LUNG-FUNCTION 8-18 YEARS AFTER INTERMITTENT POSITIVE PRESSURE VENTILATION FOR HYALINE-MEMBRANE DISEASE

Lung function and respiratory symptoms were studied in 40 children aged 8-18 years who had been ventilated for hyaline membrane disease after birth; 11 had had bronchopulmonary dysplasia. Also studied were 38 age matched children who had had hyaline membrane disease but had not required ventilation, 25 unmatched children who were born prematurely but did not develop hyaline membrane disease, and 39 randomly selected pupils of similar age. There was no difference in thoracic gas volume, total lung capacity, inspiratory vital capacity, residual volume, or transfer factor for carbon monoxide between the groups. Respiratory symptoms during the three years before the study and the frequency of clinically diagnosed asthma in patients and their family were similar in all the children with hyaline membrane disease irrespective of whether they had been ventilated or had had bronchopulmonary dysplasia. The children with bronchopulmonary dysplasia, however, had a lower forced expiratory volume in one second (FEV1) before bronchodilator (73% predicted) than the other groups (88-95% predicted). Children who had required ventilation had lower values for specific airways conductance (sGaw) and a greater increase in FEV1 (DELTA-FEV1) after salbutamol (13%) than non-ventilated children (6%); DELTA-FEV1 was associated with the peak pressure of intermittent positive pressure ventilation, a family history of asthma and a history of wheezing, recurrent respiratory illnesses, and a doctor's diagnosis of asthma during the three years before the study. These findings indicate that after eight years of age patients with bronchopulmonary dysplasia have more reversible airways obstruction, compatible with increased bronchial smooth muscle tone.