Dose-dependent evaluation of the effects of nebulized furosemide on pulmonary function in ventilated preterm infants.

OBJECTIVE We have previously shown that a single dose of nebulized furosemide improves tidal volume and pulmonary compliance for up to a 2-hour study period. This study is undertaken in order to find out (a) whether increasing the dose of nebulized furosemide from 1 to 2 mg/kg of body weight will further improve the pulmonary mechanics in premature infants with evolving chronic lung disease and (b) whether the effects of a single dose of nebulized furosemide last beyond 2 hours. STUDY DESIGN The effect of nebulized furosemide on pulmonary mechanics was studied at a mean postnatal age of 24 days (range 14 to 50 days) in 13 premature infants, 24 to 28 weeks' gestational age, who had been dependent on mechanical ventilation since birth. Furosemide was administered by nebulization at doses of 1 and 2 mg/kg of body weight, in random order, on two separate days 24 hours apart. Pulmonary function studies were performed before and 2, 4, and 6 hours after the nebulization. Urine was collected for 6 hours immediately before and for 6 hours after the nebulization. RESULTS Furosemide by nebulization at 1 and 2 mg/kg of body weight resulted in significant improvement in tidal volume and compliance. There was no difference in the magnitude of response between the two doses. Neither 1 nor 2 mg/kg of body weight of nebulized furosemide had any effect on airway resistance. The improvement was maximum for up to 4 hours and lasted for up to 6 hours after the nebulization and was not associated with diuresis or increased excretion of urinary electrolytes. CONCLUSION A single dose of nebulized furosemide improves pulmonary function for up to 6 hours after its administration. Increasing the dose from 1 to 2 mg/kg of body weight results in no further improvement in the pulmonary function. The pulmonary effects of nebulized furosemide are independent of its diuretic action.