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What Is New In Small Airways Research

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Research Reviews, September 2011

Allergist/Immunologist, Assistant Professor of Pediatrics, University of Chicago
Editor, WAO Small Airways Working Group website

Posted 19 September 2011


ATS guideline for exhaled nitric oxide levels (FENO) use


Measurement of fractional nitric oxide (NO) concentration in exhaled breath (FENO) is a quantitative and noninvasive method of measuring airway inflammation. The American Thoracic Society (ATS) aimed to develop evidence-based guidelines for the interpretation of FENO measurements.

FENO offers added advantages for patient care including:

  • detecting of eosinophilic airway inflammation
  • determining the likelihood of corticosteroid responsiveness
  • monitoring of airway inflammation to determine the potential need for corticosteroid
  • unmasking of otherwise unsuspected nonadherence to corticosteroid therapy

FENO cut-points

The guidelines propose a series of cut-points to help make clinical decisions:

  • FENO lower than 25 ppb (lower than 20 ppb in children) indicates that eosinophilic inflammation and responsiveness to inhaled corticosteroids are less likely.
  • FENO higher than 50 ppb (higher than 35 ppb in children) indicates that eosinophilic inflammation and, in symptomatic patients, responsiveness to inhaled corticosteroids are likely.
  • FENO values between 25 ppb and 50 ppb (20-35 ppb in children) should be interpreted cautiously with reference to clinical context.

Source: An Official ATS Clinical Practice Guideline: Interpretation of Exhaled Nitric Oxide Levels (FENO) for Clinical Applications. American Journal of Respiratory and Critical Care Medicine 2011;184(5): 602-615.
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Asthma exacerbations during pregnancy can be reduced with a FENO-based treatment algorithm, with a number needed to treat of 6

Asthma exacerbations during pregnancy are common and can be associated with substantial maternal and fetal morbidity. A recent article in The Lancet presented the results of a double-blind, controlled trial from Australia that included 220 pregnant, non-smoking women with asthma that were randomly assigned before 22 weeks gestation to treatment adjustment at monthly visits by an algorithm using clinical symptoms (control group) or FENO concentrations (active intervention group) used to uptitrate (FENO >29 ppb) or downtitrate (FENO <16 ppb) inhaled corticosteroid dose.

The exacerbation rate was lower in the FENO group than in the control group (0•288 vs 0•615 exacerbations per pregnancy; p=0•001). The number needed to treat was 6. In the FENO group, neonatal hospitalisations were reduced (8% vs. 17%; p=0•046). The authors concluded that asthma exacerbations during pregnancy can be reduced with a validated FENO-based treatment algorithm.

Source: Management of asthma in pregnancy guided by measurement of fraction of exhaled nitric oxide: a double-blind, randomised controlled trial. Ms Heather Powell MMedSc a b , Vanessa E Murphy PhD a, Prof D Robin Taylor MD c, Prof Michael J Hensley PhD a b, Kirsten McCaffery PhD d, Warwick Giles PhD d e, Vicki L Clifton PhD f, Prof Peter G Gibson MBBS a b g. The Lancet, 2011;9795(378):983-990.
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First validated questionnaire to assess respiratory and asthma control in young children, aged 2-5 (TRACK)
A validated questionnaire is needed to monitor respiratory control in preschool-aged children. The test for respiratory and asthma control in kids (TRACK) is a caregiver-completed questionnaire that has been in development and evaluation stage since 2008.

The Test for Respiratory and Asthma Control in Kids (TRACK) includes 5 items:

  • frequency of respiratory symptoms (wheeze, cough, shortness of breath)
  • activity limitation
  • nighttime awakenings in the past 4 weeks
  • rescue medication use in the past 3 months
  • oral corticosteroid use in the previous year

TRACK reliability is greater than 0.70. A prospective, nonrandomized, longitudinal study was conducted at 20 US pediatric sites, and included 426 children/caregivers at baseline and 396 children/caregivers at follow-up (4-6 weeks apart).

Scoring 10 or more points less than 80 on TRACK was associated with an approximately 2-fold increased odds of having uncontrolled asthma or respiratory symptoms. Changes in TRACK scores of 10 or more points represent changes in respiratory control status.

Source: Test for Respiratory and Asthma Control in Kids (TRACK): Clinically meaningful changes in score. Zeiger RS, Mellon M, Chipps B, Murphy KR, Schatz M, Kosinski M, Lampl K, Ramachandran S. Journal of Allergy and Clinical Immunology 2011 September 9. [Article in Press]
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Posted 19 September 2011

Last updated: Thursday, February 23rd, 2012