Objective We studied the synergism between high-dose furosemide and hydrochlorothiazide in patients with severe congestive heart failure and impaired renal function show ing diuretic resistance to a daily dose of furosemide of at least 250 mg.
Design and setting An open study. A general hospital in The Netherlands.Methods In 20 patients with severe congestive heart failure (stage III-IV according to the New York Heart Association) with an oedematous mass of more than 5 kg and a proven diuretic resistance to high-dose furosemide, hydrochlorothiazide (25-100 mg daily) was added to the medication for 3-12 days, leaving the other medica tion unchanged. After correction of the hydration state, hydrochlorothiazide was withdrawn. Variables included body weight, serum electrolytes, renal function and natriuresis.Results Addition of hydrochlorothiazide resulted in a mean (it standard deviation) body weight reduction of 6*7 ± 3*3 kg per patient. Mean daily urine volume increased from 1899 dt 958 ml to 3065 ± 925 ml (P<0*001). Fractional sodium excretion increased significantly from 3-5 ±3-2% to 11*5 ± 9*0% (P<0-001), The most important side effect of this combination therapy appeared to be hypokalaemia. Mean endogenous creatinine clearance decreased (not significantly) from 32*7 ± 22*5 m l. min ~ 1 . 1*73 m " 2 to 27*6 ± 22-5 ml . min" 1 , 1*73 m~2.Conclusions Addition of hydrochlorothiazide to highdose furosemide is a powerful diuretic tool, even in patients with a significantly reduced renal function. Because of its potentially dangerous side effects (hypokalaemia), it should be used in a carefully controlled