The goal of the study was to evaluate the effect of isoproterenol prescribed in goal-directed therapy for septic shock. Out of a cohort of 89 patients with septic shock, 14 patients treated with fluid and norepinephrine had inappropriate mixed venous oxygen saturation (SvO2<70%) not responding to correction of hypoxemia and anemia (>8 g.dL-1). Isoproterenol administration was started at a dose of 0.04 microg.kg-1.minute-1 with 0.025 microg.kg-1.minute-1 increments every 30 minutes until SvO2 was greater than 70%. Mean arterial pressure was maintained>or=65 mm.Hg by adjusting the norepinephrine infusion. Hemodynamic, oxygen, and renal variables were collected during a 12-h period. Patients with a known prior history of coronary disease were not eligible. Isoproterenol administration increased significantly SvO2 (62%+/-10% to 71%+/-9%), cardiac index (3.1+/-0.6 to 4.4+/-1.4 L.min-1.m-2), stroke index (27+/-3.4 to 38+/-6.1 mL.m-2), and left ventricular stroke work index (24+/-3.4 to 40+/-5.0 g.m-1.m-2). Heart rate rise did not reach a significant level. Arterial lactate concentration decreased significantly during the study period (5.7+/-2.8 to 3.4+/-1.6 mmol.L-1). No cardiac adverse events occurred with any electrocardiographic aspects of myocardial ischemia. This study suggests that isoproterenol is efficient to improve hemodynamics and oxygen variables in septic shock patients. There is a need for future investigations in larger groups of patients to determine whether isoproterenol can be an alternative to dobutamine.