Ventilation inhomogeneity in infants with recurrent wheezing

Background The care of infants with recurrent wheezing relies largely on clinical assessment. The lung clearance index (LCI), a measure of ventilation inhomogeneity, is a sensitive marker of early airway disease in children with cystic fibrosis, but its utility has not been explored in infants with recurrent wheezing. Objective To assess ventilation inhomogeneity using LCI among infants with a history of recurrent wheezing compared with healthy controls. Methods This is a case–control study, including 37 infants with recurrent wheezing recruited from outpatient clinics, and 113 healthy infants from a longitudinal birth cohort, the Canadian Healthy Infant Longitudinal Development study. All infants, at a time of clinical stability, underwent functional assessment including multiple breath washout, forced expiratory flows and body plethysmography. Results LCI z-score values among infants with recurrent wheeze were 0.84 units (95% CI 0.41 to 1.26) higher than healthy infants (mean (95% CI): 0.26 (−0.11 to 0.63) vs −0.58 (−0.79 to 0.36), p 1.64 z-scores). Elevated exhaled nitric oxide, but not symptoms, was associated with abnormal LCI values in infants with recurrent wheeze (p=0.05). Conclusions Ventilation inhomogeneity is present in clinically stable infants with recurrent wheezing.