Airways resistance and lung volume before and after bronchodilator therapy in symptomatic preterm infants.

Preterm infants who are symptomatic at follow-up frequently have a high airways resistance (RAW) and a low functional residual capacity to thoracic gas volume ratio (FRC:TGV). The aim of this study was to assess the effect of bronchodilator therapy on these lung function abnormalities. Thirty-four infants who had recurrent respiratory symptoms and a median gestational age 28 weeks, were studied at a median postnatal age of 10 months (range 6-20). TGV and RAW were measured using a plethysmographic technique and FRC by helium gas dilution. Specific conductance (SGAW) was calculated from TGV and RAW. All measurements were made immediately before and 15 min after nebulized salbutamol. Administration of nebulized salbutamol was associated with a reduction of RAW (P < 0.001) and an increase in SGAW (P < 0.001), FRC (P < 0.001). These effects on lung function were independent of postnatal age.