Drug Choice

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Choice of drug depends on:​​

• Familiarity​

• Ease of administration

• Availability

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For more detailed explanations, you might refer to LITFL

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Metaraminol

• Frequently used both on the wards and in critical care environments to resuscitate patients with hypotension

  • Available in preprepared syringes (0.5 mg/ml typically - Always check!)​

  • May be administered via peripheral line

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If your patient is unstable - call a MET CALL - you should not be administering this drug on your own!

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Features:

• Receptor activity:

  • Almost pure alpha-1 adrenoceptor agonism

• Predominant clinical effect:

  • Vasoconstriction

• Indication:

  • Immediate treatment of hypotension (any cause of shock)

• Side effects:

  • Excessive vasoconstriction​​​

  • Extravasation and skin necrosis

  • May cause a reflex bradycardia​​

  • Take care when handling the metaraminol syringe - inadvertent large bolus will cause harm

• When to start:

  • Bolus of metaraminol may be given before, during or after fluid resuscitation​

  • Depends of how unstable the patient is

• Dosing:

  • 0.5mg boluses every 1-2 minutes​

  • Check BP between each dose

    • Remember that the shocked patient may have​ reduced circulation time - allow time for the drug to circulate before giving another bolus

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Noradrenaline

• 1st line vasopressor agent at Western Health in ICU

• Indicated for:

  • Vasodilatory states

  • Profound hypotension

• Mechanism of action

  • Alpha-1 adrenoceptor agonist​

  • Rapid onset/offset

    • Easily titratable​

• Practical points

  • Equipment​​

    • Access​​​​​​​

      • Central access ideal​

        • Via CVC or PICC​

        • Vascath may be utilised if necessary

      • Ensure central access device placement has been confirmed prior to administration

        • See CVC placement confirmation​

      • Peripheral administration may be appropriate in an emergency, but plan for urgent central access

        • Note: more dilute concentrations are necessary for peripheral administration​

    • Haemodynamic monitoring​

      • Cardiac monitoring/telemetry​

      • Invasive arterial blood pressure monitoring

        • May be commenced without arterial access but plan for urgent arterial line insertion​

          • Set blood pressure cuff for 1-2 minutely​​

    • Giving set

    • Infusion pump

  • Drug preparation

    • Central access concentration​

      • 6mg noradrenaline in 100ml 5% dextrose (6 mcg/ml)​

    • Peripheral access concentration

      • 2mg noradrenaline in 500ml 5% dextrose (0.4 mcg/ml)​

  • Dosing

    • Commence at 5 micrograms/minute​

      • When commencing central noradrenaline, it may take a period of time for the noradrenaline to move down the catheter and begin to enter the blood stream​

        • Multiple bolus doses of metaraminol may be required until noradrenaline activity commences

    • Titration​​

      • Titrate dose to response ​

      • Increase/decrease dosing in 2 - 5 microgram/minute increments

      • NEVER bolus noradrenaline

    • Dosing range = 1 - 100 micrograms/minute

      • Dosing requirements > 20 - 30 micrograms/minute = severe haemodynamic instability​

      • If dosing requirements increase above 10 micrograms/minute, alert the ICU registrar

  • Final Check

    • Have I optimised the fluid state?​

    • Am I administering the correct concentration through the correct line?

    • Has central line placement been confirmed?

    • Is the patient on telemetry?

    • Do I need to escalate to obtain urgent central venous or arterial access?

    • Do I have metaraminol available as an interim measure until the noradrenaline begins to work?