Haemodynamic effects of dopamine in septic shock

Abstract

The Haemodynamic response to dopamine infusion has been assessed in 30 patients in septic shock with myocardial dysfunction. Dopamine infusion resulted in a haemodynamic improvement as indicated by significant increases in cardiac output of 38.4% (p>.001), stroke volume 18.7% (p<.001), and mean arterial pressure of 33% (p<.001). Despite the inotropic effect, left ventricular filling pressure did not change in 20 cases and increased in 10 cases. Mean peripheral resistance remained unchanged with a scatter of individual responses depending upon factors such as dopamine dose and initial vascular resistance. Dopamine increased intrapulmonary shunting by 48% (p<.001), insignificantly decreased PaO₂, increased mixed venous oxygen saturation by 16% (p<.02) and decreased pulmonary vascular resistance by 15% (p<.02). Both isoprenaline and dopamine improve stroke volume by an inotropic action, with an increase in venous return in the case of the latter and a reduction in afterload in the former. It is cocluded that the usefulness of dopamine in septic shock may be limited in patients with previous myocardial disease because of the risk of increasing preload and in hypoxaemic patients because of the risk of increasing intrapulmonary shunting.