Lung function determined by impulse oscillometry in preschoolers hospitalised for moderate or severe bronchiolitis in infancy

Abstract

Background: Bronchiolitis in infancy has been associated with reduced lung function and increased asthma prevalence in later life. Few studies have quantitatively assessed lung function in preschoolers after bronchiolitis and considered the severity of the illness. Aim: To assess lung function and bronchodilator response in preschoolers who have been hospitalised with either moderate or severe bronchiolitis in infancy. Subjects and methods: Using impulse oscillometry (IOS), we measured airway resistance (R), reactance (X), impedance (Z), resonant frequency (Fres) and reactance area (Ax) over 5-35Hz, both pre and post bronchodilator (6 inhalations of Salbutamol via spacer), in 46 preschoolers at a mean age of 45 months (range 39-54 months). Bronchiolitis severity was determined according to NSW Health clinical practice guideline (http://www0.health.nsw.gov.au/policies/pd/2012/pdf/PD2012_004.pdf). All infants with severe bronchiolitis and none with moderate bronchiolitis required intensive care unit admission. Results: There was no significant difference in R5Hz, X5Hz, Z5Hz, Fres and Ax between the severe (n=19) and moderate (n=20) bronchiolitis cohort before or after bronchodilator inhalation. The severe bronchiolitis cohort showed a greater bronchodilator response at R5Hz as compared to the moderate bronchiolitis cohort (mean % change/SD: -29.5/13.2 versus -12.6/16.6; p Conclusion: Preschoolers hospitalised for severe bronchiolitis in infancy may have a significantly greater rate of bronchodilator response than those admitted with moderate bronchiolitis.