ACLS Drugs – Epinephrine

Epinephrine Overview

Epinephrine, also known as adrenaline, is a substance produced naturally in the body. Specifically, it is produced in the adrenal glands’ cortex.

Related Video – Physiology of the Adrenal Gland

Epinephrine binds to adrenergic receptors, a part of the sympathetic nervous system. The body produces epinephrine during its fight or flight response. 

Epinephrine quickens and directly stimulates the sympathetic nervous system. Therefore, epinephrine is a sympathomimetic.

Epinephrine is produced in the adrenal glands.

Effects of Epinephrine

Epinephrine affects alpha and beta receptors. Alpha-1 receptors are located in the periphery blood vessels. When stimulated, they cause vasoconstriction and raise blood pressure. 

Physicians can help return oxygenated blood to the heart and brain by administering epinephrine with quality chest compressions.

There are two types of beta receptors:

• Beta-1 receptors are in the heart.
• Beta-2 receptors are in the lungs.

A nice mnemonic to remember is you have one heart and two lungs.

Read: ACLS Drugs – Dopamine

Beta-1 receptors cause the heart to beat faster. They increase the heart rate, known as a positive chronotrope. It improves conduction through the AV node, which is a positive dromatrope. Finally, it causes the heart to contract harder, known as positive inotrope. When the heart contracts, it “squeezes” the myocardium and increases cardiac output,  which elevates blood pressure.

Remember, Beta-2 receptors in the lungs cause bronchial dilation. That is great if you’re administering epinephrine during an allergic reaction with bronchoconstriction.

Indications and Dosing of Epinephrine

There are several situations in which we administer epinephrine, including cardiac arrest, bradycardia, and anaphylaxis.

Cardiac Arrest

If a patient experiences cardiac arrest, administer epinephrine at a 1:10,000 concentration at 1 mg every 3–5 minutes. The 1:1000 concentration IV is too concentrated to inject directly into a vein. The vessel would close right up.

The 1:10,000 concentration of epinephrine is used in cardiac arrest.

Bradycardia

Epinephrine may be used during bradycardia protocol. If atropine and transcutaneous pacing are ineffective, start an epinephrine drip between 2 and 20 mcg per minute.

Related Video – Understanding the Adult Bradycardia with a Pulse Algorithm

Epinephrine may be used as an infusion in bradycardia if atropine and pacing are ineffective.

Allergic Reaction and Anaphylaxis

You may also administer epinephrine in an allergic reaction. Use the 1:1000 preparation in a 1 mL vial. Administer between 0.2 and 0.5 mg IM right into the muscle. The epinephrine is absorbed more rapidly when given intramuscularly because more blood vessels are associated opposed to a subcutaneous administration.

Related Video – Anaphylaxis: Introduction

The 1:1000 concentration of epinephrine is given during anaphylaxis.

Special Considerations

It’s important to remember all IV medications administered during a cardiac arrest are followed by 10–20 mL of saline to help push the drug to the heart. Studies show the drug will get to the heart almost twice as fast and at about 30% greater concentration, so make sure to administer a saline syringe whenever you give a patient epinephrine.

Summary

The body naturally produces epinephrine, also known as adrenaline. It speeds up cardiac output and is administered in the case of cardiac arrest, bradycardia, and anaphylaxis. Dosings differ based on the patient’s ailment. Physicians should follow up any epinephrine administration with a 10–20 mL saline push.