Dose range is 0 01-0 4 micrograms kg-1 per minute. Norepinephrine is a potent a agonist (vasoconstrictor), raising blood pressure by increasing systemic vascular resistance. It has some pi receptor activity causing increased contractility, heart rate, and cardiac output but it has no effect on p2 receptors. It increases myocardial oxygen demands without increasing coronary blood flow. It acts mainly as a vasopressor, with little inotropic effect. Norepinephrine reduces renal, hepatic, and muscle blood flow but, in patients with severe sepsis, it can increase renal blood flow and urine output by increasing perfusion pressure. The indications for and disadvantages of norepinephrine are given in Box 6.6.
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