Availabe time for inclusion ended (master thesis)

Chronic respiratory diseases (CRDs) affect the airways and other structures of the lungs and thereby lead to ventilation inhomogeneity. The most common CRDs in children are asthma, bronchiectasis and cystic fibrosis (CF). All three are obstructive diseases. However, while asthma is mostly characterized by obstruction due to bronchoconstriction of the airways, obstruction in bronchiectasis and CF originates primarily from mucus retention due to abnormal airway clearance mechanisms.

The Nitrogen Multiple Breath Washout test (N2-MBW-test) is a robust and sensitive detector of early pulmonary changes and ventilation inhomogeneity. The minimal cooperation which is required for this test makes it very convenient for use in any age category.

Research on LCI described it as a reliable indicator of obstructive lung disease in pediatric CF patients as from 6 years of age. Whether LCI is a reliable parameter for early lung disease in asthma children is less clearly demonstrated. No data were found on LCI calculated from the N2-MBW-test in children with bronchiectasis.

Subjects of all the intervention groups will perform three consecutive nitrogen multiple breath washout tests (N2-MBW-tests) when attending the Universitair Ziekenhuis Brussel (UZB) for their scheduled pulmonology consultation. Only the best measurement (based on LCI result) will be taken into account when comparing the groups. Every subject will be positioned in the same seated position.

Inclusion Criteria:

• Patients with stable asthma
• Patients with non-CF bronchiectasis
• Patients with cystic fibrosis
• Aged 6-17 years
• FEV1 (%pred) >50%
• Written informed consent from the parents or legal guardian

Exclusion Criteria:

• Unstable disease (e.g. pulmonary exacerbation, acute deterioration, acute asthma crisis)
• Patients mentally not capable to participate in the study