Discontinuation of furosemide decreases PaCO(2) in patients with COPD.

STUDY OBJECTIVE

To evaluate whether the discontinuation of furosemide treatment resulted in a decrease in PaCO(2) and an increase in daytime and nocturnal oxygenation.

BACKGROUND

Furosemide is widely prescribed in patients with COPD for the treatment of peripheral edema. It is known that furosemide causes a metabolic alkalosis. A diminished chemoreceptor stimulation may cause a decreased alveolar ventilation.

DESIGN

Randomized, double-blind, placebo-controlled, crossover trial.

SETTING

Department of Pulmonology, Rijnstate Hospital Arnhem, the Netherlands.

PATIENTS

Twenty patients with stable COPD (10 men; median age, 70 years [range, 58 to 81 years]; FEV(1) 35% predicted [range, 19 to 70% predicted]). Subjects were included if they had received furosemide, 40 mg/d, for the treatment of peripheral edema for at least a month and if they had a mean nocturnal arterial oxygen saturation (SaO(2)) < 92%. Patients with cardiac left and/or right ventricular dysfunction, sleep apneas, and patients receiving other diuretics, angiotensin-converting enzyme inhibitors, potassium or chloride replacement therapy, or long-term oxygen treatment were excluded.

INTERVENTION

Furosemide was discontinued for 1 week and replaced by placebo treatment in the first or the second week.

MEASUREMENTS AND RESULTS

Ventilation, daytime arterial blood gas levels, and nocturnal SaO(2) were measured at baseline, after 1, and after 2 weeks. Sixteen subjects completed the study. Ventilation increased from 10.4 L/min (range, 6.7 to 15.4 L/min) at baseline to 11.6 L/min (range, 8.7 to 14.0 L/min) after discontinuation of furosemide (p < 0.05). PaCO(2) decreased from 45 mm Hg (range, 35 to 64 mm Hg) to 41 mm Hg (range, 32 to 61 mm Hg; p < 0.01). Daytime and nocturnal oxygenation did not improve.

CONCLUSIONS

Although it does not improve oxygenation, the discontinuation of furosemide decreases PaCO(2) in patients with COPD.