Epinephrine Hydrochloride (Adrenaline)

Anesthesia Implications

Classification: Mixed Alpha/Beta Adrenergic Agonist, Sympathomimetic
Therapeutic Effects: Increased coronary blood flow, bronchodilation, local anesthetic adjunct, resuscitation, croup treatment
Time to Onset: IV: 30-60 seconds
IM: 6-15 minutes
Intratracheal: 5-15 seconds
Time to Peak: IV: 3 minutes
Duration: IV: 5-10 min
Intratracheal: 15-25 min

Contraindications

Epinephrine should NEVER be added to solutions to be injected into fingers, toes, penis, nose, or ears.

Use with caution in patients with:
parturients with uteroplacental insufficiency, cardiovascular disease, diabetes, hypertension, and hyperthyroidism

Primary Considerations

Epidural Test Dose – This is typically 10-15 mcg (2-3 mL) of 1:200,000 epinephrine mixed with local anesthetic. Accidental intravascular injection would manifest as an increase in heart rate > 10 bpm within 30-45 seconds.

‘Crashing’ Patients – it is recommended NOT to give an amp (1:1000 or 1 mg) of epinephrine to anyone that still has a heartbeat. Doing so can lead to malignant hypertension, dysrhythmia, and cardiac arrest. It is recommended that 50 mcg, while being well above the typical supporting starting dose, is still far safer than giving an entire 1 mg.

Reduced local anesthetic toxicity risk – when epinephrine is added to local anesthetics, it constricts the local blood vessels and reduces the systemic absorption rate. This keeps less local anesthetic in the blood and reduces the likelihood of toxicity.

High dose epinephrine administration – the American Heart Association currently is AGAINST the use of high-dose IV epinephrine (eg 5-10 mg every 3-5 minutes) in adult cardiac arrest. This was a practice sometimes used after administration of the standard 1 mg doses during cardiac arrest.

Dilution – 1:200,000 (0.1 mg epinephrine diluted in 20 mL of local anesthetic) or 1:100,000 (0.1 mg epinephrine diluted in 10 mL of local anesthetic). These produce 5 mcg/mL and 10 mcg/mL respectively.

OB – epinephrine reduces uteroplacental blood flow, so should be used with extreme caution in the parturient – especially considering those patients with conditions that compromise uterine blood flow.

Drug interactions – digitalis and volatile anesthetics in conjunction with epinephrine increases the risk of arrhythmias.

Endotracheal administration – some favor the administration of endotracheal epinephrine for cardiac arrest. The rationale is that by comparison to the intravenous route, it bypasses sluggish blood flow, hemodilution, and blood stream degradation. Time taken to place an IV or IO could also be substantially longer than ETT placement.

Septic Shock – Epinephrine is considered the best first alternative or addition to norepinephrine in septic shock. Something to note is that epinephrine will cause vasoconstriction in skeletal muscle, which will cause an increase in lactate levels.

IV push dose

Blood pressure support: 5-20 mcg PRN every 1-5 minutes. Typically prepared by drawing 1 ml (100 mcg) of 1:10,000 concentration of epinephrine (the typical cardiac epinephrine prefilled syringe) into 9 mL of normal saline. This makes a concentration of 10 mcg/ml.

Cardiac Arrest: 1 mg every 3-5 minutes PRN. Injection through a peripheral IV should be followed by a 20 mL bolus flush of IV fluid.

IV infusion dose

Septic Shock / Inotropic support: 2-10 mcg/min (0.1-1.0 mcg/kg/min), MAX 30 mcg/min. Titrate 0.5 mcg/min every 10 min.
Typically diluted by adding 3 mg to 250 mL of normal saline or D5W (makes a 12 mcg/mL solution)

IM dose

-Anaphylaxis-
Adult: 0.1 – 0.5 mg
Pediatric: 0.01 mg/kg, MAX: 0.5 mg

Epidural bolus dose

Epidural Prolongation: 1:200,000 or 1:100,000 mixture. Max dose is 250 mcg (3-5 mcg/kg).

Method of Action

Epinephrine is an endogenous (native) catecholamine. It is the classic ‘fight or flight’ hormone. It stimulates both alpha and beta adrenergic receptors. Predominately, the affects are on the beta receptors at lower doses. This causes relaxation of skeletal and smooth muscle (bronchodilation), increase in heart rate and contractility, and decreased peripheral resistance. In addition, it relaxes uterine constriction, which can prolong/slow labor. At higher doses alpha receptors predominate. This increases peripheral resistance. Increases will be seen in uterine activity and vasoconstriction with a decrease in uterine blood flow.

Epinephrine slows the absorption of local anesthetics by constricting local blood vessels.

Metabolism

Hepatic, renal, GI tract

Additional Notes
Adult ACLS tracheal dose (adminstered down the ETT tube) for asystole: 10 mL of normal saline mixed with 2.0 – 2.5 mL of 1:1,000 epinephrine.

Neonatal Resuscitation ETT dose: 0.05–0.1 mg/kg through the ETT