HAEMODYNAMIC EFFECTS OF DOPEXAMINE HYDROCHLORIDE IN COMPARIS0N WITH DOPAMINE IN LOW CARDIAC OUTPUT SYNDROME DURING OPEN HEART SURGERY

Abstract

Despite Advances in Cardiac surgery and perioperative care, the prevention and treatment of postoperative complications continue to be an integral part of the care of the cardiac surgery patients. As older and sicker adult patients undergo suregry with greater frequencies, the incidence of complications has increased.

Patients recovering from cardiac surgery involving cadiopulmonary bypass often exhibit systemic and regional haemodynamic disturbances.

Common features are low cardiac output with increased left ventricular afterload, increased vascular resistance and inadequate renal and hepatosplanchnic perfusion.

• The aim of therapy after cardiopulmonary bypass surgery is therefore to maintain cardiac output and to reduce vasoconstriction

which assists in restoring blood fow to vital organs.

It has been suggested that the optimal drug should combine systemic vasodilation, renal vasodilation, augmentation of myocardial relaxation and should not have too strong positive inotropic effect. Various drugs optimize cardiac output through their effects on myocardial contractility (inotropic effect), effects on the peripheral resistance (afterload effect) or both. Positive inotropic agents act to increase the force anq speed of myocardial fiber contraction.

The sympathetic amines (epinephrine - norepinephrine - isqproternol - Dopamine) improve cardiac output by a direct beta­ adrenergic inotropic effect and have selectively different effects on the peripheral vasculature.