Single-breath diffusion capacity of the lungs for carbon monoxide in children with cystic fibrosis: methods of interpreting results

Abstract

Introduction. Progression of pulmonary and heart failure often causes death in patients with cystic fibrosis (95%). Therefore, monitoring of lung condition is very important for patients with cystic fibrosis (CF). Structural changes are visualized by computed tomography of the chest (CT) and are scored using the Brody scale. For children older than 5 years, pulmonary function tests (PFTs) tests (which are evaluated in percent of predicted (%) values) are available, such as spirometry, body plethysmography (BP), diffusion capacity of the lungs (DL) test. The results of the single-breath (SB) DL for carbon monoxide test are DLCO-SB, alveolar volume (VA-SB) and their ratio (KCO-SB). In the presence of non-communicative zones for gas perfusion, VA-SB may not present true VA. For patients with CF, it is proposed to use VA determined by BP for calculating KCO-BP, or to adjust the predicted DLCO-SB and KCO-SB for VA.Aim. To assess the informativeness DLCO-SB, KCO-SB and KCO-BP in children with CF.Materials and methods. 28 children with CF (8–18 years old) were examined in the department of pulmonology of the National Research Center for Children’s Health. PFTs included DLCO-SB, spirometry and BP. Additionally, we evaluated the data of the blood gas and acid-base values, age, body mass index and CT scores.Results and discussion. We found that in most patients DLCO-SB and KCO-SB were within the normal range, and decreased in children older than 14 years with background of severe bronchiectasis.Conclusion. Thus, in children with CF the DL test is informative, and adjustment for VA is useful.