Impulse oscillometry (IOS) identifies uncontrolled asthma in children
Published Online: December 19, 2011
Assessing asthma control in children is particularly challenging for many reasons including a discrepancy in perceived symptoms between the child and parents, and the poor correlation between symptoms and traditional objective tests such as spirometry. Impulse oscillometry (IOS) being a new non-invasive technique has been increasingly used for the diagnosis of asthma. IOS is effort-independent and able to separately quantify the obstructions in proximal and distal airways, but has not previously been utilized to assess asthma control in children.
In a recent article in The Journal of Allergy and Clinical Immunology (JACI), Shi et al. measured IOS in 101 children (6-17 yrs) with mild-to-moderate asthma. Physicians were blinded to the IOS data and used symptom history and standard spirometry to assess asthma control according to ATS guidelines. The researchers compared the IOS indices of small and large airways between controlled versus uncontrolled asthma and established IOS cut-points to identify uncontrolled asthma in children.
The authors found small airway IOS measurements were significantly higher in uncontrolled asthma children compared to controlled asthma. However, there was no difference in large airway IOS parameters. Cut-points of the small airway IOS including frequency dependence of resistance (R5-20, 1.5 cmH2O∙L-1∙s) and reactance area (AX, 9.5 cmH2O∙L-1) were able to effectively discriminate controlled versus uncontrolled asthma, and correctly classified more than 80% of the population.
These findings strongly support that uncontrolled asthma is associated with distal airway obstruction. IOS is simple for the patients to perform, and provides additional information to the traditional history and spirometry. IOS can be useful in the clinical assessment of asthma control in children.
The Journal of Allergy and Clinical Immunology (JACI) is the official scientific journal of the AAAAI, and is the most-cited journal in the field of allergy and clinical immunology.