Measuring Airway Obstruction in Severe Asthma in Children

Abstract

Lung function is an important tool in the diagnosis and monitoring of patients with asthma at all ages. Airway obstruction is a typical feature of asthma and it can be assessed with several lung function techniques. Spirometry, respiratory resistance and reactance, and lung volumes are available to measure it at different ages and in children. The assessment of a bronchodilator response is always recommended to show the reversibility of the obstruction. Poor lung function is a predictor of poor asthma outcome and a low Forced Expiratory Volume in the first second of expiration percent predicted measured with spirometry, has been shown to be associated with a higher risk of having an exacerbation during the following year independently of the presence of asthma symptoms. In severe asthma lung function assessment is used to distinguish different phenotypes, children with severe asthma have worse airflow limitation prior to administration of a bronchodilator than children with non severe asthma. Airway resistance and reactance are indirect measurements of airway obstruction and they can be measured with the forced oscillation technique, which is feasible also in non-collaborative children. This technique can be more informative in discriminating patients with asthma from healthy controls and is able to indicate a more peripheral involvement of the airways. The role of this technique in severe asthma is still debated. In conclusion lung function is useful in the clinical management of children with severe asthma.

Approaches to Asthma Diagnosis in Children and Adults

“…As a result, the application of tidal breathing or effort independent tests is currently limited predominantly to the research setting and being tested mainly in preschool children being assessed at specialist centers. The assessment of airway obstruction in children with severe asthma has been reviewed elsewhere (55) and the utility of forced oscillation technique and impulse oscillometry for asthma diagnosis have also been reviewed (56).…”

Impact of parasitic infection with Ascaris lumbricoides on pulmonary function tests in asthmatic and non-asthmatic children

“…The significant change in the PFT was only due to the effect of asthma, even in case of mild obstruction. Asthma results in a decline in PFT especially FEV1 and FEV1% because of the limitation of airflow that occurs as a result of the allergic inflammatory process which characterized by edema of air passages and bronchoconstriction that lead to increased airway resistance [ [16] , [17] , [18] , [19] ]. This result was consistent with previous studies [ 11 , 18 ].…”

Overview of Severe Asthma, with Emphasis on Pediatric Patients: A Review for Practitioners

“…Obtaining reproducible and acceptable flow-volume loops in young children may be difficult 57. Children may also have an intact FEV 1 and therefore the FEV 1 :FVC ratio (<80%) is an important obstruction marker in children 58. The utility of forced expiratory flow 25–75 is controversial because it lacks specificity and is not reliable 59.…”