UNCONTROLLED WHEN PRINTED
Introduction
  • Metaraminol is a sympathomimetic, adrenoceptor stimulant.
  • It directly and indirectly stimulates the alpha receptors in the sympathetic nervous system.
  • Alpha stimulation causes vasoconstriction with an increase in both systolic and diastolic blood pressure and an increase in systemic vascular resistance.
  • It has a positive inotropic effect on the heart and a peripheral vasoconstrictor action
  • Onset: 1 to 2 minutes. Duration up to 20 minutes. Half-life only minutes.
Indications

Adjunctive treatment of hypotension after adequate fluid resuscitation due to:

  • Post anaesthesia
  • Haemorrhage
  • Cardiogenic shock
  • Septicaemia
Contraindications
  • Hypersensitivity.
  • Hypovolaemia
  • MAOIs or within 14 days of such treatment
Precautions / Notes
  • Use of Metaraminol with (MAOI’s) or tricyclic antidepressants may result in potentiation of the pressor effect.
  • Hypotension can be defines as less than 30% of the patients base line SBP or in children (70mmHg +(2xage)) in the 1- 10yo.
  • Asthma – risk of allergy to sulphides
  • Digitalised patients – risk of arrythmias
Management
Critical Care Paramedic only

Adult:

  • IV/IO:
    • IV/IO 0.5mg - 1mg, repeat >3 min
    • Dilute 10mg/1ml into 20ml NaCl 0.9% to provide a solution of 0.5mg/ml.
  • Infusion:
    • 20mg in 50ml in NaCl 0.9% at 0.5 to 5 ml/hr (0.4mg/ml) titrate to BP/haemodynamic status
Dose RangeRate of infusion (SD)
0.05μg/kg/min0.5mL/hr
0.1μg/kg/min1mL/hr
0.2μg/kg/min2mL/hr
0.3μg/kg/min3mL/hr
0.4μg/kg/min4mL/hr
0.5μg/kg/min5mL/hr

Paediatric:

  • IV/IO:
    • 0.01mg/kg, repeat >3 min
    • Dilute 5mg/0.5ml into 50ml normal saline to provide solution of 0.1mg/ml
  • Infusion:
    • 0.15mg/kg in 50ml in normal saline at 1 to 10 ml/hr (0.05-0.5mcg/kg/min)
    • Titrate to BP / haemodynamic status.
WeightDose
5kg0.75mg
10kg1.5mg
15kg2.25mg
20kg3mg
30kg4.5mg
40kg6mg
50kg7.5mg
Dose RangeRate of infusion (SD)
0.05μg/kg/min1mL/hr
0.1μg/kg/min2mL/hr
0.2μg/kg/min4mL/hr
0.5μg/kg/min10mL/hr
Special Considerations

Administer dose cautiously as rapidly induced hypertensive response may cause:

  • Arrhythmias
  • Pulmonary oedema
  • Cerebral haemorrhage
  • Cardiac arrest.

Causes tissue necrosis, avoid extravasation.


References
References
Presentation
10mg/ml ampoule
Colour assist:

Document Control


Directorate
Clinical Services

Responsible Manager
Head of Clinical Services

Date of Issue

Date of Expiry

St John WA © Copyright 2020. All Rights Reserved

Privacy Policy | Copyright Statement & Disclaimer