Frequency dependence of resistance (R5-20) assessed by impulse oscillometry (IOS) is suggested to be a measure of small airways. Small airways involvement during induced bronchoconstriction has been shown to reflect severity of asthma in adults.
The researchers from Finland evaluated if methacholine (Mch) induced changes in R5-20 are associated with the severity of exercise induced bronchoconstriction (EIB) in 109 young children, aged 3-8 years (95 with obstructive symptoms, 14 healthy controls).
R5-20 was measured at baseline and after the Mch challenge. In a standardized exercise test, the children were grouped according to the severity of EIB expressed as the percentage increase in resistance at 5 Hz (ΔR5).
The baseline R5-20 was not associated with the severity of EIB. However, the change in R5-20 during Mch induced bronchoconstriction was significantly higher in children with severe EIB.
Frequency dependence of resistance (R5-20) measured by IOS during the Mch induced bronchoconstriction is associated with severe EIB in young children.
Aberrant small airways function relates to asthma severity in young children. Kalliola S et al. Respir Med. 2015 Dec 19. pii: S0954-6111(15)30097-4. doi: 10.1016/j.rmed.2015.12.006. [Epub ahead of print]
The World Allergy Organization (WAO) Small Airways Working Group publishes a monthly "What's New?" summary and I have served as its editor since 2011. The summary features the top 3 asthma/small airways articles each month. The article above is a part of the project. The archive is here: http://www.worldallergy.org/small_airways_group/reviews/archive.php