Haemodynamic effects of different doses of dopexamine hydrochloride in low cardiac output states following cardiac surgery.

We studied the haemodynamic effects of dopexamine hydrochloride, a beta 2-adrenergic agonist with dopaminergic (DA1) activity, in 20 patients with low cardiac output following surgery for coronary artery bypass grafting and/or valve replacement or repair. Following titration of four doses (1, 2, 4 and 6 micrograms.kg-1.min-1), the dose producing the optimal response was infused for up to 48 h (five patients). During the infusion, significant increases in cardiac index and stroke volume were accompanied by significant decreases in systemic vascular resistance. Heart rate increased significantly up to 6 h and thereafter returned to control levels. Mean blood pressure was reduced but did not fall below 60 mmHg. However, in five patients treated for 48 h mean blood pressure had returned to control levels. Unwanted effects (tachycardia and hypotension) were seen chiefly at higher doses, leading us to conclude that infusion rates of 4 micrograms.kg-1.min-1 or less will be useful in the treatment of low cardiac output following cardiac surgery.

Usefulness of dopexamine hydrochloride versus dobutamine in chronic congestive heart failure and effects on hemodynamics and urine output.

The hemodynamic effects of dopexamine hydrochloride and dobutamine were compared during dose-response infusions of dopexamine (1.0 to 4.0 micrograms/kg/min) and dobutamine (2.5 to 10.0 micrograms/kg/min) and during 48-hr infusions at doses producing initial matched increases in cardiac output. Thirty-three patients with severe, stable, chronic congestive heart failure (CHF) (New York Heart Association class III to IV) participated. Both drugs produced an increase in cardiac index, brought about by increased stroke volume index and heart rate, and systemic vasodilatation. The relative contribution of these mechanisms differed, dopexamine proving the more potent vasodilator. The effects of dopexamine were maintained without variation during the 48-hr infusion, apart from a reduction in the increase in heart rate. The effects of dobutamine, while remaining above control at most time-points during the 48-hr infusion, attenuated toward control values. Dopexamine also appeared to promote increased urine output and creatinine clearance during the 48-hr infusion. Both drugs were well tolerated. Dopexamine elicited larger peak hemodynamic effects at dosages that had equivalent effects on cardiac output, and favorable renal responses, and demonstrated no long-term attenuation of effect.