Rationale: The existence and significance of bronchodilator responsiveness in wheezy infants is unclear.
Objectives: To investigate whether bronchodilator responsiveness exists in infants and whether it is associated with the continuation of respiratory morbidity in early childhood.
Methods: Lung function testing was performed on infants (<2 years) with chronic or recurrent wheezing or coughing. Infants with an obstructive profile were included. The infants were divided into two groups based on whether a response to salbutamol was observed on lung function testing. A response was defined as a relative improvement of 20% or greater in maximal expiratory flow at the point of functional residual capacity (VmaxFRC), 20 minutes after salbutamol administration. Follow up data were gathered after a mean two years.
Measurements and Main Results: Sixty one infants were included in the study of whom 25 (41%) demonstrated responsiveness. The infants in the responsive group had a significantly higher frequency of physician visits for wheezing (3.4 mean visits/year vs. 1.5, P=0.03) and had a higher likelihood of having received asthma medication in the last year of the follow up period (84% vs. 55%, P=0.03). At the end of the follow up period more parents in the responsive group reported continuation of respiratory disease (67% vs. 30%, P=0.03). No connection was found between responsiveness and signs of atopy in the infant or in the family history.
Conclusions: Bronchodilator responsiveness can be demonstrated by LFT in infants with recurrent wheezing and can predict the continuation of increased respiratory morbidity until age 3 years.
