Hanna Knihtilä1, Anne Kotaniemi-Syrjänen2, Anna S Pelkonen2, Mika J Mäkelä2, L Pekka Malmberg2. 1. Pediatric Unit, Department of Allergy, Skin and Allergy Hospital, University of Helsinki and Helsinki University Hospital, Helsinki, Finland. Electronic address: hanna.knihtila@helsinki.fi. 2. Pediatric Unit, Department of Allergy, Skin and Allergy Hospital, University of Helsinki and Helsinki University Hospital, Helsinki, Finland.
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.
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.
Authors: Toby C Lewis; Ediri E Metitiri; Graciela B Mentz; Xiaodan Ren; Adam M Goldsmith; Breanna N Eder; Kyra E Wicklund; Megan P Walsh; Adam T Comstock; Jeannette M Ricci; Sean R Brennan; Ginger L Washington; Kendall B Owens; Bhramar Mukherjee; Thomas G Robins; Stuart A Batterman; Marc B Hershenson Journal: Ann Allergy Asthma Immunol Date: 2018-10-29 Impact factor: 6.347