Boosting systemic pressure with phenylephrine: arterial or venous modulation?

Excerpt

Given that systemic circulation is a closed-loop system, the mean left ventricular (LV) cardiac output (CO) is equal to the systemic venous return. In this regard, both volume expansion and vasopressors are used to maintain vital organ perfusion pressure. The vast majority of haemodynamic studies evaluating the effects of inotropes and vasopressors on blood circulation have focused on cardiac performance and arterial tone without systematically assessing the role of venous return [1]. A more realistic conception of the positive effect of vasopressors on CO during hypovolemia is to consider the role of these agents on the venous system (enhancement of venous return via venoconstriction) rather than on ventriculo–arterial coupling [1]. …