Short- and long-term effects of furosemide on lung function in infants with bronchopulmonary dysplasia.

Although furosemide improves lung mechanics in some infants with broncho-pulmonary dysplasia (BPD), this may not be important unless gas exchange also improves. To determine the relationship between improvement in mechanics and improvement in gas exchange, the short- and long-term effects of furosemide therapy were studied in 16 spontaneously breathing infants with severe BPD who were both oxygen dependent and hypercarbic (mean PCO2 54 +/- 11 torr). Each infant was examined at least three times: before furosemide therapy, 1 hour after the first dose of furosemide, and after a 6- to 10-day course. Ten of the 16 infants were also examined three times during a 7-day control period. Transcutaneous PO2 and PCO2, esophageal pressure, air flow, and tidal volume were measured. Pulmonary resistance, lung compliance, and the alveolar to skin PO2 difference were calculated. After a single dose of furosemide, only compliance significantly improved. After prolonged therapy, compliance, resistance, and oxygenation significantly improved in the group as a whole, but better oxygenation was achieved in only six of 16 infants. tcPCO2 was unaffected by long-term furosemide therapy, but in all infants with decreased tcPCO2 1 hour after a single dose, there was sustained decrease in PCO2 after prolonged therapy. Changes in gas exchange were not explained by changes in lung mechanics. These data indicate that long-term diuretic therapy can improve the mechanical properties of the lungs of spontaneously breathing infants with BPD, but that gas exchange is usually unaffected.