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- Drugs that promote blood flow and BP, by stimulating adrenergic receptors
- Used to improve cardiac output, especially in sepsis or trauma
- No individual drug has been shown to be superior to the others for clinical outcomes
- Dobutamine
- 'Inodilator': improves cardiac contractility as well as reducing systemic and pulmonary vascular resistance, so doesn't change the BP much overall
- Minimal change in heart rate
- Improves coronary flow and myocardial perfusion, but at the expense of an increase in myocardial oxygen consumption - sometimes worsening the picture
- Best use for myocardial depression in septic shock, in conjunction with a vasoconstrictor to raise the BP
- Sometimes used augment cardiac output in decompensated heart failure, but not so much any more
- Dopamine
- Precursor for noradrenaline
- Activates alpha and beta receptors at different doses
- Renal, mesenteric, coronary and cerebral vasodilation
- Low dose - particularly evident renal artery vasodilation
- High dose - activates alpha receptors, acting as vasopressor
- Not used as much any more, but sometimes used in cardiogenic shock or septic shock
- Also may be useful in intestinal ischaemia at low doses
- Adrenaline
- Most potent natural beta-agonist
- Stimulates both alpha and beta receptors, increasing heart rate, stroke volume and BP
- Resuscitation of cardiac arrest, anaphylactic shock
- Noradrenaline
- Noradrenaline = meteraminol = aramine
- Both alpha and beta. Potent activity as a vasopressor.
- Vasoconstrictive effects = increased MAP, minimal change in HR
- Used for profound hypotension with adequate volume
- Septic shock - just because it has fewer adverse effects than other catecholamines
- Severe neurologic events
- If max noradrenaline can't reach MAP of 65, dopamine or vasopressin will be added, but there is no evidence that that improves outcomes
- Reduces both preload and afterload - reduces metabolic demands of myocardium
- Useful with poorly controlled HTN immediately post-op
- Nitroprusside
- Effective vasodilator on artery and veins
- Rapid onset and offset
- 0.5microg/kg/min then titrate up
- Favoured in hypertensive emergencies
- Risk of cyanide intoxication
- Nitroglycerin
- Predominately venodilation, but also arteries
- Dilates coronary arteries - preferable in CAD
- Used to augment cardiac output in decompensated heart failure and to relieve chest pain in patients with stable angina
- Septic/neurogenic shock whose blood pressure fails to respond to volume resus
- Useful in maintenance of BP that has been lowered by GA or regional anaesthetic
- Vasopressin
- "ADH" - antidiuretic hormone
- Produces vasoconstriction by actions on vascular smooth muscle
- Often added to noradrenaline in severe septic shock - no survival benefit
- Promotes splanchnic vasoconstriction in variceal bleeding
- Phenylephrine
- Pure alpha agonist
- Useful in maintaining BP in patients with epidurals, but somewhat questionable in this circumstance
- Bradycardia, low cardiac output, renal hypoperfusion
