EFFECT OF BOLUS INJECTION VERSUS CONTINUOUS-INFUSION OF FUROSEMIDE ONDIURESIS AND NEUROHORMONAL ACTIVATION IN PATIENTS WITH SEVERE CONGESTIVE-HEART-FAILURE

Previous studies have demonstrated that continuous infusion of furosem ide results in increased diuresis and natriuresis compared with bolus administration of the drug in patients with severe heart failure. We r easoned that continuous infusion of furosemide caused less activation of neurohumoral mechanisms, since other studies have shown that bolus administration of furosemide may activate this system. We therefore te sted the hypothesis that continuous administration of furosemide would increase water and sodium excretion due to less activation of neuroho rmones. Eight patients with severe heart failure were studied during c ontinuous infusion over 24 h and bolus injections of furosemide twice daily in a randomized cross-over study. Bolus administration of furose mide increased diuresis and natriuresis significantly in the first 4 h after administration compared with continuous administration, but thi s was later reversed, resulting in similar 24 h total output. The neur ohormones measured at baseline were all markedly elevated. Neither reg imens of furosemide caused any further significant changes in neurohum oral response except that pro-ANF decreased more during the first 8 h after bolus administration compared to continuous infusion. This study :has demonstrated that bolus administration of furosemide in conventio nal doses is equally effective as continuous intravenous infusion in p atients with severe heart failure. This may be due to maximal neurohor monal activation in severe heart failure (NYHA III-IV) which could not be further activated by bolus administration.