Use of Dynamic Chest Radiography to Assess Treatment of Pulmonary Exacerbations in Cystic Fibrosis

Background Although spirometry is an important marker in the management of pulmonary exacerbations in cystic fibrosis (CF), it is a forced maneuver and can generate aerosol. Therefore, it may be difficult to perform in some individuals. Dynamic chest radiography (DCR) provides real-time information regarding pulmonary dynamics alongside fluoroscopic-style thoracic imaging. Purpose To assess the effect of pulmonary exacerbation treatment by using both spirometry and DCR and assess the clinical utility of DCR in participants with CF experiencing pulmonary exacerbations. Materials and Methods In this prospective, observational, single-center pilot study, spirometry and DCR were performed before and after treatment of pulmonary exacerbations in participants with CF between December 2019 and August 2020. Spirometry measured forced expiratory volume in 1 second (FEV₁) and forced vital capacity. DCR helped to measure projected lung area (PLA), hemidiaphragm midpoint position, and speed during tidal and deep breathing. Data were analyzed by using the paired t test or Wilcoxon signed-rank test. Correlation was assessed by using the Spearman rank correlation coefficient. Results Twenty participants with CF (mean age, 25 years ± 7 [standard deviation]; 14 women) were evaluated. Spirometry showed that percentage predicted FEV₁ improved from a median of 44% (interquartile range [IQR], 17%) before treatment to 55% (IQR, 16%) after treatment (P = .004). DCR showed improvement in median deep breathing excursion for left and right hemidiaphragms (from 18 [IQR, 11] to 25 [IQR, 16] mm [P = .03] and from 13 [IQR, 6] to 19 [IQR, 14] mm [P = .03], respectively) and in median expiratory speed following deep breathing for left and right hemidiaphragms (from 7 [IQR, 2] to 11 [IQR, 5] mm/sec [P = .004] and 6 [IQR, 3] to 9 [IQR, 6] mm/sec [P = .004], respectively). PLA rate of change during full expiration and change in PLA during tidal breathing improved (from a mean of 42 cm²/sec ± 16 to 56 cm²/sec ± 24 [P = .03] and from a mean of 29 cm² ± 14 to 35 cm² ± 10 [P = .03], respectively). Conclusion Dynamic chest radiography demonstrated improvement in diaphragm speed and range of chest wall movement during respiration aftere treatment for pulmonary exacerbations in cystic fibrosis and showed potential as a tool to investigate the effect of pulmonary exacerbations on lung mechanics. Clinical trials registration no. NCT01234567 Published under a CC BY 4.0 license. Online supplemental material is available for this article.