Small airway function in children with mild to moderate asthmatic symptoms

Ann Allergy Asthma Immunol. 2018 Oct;121(4):451-457. doi: 10.1016/j.anai.2018.07.026. Epub 2018 Jul 27.

Abstract

Background: Clinical significance of small airway obstruction in mild pediatric asthma is unclear.

Objective: To evaluate small airway properties in children with mild to moderate asthmatic symptoms and the association of small airway function with asthma control and exercise-induced bronchoconstriction (EIB).

Methods: Children (5-10 years old) with recurrent wheezing (n = 42) or persistent troublesome cough (n = 16) and healthy controls (n = 19) performed impulse oscillometry (IOS), spirometry, and a multiple-breath nitrogen washout (MBNW) test. Exhaled nitric oxide (NO) was measured at multiple flow rates to determine alveolar NO concentration (Calv). Asthma control was evaluated with the Childhood Asthma Control Test (C-ACT), short-acting β2-agonist (SABA) use within the past month, and asthma exacerbations within the past year.

Results: IOS, spirometry, and exhaled NO indexes that are related to small airway function differed between children with recurrent wheezing and healthy controls, whereas only forced expiratory flow at 25% to 75% of the forced vital capacity was associated with persistent cough. The MBNW indexes showed no difference between the groups. Among symptomatic children, conducting airway ventilation inhomogeneity and Calv were associated with asthma exacerbations (P = .03 and P = .002, respectively), and lung clearance index and Calv were associated with EIB (P = .04 and P = .004, respectively). None of the proposed small airway indexes was associated with the C-ACT score or SABA use.

Conclusion: Subtle changes were observed in the proposed small airway indexes of IOS, spirometry, and exhaled NO among children with mild to moderate recurrent wheezing. Small airway dysfunction, expressed as ventilation inhomogeneity indexes and Calv, was also associated with asthma exacerbations and EIB.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adrenergic beta-2 Receptor Agonists / therapeutic use
  • Airway Obstruction / diagnosis*
  • Airway Obstruction / drug therapy
  • Asthma / diagnosis*
  • Asthma / drug therapy
  • Asthma, Exercise-Induced / diagnosis*
  • Asthma, Exercise-Induced / drug therapy
  • Breath Tests
  • Child
  • Child, Preschool
  • Female
  • Humans
  • Male
  • Nitric Oxide / metabolism
  • Oscillometry
  • Respiratory Function Tests
  • Respiratory System / physiopathology*
  • Spirometry

Substances

  • Adrenergic beta-2 Receptor Agonists
  • Nitric Oxide