Efficiency of ventilation in neonatal pulmonary maladaptation.

Lung physiology was studied in sixteen infants with pulmonary maladaptation (PMA) during the course of the disease and after clinical recovery. A sensitive nitrogen washout method was used. During the disease the infants showed reduced ventilatory efficiency and increased dead space. Total ventilation increased simultaneously, while alveolar ventilation was maintained. The majority of the infants showed greater functional residual capacity during the disease than after clinical recovery. The results suggest that gas mixing efficiency is impaired in infants with PMA and that this might be due to effects on the small airway function in the lungs.