Lung Function Deterioration in School Children with Cystic Fibrosis.

INTRODUCTION Lung disease in cystic fibrosis (CF) begins early in life but the capabilities for detecting abnormalities of pulmonary dysfunction in children remain limited. OBJECTIVES The study aimed to evaluate the early progression of lung function by the analysis of pulmonary hyperinflation, ventilation inhomogeneity (VI), trapped gas and airway obstruction with age. METHODS One hundred CF children aged 7-18, divided into two groups aged 7-12 (n=40) and 13-18 (n=60), were enrolled. Patients performed MBNW tests and plethysmography for measurements of lung clearance index (LCI), functional residual capacity (FRCpleth , FRCMBNW ), volume of trapped gas (VT ), total resistance (Rtot ), and effective and specific effective airway resistance (Reff , sReff ). RESULTS We obtained a positive correlation of FRCpleth , FRCMBNW , and LCI with age. A linear correlation between FRCMBNW and FRCpleth (p 2 z-score) was present in 58% of all subjects (50%, 63.3% respectively). Pulmonary hyperinflation (FRCpleth >2 z-score) was observed in 33% of all patients: 25%, 36.6 % respectively. Trapped gas (VT >2 z-score) was present in 18% of all children: 30%, 10% respectively. CONCLUSIONS A gradual decline in lung function is associated with an increase in ventilation inhomogeneity, airway obstruction, pulmonary hyperinflation and development of trapped gas. In children who cannot perform either spirometry or plethysmography, MBNW can deliver a measurement of LCI connecting with VI as well as FRCMBNW to indicate indirectly the increase of hyperinflation. This article is protected by copyright. All rights reserved.