Abstract Introduction Characterizing the impact of distending pressure on airway structure across different generations is useful for guiding fluid-structure interaction in computational modeling of airflow in the lungs. We evaluated the impact of airway pressure and lung volume on airway lengths, diameters, branching angles, and curvature of porcine airway segments in-vivo. Specifically, we quantified pressure-induced structural changes in porcine airway segments, by analyzing CT-derived morphometry from the trachea to the fourth generation during static breath holds at multiple distending pressures. Methods Whole-lung CT scans from six porcine subjects (39.0 to 47.7 kg) under anesthesia were obtained at constant airway pressures from 30 to 0 cmH2O in decrements of 5 cmH2O. 3D Slicer and Vascular Modeling Toolkit were used to semi-automatically segment and skeletonize the airway trees from the CT images. For each subject, the same airway segments were matched across all distending pressures. Segments included the trachea, and one airway segment from the 1st to the 4th generation, for left and right lungs. Airway lengths, diameters, branching angles, and curvatures were normalized to the maximum values and averaged across all subjects. ANOVA was used to compare dimensions across pressures, with p 0.01 considered statistically significant. Results Figure 1 shows the trend across all geometric parameters. Tracheal, as well as left and right lung diameters across all generations from 30 to 15 cmH2O were significantly different than those at 5 and 0 cmH2O. Significant differences in curvature were observed in the first generation of the right lung only. Curvatures at 25 and 15 cmH2O were significantly different from the curvature at 0 cmH2O. For branching angles, significant differences were observed in the second and fourth generations of the left lung. Branching angles for pressures between 30 and 25 cmH2O were significantly different from the angle at 0 cmH2O for both generations. No significant differences in curvatures were observed in the right lung across generations. Conclusions Our data indicate that airway diameter is significantly dependent on distending pressure for all generations examined. Tracheal diameter, as well as right and left lung airway diameters, exhibited a curvilinear dependence on pressure. Tracheal length, as well as right and left lung airway lengths, were fairly constant, while curvature and branching angles showed no consistency. These results highlight the interplay between airway mechanics and distending pressure, which may be important for improving computational airflow simulations and refining models of airway mechanics under healthy and diseased conditions. This abstract is funded by: T32 HL144461- 03, W81XWH-16-1-0434, W81XWH-21-1-0507, W911NF-23-1-0004
Akor et al. (Fri,) studied this question.