Neuromuscular Blocking Drugs (NMBs) (Nursing)

00:00 Hi, welcome to our pharmacological video series. In this one, we are going to look at neuromuscular blockers. Now, before those drugs make sense, we want to introduce you to the neuromuscular junction. We'll call that the NMJ because that becomes a mouthful for me to say. So, we're going to talk about neuromuscular drugs. Now, let me just give you a little intro to these drugs. They will completely paralyze a patient, but they are awake at the same time. So, they can't move any skeletal muscle in their body, but they can hear, they can see, they can feel pain. Well, they can't really see because they can't raise an eyelid. So, let's talk about how these drugs work. So, where do they work? Well, I just told you, didn't I? They work at the neuromuscular junction. Now, you probably already figured this out, but let me break that down. Sometimes, we use so many words so quickly in education that you kind of miss this. So, I want to break down neuro and muscular. That is where the nerves and the muscles communicate. So, the neuromuscular junction is where they meet up, the nerves and the muscles. So, this is where this medication acts. Now, neuromuscular blockers. Well, blocker tells us it's stopping something. Right? So, what are they stopping? Well, they work after the synapse or postsynaptically. That's not some kind of crazy movie in the future. We are talking about after the synapse. They work at the acetylcholine receptors of the motor nerve endplate, and that's what causes the paralysis of skeletal muscles. Now, you have skeletal muscles all over your body including your diaphragm. So, if you don't mind, write yourself a little note including diaphragm because when that becomes paralyzed, the patient can't breathe on their own. So, neuromuscular blocker medications, they work after the synapse or postsynaptically. They block the acetylcholine receptors of the motor nerve endplates.

02:06 Now, in case you don't have a good frame of reference, don't worry. That is why we are doing this video. We'll help you understand it, and it will make perfect sense. I promise. But the end result, paralysis of skeletal muscles. So, paralyzing the muscles that are used for breathing, so that is the problem. It's usually not our goal to paralyze the respiratory muscles, but the diaphragm is a thin piece of skeletal muscle. So, when we use these drugs, we often use them with anesthesia or we use it with patients who are critically ill, but both groups of these patients need to be on mechanical ventilation or ventilator support because they can't draw in a breath on their own. Now, it doesn't affect the CNS. Remember, we talked about that in the introduction. So, to me, this is like that bizarre feeling where people say, "I was awake for my surgery." Now, those are stories that are usually on TV. But a neuromuscular blocker doesn't affect the CNS because remember it works where the nerves meet the muscles. So, the patient is fully awake and aware of pain. So, that's why general anesthetics are used, or analgesics or sedatives have to be given to the patient when you give a neuromuscular blocker. It's only the appropriate thing to do. Now, they are really helpful in surgery and in areas where we need the patient to be very still as long as you're aware of the risks. They are able to breathe on their own, but they still will be aware unless you give them other medications in addition to the neuromuscular blockers that will help sedate them or deal with pain. So, let's break down how they work. We have got a graphic here for you to help you walk through the process and recognize the players. Let's talk about skeletal muscle paralysis. It sounds kind of weird, doesn't it? Hi, today we're talking about skeletal muscle paralysis, but that's what these drugs do. It's an extreme skeletal muscle relaxation or complete paralysis.

04:06 Now, we've got a drawing for you there, and to break it down, we've got it numbered. I want to kind of walk through what the different parts are. Neuromuscular blockers, you already have been introduced. They prevent acetylcholine from activating the nicotinic M receptors at the skeletal neuromuscular junction. So, now we're getting really down specific to the actual receptors. Acetylcholine is not allowed if blocked from activating the nicotinic M (M just stands for muscle, those receptors at the skeletal neuromuscular junction). So, when nicotinic M receptors are blocked, the patient no longer has control of the skeletal muscle and is paralyzed. Okay, so you've got the groundwork. Let's take a little bit more closer look at the neuromuscular junction.