The hemodynamic differences between bolus administration and constant intravenous infusion over a 48-h period with enoximone, a new positive inotropic/vasodilator agent, were evaluated. Twenty-four patients were studied, 15 patients in the bolus group (Group A) and nine patients in the constant infusion group (Group B). The overall hemodynamic results were similar in both groups. Cardiac output increased in Group A from 3.1 +/- 0.71 to 5.5 +/- 1.3 L/min and in Group B from 3.6 +/- 1.0 to 5.9 +/- 1.2 L/min. Significant decreases occurred in pulmonary capillary wedge pressure (30 +/- 7 to 20 +/- 8 mm Hg and 37 +/- 5 to 21 +/- 11 mm Hg) and systemic vascular resistance (2184 +/- 456 to 1300 +/- 305 dyn.s.cm-5 and 1752 +/- 415 to 1035 +/- 130 dyn.s.cm-5). Group A required repeat drug boluses every 3-5 h to maintain these hemodynamic effects. The terminal blood half-life of enoximone derived following the continuous infusion in Group B was 10.6 +/- 7.0 h. In conclusion, intravenous enoximone produces acute salutary hemodynamic effects in patients with severe congestive heart failure that can be sustained for at least 48 h by intermittent boluses or a continuous infusion.