Clinical Pearls: Epi Doses

Is it the 1:10,000, the 10ml, the carpujet, or the cardiac dose of epi? Might they all be the same (insert shrug)? Epinephrine doses, along with heparin doses, are shrouded in mystery. I feel like this is a manufacturers gatekeeping. A way for big pharma to appear smarter than us plebians. Back in the day this is how people used to refer to epi, and I still find that folks use these interchangable terms and that is why there is confusion. And that’s a big deal. This is not a benign drug. It has a huge range of effects from local anesthesia to systemic life saving efforts to jump start your heart into hyperdrive. Here’s the scoop on Epinephrine.

I went sky-diving once and I would imagine that’s as close to a natural catecholamine high as one can have. That is how I imagine code dose epi feels (assuming one were alert to know).

Ok, so Epinephrine comes in five (ish) doses for five different indications. At least in the ICU realm, it gets really weird when you get into lidocaine with epi and dental dosing. What makes Epinephrine so confusing is that the concentration (g:ml) is very small so for example 1g:10,000ml is also 1g:10L. No one is giving 10L of anything. We break it down into concentration per ml which is 0.1mg/ml. It used to be that the order, the carpujet, and the sticker on the medication read 1:10,000. In 2017 the FDA required drug relabeling on all single entity injectibles to limit confusion. No longer were ratio expressions on the label, instead they now just read standard concentrations in mg/ml. That simplifies things a bit. But then throw into the mix a further dilution of the medication (like you would do for “slow code” or “push dose” epi and we’re right back to being confused). The big takeaway here is knowing that Epi is complicated because of the tiny doses/concentrations we are talking about and the huge range of therapeutic effects at different doses. The more you dilute it the less potent it becomes. Remember it this way: the bigger the dose (most concentrated) the less systemic it should be, in general. Starting from most concentrated to least:

1. 1:100 (10mg/ml)

   AKA: racemic epi, inhaled epi nebs Indication: laryngeal edema, stridor, asthma Dose: 0.25 ml in 2 ml (0.25ml) Route: Nebulizer

2. 1:1000 (1mg/ml)

   AKA: epi-pen Indication: anaphylaxis Dose: .3-.5mg Route: IM

3. 1:10,000 (0.1mg/ml)

   AKA: code dose, cardiac dose, crash cart, “1mg of epi in” Indication: cardiac arrest Dose: 1mg/10ml give all 10ml Route: IV push

4. 4g/250ml (16mcg/ml) titratable infusion; can be max concentrated at 10g/250mln (40mcg/ml)

   AKA: Epi drip Indication: Shock of all types and bronchospasm in asthma (because of the Beta 2 effect) Dose: Start low and titrate up to 20 or 30mcg/m (some institutions prefer weight based). There is really no max but somewhere around 25-30 there is no greater efficacy. Route: continuous IV infusion

5. 1:100,000 (10mcg/ml)

   AKA: push dose pressor. also known as “lidocaine with epi” for local injection anesthesia

   Indication: slow code, but not for cardiac arrest, someone who’s bp is tanking fast but has a pulse. It is also the same concentration used in Lidocaine with 1% or 2% Epi (yes I know it’s weird). Epi for local injection is given for two reasons. Both effects are induced because it is a vasoconstricting agent. One is hemostasis. Two is because it helps keep the lidocaine contained to the local region you are treating and therefore maintain anesthesia longer.

   Dose: Take the code dose syringe of epi and remove 1ml. Mix this with 9ml of NS (in a syringe is easiest). This gives you a concentration of 0.1mg in 10ml and you administer in 1-2ml increments. Very fast half-life so you will be pushing frequently.

   Route: IV push for slow code(do not push the entire syringe) or SQ as an adjunct with local anesthesia Indications: local anesthesia is self- explanatory. IV push is more nuanced and debatable. When do I use it? If for some weird reason it’s taking a while to get an infusion or if the infusion is maxing out quickly and I want to add a temporary solution. Typically this involves waiting on family to come to the bedside for goals of care discussions. Since it rapidly loses efficacy the families can visualize how much effort is being put forth to keep the heart going. I find if the numbers on the monitor look good that’s all they see, even when I point out it is taking 4 drugs to keep it there. But if they see the drops and the constant efforts to fix it there is more impact.

   Takeaways: When you mix for slow code, do not forget to label the syringe. Why do I like this dose versus another push dose like Neosynephrine which many places keep pre-mixed? To me the properties are preferred in undifferentiated shock or in known cardiogenic shock. With Neo you only get alpha (vasoconstriction), with Epi you get Beta and Alpha so there will be some heart squeeze as well. Also, this is likely a person who already has a crashcart at the bedside so it’s easy and you don’t have to walk away.

---

Some Notes About Epinephrine

If your pt is on or being given a beta blocker what are you even doing? If you block the Beta receptor, which is where Epi binds and therefore creates it’s effect you are limiting if not outright preventing Epi from working. The receptors won’t receive the drug. You have to first stop and potentially reverse the beta blocker. Think glucagon (1-5mg IV slow push because they may vomit | followed by an infusion of 5-15mcg/m).

Epi will increase blood glucose.

Epi will raise your lactate level. It is an independent factor in lactate generation as it acts on the skeletal muscle leading to transient increases in lactate.

Half-life: 2-3 min, longer for IM/SQ.

Click on the picture

In this tiktok I talk about severe status asthmaticus and how I’ve used epinephrine to treat.