Impact of airway obstruction on lung function in very preterm infants at term.

OBJECTIVE

Morbidity and mortality in preterm infants is significantly determined by the development of pulmonary complications. We thus investigated the impact of obstructive ventilatory disorders on lung function in very preterm infants with a history of respiratory distress syndrome and/or bronchopulmonary dysplasia using repeated body plethysmographic measurements before and after bronchodilation.

DESIGN

Lung function, including effective airway resistance (Raw), specific conductance (SGaw), functional residual capacity (FRCbox), and total respiratory system compliance (Crs, multiple occlusion technique) was assessed in 27 preterm infants pound31 wks gestational age at a median postmenstrual age of 38 wks after mild oral sedation before and after inhalation of nebulized salbutamol (1.25 mg/2.5 mL; PARI JuniorBOY N) using the MasterScreen Baby Body (Jaeger, Hoechberg, Germany).

RESULTS

In preterm infants median Raw was initially found to be within the normal range as determined for healthy term newborns, but decreased significantly after administration of salbutamol; SGaw changed accordingly. FRCbox was significantly reduced compared with healthy term newborns (16.6 vs. 19.6 mL/kg, mean) and decreased further after bronchodilation, whereas Crs was not significantly altered.

CONCLUSIONS

This is the first report quantifying the important impact of obstructive ventilatory disorders on lung function in very preterm infants at term. Besides its important role in preterm lung function consecutive overinflation could furthermore be shown to mask reduction of lung volume in these infants. Thus, body plethysmographic measurements seem to be an important diagnostic tool in preterm infants at term before hospital discharge in order to quantify ventilation disorders and to define therapeutic strategies.