EMCrit Podcast 6 – Push-Dose Pressors

Hello, and welcome to Podcast Number Six. of the M Crit Podcast. Today we're finally gonna get off of intubation topics, at least for a little while, and we're gonna talk about bolus dose pressors. The anesthesiologists have been using this stuff for years and it has not penetrated into emergency medicine. Not sure why? It's so incredibly useful to be able to just give an injection and rapidly correct blood pressure.

Now you might say to yourself, Well, why bother with this? We could just start them on a presser drip. Bullist dose pressors are for situations where you have a temporary decrease in blood pressure, you think it's gonna resolve, maybe they need some fluids, you're putting them in, in the meantime you just wanna keep that blood pressure up.

To maintain perfusion to the heart, lungs, and brain. Maybe it's a post intubation hypotension where things are gonna get better in a couple of minutes, but you don't want to leave them with a map of forty. You don't have to wait for the nurses to mix these medications. I'm going to show you how to mix them yourself. It's very easy, and that way you could rapidly administer treatment for hypotension, while the presser drips usually take a while to get set up. Beyond that

Drips are generally uh they have a barrier to entry. You you look at a patient you're like, I don't want to start this guy on a norepinephrine drip. He's not that sick. Um so you just kind of let them languish with a low blood pressure for a while until it corrects. uh bowls those pressures you really have uh minute to minute control of what's going on. We're gonna talk about three of them, but I only really use two.

So let's talk about the one I don't use very often at all anymore. And that's ephedrin. Now the anesthesiologists love ephedrin. Every time they give a spinal and they're expecting some hypotension, they'll generally either pretreat or post-treat with ephedrin. It's predominantly a beta agonist, so beta one effects. It's going to increase heart rate. It's going to increase cardiac output. It also has some indirect alpha effects, so you're going to have some vasopressor response.

Problem I have with this agent is it lasts a long time. Its onset is almost instantaneous and its duration is about an hour. Now if I need someone to have a Presser andotrope response for an hour, I might as well start them up on the drips. Most of the things I'm using bullish dose presses for are reversible. They're short-lived. So I don't want an hour's duration. That might be too long.

So I don't find myself using this one very often. Um before I discovered epinephrine I was using this as my inotrope bolus. drug, but as I'll tell you in a sec, I like epinephrine better. So don't really use ephedrin anymore. I'm not even gonna discuss how to mix it up. It'll be in the show notes if you're interested.

Alright, let's get to the inotrope I like, and that would be epinephrine. Epinephrine is a common emergency medicine drug, we're fairly familiar with it. A lot of the time I've seen it used the wrong way as a bolus dose pressor. Sometimes uh folks will have precipitous drops in their blood pressure. map is thirty and someone reaches for an amp of epinephrine and administers it. Now that one milligram dose is dramatically

Too high. Uh dangerously high. Don't do that. Never give an amp of cardiac epinephrine to a patient who has a pulse. That's a dose for a patient in cardiac arrest. What you want to do with that amp of epinephrine is take a syringe with nine C Cs, nine MLs of normal saline, And just draw up one ML of that one to ten thousand epinephrine ampule. So you're taking one C C one ML from the normal cardiac arrest epinephrine amp, and you're putting it with nine C's of normal saline.

And what you're gonna get is now you're gonna have ten C C's of ten microgram per ml epinephrine. And this is the perfect way to mix up this medication. Cause now, if you give one C C You have 10 micrograms. And if you give two cc's, you have 20 micrograms. And the normal drip dose of epinephrine is somewhere between five and twenty micrograms. So if you give one cc of that newly mixed.

Epinephrine, you're giving ten micrograms. If you give that every minute or so, you're giving them the same dose they'd be on on a drip. Now the way I use this is when I need five. a partial press response when I need inotropy because the patient's cardiac output has dropped, whether it be because of medications or due to a sepsis-induced myocardial dysfunction, and I just want to see what they'll do with an inotrope. or I've intubated a patient and now they have decreased cardiac output and

I'm giving them the fluid load, but I just need something to tie them over for a few minutes. I'll give one or two CCs of this bolus dose epinephrine and we'll have a nice temporary increase in their blood pressure and their cardiac output. So the onset is in about a minute. It only lasts between five and ten minutes. So this is a very safe, very tight tradable.

drug. And if you give half one or two MLs of this, you'll see an immediate response and it'll go away very rapidly. I just love bolistose epinephrine. So just to conclude that never ever ever Give patients with pulses the one milligram of epinephrine. Mix it up the way I taught you. If you give maximum of one to two cc's every minute or so, you're going to be well within the normal dose range. Oh and the other cool thing about this is if you mix it up like I told you

It's the same concentration as lidocaine with epinephrine. You know, that medication you inject all the time in the subcutaneous tissue. So if this drug does extravisate out of a bad IV, you're basically giving two cc's of lidocaine with epinephrine, which you inject all the time. Just don't inject it in the tip of the penis and you should be fine. So this is a very safe medication to give through a peripheral IV.

Last but not least is my favorite, bolus dose phenyphrine. Now, as you know, phenylephrine is a pure alpha agonist. It has just vasoconstrictive effects, no effects on the heart whatsoever. So you're not gonna increase heart rate. You might even decrease heart rate. This drug is just great. I have this drug next to me for every high risk intubation where I might see hypotension. I have it next to me during every conscious sedation where I might have drug-induced hypotension.

It is just clean and easy. Now this the way you mix this drug up is you take one ml out of the phenylephrin vial. And that phenylephrin vial is ten milligrams per ml. And you take that Cc and you put it in a hundred CCs of normal saline, you know, just a bag of a hundred mls of normal saline, and you just mix that puppy up. And now you take out in a 10 cc syringe, you draw up ten cc's of that newly mixed bag. And what you're gonna have is you're gonna have phenophrine, 100 micrograms per cc.

And the dose you want to use is you want to use half to one to two mLs every minute or so. And so that'll give you between fifty and two hundred micrograms of phenylephrine. The same dose you get in a phenylephrine drip. Now what you're gonna get is you're gonna get in about a minute. a pure vasopressor response.

Benilafrin only lasts about twenty minutes, so you're not gonna have a long standing effect. It'll go away and you'll be able to reevaluate what your patient's doing on their own. You're gonna see an increase in blood pressure, you're not gonna see any increase at all in heart rate. or cardiac output. And in fact this drug sometimes will decrease cardiac output if you're giving it to a patient with normal afterload. But if you're giving it to a patient with

profoundly dropped after load, you might even see an increase in cardiac output because they weren't perfusing their heart with that map of thirty. And now you take them up to a map of seventy, all of a sudden they're getting heart perfusion and their heart starts beating normally. So phenyphrine is a very clean, safe medication. When do I use it? Well, when you given medications that have pure vasodilatory responses, like for instance propofol,

Phenylephrine will fix it and it'll fix it very cleanly. And what about that atrial fibrillation patient? Blood pressure is in the toilet. It's fifty over thirty and yeah, you've tried your immediate countershocks because this is an unstable patient and they haven't worked at all, which is very common in the patients who have had chronic atrial fibrillation. So what do you do?

Well, what I like to do is I just immediately give them some phenyphrine, because first of all, it's going to perfuse that heart and make it more likely for them to convert. And it's also gonna maintain brain perfusion so the patient's not gonna go unconscious and need to be intubated. And now I got some time. Maybe I'll give some amiodarone. Maybe that'll stop it, but probably not. But what it will do is it'll make the potential for them to

uh shock out of it on the next round of countershocks more likely. So now I have bought myself some time. I've taken an uh grossly unstable patient and given them some stability with my bolus dose phenylephrine. So just to wrap up, ephedrin's out there, it's used by the anesthesiologist, I don't like it.

Epinephrine, if I need an inotropic and pressure response, very safe, very commonly used in emergency medicine for cardiac arrest, but now it can be used for other patients as well as a bolus dose.

But phenylephrine is still my favorite because that one is just so nice and clean, you just get a pure vasopressor response. You give the medication, a minute later, increase blood pressure. If you need to give more, wait a minute or two and give more. Half to two mls every couple minutes, and you will have a very nice clean presser response. Alright, that's it for this week. Um just to wrap up, I just want to tell ya of all the options for a subscription we have.

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