Hi. I’m Mark from ACLS Certification Institute. In today’s video, we’re talking about pharmacology, ACLS pharmacology, with an emphasis on atrial rhythms, medications that we use to treat atrial arrhythmias.
It’s not uncommon that sometimes you’ll be looking up a drug, looking up the mechanism in PDR or Epocrates and it will say the exact mechanism of the drug is unknown. Like, what the heck is that? You don’t know what the drug does? We have an idea what it does, but the exact mechanism is unknown. So, you go talk do Dr. Fictitious, and you go, “Hey, professor, how does this drug really work?” “And that is a great question, how does this drug work exactly. Let’s take a look. Now, if you look over here, see this? And then look right here, see this part here? Now, look over here. Not so much here, but this part right here. If you look at this, it is obvious we have no idea how this drug works. Couldn’t tell ya.” Ah, that was all but useless. Let’s say we just move on to the drugs.
Here’s a drug you can have fun with your friends with: adenosine. Adenosine is used to treat narrow-complex symptomatic tachycardia—the patient’s stable, but symptomatic with narrow-complex tachycardia. Adenosine has a very, very short half-life. Once it hits the body, it’s only hanging on for a few seconds. Adenosine is one of those drugs that you have to flush in quickly and then hit immediately with 20 cc syringe bolus to push that drug to the heart. Otherwise, it’s not going to work. It’s fun for the new paramedics, and here’s why. You’ll be in the back of the rig and you’ll see this strip going on, and you go, “Okay, Timmy, go ahead. Give him this drug.” It’s adenosine. You tell him how to give the adenosine. He pushes the adenosine and then you see this on the monitor: “scared look”. “Timmy, what’d you do? What’d you do? … Ah, never mind, it’s okay.” It scares the hell out of Timmy because you’re going to have that asystole pause that is characteristic of adenosine administration. Try to have some fun with it while you’re at it. If the first dose of adenosine doesn’t work, double it. You can give a second dose of 12 mg IV push. If that still doesn’t work, maybe you want to step back and we have something else going on. Maybe this could be a ventricular arrhythmia with an aberrant conduction. Something else is going on. That’s why we give adenosine—sometimes, in ventricular arrhythmias, to just diagnose is this really ventricular or atrial in origin? That’s another way we can use adenosine, to rule that out. If it’s ventricular, it’s probably not going to do anything. If it’s a narrow-complex tachycardia, I’ve had great results with adenosine breaking that tachycardic cycle.
Let’s talk about verapamil for a minute, a drug that we use for narrow-complex irregular tachycardias. We use adenosine for regular narrow-complex tachycardias. We can use verapamil for narrow-complex irregular tachycardias. Can you use verapamil for narrow-complex regular tachycardias? Absolutely, so you could use verapamil for regular or irregular narrow-complex tachycardias. It’s a calcium channel blocker. You want to give it slowly. The dose is 5 mg slow IV push over 3 to 5 minutes. You want to have one finger on that print button on the monitor so that as soon as the patient starts to convert or break that tachycardic cycle you can capture it on film.
Another calcium channel blocker we use for treating narrow-complex tachycardias is Cardizem. The dose of Cardizem is 0.25 mg/kg. You can repeat with 0.35 mg/kg. Once the patient converts and they’re out of that tachycardic rhythm, you can start a Cardizem drip at 5 to 15 mg/h. Again, it’s a calcium channel blocker. I’ve had great results with Cardizem converting narrow-complex irregular tachycardias and slowing that rate down. Rate control—that’s really what the Cardizem is for is controlling that rate.
What about atropine? What about atropine. Atropine is a parasympathetic blocker. This is how a lot of drugs work. A lot of drugs, when they’re introduce to the body, really don’t do anything. They either inhibit or enhance a body’s normal function. That’s kind of how atropine works. Let’s take the sympathetic/parasympathetic system as an example because atropine is a parasympathetic blocker. Say I’m driving a car 10 miles an hour. I have my foot on the brake and my foot on the gas at the same time, pushing down on both. Doing that, I’m getting the car to move 10 miles an hour. Fantastic, I want the car to go a little faster. I could push on the gas, but atropine doesn’t do that. Atropine blocks the brake. It’s a parasympathetic blocker. It simply takes off the brake, leaving the gas unopposed, so the car goes faster. That’s how atropine works. It blocks the parasympathetic system, leaving the sympathetic system unopposed, and that raises the heart rate. Cool, it didn’t really do anything to raise the heart rate, it just stopped the brake. Make sense? Why do we use atropine? We use atropine for symptomatic bradycardia and some blocks. For third-degree blocks and higher blocks, it’s probably not going to work, but lower blocks and bradycardia absolutely indicate it. The dose is 0.5 mg IV push to a max dose of 0.04 mg/kg for a total of 3 mg. If the atropine isn’t working, if you have a symptomatic patient who’s bradycardic and the atropine isn’t working, get your pacer pads ready; those are coming up next. Atropine is a great parasympathetic blocker and a great drug for raising heart rate.
As much as we joke around in these videos, probably nothing is more serious than drug administration or administering a medication to a patient. They estimate about 100 thousand people are going to die this year from medication errors caused by us. Be careful when you’re administering a medication. Know the drugs you’re administering. At 3 in the morning, I’m double-checking. I’m going, “Hey, is this verapamil? … No? Vecuronium? Oh okay, well, good thing I didn’t give that.” Double-check your drugs. Remember, it’s not why do you want to give a drug, it’s why do you not want to give that drug. Double-check. Make sure you have the right patient, the right drug, the right dose, the right route, the right time, and you’re documenting it properly. Take drug administration seriously or as seriously as we can.
Thanks for watching.
