Visualization of dynamic airway bronchoconstriction in live rats (870.6)

Abstract

Airway hyperresponsiveness severely limits gas exchange in patients with asthma. Imaging studies have shown that bronchoconstriction causes patchy patterns of ventilation defects throughout the lungs, and computational models have predicted that these regions are due to constriction of small airways. Since these imaging approaches are limited in their ability to capture dynamic changes in small airways, we utilized tantalum dust and microfocal X‐ray imaging of rat lungs to obtain dynamic images of airways in an intact animal model. The flexiVent system was used to simultaneously measure airway resistance. Custom software was used to track changes in airway diameters up to 13 generations (~0.3 mm to 3 mm in diameter). The objective of the study was to identify the size and location of airways with changes in diameter during bronchoconstriction in response to methacholine. In contrast with the model predictions, we observed significantly greater percent constriction in larger airways in response to methacholine challenge. Although there was a dose‐dependent increase in airway resistance, the percent change in airway diameters was similar for increasing doses. Paradoxically, a deep inspiration following methacholine caused greater percent constriction in smaller airways. These measurements allow us to directly quantify dynamic changes in airways during bronchoconstriction.Grant Funding Source: Supported by NIH HL094366 (CMW) and APS UGSRF (TNP)