Last time, Jenny Finnell discussed all about norepinephrine. For this episode, she delves into epinephrine, the hormone also known as adrenaline. Jenny explains why it is crucial for the body’s flight-or-fight response, presents its dose calculations and mixtures, and shares some fun trivia and facts.
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Epinephrine: What Is It And How Does It Work? Free Study Guide Included!
What Is Epinephrine?
In this episode, we’re going to talk about epinephrine. If you missed the last episode, we talked about Norepinephrine, so be sure to go back and listen to that episode. Without further ado, let’s go ahead and break down epinephrine. What is epinephrine? Epinephrine is also known as adrenaline. It’s a crucial hormone in a neurotransmitter and the body’s response to stress or danger. It produces a fight-or-flight reaction. It can be administered exogenously to exert a therapeutic effect.
Epinephrine, also known as adrenaline, is a crucial hormone and neurotransmitter in the body’s response to stress or danger. Click To TweetLet’s get into the pharmacological action. First, we have the classification, which is that it’s a sympathomimetic medication mimicking the effects of the sympathetic nervous system. It’s primarily used in various clinical settings, including anaphylaxis and cardiac arrest, and to prolong the effects of local anesthetics due to vasoconstrictive properties.
Let’s go ahead and talk about the mechanism of action. The adrenergic receptor activation stimulates both the alpha and beta adrenergic receptors facilitating a comprehensive sympathetic nervous system effect. We have your alpha-1 which promotes vasoconstriction increasing peripheral resistance in blood pressure and then we have your beta-1 which enhances cardiac activity by increasing heart rate and force of contraction.
You also have your beta-2 which induces bronchodilatation and vasodilatation in the skeletal muscle improving oxygen delivery. Keep in mind that alpha-2 is also activated but it works as a negative feedback loop. Let’s go on to the release and metabolism. Epinephrine is produced in the adrenal medulla and released into the bloodstream during stress.
Fun Trivia And Facts About Epinephrine
Now, for some fun trivia and facts. What happens to systolic and diastolic pulse and mean arterial pressures with low dose epinephrine? For your systolic blood pressure, you will have increases due to beta-1 receptor-mediated increase in cardiac output. For your diastolic pressure, you will have a decrease due to beta-2 receptor-mediated vasodilatation. For your pulse pressure, we typically see an increase. For the mean arterial pressure, generally, it increases, but it could decrease or remain unchanged. The change in mean arterial pressure depends on how much systolic pressure increases and how much diastolic pressure decreases.
If the mean arterial pressure decreases with low-dose epinephrine, what adrenergic receptor would be responsible? This would be your beta-2 adrenergic receptors. Beta-2 adrenergic receptor stimulation leads to a decrease in systemic vascular resistance, which decreases diastolic blood pressure and possibly mean arterial pressure as well. Epinephrine is metabolized by what enzymes? If you recall, epinephrine is metabolized by the MAO and the COMT enzyme.
Epinephrine Dose Calculations And Mixtures
We now go into some dose calculations and mixtures. If you have 25 ml of 0.25% bupivacaine with epinephrine 1 to 200,000, I want you to calculate the amount of each drug in milligrams. Again, you have 0.25% of bupivacaine which is 2.5 milligrams per ml. To do that, you move the decimal place over by one spot. Any percentage you have, you move it over by one spot and you get the milligrams per ml.
You’re looking at 2.5 milligrams per ml times 25 ml, which equals 62.5 milligrams of bupivacaine. You then have to figure out the concentration of 1 to 200,000 of epinephrine. To do this calculation, you have to see this ratio as equivalent to essentially saying 1000 milligrams and 200,000 ml. If you divide 1,000 milligrams into 200,000 ml, you get 5 mics per ml or 0.005 milligrams per ml. Since we want our answer in milligrams, you then would take the 0.005 milligrams per ml and times it by 25 ml, which will equal 0.125 milligrams of epinephrine.
I am going to be providing these notes in a PDF format and inside these notes I’m going to have a little chart that’s going to have a concentration in ratios with the dose equivalence and the percent. I think this will help you practice your calculations. This is a pretty standard type of formula or equation that you will see in anesthesia that you will get very accustomed to doing head math with. We’re going to practice one more problem to drive this home.
Now, let’s say you have 1 to 100,000 or equivalent to saying 1,000 milligrams and 100,000 ml. This equals 0.01 milligrams per ml or 10 mics per ml. In order to get the milligrams to mics, you simply take the decimal place and move it over by three places. 1 to 100,000 is essentially saying that you have 1,000 milligrams in 100,000 ml, which if you divide that, you will get 0.01 milligrams per ml, which is equivalent to 10 mics per ml.
To wrap this episode up, what drugs can you give down the endotracheal tube? To make this easy, remember the acronym NAVEL. It stands for Narcan, Atropine, Vasopressin, Epinephrine, and Lidocaine. I hope you guys enjoyed this episode. It was fun to make. We’ll see you next time. We’re going to cover NEO next time or phenylephrine. Again, if you missed our last episode, we did norepinephrine. This episode was epinephrine, and the next episode will be phenylephrine. Again, I hope you enjoy this little mini vasopressor series. Until next time, take care.
Important Links
Get Your Free Epinephrine Study Guide: https://www.cspaedu.com/Epinephrine
Thousands of nurses have gained CRNA school acceptance with CRNA School Prep Academy. Join today for access to all of the tools proven to accelerate your CRNA success! Click here:
Join the CSPA email list: https://www.cspaedu.com/podcast-email
Join the Free Facebook Community here! https://www.facebook.com/groups/crnaschoolprepacademyfree
Book a mock interview, resume or personal statement critique, transcript review and more: www.teachrn.com
