface membrane and initial trachea indention were identified as key parameters with the final model correctly predicting all phases of expansion within a value of 5% of the in vivo data. Applications of the current biomechanical model are related to endotracheal intubation and include determination of effective mucus suctioning and evaluation of cuff sealing with respect to gases and secretions.

INFLUENCE OF XUANFEI–GUBEN PRESCRIPTION ON MECHANICAL CHARACTERISTICS OF AIRWAY REMODELING IN ASTHMATIC RATS

During the past few years, studies of structural and functional changes in living tissues in adaptation to the mechanical environment have become a major focus of medical research. The mechanical characteristics during asthma airway remodeling have begun to attract the attention of scholars. Repeated episodes of asthma influence the quality of life for patients' and their families. To explore effective therapies for asthma is a high priority for medical researchers. The purpose of the current study was to determine the mechanical characteristics of asthmatic airways in rats and the effects of Xuanfei–Guben on the airways. Thus, Xuanfei–Guben and dexamethasone were used as treatment in an ovalbumin copy asthmatic rats model. A multi-channel physiological signal acquisition and processing system and an injection pump was used to establish a biomechanical testing system. Compliance of asthmatic rat lung compliance and alveolar maximum stress and duration were determined in vitro. When rat lungs were perfused with ≤ 3 mL saline in vitro, there was no significant difference in pressure across the group. After 4 mL of water was perfused, the transpulmonary pressure increased significantly in the other groups compared with the normal group. The transpulmonary pressure in Xuanfei–Guben treatment group was less than the model and dexamethasone groups. Asthmatic rat lung compliance is poor, and a traditional Chinese medicine can improve lung compliance.