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.