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Dr. Daniel Sakai on Effective Clinical Use of Neuromuscular Blocking Agents
343 Plays5 months ago
Happy Halloween, and welcome to another chilling episode of the NAVAS podcast, where we venture into the eerie depths of veterinary anesthesia! Join us as we lift the curtain on a topic that, while vital to advanced anesthesia practice, often sends shivers down the spine of even the bravest veterinary professionals—neuromuscular blocking agents (NMBAs) in veterinary patients.
While paralytic agents play an important role in providing excellent quality muscle relaxation that can help facilitate a variety of procedures, their use often spooks even the seasoned anesthetist, as they can cause frightening problems if not used with great care. After listening to this episode, we hope you can avoid a jump scare anytime you need to use NMBA.
Our guest for this spine-tingling episode is the highly esteemed Dr. Daniel Sakai from the University of Georgia College of Veterinary Medicine. Dr. Sakai, boarded veterinary anesthesiologist, has conducted extensive research on NMBAs, exploring their invaluable role in patient immobilization as well as how to optimize recovery from neuromuscular blockade. He’s here to help us demystify these powerful agents, dissect their practical applications, and reveal how to use them safely and effectively to prevent any nightmarish outcomes for your patients.
So, as the leaves fall and the shadows lengthen, grab a cozy blanket, tune in, and get ready to learn from one of the top minds in veterinary anesthesia. Just be warned—this episode might leave you spellbound!
If you like what you hear, we have a couple of favors to ask of you:
Become a member of NAVAS for access to more anesthesia and analgesia educational and RACE-approved CE content.
Spread the word. Share our podcast on your socials or a discussion forum. That would really help us achieve our mission: Reduce mortality and morbidity in veterinary patients undergoing sedation, anesthesia, and analgesia through high-quality, peer-reviewed education.
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If you have questions about this episode or want to suggest topics for future episodes, reach out to the producers at education@mynavas.org.
All opinions stated by the host and their guests are theirs alone and do not represent the thoughts or opinions of any corporation, university, or other business or governmental entity.
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Transcript
Introduction to NAVAS Podcast
00:00:07
Speaker
Hello, gas passers. Welcome to another episode of the North American Veterinary Anesthesia Society podcast. I'm your host, Dr. Bonnie Gatson. Our goal with this podcast is to advance and approve the safe administration of anesthesia and analgesia to all animals.
00:00:26
Speaker
It's been a hot minute since we had an episode where we took a deep dive into a single topic related to veterinary anesthesia. I think our last one was about a year ago where we discussed the pros and cons of different anesthetic induction agents.
Exploring Anesthetic Drugs
00:00:41
Speaker
So today we're going to talk about drugs again because this is an anesthesia podcast, but we're going to focus on a class of drugs that is a bit more esoteric and not really used on a day-to-day basis. Of course, I don't think that makes this discussion any less fascinating or interesting, especially if you are an anesthesia nerd like myself. And if you've made it this far, I'm assuming you are too. These drugs can be powerful tools to help your patients under anesthesia, but
00:01:19
Speaker
They require careful understanding and monitoring to ensure patient safety because their side effects and consequences can cause serious issues.
Sponsor Acknowledgment and NAVAS Membership
00:01:29
Speaker
But before we get started and before I reveal the class of drugs we're going to talk about today, I want to give a shout out to the sponsor of this podcast, Decra. Their generous donation allows us to provide monthly continuing education to all you gas pastors out there using this format. So we are very grateful to them. Please visit www.decra-us s dot.com and check out their line of veterinary anesthesia related products.
00:01:59
Speaker
Also, if you are not a member of the North American Veterinary Anesthesia Society, then what are you waiting for? As a member of NAVAS, you get tons of benefits, including access to CE events, focusing on anesthesia and pain management, blog posts, fireside chats with boarded anesthesiologists, as well as specialty technicians, and just so much more. Visit www.mynavas.org to advance your anesthesia journey today.
Understanding Neuromuscular Blocking Agents
00:02:30
Speaker
When people think of neuromuscular blocking agents, I think maybe some people have heard of using these drugs exclusively for eye surgery, but I also get this feeling that people hear of paralytics and think that it sounds really scary and to just stay away from the whole thing. However, I'm hoping to convince you that you can include paralytic agents for a wide range of conditions, since they can work synergistically with inhalant anesthetics,
00:02:59
Speaker
which can smooth out the overall plane of anesthesia in your patients and make surgery a little easier with the accompanying muscle relaxation. However, before jumping into using these drugs on your next surgical case, it's super important to have a good baseline knowledge of how these drugs work to avoid predictable but potentially catastrophic complications with their use.
00:03:23
Speaker
To help us navigate this complex subject, we have a special guest, Dr. Daniel Sakai, a veterinary anesthesiologist from the University of Georgia College of Veterinary Medicine. Dr. Sakai has conducted extensive research on the use of neuromuscular blocking agents in animals, and he joins us today to break down how these drugs work, when they should be used, and most importantly, how to use them safely.
Dr. Sakai's Journey to Anesthesiology
00:03:49
Speaker
In this episode, we'll cover the situations where paralytics can benefit your anesthesia protocols, how to monitor their effects in your patients, and how to reverse their actions safely and effectively. Whether you're familiar with neuromuscular blocking agents, or you've never used these drugs, but you're curious to learn, this episode will provide valuable insights into their safe and effective use. Let's get started right here on the NavAss Podcast.
00:04:22
Speaker
Dr. Sakai, can you tell me a little bit about what your journey was to become an anesthesiologist? I was in Brazil my fourth year of vet school and my professor of anesthesia. She invited me to do some research with her and then started it from there. So I enjoyed and I thought that was a good career to follow. And in 2005, I did an externship at Florida with Dr. She.
00:04:49
Speaker
And he was my first influencer in the United States. And I decided that I i would and eventually try to become one anesthesiologist here as well. so Yeah, so where did you do your training? I did a two-year residency in Brazil back in the 2000s. And then I worked a couple years in practice. practice And I did another residency at Cornell for three years.
Mechanism of Neuromuscular Blocking Agents
00:05:17
Speaker
I stayed there two more years as an instructor and two more years as a fellow. And now I started to work in at UGA. I've been here for one year. Great. Okay. So today we're going to talk about a class of drugs that I think some people may have some familiarity about. Some people probably don't use them that often, but we're going to talk today about neuromuscular blocking agents.
00:05:43
Speaker
And so let's just start by introducing this class of drugs a little bit. So where did they come from and why would we use them? There are drugs that are different from the other anesthetics that we use that they have just peripheral effects that just act in the muscle. They don't have any effect in in the brain. so You need to be careful when you use that, because if you're just using them alone, you will just provide relaxation, but the animal will be totally awake. Right. So I think the first use of them was by indigenous people in Brazil when they hunt, and they put the corrarian on the tip of the arrows to hunt animals. Probably was a bad.
00:06:28
Speaker
That was terrible, probably. And then people realized that that would be useful for medicine as well. And there are some descriptions of people being paralyzed without any seizure and they describe how was the feeling about being paralyzed. Oh, that's weird. Yeah. I also feel like there is some historic documentation of like clinical inducing anesthesia with like succinylcholine in like horses. Yeah, that that was bad. i That's not used anymore. So there are some all three parts of people doing castrations in the field with just succinylcholine and that's totally inappropriate. Yeah, completely inhumane. Yeah. Don't do it. Don't do it.
00:07:14
Speaker
Okay, so how do these drugs work? So you said they work in the periphery. What's their mechanism of action? How do they how they create muscle relaxation? Yeah, so the way they do, do they compete with neurotransmitters that you have in the muscle. So they compete with acetylcholine.
00:07:31
Speaker
So each muscle fiber, they have a connection with nerve ending. And this nerve ending just releases acetylcholine that will interact with these receptors and they will depolarize the muscle fiber.
00:07:46
Speaker
and made the muscle fiber to contract. So depending on how much acetylcholine releases in the neuromuscular junction, the more contraction we will have. And the neuromuscular blocking agents, they will compete with the acetylcholine for these receptors, and the receptors will not be more available anymore for the acetylcholine. So it's a competitive antagonism that usually
Applications in Veterinary Procedures
00:08:10
Speaker
how it works.
00:08:11
Speaker
Yeah. So I know that there's two different like classes of neuromuscular blocking agents. Can you describe a little bit about the different classes and how their mechanisms are a little different? Yeah. So we have to depolarizing the neuromuscular blocking agents. That's the sux new choline. It's not used a lot. I just use more once in a quick research at Cornell.
00:08:34
Speaker
And the way they they act, they interact with their as the acetylcholine receptors, the nicotinic acetylcholine receptors, and they depolarize the cells, so you have an initial contraction. But they don't go back to the resting stage, so this fiber won't be able to contract anymore after the initial contraction.
00:08:54
Speaker
And we have the non-tipolarizing neuromuscular blocking agents that they interact with the receptor, but they don't open the part, so the muscle fibers, they don't contract, so you have a relaxation from the from the start.
00:09:06
Speaker
why would we be utilizing these agents? I know, or at least in human anesthesia, neuromuscular blocking agents are oftentimes incorporated into the anesthetic protocol, specifically sometimes to like intubate people or to provide like extra muscle relaxation during surgery. But like what are some of the indications for using these agents in our veterinary species?
00:09:26
Speaker
The most common procedure that we use and relaxants are for stomach procedures that you want to have a good relaxation of the eye globe to make sure the eye globe is central for the surgeons to be able to do surgery in the cornea. Yeah, it's important to note, like especially for dogs and cats, like their eyes roll ventromedially when they're in an appropriate surgical plane of anesthesia. And so we want the globe to be central, like you said. Yeah. In some cases, I did a study in cats that we can use and similar to people as an induction protocol to help to relax their lungs a little bit more, to provide intubation. Cats are prone to laryngospasms during intubation. And similar to people, they are hard to intubate, and there's an association of intubation in cats with higher mortality. So it's an association, not causation, but you need to be careful when you're intubating cats. And so it might be useful in this case as well. So there's just one report out there. But there's a couple of reports of using relaxants in intubation in cats. And anytime that you want an extra relaxation, if the
00:10:36
Speaker
The surgeon requires more relaxation and you don't want to give more anesthetics because you don't want to cause more cardiovascular depression. You cannot use a relaxant to balance your anesthesia a little bit more.
00:10:51
Speaker
I think the only other way I've ever really used it is for like animals that had like really bad contracture or fractures. The surgeons were like struggling to put things back in place. I've used it that way. We have a surgeon at Florida that really likes to use muscle relaxants if they have abdominal procedures that are like very deep so like adrenal surgeries where it helps to kind of have more muscle relaxation for them to like get to where they need to go for dissection. How often are you using neuromuscular blocking agents as part of your anesthetic protocols? So here as we are in the academic institution
00:11:26
Speaker
I use much less than I used to use when I was doing my own aniseases when I was a resident. yeah Because I think you need to have a ah good knowledge about relaxants, how to use them, especially when to reverse them. So it I feel a little bit concerned if everybody is using the this class of drugs without having good knowledge about how they really works and what are the possible consequences for recovery. So here I just use for stomach procedures and when the surgeon requests for more relaxation.
Monitoring and Safety in Anesthesia
00:12:00
Speaker
Yeah. I think that that's a really good point is that, you know, these drugs can cause like pretty significant complications in your patient if you're not using it correctly. So let's talk a little bit about how to use these agents responsibly. So what are some things that we need to take into consideration when we're using these agents?
00:12:18
Speaker
The relaxants, they will block every muscle that you have in your body. It's not just kind of the muscle that you want to relax, but they will relax the diaphragm. So that's the major concern so in any seizure that you need to use a mechanical ventilation. You need to ventilate for the patient because the patient will stop breathing when you give a relaxant. So you need to prepare to start providing ventilation.
00:12:43
Speaker
And he won't have control anymore of the larynx. So if you exubate the patient accidentally and he has material in his oropharynx, he will aspirate that material and he will have aspiration pneumonia as well. So right yeah so even residual levels of neuromuscular block effect can be very drastic, the results of the patient.
00:13:12
Speaker
Yeah. And let's talk about some of the effects of the agents themselves. So there's lots of different agents, like we talked about, succinylcholine being the de polarized the major depolarizing neuromotor blocking agent. And let's talk about some of the effects of those drugs specifically, so because we have to take that into consideration. So we already mentioned that succinylcholine is not used all that commonly, but what are some like pharmacologic effects that we might see when we utilize that agent?
00:13:37
Speaker
Succinylcholine is not a really classy drug. That's why we don't use that often. In human medicine, it's interesting they use a lot on that. It's a really fast drug, so you give that, and the effect is gone in five minutes. Because you you don't you just need the plasmatic steroids to break that down, so and the effect is gone. Yeah. That's why they use a lot for fast sequence intubation. They want just to give relax and to relax the larynx intubate quickly.
00:14:05
Speaker
Yeah, and then the drug is just like poof gone. The drug is gone. But the initial contraction of the succinylcholine that occurs is what usually causes problems. So you have massive contraction initially of the muscles, and that can release lots of potassium in a circulation. So you can have dangerous effects from this massive hyperkalimide that you have. so There are some reports of sudden deaths of the administration of succinylcholine in people. Yeah, because the hyperkalemia is just really sudden and pretty profound. Yeah, so if the patient is already he's already contraindicated to use succinylcholine because it will increase even more to potassium level.
00:14:49
Speaker
Yeah, let's talk about the nondepolarizing drugs. So what are some of the effects that we see from those particular drugs? There's many of them, so we can kind of maybe go through a few of them. We have two major classes in this category. We have the amino steroids and we have the benzokinolones.
00:15:08
Speaker
Yeah, it said it's like benzo-isokinolones. Benzo-isokinolones, yes. Atracurium cis-atracurium are the benzo-isokinolones that we use more often. Rokuranin and vekuranin are the steroids type that we use more often. The problem with the atracurin and cis-atracurin, they have the potential to release histamine in the circulation so you can have some hypotension depending on the dose that you use.
00:15:36
Speaker
i Personally, I don't see that as a big problem. When I give a turquoise a turquoise, if I see some hybridization, it's minor and it's translucent. Yeah. I've actually never seen it. Yeah. And I use aducurium pretty frequently. It will be like a 20 seconds effect and kind of drop a little bit in.
00:15:56
Speaker
All right. ri So if you're giving in and don't look at the monitor right after, probably you missed ah this kind of quick. But some dogs, that can they can have massive muscle degradation. Some dogs can have some more a profound effect. Yeah. yeah And steroids, they are known to be more cardiovascular stable, but the metabolism of them are a little bit different, so they need to be cis-atrocodinatrocodin. The great thing is that they are breakdown with physiological pH and temperature, so you give that to the patient and you don't need liver, you don't need kidneys for the cis-atrocodin to be broken down. Right. So it's like Hoffman elimination. It's the Hoffman elimination. For this class of drug, it's important to keep the temperature of a patient. If your patient gets cooler, that happens a lot in the anesthesia, the recall is going to be prolonged as well. Yeah, yeah. And the regular and the regular and the dependent are going to be eliminated.
00:16:58
Speaker
So for the, like, rock harem and big harem, it's more like liver metabolized, renal excreted. So that's probably important to keep in mind when you're thinking about which class of drugs do you want to use might be dependent, like, does your patient have significant hepatic disease or renal insufficiency or something like that that might prevent appropriate metabolism of those drugs may prolong the action of those drugs, potentially. Yes, yes. So the major concern for me is how long the action it is for these drugs because during any seizure we have a controlled the environment, we are providing mechanical ventilation, we have the airway protected, but if it is an effect that exists beyond this anesthetic event is when we we need to be concerned because the patient won't be able to be controlled anymore. Yeah, let's talk a little bit about how we make these agents kind of disappear at the end of the procedure. Because like you said, when a patient wakes up from anesthesia, I mean, they're in a controlled environment, but then we're not mechanically ventilating these patients anymore.
Techniques for Assessing Neuromuscular Function
00:18:00
Speaker
We're not protecting the airway anymore. So how do we appropriately ensure that these agents don't have residual effects kind of in the post-operative period?
00:18:10
Speaker
Yeah, the cool thing is that the peripheral relaxants, you can monitor them with peripheral nerve shmellator. So it's basically two electrodes that you apply close to a peripheral nerve. So usually we monitor the ulnar nerve or the peroneal nerve, and we give electrical shmallows and we measure the muscle response. And there are several patterns that you can use to simulate the nerve. The most common one is to keep the train of fire or tough. Yeah. So it's just kind of far really rapid electrical stimuli given over two seconds. And you should they see the response when you don't have any relaxation, and they should be, all the response should be the same height and strong.
00:18:56
Speaker
When you have ah a partial block, you you see a fade. So the first switch is stronger than the second, it's stronger than the third and they're on. And when you have a complete block, you don't see any response. So you keep the partial malay and you have zero responses on your muscle.
00:19:15
Speaker
So to confirm that you have recovered, you need to give the system and should see if you have far strong responses. Yeah. And there is ways that and you can measure these responses. You can measure just looking by them. So just visually or palpating the response, or you can measure with other measures, ah measure as surrogates for farce.
00:19:39
Speaker
What do you guys, I think in my residency, we just hit the train of four button and just like watch the paw, yeah which is kind of a crude way of doing it. But I guess like if you see four twitches, I usually feel, or you see the leg kick four times and you're like, okay, that's probably fine.
00:19:54
Speaker
But there are things like accelerometers, which I started using a little bit after my residency. you' nice It's actually like a device that you put on the pawn. It will measure like how quickly that paw is moving, like the momentum of the paw, essentially, during those but four twitches. And it actually can like calculate a ratio for you. Those are really nice to use. They are a little bit expensive. If you don't have you know an accelerometer, it doesn't mean you can't monitor, yeah essentially. But it's probably better to use. like It's more scientific or evidence-based if you use like an accelerometer.
00:20:24
Speaker
but The problem is that if you adjust your visualization, adjust your eyes, we think that our eyes are good to see how fast they move, they are not. Yeah, I'm sure you're right about that. Yeah, they are really not. So you can have a 50% of fade, so top of 0.5, and you can think that all four twitches are fine if you just look at them. So actually you have a really good degree of residual block if you recover at this level and you ask what kind of just trick you. And accelerat if you use ah objective measurement like acceleration, so to be really nerdy is kind of
00:21:03
Speaker
You use the Newton's second law for that. So farce is equal mass mass times acceleration. So we are indirectly measuring the farce. So the higher the acceleration, the highest the farce. And you give numbers that are closer related to the actual farce. That's what really matters for us. It's not the acceleration, but it's the farce that really really matters. so But even the objective measurements in dogs and We did some studies and they are not super great as well. They have a ah wide discrepancy with the actual forest that you have. So you can have a good acceleration, but the forest might not be still great. Oh, that's interesting. So what have you found is maybe the most accurate or is there like no accurate?
00:21:54
Speaker
Yeah, so got us in trouble because was our line of research, okay, we thought that, okay, let's do, I think, super straightforward kind of measurements that they should be good. Then we saw that our measurements might not be super super good. Okay, so we are kind of going in circles here. So yeah I think for research, is it's good to have the measurements, the objective measure measurements, but on clinical basis, I think we should do do something else. I think we need to apply systematic reversal for our patients that have relaxants. Oh, that's that's really interesting. So, and also before we kind of get down to what systematic reversal kind of means, it should also be noted that the train of four patterns that we were describing are more for the non-depolarizing as opposed to the depolarizing, although there is like the first phase and the second phase for, yeah that's kind of like jargon, we won't
Pharmacologic Differences Among Agents
00:22:50
Speaker
get into that. Yeah, so first phase, second phase is second phase is when you give a lot of succinylcholine and they start behaving like a non-double arising agent and is you start seeing the fade. But in theory, you should not see yeah you shouldn't see any fade with succinylcholine.
00:23:08
Speaker
and I don't think that the way that, I mean, I could be totally wrong, but because people are, at least in human medicine, they're just usually just quickly administering succinylcholine just to intubate. Like i I don't think that they're really doing very good, like they're not using monitoring for that. At least that's my understanding.
00:23:26
Speaker
Well, it's kind of comforting in a bad way that as anesthesiologists, they are a little bit lax on the reversal like us and monitoring as well. yeah So ah we if you see the surveys that they do, the numbers were kind of similar to the survey that we did about the use of reversal and monitoring. So there are some groups that are really into monitoring neuromuscular blocks, but yeah the majority of anesthesiologists don't monitor relaxation. Yeah, that's probably true. I remember once I was reading this article about these people who administered succinylcholine to intubate a human, and this human had like a plasma estuaries deficiency. yeah And so they obviously were not monitoring their blockade. So they administer succinylcholine, but because it couldn't be metabolized through a traditional methods, because this person had like a plasma esterase deficiency that wasn't detected like before anesthesia. So they tried to recover this patient and just like the patient couldn't like breathe essentially. And so they had to keep this patient on a ventilator for like, like at least 24, like one or two days before they can actually extubate it. And there was like, they couldn't figure out what was going on.
00:24:41
Speaker
Yeah, it's important to monitor our individual differences, and there might be these problems that don't have steroids. So it's a significant quality and we stay there forever. so Yeah, and I think that other important point, too, when you're talking about systematic reversal is like,
00:24:57
Speaker
For example, atricurium undergoes Hoffman elimination, but how quickly that drug's actually metabolized is dependent upon not only your patient's temperature, but like a huge other variety of factors. So do you want to talk about some of those factors that might affect how quickly your atricurium dissipates?
00:25:14
Speaker
It depends on the way that the effect is gone from the, from our muscle relaxants is how fast it goes away from the neuromuscular junction. So you give a big dose of the relaxants. You have a high concentration in the blood and this high concentration of blood will excite the concentration of the muscle. Right. And it will transfer the atrocurum to the muscle. Then you start breaking down atrocurum and it will go back to the, from the muscle will be higher concentration and it will move the other way.
00:25:43
Speaker
Yeah, so go from the muscle to the plasma.
00:25:50
Speaker
so they must He's doing some very dramatic hand movements, I just want everyone to know. It depends on how fast it decays the plasmatic concentration factor occurring, how fast it will decay the effect of the of the relaxation. right So temperature is one of the big important thing, but there are other things that are important, is like how fast your blood is circulating in the body. Half a month elimination is not the only way that other organs are eliminated. It has other ways of elimination as well. So and it depends on organs as well. So it doesn't mean that you if you have renal sufficiency, hepatic insufficiency, it means that it won't affect
00:26:29
Speaker
how fast that recruitment is cleared. so Because when we teach that it has half of my elimination, we forgot it's just that it has other ways of elimination. Yeah, it does have other eliminations as well. That's just like the classic. Yeah, it's just, oh, this is cheaper and than this rug, but it doesn't mean that this is the only way. So it depends on other ways as well. Yeah. And then, of course, like different electrolyte concentrations can also affect yeah how quickly those drugs dissipate. And drug interactions, some antibiotics, they, I mean, a glycosides, they can prolong the effects of relaxants as well. Yeah. Yeah. So there are a lot of things that can interact with the amount of relaxation duration of that autocurium. Yeah. So let's talk a little bit about systemic kind of reversal. So or systematic reversal. So how do we go about doing that? Yeah. so
00:27:17
Speaker
As we saw that we have a train of four, the four twitches are present. We think that's good. We can still, we have a good relaxation still. If you give a reversal that we can use, in fact medicine usually we use nostagemine because we don't have edrophonium anymore available but in the US. And I don't think they have available in Europe as well. Yeah. We just got, we just like got a bottle of edrophonium at UF pretty recently. I won't ask your sources.
00:27:49
Speaker
It's okay. I don't know if we still have, I haven't used edrophonium in quite a while. um So let's talk a little bit about like edrophonium and neostigmine. So how do those drugs work? They make the concentration of acetylcholine to be, to increase.
00:28:06
Speaker
Yeah. Yeah. So the way that they do that, they block the enzyme that breaks down acetylcholine in the gap. So acetylcholine is broken down super fast in the neuromuscular junction. Actually, most of the acetylcholine that the nerve ending releases, it doesn't even reach the other side because of the acetylcholinesterase. Right. So atrophying and nystigamine are inhibitors of this enzyme. Right. So if you increase the amount of a surgical in the gap, you start kind of winning the competition. So it's a competition thing. You have more surgical in, you will have more likely to contract the the muscle effort after each action potential. Okay. So you will just be effective if you have a certain amount of other current or the current in the gap. If you have too much of that, there's no way that you win the competition, no matter how much
00:28:59
Speaker
as a tricholine you have in the gap. Yeah, that's important. So that's why monitoring the train of four is so important, because in theory, the amount of contractions you have is dependent upon how much educurium or whatever neuromuscular blockage you have is like actually inside the junction competing for acetylcholine. So you need to have some spontaneous reversal of the relaxation prior to giving this rug.
Reversal Strategies and Post-Anesthesia Care
00:29:22
Speaker
Yeah.
00:29:23
Speaker
Yeah. And so you have acetylcholine everywhere in your body as well, not just in the muscle. That's what's kind of, we need to be careful to inject that because it always associated with atropine. That's an anti-musculine agent. Because if you increase acetylcholine in the heart, you can cause severe bradycardia. Yeah, that's really important to note. So you can't just like pop these drugs into dogs and cats and whatever, like all willy nilly. You've got to give some kind of, or you have to consider giving a anticholinergic beforehand. Yeah. So I give always atropine first and now I always dilute my atrophonic. Oh, you dilute it? Yeah, dilute it. I've never done that. That's really interesting. And then just because it's easier to keep slowly. So then I keep slowly, I check the the heart rate. If the heart rates are dropping, I slow down a little bit more. bit kind of and Because I saw happening, you're stopping the heart with atrophonium. Even if atrophon is it's safer to obviously have atropine and follow up with the heart rate. Yeah. I have a question too about how you do that, like what the sequence of events is. The way I always did it was like I would give atropine and then I wait for the heart rate to actually increase. And then I would give my the like atrophonium or neostigmine. Do you just give it like atropine and then slam in the drug later? Do you wait a certain amount of time? Well, how do you practice doing that?
00:30:58
Speaker
How I practice, I keep similar to you. I give atropine, and it starts kind of increasing. I don't wait to to have the full effect of atropine, because we never know how fast the atropine will work yeah and how much it will increase heart rate. But if I see the heart rate's training to increase, or it's been some time, I start giving slowly. okay Some dogs, they don't respond at all to heart rate anyway. Yes, of course not. But I start giving slowly. And and some people, they keep even combining them together. and give the Give them at the same time. give that that That's interesting. But I'm not that brave. No, not here. The other thing I wanted to ask about in horses, because we'll utilize neuromuscular blocking agents in horses as well, but then there's always a fear of giving an anticholinergic to horses because atropine is pretty well known to cause like ileus and potentially colic. Do you give an anticholinergic in horses before? Yeah, I don't either. The horses is when I dilute really well and give really, really slowly. But I try as much as I can to give relaxation to horses because I'm scared about recovering horses and having a horse with weak muscles because the relaxation is kind of my night nightmare. Yeah, we give neuromuscular walking agents pretty commonly to horses that are getting ophthalmic procedures, although we try to only give like a single bolus kind of at the start of the procedure. And if the, like we rarely are doing like concentrate infusions or anything like that. So usually give it and then reverse it at the end of the procedure. i I mean, there's, I will say there's a difference in opinion between like anesthesiologists, but the way I do it, it's like we'll give a single bolus like at the beginning of the procedure.
00:32:44
Speaker
hope that we're good on that as far as like where the eye position is. And then what we I always reverse, like regardless of how long it's been since I last gave at your career. I could have been like three hours later and I still give it. Just because I so i agree with you, like I'm scared of residual neurobuscular walking relaxation like while the horse is standing up. And I don't give it any anticholinergics.
00:33:07
Speaker
yeah I do similar. Only thing that I sometimes we we are doing lately here is we are not given any relaxants. Like at all? At all. If the surgeon is happy with that, if you can make the eye centralized without relaxants, they are not complaining with us. That's interesting, yeah. Especially now that we don't have much atrophying available anymore.
00:33:28
Speaker
Etrifunum has a little bit less effect on the GI than nostigumine. So nostigumine, when it gives, we can cause some GI hypermobility. Yeah, like the opposite of atropine. Yeah. I also remember I saw this study. So they were giving phycostigumine to horses to try to like speed recovery, which I thought was really interesting. Phycostigumine, I think it's a little bit different than nostigumine etrifunum.
00:33:56
Speaker
If I remember, it crosses the blood-brain barrier, and yeah that's why it has some central effects as well. yeah And I think on that paper, they had lots of side effects. and Yes, like like lots of diarrhea. every yeah Yeah. But I don't think people use Pfizer-Stigming to reverse their musical block. No, not commonly. No, and no, no, no.
00:34:20
Speaker
Okay, so we talked a little bit about how to give the reversal agent. How can I be sure, like even after I gave the reversal agent, I tried to do everything in my power to make sure that this neuromuscular blocking agent is gone the time the patient wakes up. What are some other things that we can do to see it like clinically if the patient is recovering from his neuromuscular blocking agent appropriately?
00:34:44
Speaker
I think the gold standard is to see Susan Perry from nephshimalase, so you set it off. So there are some clinical evaluations that they try to use instead of the personal stimulation, like testing the phytocapacity of the lungs and see how much the lungs work. It doesn't have a good sensitivity to detecting that.
00:35:05
Speaker
I think the major thing is going to avoid using all the drugs that are really long acting agents like pankuranum, I think it would be, ah and drugs that are shorter to intermediate acting, it will be much less likely to have problems, but you need to kind of assess your patient physically, make sure that he's breathing fine, he does he's not obstructing to the recovery, he can have control of his movements and Like lifting the head. Lift the head. Yeah, lift the head was kind of one touch that they used to use initially in people, but people could lift their head, but they were were super weak as well. So yeah. Yeah. If if they cannot lift their head, it means that the the block is super intense. Yeah, exactly. I think that's really important point is like the muscles that are controlling functions of like the larynx, for example, those are a little bit more kind of, so i I don't know if I would say sensitive.
00:36:02
Speaker
Yeah, so this is another thing that I think we should reverse all the patients because we did a study comparing the train of four of the larynx. We measured the train of four of the larynx and the train of four of the larynx, where I usually measure the train of four. And in people, the larynx record first.
00:36:20
Speaker
Yeah. So in people, it means that in people that they measure, you know, a doctor policies. Yeah. So if your thumb is recovered, your larynx is already recovered. Yeah. You thought that same would happen with animals, but in animals, it was the opposite. Right. Right. So their life recovered and the larynx was still 50% of block. Oh, that's terrifying. Yeah, that's yeah that's why it's another thing.
Advancements in Neuromuscular Agents
00:36:45
Speaker
Okay, so you're measuring the train of 500%, but the lines might they still set have some...
00:36:52
Speaker
a residual paralysis. That's another reason why I think we might think about giving a reversal of the patients. Interesting. Okay. Something that I do in my practice, I want to get your opinion on it, like we'll reverse a dog, but then in order to actually test like the efficacy of the block, we'll actually do is take the reservoir bag off the anesthesia machine and like occlude the port essentially where the reservoir bag is while the patient is spontaneously breathing.
00:37:20
Speaker
And so if that patient can generate like a significant negative pressure in the pressure gauge manometer that's measuring the pressure in the circuit, we are like, oh, that's good. Everything's good. And we'll like pop the reservoir back on. I don't know if you feel, if that's like really crude way of testing. if I don't know if we know anything about that. Yeah, that's the old description how you you can do monitoring of that. So that's one of the preliminary tests that you you could potentially do. But then andfinta ah sensitive I sensitive as using a peripheral nerve. Right, right, yeah.
00:37:55
Speaker
so so You use a peripheral nerve stimulator. That seems to be the answer. and at The lungs, the diaphragm might be working great, but the larynx might not be working great. so thats work You test how well your intercostal muscles and you know diaphragm are working, how much negative pressure can generate. You have a duct that's intubated. You are not assessing your laryngeal function. Yeah.
00:38:20
Speaker
might be still not be ah be able to open or close effect in a good way. So yeah, good point. So check your train of four. I would check her train of four. And I think reversal, I don't see lots of a small animals. I don't see lots of side effects giving reverse. So if you do the atropine first, I think, uh, and it's not expensive nasty immuno or atropine. I think we can give to all the patients and you probably would be safer, but we still need to know. I don't know several other adverse reactions when you give atropine and now see you into patients. Yeah, I also have not, like I've given lots of neostigmine and atropine to patients and I have yet to see like severe, I've never seen a severe bradycotic event, but I don't think that doesn't mean it can't happen. Yeah. I just saw when people didn't give the atropine. Interesting. I don't think I've ever been that brave. Yeah. Yeah. I'm not brave that either, but I've observed that it's happening. Okay. And at the atropine, some people, they don't give atropine before. Yeah, I was actually interested to talk to you about that because I remember like some of my faculty and my residency, I would say like, oh, edrophonium has like no cardiovascular effects. And I couldn't really find anything about that. When I went back to kind of check that in the literature, is that really like true? And if it is like, why, why would edrophonium have less cardiovascular effects than neostech bean? Hethrophenium is less potent than Nalsy. So it means that the reversal potency is slower as well. So it's less like it would cause bradycaria, but it can cause. I saw that happening. I saw Hethrophenium decrease the heart rate a lot. So I would give Hethrophenium as well with Hethrophenium. Okay. Well, I think that's all we have time for. Do you have anything else you want to say?
00:40:13
Speaker
ah think that Other ways that you you might start seeing the feature, now we have Sugamadex available in the United States, but it's kind of expensive. Have you used it? No, it's my I want to use one way, but maybe some research. yeah I've never used it. I've never even seen a vial, yeah except like on like in a book. Yeah.
00:40:36
Speaker
Me too. So it's a second edX just works for the curriculum or Rokuran doesn't work with since that are occurring or other occurring. And but I hope is now we can have that in the United States. So it was a, it was licensed in Europe for a long time. And I think just the in the last four years was licensed in the US. And in human medicine, they use in more and more of that.
00:41:06
Speaker
Hopefully it will become cheaper and we can start using animals as well. Yeah. I mean, I think it's important to note suammma that sugamidex works differently from like neostigmine androphonia because it kind of just like has this little, I don't know what to say, it's like a bubble essentially. And it just like puts the rachiorum inside of it as opposed to actually having... It looks like a cylinder and it encapsulates the molecules.
00:41:31
Speaker
The major thing is that you can reverse really deep blocks, so you can have no no response at all and then train afar and then give the Sugama decks. You just take out the... Exactly. ...the Rokuran from the body and you'll recover right away. so Yeah, and you don't have to worry about the cardiovascular side effects. Yes. Okay. Yeah.
00:41:51
Speaker
I was preparing a lecture and I was looking for Sugamadex. I found a girl that did a tattoo on her. She has a tattoo, like a Sugamadex tattoo? Yeah. Okay. Well, I mean, that makes it like to a whole new level of cool. Yeah. probably If you look Google that, you will find the Sugamadex tattoo. That's really funny, actually. Yeah. Have you used Rock Your Own Name? I haven't used it before.
00:42:16
Speaker
I used to one on the CAT study, I used recurren with the eat a fast sequencing division, and it works well. So recurren is less potent, so we need a higher amount of volume, so the onset time is shorter. so yeah That's one alternative to succinylcholine to give a work room. And yeah I think they all worked very similar to smart modern drugs, work room, work room, and at work room, and cis at work room. I think at work room and cis at work room, I think finta very similar. you
00:42:56
Speaker
since Atrakurin is just one of the isomers of Atrakurin, which I think are more purified. Yeah. But I think they... Like quickly speaking, like what's really the difference between them? I don't see much difference between them. Yeah. Okay. Just in price. Just in price. That's fair. Okay.
Closing Remarks and Future Episodes
00:43:15
Speaker
Well, thank you for taking time to talk to me today. Thank you for coming all the way up to Georgia. Of course.
00:43:28
Speaker
If you'd like what you heard today, I encourage you to check out the North American Veterinary Anesthesia Society and consider becoming a member. As a member of NAVAS, you get tons of benefits, including access to CE events, focusing on anesthesia and pain management, blog posts, fireside chats with boarded anesthesiologists as well as specialty technicians, and just so much more. VIN rounds are another benefit for NAVAS members.
00:43:54
Speaker
VIN rounds are hour-long presentations on a specific topic in veterinary anesthesia that provide tips and tricks that you can use on your next day at work. If any of this sounds interesting to you, visit www.9navas.org to advance your anesthesia journey today.
00:44:10
Speaker
If you have been enjoying the content of this podcast, I would sincerely appreciate it if you could give us a like or subscribe to our podcast, write a review, or simply spread the word about this podcast to your friends and coworkers. We appreciate any and all listener support. If you have any questions about this week's episode or the Nav Vast podcast in general, or if you want to suggest topics you would like for us to discuss in future episodes, please reach out to us at education at mynavvast.org.
00:44:40
Speaker
We would love to hear from all of you. Also, a huge thank you to our sponsor, Decra, without whom this podcast would not be possible. Visit their website, www.decra-us s dot.com to learn more about their line of veterinary anesthesia products.
00:44:56
Speaker
I want to thank our guest, Dr. Daniel Sakai for this insightful discussion on neuromuscular blocking agents. This podcast was produced by Maria Bridges, edited by Chris Webster of Chris Webster Productions, and technical support was provided by Saul Jimenez.
00:45:11
Speaker
And lastly, a huge thank you to all the gas casters out there who choose to spend their time with me today on the North American Veterinary Anesthesia Society podcast. Becoming a skilled anesthetist is a lifelong journey of learning and self-discovery. So I hope you consider listening in the future. I'm your host, Dr. Bonnie Gatson, and thank you for listening. See you next month with another episode of the NavVis podcast.