Very prematurely born infants wheezing at follow-up: lung function and risk factors

Objectives: To determine whether abnormalities of lung volume and/or airway function were associated with wheeze at follow-up in infants born very prematurely and to identify risk factors for wheeze. Design: Lung function data obtained at 1 year of age were collated from two cohorts of infants recruited into the UKOS and an RSV study, respectively. Setting: Infant pulmonary function laboratory. Patients: 111 infants (mean gestational age 26.3 (SD 1.6) weeks). Interventions: Lung function measurements at 1 year of age corrected for gestational age at birth. Diary cards and respiratory questionnaires were completed to document wheeze. Main outcome measures: Functional residual capacity (FRCpleth and FRCHe), airways resistance (R-aw), FRCHe: FRCpleth and tidal breathing parameters (T-PTEF:T-E). Results: The 60 infants who wheezed at follow-up had significantly lower mean FRCHe, FRCHe:FRCpleth and T-PTEF:T-E, but higher mean R-aw than the 51 without wheeze. Regression analysis demonstrated that gestational age, length at assessment, family history of atopy and a low FRCHe:FRCpleth were significantly associated with wheeze. Conclusions: Wheeze at follow-up in very prematurely born infants is associated with gas trapping, suggesting abnormalities of the small airways.