The Journal of Allergy and Clinical Immunology
Volume 122, Issue 4 , Pages 781-787.e8, October 2008

Effects of time, albuterol, and budesonide on the shape of the flow-volume loop in children with asthma

  • Anand C. Patel, MD

      Affiliations

    • Division of Allergy/Pulmonary Medicine, Department of Pediatrics, Washington University School of Medicine, and St Louis Children's Hospital, St Louis, Mo
    • Corresponding Author InformationReprint requests: Anand C. Patel, MD, Washington University School of Medicine, 660 S Euclid Ave, Campus Box 8052, St Louis, MO 63110.
    • ,
  • Mark L. Van Natta, MHS

      Affiliations

    • Childhood Asthma Management Program Coordinating Center, the Johns Hopkins Bloomberg School of Public Health, Baltimore, Md
    • ,
  • James Tonascia, PhD

      Affiliations

    • Childhood Asthma Management Program Coordinating Center, the Johns Hopkins Bloomberg School of Public Health, Baltimore, Md
    • ,
  • Robert A. Wise, MD

      Affiliations

    • Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, the Johns Hopkins University School of Medicine, Baltimore, Md
    • ,
  • Robert C. Strunk, MD

      Affiliations

    • Division of Allergy/Pulmonary Medicine, Department of Pediatrics, Washington University School of Medicine, and St Louis Children's Hospital, St Louis, Mo
    • ,
  • Childhood Asthma Management Program Research Group

Received 15 August 2007; received in revised form 13 August 2008; accepted 15 August 2008.

Background

Assessment of asthma through spirometric analysis in children is challenging because of often normal FEV1 values.

Objective

We used Mead's slope ratio (SR; ) to analyze the shape of the flow-volume loop.

Methods

We analyzed the effects of time, albuterol, and budesonide on FEV1, FEV1/forced vital capacity (FVC) ratio, forced expiratory flow from 25% to 75% of expired volume, and Mead's SR both early (between 75% and 50% of FVC, SR61) and late (between 75% and 50% of FVC, SR35) in exhalation in the Childhood Asthma Management Program cohort at baseline, 4 months, and the end of the study in participants who received either inhaled placebo or budesonide twice daily.

Results

In the placebo group both SR61 and SR35 improved over time. Bronchodilator consistently improved both SR61 and SR35, without change in degree of improvement over time. Similarly, in the budesonide group time and bronchodilator each independently improved both SR61 and SR35. At 4 months and the end of the study, patients receiving budesonide had significant improvements in SR61 relative to patients receiving placebo, which was independent of bronchodilator effect. Budesonide and placebo were not different with respect to prebronchodilator or postbronchodilator SR35.

Conclusion

Budesonide-treated patients have less concave flow-volume loops when compared with placebo-treated patients. Time and bronchodilator also make the flow-volume loop less concave. Furthermore, it appears that there are discrete bronchodilator- and corticosteroid-responsive components of airflow obstruction in pediatric asthma.

Key words: Spirometry, slope ratio, asthma, pediatric, children

Abbreviations used: CAMP, Childhood Asthma Management Program, COPD, Chronic obstructive pulmonary disease, FEF25-75, Forced expiratory flow from 25% to 75% of expired volume, FVC, Forced vital capacity, MEFVL, Maximal expiratory flow-volume loop, SR, Slope ratio, SR35, Slope ratio at 35% FVC, SR61, Slope ratio at 61% FVC

 

 Supported by T32 HL007317 from the National Heart, Lung, and Blood Institute. The Childhood Asthma Management Program is supported by contracts NO1-HR-16044, 16045, 16046, 16047, 16048, 16049, 16050, 16051, and 16052 with the National Heart, Lung, and Blood Institute and General Clinical Research Center grants M01RR00051, M01RR0099718-24, M01RR02719-14, and RR00036 from the National Center for Research Resources.

 Disclosure of potential conflict of interest: R. A. Wise has consulting arrangements with AstraZeneca, Genentech, GlaxoSmithKline, and Novartis and has received research support from GlaxoSmithKline. The rest of the authors have declared that they have no conflict of interest.

PII: S0091-6749(08)01503-0

doi:10.1016/j.jaci.2008.08.010

The Journal of Allergy and Clinical Immunology
Volume 122, Issue 4 , Pages 781-787.e8, October 2008

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