Effect of inhaled furosemide on Functional Residual Capacity (FRC) in Very Low Birth Weight(VLBW) infants with Bronchopulmonary Dysplasia (BPD)

In patients with asthma, inhaled furosemide has been shown to decrease the bronchoconstrictive effects of exercise, cold air hyperventilation ,and antigen challenge. Recently inhaled furosemide has been tested in intubated VLBW infants at a dose of 1 mg/kg. No one has reported the effect of inhaled furosemide on FRC in infants with BPD, not has a higher dose of 3 mg/kg of inhaled furosemide been evaluated. We conducted a randomized , double blind crossover study in 18 patients with BPD (requiring oxygen supplementation at 28 days and chest x-ray changes) with each serving as their own control. The infants had a mean birth weight = 863 g; gestational age = 25.8 wks; postnatal age = 67d ; FIO₂=27.4%. Six of the infants were intubated at time of study. Each was randomized to receive an aerosol dose of furosemide (3 mg/kg in 2 ml of saline) or furosemide (1 mg/kg in 2ml of saline) or placebo (2 ml of saline) on 3 consecutive days of study. Pulmonary mechanics were measured pre, 1, and 2 hours after the inhalation . FRC was measured with the nitrogen washout technique. A minimum of two measurements were performed with the neonate supine and quiet. A study was acceptable if the measurement had a coefficient of variation (CV) of < 10%. In the infants that were intubated, respiratory compliance was measured with the single breath occlusion technique (SensorMedics 2600). A minimum of 10 breaths with a CV of<20% were required. Values mean ± SEM. FRC(ml/kg) Pre 1 Hr Post 2 Hr Post Placebo 20.5 ± 2.0 21.8 ± 2.4 21.0 ± 2.1 Furosemide (1 mg/kg) 20.2 ± 1.3 19.7 ± 1.7 21.5 ± 2.0 Furosemide (3mg/kg) 20.4 ± 1.6 22.8 ± 1.7 21.1 ± 1.6 P>0.05 for all measures There was no significant change in respiratory compliance measurements pre, 1, or 2 hours after treatment with furosemide at 1 mg/kg or 3 mg/kg. There was no difference in the response between intubated and extubated patients. In this population of VLBW infants with BPD,a single dose of 1mg/kg or 3mg/kg of inhaled furosemide does not improve FRC or respiratory compliance.