Houston Area Pediatric Specialists

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Saturday, April 20, 2013

Advanced Lung Function Testing in Children/Adolescents With Asthma

A major problem in pediatric asthma is getting objective, reliable data about how a child's lungs function.  Much of the testing available in children requires exceptional breathing efforts that force a child's lungs to perform in a somewhat artificial way.  These tests include spirometry, a highly researched and standardized test that is used to assess asthma control.  However, it is often difficult to perform in young children, fails to properly identify "small airways disease" in many cases, and is often too insensitive to diagnose asthma in some children.  Impulse oscillometry offers a solution to these problems by providing an effort independent, highly sensitive and reproducible test which can be performed in very young children (often as young as 3 years).  Moreover, it is the test of choice to identify the location of the problem in many children with asthma  --  the "small airways".  A growing body of research including the reference below suggest that impulse oscillometry (IOS) should have greater use in a pediatric asthma practice.  Dr. Susarla

Peripheral airway impairment measured by oscillometry predicts loss of asthma control in children.


Department of Biomedical Engineering, University of California, Irvine, Calif.



We previously showed that impulse oscillometry (IOS) indices of peripheral airway function are associated with asthma control inchildren. However, little data exist on whether dysfunction in the peripheral airways can predict loss of asthma control.


We sought to determine the utility of peripheral airway impairment, as measured by IOS, in predicting loss of asthma control inchildren.


Fifty-four children (age, 7-17 years) with controlled asthma were enrolled in the study. Spirometric and IOS indices of airway function were obtained at baseline and at a follow-up visit 8 to 12 weeks later. Physicians who were blinded to the IOS measurements assessed asthma control (National Asthma Education and Prevention Program guidelines) on both visits and prescribed no medication change between visits.


Thirty-eight (70%) patients maintained asthma control between 2 visits (group C-C), and 16 patients had asthma that became uncontrolled on the follow-up visit (group C-UC). There was no difference in baseline spirometric results between the C-C and C-UC groups, except for FEV(1)/forced vital capacity ratio (86% vs 82%, respectively; P < .01). Baseline IOS results, including resistance of the respiratory system at 5 Hz (R5; 6.4 vs 4.3 cm H(2)O · L(-1) · s), frequency dependence of resistance (difference of R5 and resistance of the respiratory system at 20 Hz [R5-20]; 2.0 vs 0.7 cm H(2)O · L(-1) · s), and reactance area (13.1 vs 4.1 cm H(2)O · L(-1)), of group C-UC were significantly higher than those of group C-C (P < .01). Receiver operating characteristic analysis showed baseline R5-20 and reactance area effectively predicted asthma control status at the follow-up visit (area under the curve, 0.91 and 0.90).


Children with controlled asthma who have increased peripheral airway IOS indices are at risk of losing asthma control.
 2012 Nov 10. pii: S0091-6749(12)01544-8. doi: 10.1016/j.jaci.2012.09.022.

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