Abstract
IntroductionIn Cystic Fibrosis (CF), exercise ventilatory inefficiency and dynamic hyperinflation (DH) cause exercise limitation and induce poor exercise tolerance. High-resolution computed tomography (HRCT) of the lung can detect pulmonary abnormalities in CF patients. We aimed to identify the determinants of exercise ventilatory inefficiency and DH using HRCT-derived metrics.MethodsFifty-two adult CF patients were prospectively enrolled; all participants underwent cardio-pulmonary exercise test (CPET) and HRCT. Radiological impairment was evaluated by the Brody II scoring system. Slope and intercept of the minute ventilation/CO2 production (V’E/V’CO2) regression line and the ratio of inspiratory capacity/total lung capacity (IC/TLC) at rest and at peak of exercise were measured.ResultsFour groups of patients were identified based on the combination of ventilatory efficiency (Vef) or inefficiency (Vin) and the presence/absence of DH. Compared to other groups, CF adults with Vin and DH had worse functional status and higher total (T), bronchiectasis (B) and air trapping (AT) scores at HRCT. Significant correlations were found between V’E/V’CO2 intercept and V’E/V’CO2 slope (ρ − 0.455, p = 0.001) and between V’E/V’CO2 intercept and Δ inspiratory capacity (IC) (ρ − 0.334, p = 0.015). Regression analysis identified AT score (cut-off 7.9, odds ratio-OR 3.50) as the only independent predictor of Vin and T (cut-off 53.6, OR 4.98), B (cut-off 16.1, OR 4.88), airways wall thickening (AWT) (cut-off 13, OR 3.41), and mucous plugging (MP) scores (cut-off 11.7, OR 4.18) as significant predictors of DH.ConclusionIn adult CF cohort, values of HRCT metrics are determinants of Vin (AT) and DH (T, B, AWT, MP).
Highlights
In Cystic Fibrosis (CF), exercise ventilatory inefficiency and dynamic hyperinflation (DH) cause exercise limitation and induce poor exercise tolerance
Variables related to spirometry and cardio-pulmonary exercise test (CPET) demonstrated that, in comparison to patients with ventilatory efficiency (Vef) and without DH and patients with ventilatory inefficiency (Vin) and without DH, patients with Vin and with DH had statistically significant lower values of
Examples of High-resolution computed tomography (HRCT) metrics according to the Brody II score are provided in Fig. 1, while in Fig. 2 are illustrated for all patients the HRCT variables related to the Brody II scores
Summary
In Cystic Fibrosis (CF), exercise ventilatory inefficiency and dynamic hyperinflation (DH) cause exercise limitation and induce poor exercise tolerance. High-resolution computed tomography (HRCT) of the lung can detect pulmonary abnormalities in CF patients. In adults with CF, a high prevalence of exercise dynamic hyperinflation (DH) was found, secondary to the development of air trapping during exercise; DH was shown to be associated to poor resting lung function, reduced exercise tolerance and increased exertional dyspnea [6]. High-resolution computed tomography (HRCT) of the lung is able to demonstrate a broad range of pulmonary abnormalities in CF patients with mild-to-moderate lung disease [7], identifying lower airway inflammation and early lung impairments [8]. In CF patients, higher Brody scores indicate more severe disease [7]; they are strongly associated with lung disease progression [10], predicting the rate of pulmonary exacerbations up to 10-year follow-up [11]
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