How Vasoactive Agents May Influence Regional Blood Flow

Abstract

Vasoactive agents are commonly used to correct hypotension or to increase cardiac output in septic patients. However, these agents may influence blood flow distribution and cellular metabolic needs, so that the balance between oxygen supply and demand can be threatened. In this article, we will review the regional effects of vasoactive agents with particular reference to the splanchnic circulation. Among vasopressor agents, dopamine and norepinephrine usually increase splanchnic blood flow. The effects of epinephine have been studied less. The effects of dopamine and norepinephrine on the gut mucosa are inconsistent, while epinephrine worsens mucosal acidosis and endotoxin-induced histologic lesions. The use of low doses of dopamine (“dopaminegic doses”) has not been shown to provide any substantial benefit on splanchnic circulation. Among inotropic agents, dobutamine and dopexamine similarly increase splanchnic blood flow, but dobutamine improve gut mucosal acidosis in most patients, while dopexamine has more variable effects on this parameter. The effects of non-adrenergic vasoactive agents are also discussed briefly.