Adrenaline infusion
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adrenaline epinephrine infusion dosing indications
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adrenaline infusion preparation administration ICU vasopressor
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Adrenaline (Epinephrine) Infusion
Pharmacology
Adrenaline acts on α1, α2, β1, and β2 adrenoceptors. The predominant effects are dose-dependent:
| Dose | Dominant Receptors | Key Effects |
|---|---|---|
| Low (< 0.05 mcg/kg/min) | β1, β2 | ↑ HR, ↑ contractility, ↓ SVR (vasodilation) |
| Moderate (0.05–0.2 mcg/kg/min) | β1 > α1 | ↑ HR, ↑ contractility, mixed vascular effect |
| High (> 0.2 mcg/kg/min) | α1 dominant | ↑↑ SVR (vasoconstriction), ↑ BP |
Indications
- Cardiac arrest (anaphylaxis and peri-arrest) — IV bolus first, then infusion if ROSC is tenuous
- Anaphylactic shock — first-line vasopressor when hypotension persists after IM adrenaline
- Septic shock — second-line vasopressor added to noradrenaline (per Surviving Sepsis Campaign 2021)
- Cardiogenic shock — for inotropic support (particularly where vasodilation is also needed)
- Post-cardiac surgery low output states — inotrope of choice in many centres
- Bradycardia refractory to atropine — bridge to pacing
Dosing
Standard infusion range
0.01–1.0 mcg/kg/min IV, titrated to effect.
Typical starting doses by indication:
| Indication | Starting Dose | Usual Range |
|---|---|---|
| Septic shock (adjunct) | 0.05 mcg/kg/min | 0.05–0.5 mcg/kg/min |
| Cardiogenic shock | 0.05–0.1 mcg/kg/min | 0.05–0.3 mcg/kg/min |
| Post-arrest | 0.1 mcg/kg/min | 0.05–0.5 mcg/kg/min |
| Anaphylaxis (infusion) | 0.05–0.1 mcg/kg/min | Titrated to MAP |
Preparation
Standard concentrations (adult)
- 4 mg in 50 mL (80 mcg/mL) — most common ICU syringe
- 8 mg in 100 mL (80 mcg/mL) in normal saline or 5% dextrose
- Some centres use: 1 mg in 50 mL (20 mcg/mL) for low-dose inotrope infusions
Infusion rate calculation
Rate (mL/hr) = [Dose (mcg/kg/min) × Weight (kg) × 60] ÷ Concentration (mcg/mL)
Example: 0.1 mcg/kg/min for 70 kg patient using 80 mcg/mL solution:
(0.1 × 70 × 60) ÷ 80 = 5.25 mL/hr
Administration
- Preferred route: Central venous catheter (CVC) — reduces risk of extravasation injury
- Peripheral administration: Acceptable short-term (< 6 hours) via a well-sited antecubital or proximal forearm IV while awaiting central access (Surviving Sepsis Campaign 2021, p. 31). Avoid distal sites — 85% of extravasation events occur distal to the antecubital fossa.
- Dedicated lumen recommended to avoid inadvertent bolus from line flushes
- Infuse via a syringe driver or volumetric pump — never free-flow
Monitoring
- Continuous ECG — tachyarrhythmias (AF, VT) are common, especially at higher doses
- Invasive arterial line — for beat-to-beat BP monitoring
- Lactate — adrenaline causes dose-dependent hyperlactatemia (glycogenolysis) independent of tissue hypoperfusion; do not use lactate in isolation to guide dosing
- Blood glucose — causes hyperglycaemia via glycogenolysis/gluconeogenesis
- Potassium — β2 stimulation causes intracellular potassium shift and hypokalaemia
Adverse Effects
| Effect | Mechanism |
|---|---|
| Tachycardia / arrhythmias | β1 stimulation |
| Hypertension | α1 stimulation |
| Myocardial ischaemia | ↑ O₂ demand + coronary vasospasm |
| Hyperlactatemia | β2-mediated glycogenolysis (not always ischaemic) |
| Hyperglycaemia | Hepatic glucose production |
| Hypokalaemia | β2-mediated K⁺ shift |
| Tissue necrosis (extravasation) | Local α1-mediated vasoconstriction |
| Pulmonary oedema | ↑ preload + afterload mismatch |
Special Considerations
- Anaphylaxis: IM adrenaline (0.5 mg) is always first-line; infusion is reserved for refractory cases or ongoing cardiovascular compromise
- Septic shock: Surviving Sepsis Campaign 2021 recommends noradrenaline as first-line vasopressor; adrenaline is added when noradrenaline doses are escalating or cardiac output is inadequate
- Lactate interpretation: A rising lactate on adrenaline infusion does not necessarily indicate worsening perfusion — adrenaline-induced hyperlactatemia is well recognised and should be interpreted alongside other perfusion markers (ScvO₂, clinical signs, urine output)
- Weaning: Taper gradually (e.g. reduce by 0.02–0.05 mcg/kg/min every 30–60 minutes) once haemodynamics are stable to avoid rebound hypotension
4 mg how many ampoules
Adrenaline ampoules come in two standard concentrations:
| Ampoule | Concentration | Adrenaline per ampoule |
|---|---|---|
| 1 mL ampoule | 1:1,000 (1 mg/mL) | 1 mg |
| 10 mL ampoule | 1:10,000 (0.1 mg/mL) | 1 mg |
For 4 mg:
- 1:1,000 (1 mg/mL) → 4 ampoules (1 mL each)
- 1:10,000 (0.1 mg/mL) → 4 ampoules (10 mL each)
Most ICUs use the 1:1,000 ampoules for infusion preparation — draw up 4 × 1 mL ampoules into a syringe, make up to 50 mL with normal saline = 80 mcg/mL.
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