Negative bronchodilator response can exclude asthma in young kids


27 Oct 2016

Spirometry can be useful in preschool aged children to help predict asthma – with a bronchodilator response based on FEV0.75 shown to offer the most discrimination, Australia experts say.

The research, conducted in a cohort of 720 preschoolers in Argentina, found an 11% increase in FEV0.75 was the threshold for a positive bronchodilator response.

A negative bronchodilator response could exclude a diagnosis of asthma in young children with a high degree of certainty.

Co-researcher Professor Peter Sly, director of the WHO Collaborating Centre for Children’s Health and the Environment at the University of Queensland, told the limbic the findings were as relevant in resource-limited settings in Australia.

“We know that in Australia about 40% of preschoolers have recurrent episodes of wheeze but only about a third of those children develop persistent asthma.”

“Yet it is difficult to ensure that young children who do not require medications such as inhaled corticosteroids and combination treatments are not inappropriately treated and exposed to potential side effects.”

He said the next question to answer was whether it was safe and effective to take those predictions and not treat, or only treat symptoms, in the children who were unlikely to have asthma.

Professor Sly said the study confirmed that FEV1 was not effective in children younger than five or six who would completely empty their lungs within one second.

“FEV0.75 in young children is physiologically comparable to FEV1 in older children and adults and this study shows that spirometry can be useful if performed carefully.”

However he said design issues with some spirometers and training inconsistencies in how to perform spirometry sometimes conspired against the reliable measurement of airflow limitation in young children, particularly outside specialised respiratory laboratories.

“Ideally we shouldn’t have to rely on forced expiration but on tidal breathing and easier tests which are more sensitive to airway obstruction in this age group.”

The study was published in Thorax.

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