Adrenaline

Adrenaline (Epinephrine)

Uses

Adrenaline is a life-saving, non-selective adrenergic agonist used in critical and emergency care settings for its potent vasoconstrictive, cardiac stimulant, and bronchodilatory effects.

Indications

1. Anaphylactic Shock:

   • Rapid reversal of symptoms like airway obstruction, hypotension, and severe bronchospasm.

2. Cardiac Arrest:

   • Enhances myocardial and cerebral perfusion during cardiopulmonary resuscitation (CPR).

3. Severe Asthma Exacerbations:

   • Bronchodilation and reduced airway resistance in life-threatening situations.

4. Septic Shock:

   • Helps maintain mean arterial pressure (MAP) and organ perfusion when unresponsive to initial treatments.

5. Croup (Off-label Use):

   • Nebulized adrenaline is used to reduce upper airway obstruction in moderate to severe croup.

6. Post-Extubation Stridor (Off-label Use):

   • Nebulized adrenaline can reduce laryngeal edema.

7. Local Hemostasis (Adjunct Use):

   • Often combined with local anesthetics to reduce bleeding and prolong anesthetic effect.

Mechanism of Action

Adrenaline acts as a non-selective adrenergic agonist, targeting:

• α1 Receptors: Causes vasoconstriction, increasing blood pressure and reducing mucosal edema.
• β1 Receptors: Increases heart rate (chronotropy), myocardial contractility (inotropy), and cardiac output.
• β2 Receptors: Induces bronchodilation and relaxes smooth muscle in the airways.

Dosage and Administration

Anaphylaxis:

• Adults and Adolescents:
  • 0.3–0.5 mg IM every 5–15 minutes as needed (maximum dose: 0.5 mg per injection).
• Children:
  • 0.01 mg/kg IM (maximum 0.3 mg per dose), repeat every 5–15 minutes as needed.
• IV Administration (Severe Cases Only):
  • 0.01 mg/kg slow IV bolus (maximum 0.5 mg per dose).

Cardiac Arrest:

• Adults:
  • 1 mg IV/IO every 3–5 minutes during resuscitation.
• Children:
  • 0.01 mg/kg IV/IO every 3–5 minutes (maximum dose: 1 mg).
• Endotracheal Administration (When IV Access Unavailable):
  • 0.1 mg/kg (diluted in saline) via the endotracheal tube.

Shock (Septic or Cardiogenic):

• Adults:
  • Continuous IV infusion: 0.01–0.5 µg/kg/min, titrated to maintain blood pressure and perfusion.
• Children:
  • 0.1–1 µg/kg/min IV infusion, titrated to response.

Nebulized Adrenaline:

• Croup or Post-extubation Stridor:
  • 0.5 mL/kg of 1 mg/mL solution diluted in saline to a total volume of 3 mL, nebulized every 2–4 hours as needed.

Presentation

• Injectable Solutions:
  • 1 mg/mL (1:1000) ampoules for IM/SC administration.
  • 0.1 mg/mL (1:10,000) ampoules for IV bolus during resuscitation.
• Auto-Injectors:
  • Preloaded syringes (e.g., EpiPen) delivering 0.3 mg or 0.15 mg doses for emergency use.
• Nebulized Formulations:
  • Solutions prepared from injectable adrenaline diluted for nebulization.

Side Effects

Common:

• Palpitations, tachycardia, headache, sweating, and anxiety.

Serious:

• Arrhythmias (e.g., ventricular fibrillation).
• Severe hypertension, leading to hemorrhagic stroke in rare cases.
• Myocardial ischemia in patients with coronary artery disease.

Localized Effects:

• Tissue necrosis if extravasation occurs during IV infusion.

Contraindications and Precautions

Contraindications:

• Hypersensitivity to adrenaline or excipients in the formulation.
• Non-life-threatening conditions in patients with severe hypertension or tachyarrhythmias.

Precautions:

1. Cardiovascular Disease:

   • Use cautiously in patients with ischemic heart disease or arrhythmias.

2. Hyperthyroidism and Pheochromocytoma:

   • Increased risk of exaggerated effects due to heightened adrenergic receptor sensitivity.

3. Diabetes Mellitus:

   • May cause hyperglycemia by increasing glycogenolysis and gluconeogenesis.

Special Considerations

1. Auto-Injector Training:
   • Patients at risk of anaphylaxis should carry an auto-injector and be educated on its proper use.
2. Extravasation Management:
   • Treat extravasation with phentolamine to prevent tissue damage.
3. Septic Shock Use:
   • Adrenaline is considered a second-line vasopressor after norepinephrine in the Surviving Sepsis Campaign guidelines (2021 update).

Recent Updates and Guidelines

1. Anaphylaxis Management:

   • Emphasis on IM adrenaline as the first-line treatment in updated guidelines by the World Allergy Organization (2022).

2. Cardiac Arrest:

   • 2020 American Heart Association (AHA) guidelines reaffirm adrenaline as a cornerstone of advanced cardiac life support (ACLS).

3. Sepsis:

   • Adrenaline remains a critical adjunct in refractory septic shock when norepinephrine fails to achieve target blood pressure.

References

1. Resuscitation Council UK: Guidelines for Anaphylaxis (2021).
2. American Heart Association (AHA): ACLS Provider Manual (2020).
3. World Allergy Organization: Guidelines for Anaphylaxis Management (2022).
4. Surviving Sepsis Campaign: Critical Care Guidelines (2021).
5. Oxford Handbook of Clinical Pharmacology and Drug Therapy (3rd Edition).