The use of pulmonary function tests (PFTs) has been widely described in airway diseases like asthma and cystic fibrosis, but for children's interstitial lung disease (chILD), which encompasses a broad spectrum of pathologies, the usefulness of PFTs is still undetermined, despite widespread use in adult interstitial lung disease. A literature review was initiated by the COST/Enter chILD working group aiming to describe published studies, to identify gaps in knowledge and to propose future research goals in regard to spirometry, whole-body plethysmography, infant and pre-school PFTs, measurement of diffusing capacity, multiple breath washout and cardiopulmonary exercise tests in chILD. The search revealed a limited number of papers published in the past three decades, of which the majority were descriptive and did not report pulmonary function as the main outcome.PFTs may be useful in different stages of management of children with suspected or confirmed chILD, but the chILD spectrum is diverse and includes a heterogeneous patient group in all ages. Research studies in well-defined patient cohorts are needed to establish which PFT and outcomes are most relevant for diagnosis, evaluation of disease severity and course, and monitoring individual conditions both for improvement in clinical care and as end-points in future randomised controlled trials.

Clinic for Paediatric Pneumology Allergology and Neonatology Medizinische Hochschule Hannover Zentrum fur Kinderheilkunde und Jugendmedizin Hannover Germany

Dept of Paediatrics Univerzita Karlova Praha 2 lekarska fakulta Prague Czech Republic

Dept of Pediatrics University of Padova Padova Italy

Institute of Biomedical Research and Innovation National Research Council of Italy Palermo Italy

Joint first authors

Joint last authors

Neumologia Infantil y Unidad de Cuidados Intensivos Pediatricos Hospital Universitario Salamanca Salamanca Spain

Paediatric Pulmonary Service Dept of Paediatrics and Adolescent Medicine Copenhagen University Hospital Rigshospitalet Danish PCD and chILD Centre CF Centre Copenhagen Copenhagen Denmark

Paediatric Respiratory Medicine Royal Brompton and Harefield NHS Foundation Trust London UK

Paediatrics and Paediatric Respiratory Medicine Imperial College London London UK

Pediatric Pulmonary Unit Anna Meyer Pediatric University Hospital Florence Italy

Pediatric pulmonology KUL UZ Gasthuisberg Leuven Belgium

Unidad de Neumología infantil y Fibrosis quística Hospital Clínico Universitario de Valencia Valencia Spain

University Hospital of Munich Dr von Hauner Children's Hospital German Center for Lung Research Munich Germany

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Diffuse alveolar haemorrhage in children: an international multicentre study