Increased toxicity of high-dose furosemide versus low-dose dopamine in the treatment of refractory congestive heart failure

Objective: To evaluate the safety and efficacy of low-dose dopamine, high-dose furosemide, and their combination in the treatment of refractory congestive heart failure. Methods: Twenty consecutive patients with refractory congestive heart failure were randomized to receive intravenous low-dose (4 μg/kg/min) dopamine combined with low-dose (80 mg/day) oral furosemide (group A; n = 7), intravenous low-dose dopamine with medium-dose furosemide (5 mg/kg/day through continuous intravenous administration; group B; n = 7), or high-dose furosemide (10 mg/kg/day through continuous intravenous administration; group C; n = 6). Results: The three groups showed similar improvement in signs and symptoms of congestive heart failure, urinary output (2506 ± 671 ml/24 hr, mean ± SD) and weight loss (3.3 ± 2.3 kg) after 72 hours of therapy. Mean arterial blood pressure (MAP) decreased by 14% ± 8% and 15% ± 6% in groups B and C, respectively, but increased by 4% ± 15% in group A (p = 0.017). Renal function deteriorated significantly in groups B and C: creatinine clearance decreased by 41% ± 23% and 42% ± 23%, respectively, but increased by 14% ± 35% in group A (p = 0.0074). MAP decrease was positively correlated with the decrease in creatinine clearance (r = 0.7; P = 0.0007). Patients in group B and C had more hypokalemia than group A. Two patients in group C sustained acute oliguric renal failure and one patient in group B died suddenly while sustaining severe hypokalemia. Conclusion: Combined low-dose intravenous dopamine and oral furosemide have similar efficacy but induce less renal impairment and hypokalemia than higher doses of intravenous furosemide taken either alone or with low-dose dopamine. The renal impairment induced by intravenous furosemide is probably related to its hypotensive effect in patients with refractory congestive heart failure.