ABSTRACT
This chapter discusses only vasopressors and positive inotropes. Some inotropes may be given peripherally, but for safety most units give all inotropes and vasopressors through central lines, especially as they are usually being used in patients whose peripheral blood flow is often problematic. Blood volume should be optimised before using drugs. Increasing cardiac work when there is insufficient circulating volume can cause myocardial ischaemia. The heart and blood vessels contain various types of receptors, many of which have subtypes. Adrenaline can cause gross tachycardia, ventricular dysrhythmias, hyper-glycaemia, oliguria, increased lactate, hypokalaemia, hypophosphataemia and other metabolic complications, so is not widely used in most intensive care units. Growing evidence suggests noradrenaline is useful for treating refractory cardiogenic shock, perhaps because it improves right ventricular perfusion. Dobutamine, a synthetic analogue of dopamine, is primarily a β1 stimulant. Metraminol causes peripheral vasoconstriction, so is often used during a hypotensive crisis, and as an emergency drug during transfer.
