Chest
Volume 121, Issue 2, February 2002, Pages 377-382
Journal home page for Chest

Clinical Investigations
COPD
Discontinuation of Furosemide Decreases Paco2 in Patients With COPD

https://doi.org/10.1378/chest.121.2.377Get rights and content

Study objective

To evaluate whether the discontinuation of furosemide treatment resulted in a decrease in Paco2 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]; FEV1 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 (Sao2) < 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 Sao2 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). Paco2 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 Paco2 in patients with COPD.

Section snippets

Subjects

The study was performed in 20 patients with COPD (10 men; median age, 70 years [range, 58 to 81 years]; median FEV1, 35% predicted [range, 19 to 70% predicted]).19 Subjects were included if they had a stable course of the disease. COPD was defined according to the standards of the American Thoracic Society,20 and a disease stability was defined as a fluctuation of FEV1 of < 10% over the last 6 months and an absence of exacerbations for at least 8 weeks prior to the study. Moreover, subjects

Results

Sixteen subjects completed the study. Urine analysis showed a full compliance with respect to the study medication. Of the four subjects who did not complete the study, one patient had a weight gain of 3.5 kg after 4 days without furosemide, associated with an increase in peripheral edema and worsening of dyspnea; two patients were not willing to continue the study; and one patient became unstable during the study: terminal respiratory failure (FEV1, 29% predicted; Paco2, 62 mm Hg) aggravated

Discussion

The discontinuation of furosemide, prescribed for peripheral edema in patients with stable COPD with a mean nocturnal Sao2 < 92%, resulted in an increased minute ventilation and a decrease in Paco2. This was not associated with an increase in daytime or nocturnal oxygenation.

The increased BE, accompanied by a normal pH, confirms a respiratory-compensated metabolic alkalosis at baseline. The correction of the alkalosis, due to the withdrawal of furosemide, resulted in decreased BE and

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    The study was supported by Glaxo Wellcome, Zeist, the Netherlands.

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