Pulmonary function studies in long-term survivors with artificial ventilation in the neonatal period

Lung function tests in 11 children aged 2.5--5.5 years who required intermittent positive pressure ventilation (1--624 hrs) in infancy were obtained. The conditions necessitating artificial ventilation were hyaline membrane disease, neonatal apneic spells, aspiration of milk, and birth asphyxia. On examination the probands were in a good healthy state and without any subjective signs of dyspnea. Lung volumes could be measured in all of the probands. They did not show any statistically significant deviation from standards for height and correlated with the age of the probands. Time related flow rates were sufficiently measurable in 7 probands only, who cooperated adequately. In 6 of them the expiratory flow showed a decrease of the effort independent portion with a slight increase in the total airway resistance. There was no correlation between the condition requiring artificial ventilation, the former therapeutic characteristics and the degree of the pathological lung function tests. The results of this investigation suggest damage of the smallest airways which could be the reason for the obstructively impaired expiratory patterns seen in 6 of the probands.