noradrenaline / norepinephrine

introduction

noradrenaline is the preferred 1st line vasopressor in Mx of sepsis / septicaemia not responding to iv fluid therapy
an endogenous sympathomimetic agent, its main action is as a alpha-1 agonist with beta-1 agonist actions and little beta-2 agonist actions (thus no skeletal muscle vasodilation nor the glucose metabolism effects as with adrenaline)
variable effect on HR and cardiac output:
- low doses often result in vagal reflex bradycardia accompanying the rise in MAP, and thus cardiac output may even fall.
it's alpha-1 vasocontrictive actions (vasopressor) may result in reduced peripheral, pulmonary, renal and splanchnic perfusion.

allergy and hypersensitivity reactions in those sensitive to sulphites, take care in patients with PH asthma
tachycardia, potential risk of ventricular tachycardia (VT), especially if halogenated anaesthetics which sensitise the myocardium or in patients with acute myocardial infarction (AMI/STEMI/NSTEMI) or ischaemic heart disease.
hypertension
- particularly high doses, or those with hyperthyroidism, or those on monoamine oxidase inhibitors (MAOIs) or tricyclic antidepressants
reflex bradycardia
- may occur at low doses, and may actually reduce cardiac output
prolonged administration of any potent vasopressor may result in plasma volume depletion and hypotension
theoretical risk of increased myocardial ischaemia in patients with acute myocardial infarction (AMI/STEMI/NSTEMI)
vasoconstriction
- use with care in those with heart disease, thyroid disease, hypertension, or diabetes
- may cause local ischaemia and abscesses if used im or there is tissue extravasation at iv site
  - the antidote for extravasation ischaemia is local infiltration with phentolamine
- prolonged vasoconstriction may prevent adequate volume expansion of circulation and lead to persistent shock