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Interrupter resistance to measure dose-response to salbutamol in wheezy preschool children

Using a non‐invasive lung function technique (interrupter resistance, Rint), we aimed to determine whether a dose‐response to salbutamol could be detected in wheezy preschool children and if so, which dose of salbutamol should be administered to routinely evaluate bronchial reversibility.

Measuring Airway Obstruction in Severe Asthma in Children

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.

Lung Function Tests in Preschool Children

The measurement of lung function by spirometry is routinely used to monitor and adequately treat children with asthma. The assessment and evaluation of lung function in children aged 3-5 years has been neglected for a long time because of the difficulty to perform forced expiratory maneuvers. However, the use of techniques such as the interrupter technique and the forced oscillation technique, which only require passive collaboration and where the only request to the child is to breathe at tidal volume, has overcome this limitation. Other techniques such as the measurement of specific airway resistance by plethysmography or the measurement of the lung clearance index using the multiple-breath washout might be helpful in this regard, although these techniques are less standardized in preschool children.