1755 WHAT IS THE OBJECTIVE OF FUROSEMIDE THERAPY IN INFANTS WITH CHRONIC LUNG DISEASE?

Abstract

Although furosemide (F) improves lung mechanics in infants with chronic lung disease (CLD), this effect may not be important unless gas exchange also improves. To determine the relationship between improvement in mechanics and improvement in gas exchange, we studied the acute and chronic effects of F therapy in 10 infants with CLD aged 4–24 weeks who were both oxygen dependent and hypercarbic. Each infant was studied 3 times: before F therapy, 1 h after the first dose of F (2 mg/Kg IV), and after a 6–10 day course (2 mg/Kg/day IV or 4 mg/Kg/day po). We measured skin surface (s) pO2 and pCO2, esophageal pressure, airflow and tidal volume; and we calculated pulmonary resistance (R), lung compliance (C) and the alveolar to skin (A–s) pO2 gradient. Criteria for improvement were a fall in PsCO2 > 2 torr, a fall in the A–s gradient > 10 torr, and a > 15% rise in C or fall in R. For the latter 4 variables we compared the acute effect of F with its chronic effect. We found that after both acute and chronic F, compliance, resistance and PsCO2 improved significantly from baseline values, but A–s pO2 gradient did not. Overall, mechanics improved in 9 patients, but gas excnange improved in only 6. In individual patients, improvement in R or C was unrelated to improvement in either gas exchange variable. However, the infants whose gas exchange chronically improved could be predicted by the acute change in PsCO2 or in pO2 gradient. We conclude that 1) F improves lung mechanics but may have little effect on gas exchange and 2) skin surface monitoring of the first dose of F can accurately identify those who will respond to chronic F therapy.