Editing Haemodynamic drugs


== '''Catecholamines''' ==

* 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

== '''Vasodilators''' ==

* 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

== '''Adjuncts''' ==

* 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

[[Category:Critical care]]
[[Category:Pharmacology]]