Neuromuscular monitoring in 2024

Insights, interviews and best practices by clinicians for clinicians. Welcome to GE HealthCare's Clinical View podcast.

Andrew Mortimore: Welcome everybody to this podcast produced by the Association of Anesthetists and sponsored by GE HealthCare. On the subject of neuromuscular monitoring in 2024, are we practicing to the highest possible standards? The podcast will cover four main areas.

Firstly, the pharmacology of reversal agents and benefits and side effects. Then, an overview of strategies for reversing neuromuscular block. Followed by an update on the latest American and European guidelines on monitoring neuromuscular block.

And then finally, techniques of quantitative neuromuscular monitoring, which is the best equipment to use. We hope you will enjoy this podcast and gain something from it. Now, the first speaker that we have with us today is Dr. Pavan Raju, who is a consultant anesthetist at Tayside since 2013 and has a special interest in ultrasound and regional anesthesia, neuromuscular blockade, obstetric anesthesia and preoperative assessment. His career in medicine started in Bangalore, southern India, and he completed his post-graduation in anesthesia in the University of Mumbai. He moved to the UK and continued training in London and Tayside. His non-clinical interests lies with medical education.

He's the lead for undergraduate teaching and he offers postgraduate trainee support by being an educational supervisor. He's also passionate about environment and sustainability issues in hospitals. When he's not at work, he likes to spend time with his family and tries hand in photography and painting.

So welcome, Pavan. I hope you're well.

Dr. Pavan Raju: Thank you very much, Andrew. Thanks for the invite.

Andrew Mortimore: Excellent. And the subject you're going to cover for us is techniques of quantitative neuromuscular monitoring, which is the best equipment to use. And so the first thing, if you could talk about for us, what are the key features to look for in quantitative neuromuscular monitoring equipment and how do different devices compare in terms of accuracy and ease of use?

Dr. Pavan Raju: Thank you, Andrew. That's a really good question. So unfortunately, although I'm going to start with a negative aspect here, we don't have an ideal quantitative neuromuscular monitor.

So when I say ideal, what are the things that we're looking for? Obviously, the user friendliness of the monitor that we're going to use and a portable, robust monitor that gives you accurate and reliable readings. And also a monitor that could be easily accessed during the whole of procedure, say at the induction interoperative period, especially when the hands are tucked.

And most common site of monitoring is the ulnar nerve and the erector pollicis unit. So that access is very, very important. And also a monitor which doesn't cause direct muscle stimulation.

So all these are important features. And currently, we don't have a single monitor which will do everything. But saying that, we have plenty of options available.

And I can speak through, mention about the different mechanisms and the different monitors that are available briefly and explain the advantages and disadvantages of each, if that's okay. So the most common, I mean, the gold standard is mechanomyography, but the whole setup is quite complex and it's big in size. And clinically, the monitor that can be used in clinical settings is not available.

It's confined to research. However, there are other mechanisms that have been used to develop these monitors that could be used in clinical settings. The most commonly available, and it's been in clinical practice for a longer time, is based on something called acceleromyography, which is based on Newton's second law, which states force is equal to mass times acceleration.

So this mechanism has advantages of not needing a lot of expensive disposable electrodes. So they come in two different ways, either an integrated module with the whole set of other monitors or a solitary portable unit. And also, it comes as two different display versions, depending on the company you're using.

One of them displaces a truncated train of four ratio. When I say truncated, it doesn't go beyond 100%, and I'll explain that in a minute. And a few other monitors which displace a raw TOF ratio, which means the TOF ratio, initially when recorded before paralyzing a patient, could go beyond 100%.

So what that means is, there's a couple of caveats with this mechanism. One is a well-known mechanism called reverse fade and normalization. We don't know the exact mechanism behind this, why it happens with acceleromyography only, but what it essentially means is, the initial TOF ratio when measured before paralysis, it would be beyond 100%, for example, 120% or 135%.

And the way to come around it is, we should do something called normalization, which is the international consensus for recovery of neuromuscular blockade is TOF ratio more than 90%. When I say 90%, it's the 90% of the initial reading, as opposed to 90% where the number that displayed on the monitor, if that makes sense. So for example, if the initial reading is 120%, what we should be looking for is 90% of 120%, which is 108%.

So that is what we should be aiming for. And the listeners might be wondering, what happens in those monitors where the ratio is truncated, which means it doesn't go beyond 100%. In those cases, the easy option is just to aim for 100% reversal towards the end, or at least more than 95%.

And it's not just about the number. A lot depends on the strategy used, the type of muscle relaxant that is used, and the type of reversal agent that we use. The key message here is, we should use the contradictory neuromuscular blockade monitor, and use the information it provides in the overall strategy of neuromuscular blockade management.

The second mechanism that's used and is commonly available is called electromyography. In my opinion, this is the closer one to the gold standard in terms of accuracy, in terms of reliable readings. And we don't have the caveats of acceleromyography, such as reverse fade and arms being available all the time, or thumb being available all the time.

Position of the hand really doesn't matter, and it gives accurate readings because it measures the activity at the neuromuscular junction. So its electromyography is relatively new, and there are a few monitors that are available in the market now, and it's being used extensively, and there's a lot of evidence coming out to demonstrate its efficacy. So in my opinion, if you didn't have any monitor in your workplace, I would be going for electromyography, which basically measures the compound muscle action potential of the stimulated muscle, based on the event occurring at the neuromuscular junction.

And there are other mechanisms, which I won't describe too much in detail because of the time, and there's a lot of information available in the literature, the compressor myography, which is based on cough-based mechanism, and also the other one is kinemyography, which is based on the degree of movement of the sensor, which is quite similar to AMG or acceleromyography, but there is no reverse fade phenomenon in that. And then finally, still at the research stages, is the phonomyography or acoustic myography.

So there are different mechanisms, but for practical purposes, the ones that are available to use are based on EMG and AMG. So I appreciate I've not given the entire information here, because that would take a much longer time. So this is the kind of brief summary of what is available to us, and the advantages and disadvantages of these two monitors.

Andrew Mortimore: Thanks Pavan, that's a compelling argument you've put forward there, I think, for the use of this technology, and hopefully it will enable people to bring that forward in their own departments, if they haven't already done so. So thank you very much for your time. If I could ask you if there's just one tip that you could give to people trying to persuade those that are responsible for the investment.

One thing to say to them, what would it be?

Dr. Pavan Raju: I think the biggest motivation for me, and at this moment I have to take my mentor and friend and a colleague's name, Dr. Grant Rodney, who I've learned a lot from, who's done a lot of work around this topic, is improving patient safety and the outcomes. I know it's a very complex topic, it's multifactorial, but certainly neuromuscular blockade management has a significant effect on this. And if we pay attention to this, one reason to improve the outcome is already there.

So I think improving patient safety is a big, big motivation for me.

Andrew Mortimore: Thank you very much Pavan for your time, and I'd like to extend the thanks of the Association of Anaesthetists and of the sponsors of this podcast, GE HealthCare, for the time you've taken to prepare and to deliver your thoughts in this podcast. So thank you very much.

Dr. Pavan Raju: Thank you very much for having me. It's been a pleasure.

Andrew Mortimore: This concludes the podcast on neuromuscular monitoring in 2024. Are we practicing to the highest possible standards? And we would like to thank all of the speakers who have taken part.

We'd like to thank the Association of Anaesthetists, and we'd like to thank the sponsors, GE HealthCare.

Thank you for listening to Clinical View Podcasts, brought to you by GE HealthCare. Expand your view at clinicalview.gehealthcare.com

 

Insights, interviews, and best practices by clinicians for clinicians. Welcome to GE HealthCare's Clinical View podcasts.

Andrew Mortimore: 

Welcome everybody to this podcast produced by the Association of Anesthetists and sponsored by GE HealthCare. On the subject of neuromuscular monitoring in 2024, are we practicing to the highest possible standards? The podcast will cover four main areas.

Firstly, the pharmacology of reversal agents, their benefits and side effects, then an overview of strategies for reversing neuromuscular block, followed by an update on the latest American and European guidelines on monitoring neuromuscular block, and then finally, techniques of quantitative neuromuscular monitoring, which is the best equipment to use. We hope you will enjoy this podcast and gain something from it. Okay, and so we're joined now by Professor Heidrun Lewald, who is a Professor of Anesthesia at the Department of Anesthesia and Intensive Care Medicine at the Technical University of Munich in Germany.

She has a background in basic as well as clinical research with a focus on the neuromuscular junction, pharmacodynamics and kinetics of muscle relaxants and their reversal agents, as well as neuromuscular monitoring. So thanks very much Heidi for joining us, and you've very kindly agreed to speak to us in this podcast about the pharmacology of reversal agents, their benefits and side effects. So thank you very much for that.

And if you're okay, I'd like to ask you the first question, which is, what are the key differences between traditional and newer reversal agents in terms of their mechanism of action and effectiveness?

Professor Heidrun Lewald: 

So what we consider to be traditional reversal agents are the choline esterase inhibitors, such as neostigmine. And as the name says, they inhibit the choline esterase in the neuromuscular junction, and by that they increase the concentration of acetylcholine in the synaptic cleft. And as acetylcholine competes against the muscle relaxant for binding at the receptor, the increased concentration of acetylcholine increases just a chance of it to bind to the receptor and thus it restores neuromuscular transmission and muscle contraction.

So choline esterase inhibitors act indirectly and they act intrasynaptically by inhibiting the degradation of acetylcholine. And the advantage of this indirect mechanism of action is that it works irrespective of what non-depolarizing muscle relaxant you use. It simply works for all of them.

Sugammadex, on the other hand, is a cyclodextrin, so eight glucose molecules in a circular structure with eight negatively charged side chains attached. So it is a huge molecule, which after you inject it intravenously, it rains completely intravascular. And Sugammadex was specifically designed to only bind rocuronium, but it also works with a slightly lesser efficacy for vecuronium, as are both steroidal muscle relaxants.

So it does not work if you gave your patient one of the benzo isoquinolones, namely atracurium, cisatroquarium, or mivacurium. So if we go back to the mechanism of action, what happens when Sugammadex is injected is that intravascular rocuronium is encapsulated and by that inactivated. And this really within moments leads to a concentration gradient of free rocuronium from intravascular to extravascular.

So intravascular rocuronium concentration is low, extravascular concentration, namely at the neuromuscular junction, is high. And this gradient then pulls the rocuronium away from the neuromuscular junction back into the bloodstream, where it is then also encapsulated and inactivated by free or unbound Sugammadex. So you have the indirect and intrasynaptic choline S-rays inhibitor neostigmine versus the intravascular encapsulator Sugammadex.

Now coming to the second part of the question, if you have this in mind, differences regarding the effectiveness of these two drugs are really easy to understand because with its direct encapsulating mechanism, reversal with Sugammadex is possible at any depth of rocuronium-induced neuromuscular block. It's simply a matter of dose. So you have to have 16 milligrams per kilogram for immediate reversal, 4 milligrams per kilogram if your neuromuscular monitoring shows you a post-tetanic count of 2 and above, and 2 milligrams per kilogram as soon as you have a return of the second twitch of your train of force stimulation.

Now with neostigmine, it's a bit trickier because as we said, it acts indirectly and you cannot inhibit more cholinesterase than the patient has. And if all of the cholinesterase inhibited, even if you give more neostigmine, you will not see an increase in recovery. And this is what we call a ceiling effect.

And because of this known ceiling effect, it is recommended to wait until a certain degree of spontaneous recovery from neuromuscular block has already occurred. So if you expect a fast and reliable recovery, it's ideal to wait for the train of force ratio to recover to at least 20%. For shallower blocks below 20%, neostigmine is also going to work.

It just needs more time. And of course, you have to monitor until the train of force ratio is above 90% to confirm full recovery.

Andrew Mortimore: 

What a fabulous answer. Thank you very much for that. So moving on to the next question, could you discuss for us the most common side effects associated with current reversal agents and how clinicians can mitigate these risks?

Professor Heidrun Lewald: 

Sure. If we start with neostigmine, well, all side effects can be explained by the physiology we all once learned in med school. And they're all due to the fact that acetylcholine is not only a neurotransmitter in the somatic nervous system, but also in the autonomic nervous system.

And especially in the parasympathetic system, it acts as a pre- and post-scanionic neurotransmitter. And this is why symptoms of parasympathetic overstimulation, such as bradycardia, hypotension, bronchoconstriction are common with neostigmine. And that is also why to mitigate these effects, we always combine neostigmine with a parasympathetic drug such as glycoparalyte.

Now looking at Sugammadex, when it was introduced 15 years ago, it was thought that we would only see very few side effects because it was so specific for rocoronium. And we thought, you know, maybe allergic reactions could occur simply because everyone can react allergic to a drug. But it turns out, and a recent report just confirmed this, that the two most common side effects are bradycardia and bronchospasm, just as with neostigmine.

Now the exact mechanism is not fully understood, but you really have to be aware of this. This can also occur when you use Sugammadex in your patient. However, number one adverse event, as was expected, is allergic reactions.

And there's one really interesting aspect about this, and that is allergic reactions against Sugammadex can occur even after a patient has received his very first dose. And that is because every one of us is exposed to cyclodextrins pretty much everywhere in everyday life. Not only in cosmetics or deodorant sprays or anything that encapsulates and neutralizes unpleasant odors, cyclodextrin and especially gamma cyclodextrin, so the molecule that is the backbone of Sugammadex, are officially approved in the European Union and other countries as food additives.

So you really have to be aware, even after first dose of Sugammadex, you can have an allergic reaction in your patient.

Andrew Mortimore: 

Thank you very much for that, it's fascinating. And then another question, how do newer agents like Sugammadex compare to neostigmine in terms of safety profiles and patient outcomes?

Professor Heidrun Lewald: 

That is a very interesting question and is a question that is asked fairly often, you know, should we prefer one over the other? Is one better than the other? Well, first of all, we have to exclude profound, deep and moderate block for which only Sugammadex can be used if you want to have effective reversal.

But if we look at reversal of residual block above a train of four ratio of 20%, we actually cannot give a clear recommendation for one drug over the other regarding safety profiles and patient outcomes. And I also personally think that it is not the reversal drug that makes a difference. It is whether or whether or not you use quantitative neuromuscular monitoring with every patient that receives a muscle relaxant.

You have to have a number on your screen as a basis for any subsequent decision on how to reverse. And whether you reach the goal, which is to extubate the patient at a train of four ratio of 0.9 or above with Neostigmine, Sugammadex or simply the time it needs for spontaneous recovery is absolutely secondary. Key to increase patient safety and patient outcome is quantitative neuromuscular monitoring.

Andrew Mortimore: 

Thank you for that. So can I just ask you then, I know that the monitoring is not available in all circumstances in all settings. So if you had to just help somebody to convince the budget holders that they should get the equipment necessary to allow the neuromuscular monitoring, how could you sell that quickly?

What are the most important things that they could say?

Professor Heidrun Lewald: 

The most important things are that you dose your drugs adequately, you by that ensure faster and reliable recovery, you reduce postoperative complications such as pneumonias. There are numerous studies out there showing also that you can decrease length of hospital stay, reduce complications. So it all not only increases patient safety, which should be our primary goal as physicians to have the maximum safety for a patient.

It also reduces hospital costs and subsequent costs for the hospital, but also for the whole health care system.

Andrew Mortimore: 

Okay. So finally, Heidi, could you tell me about Sugammadex and other steroidal drugs and how they can be used?

Professor Heidrun Lewald: 

That is a very interesting and a very practical question. Now, as we said, Sugammadex was designed to encapsulate steroidal muscle relaxant. So of course, it's going to encapsulate other steroidal drugs as well.

Other drugs that we use during anesthesia, for example, dexamethasone, which we use to prevent postoperative nausea and vomiting. And in general, you can say that the dose, the effective dose is going to be decreased by about 30%. So when you look at dexamethasone, for example, you might regard increasing your dose by 30%.

Another question that is very often asked is what about Sugammadex and the effect on contraceptive hormones? We come across a lot of patients that might use contraceptives and they have surgery and we're going to reverse them with Sugammadex. So what do we have to tell the patients?

What considerations should we have? Well, there are no randomized control studies investigating the effect of Sugammadex on hormonal contraceptives, but there are some in vitro data for which recommendations can be extrapolated. And as I said, in general, it is estimated that Sugammadex decreases hormone levels up to 30%, which is approximately the level of decrease of delaying the intake of a contraceptive pill by 12 hours.

Now, does this mean that ovulation is not suppressed anymore after patients under oral contraception have been given Sugammadex? To be honest, we don't know and we probably never will know, but we should always inform our patients that they received Sugammadex, a drug, but we also should always keep in mind that a lot of other factors such as perioperative stress, other drugs that we give during anesthesia also influence the female cycle. But of course, as I said, we should always inform women of childbearing age that they should use other non-hormonal contraception measures for the rest of the cycle.

The Society of Obstetric Anesthesia and Perinatology has issued a statement regarding other highly hormone dependent moments in the life of a woman, namely pregnancy, where Sugammadex should be avoided to not influence the need of high hormone levels to maintain the pregnancy in early pregnancy. When it comes to near-term pregnancy, the same caution is issued, warning the use of Sugammadex or at least giving the advice to really think if you might not use neostigmine in these patients, because Sugammadex, by encapsulating steroidal hormones, might influence lactation. And only when lactation is established in these women does the Society of Obstetric Anesthesia and Perinatology consider it to be safe to be used in these women.

There's just one thing I would also like to add. We really have to be clear. These statements issued are a what we call primarily do no harm approach, simply because we do not still know enough about how the drug interacts with steroidal hormones.

If you are, however, in an emergency situation, you should never hesitate to use Sugammadex in these patients, irrespective of the stage of pregnancy.

Andrew Mortimore: 

Brilliant. Thank you so much, Professor Lewald. I would like to extend the thanks of the Association of Anesthetists and our sponsors, GE HealthCare, for visiting us and letting us benefit from your knowledge and your wisdom.

Professor Heidrun Lewald: 

You are very welcome. It was a pleasure being here.

Andrew Mortimore: 

This concludes the podcast on neuromuscular monitoring in 2024. Are we practicing to the highest possible standards? And we would like to thank all of the speakers who have taken part.

We'd like to thank the Association of Anesthetists and we'd like to thank the sponsors, GE HealthCare.

Thank you for listening to Clinical View Podcasts. Brought to you by GE HealthCare. Expand your view at clinicalview.gehealthcare.com

Insights, interviews, and best practices by clinicians for clinicians. Welcome to GE HealthCare's Clinical View Podcast.

Andrew Mortimore: 

Welcome everybody to this podcast produced by the Association of Anesthetists and sponsored by GE HealthCare. On the subject of neuromuscular monitoring in 2024, are we practicing to the highest possible standards? The podcast will cover four main areas.

Firstly, the pharmacology of reversal agents, their benefits and side effects, then an overview of strategies for reversing neuromuscular block, followed by an update on the latest American and European guidelines on monitoring neuromuscular block, and then finally, techniques of quantitative neuromuscular monitoring, which is the best equipment to use. We hope you will enjoy this podcast and gain something from it. We're now joined by Professor Sorin Brull, who is Professor Emeritus of Anesthesiology and Perioperative Medicine at Mayo Clinic College of Medicine and Science, and is a consultant in the Department of Anesthesiology at the Mayo Clinic in Florida.

So thank you very much, Sorin, for agreeing to join us in this companion podcast sponsored by GE HealthCare to the webinar that we did recently about NMT monitoring. You've agreed to cover for us the subject of the update on the latest American and European guidelines on monitoring neuromuscular block. So thank you very much for that, and are you okay for me to ask you the first question?

Dr. Sorin J. Brull: 

Absolutely. I'm here for you.

Andrew Mortimore: 

Thank you very much. So firstly, what are the most significant updates in the latest American and European guidelines for neuromuscular monitoring, and how do they address previous gaps in practice?

Dr. Sorin J. Brull: 

Yeah. First of all, thank you for the opportunity to discuss these important points. The question is actually really important, and it's also a clinically relevant question because the guidelines were developed by a group of clinicians with experience in clinical care guidelines who had significant expertise in patient monitoring.

So the guidelines were really developed to answer the most important clinical questions regarding routine perioperative quantitative neuromuscular monitoring. So specifically, the authors addressed and made a set of eight recommendations. The first one was that they recommended against using clinical assessment.

So this is important. So let me repeat this. The American Society of Anesthesiologists recommends against using clinical assessment.

Instead, the guidelines recommend quantitative monitoring. They also confirm or they recommend confirmation of a train of four ratio greater than 0.9 prior to tracheal extubation. This is critically important because too many clinicians make the decision to extubate on flawed and inaccurate criteria.

For instance, they look at the ventilator bag, the way it contracts. They ask the patient to squeeze their hand or open their eyes. And if the patient can do all of this, the clinicians will then incorrectly assume that the patient is fully recovered and they will extubate the patient's trachea.

This practice really must change for the safety of our patients. Another recommendation is that we use the hand muscles, specifically the adductor pollicis for monitoring. And importantly, they also recommend against using the eye muscles for monitoring.

This is because previous work has shown that the use of eye muscles for monitoring actually results in a five-fold higher incidence of residual block because the eye muscles are stimulated directly, not via a nerve. And the twitches are not abolished by neuromuscular blocking agents. So the use of eye muscles for stimulation also will result in massive overdosing of neuromuscular blocking agents for the same reason, which is direct muscle stimulation.

Another recommendation is about the use of Sugamidex over Neostigmine at deep, moderate and shallow degrees of block. Not only because Sugammadex is faster and more complete at reversal, but because Neostigmine is not effective, or it's really only partially effective at reversing any block other than minimal block. And this minimal block is defined as a Train-of-four ratio between 0.4 and 0.9. Finally, the guidelines recommend that if other agents are used other than the typical Rocuronium or Vecuronium, for instance, such as Atracurium or Cisatracurium, then Neostigmine is recommended, again, only at a minimal block. As I said, a Train-of-four ratio between 0.4 and 0.9.

Andrew Mortimore: 

Thank you very much for that answer, Sorin. So just moving on then to the next question. How have these guidelines influenced clinical practice, particularly in terms of standardizing the use of quantitative monitoring techniques?

Dr. Sorin J. Brull: 

Yeah, so perhaps it would make sense to start by recognizing that one and a half years after the publication of the American and European guidelines, routine quantitative monitoring of the depth of block remains elusive. Although there has been some uptake by clinicians, the same reluctance, I would actually call it stubbornness, to using quantitative monitoring routinely remains. So in my view, and again, these are just my views, there are two overarching questions that we should try to answer.

Number one, what are the benefits of routine quantitative monitoring? And the second is, what are the costs or impediments to routine monitoring? So with these two questions in mind, allow me to summarize the most current clinical practice, at least the one that I'm familiar with.

Obviously, the statements I'll be making are generally true. And then there is a very wide range of practicing spanning from no monitoring at all to always monitoring. So generally speaking, many clinicians still believe monitoring is unnecessary.

And they continue to rely on their so-called clinical knowledge and experience. We actually know that acceleromyography or AMG monitors, such as the TofWatch, are more prevalent than the newer, recently introduced electromyography-based monitors. But really, the landscape seems to be changing as more clinicians are exposed to EMG and personally experience their ease of use and their reliability.

Next is, Sugammadex use and the doses that are being used are really amazingly high because they are given empirically, rather than being guided by the depth of neuromuscular block. And many clinicians actually opt to overdose rather than underdose in order to, they think, prevent residual neuromuscular block. The other thing is that pediatric monitors currently are used relatively rarely, although I have seen a significant renewed interest among pediatric anesthesiologists to use quantitative monitors.

Clinicians continue to claim that they need more data on quantitative monitoring cost versus benefit. And many of them seem to be unaware of the increasing body of published data that documents that, number one, quantitative monitoring is far superior to clinical or subjective evaluation. And number two, quantitative neuromuscular monitoring decreases the incidence of postoperative complications and that, number three, the savings from lower Sugammadex doses and by avoiding the complications are actually several folds higher than the cost.

So, in other words, quantitative monitoring is a cost saving practice, is not costly. So the entire argument is false. We need to better share this knowledge with our colleagues who mean well, but who lack the most recent information.

Finally, and I understand why these guidelines for monitoring exist, we must recognize that they're not a requirement.

Andrew Mortimore: 

Thank you very much. Can I just ask quickly then, do you see in the future more and more settings where it's taken up, where more people start to employ the monitoring?

Dr. Sorin J. Brull: 

Yeah, I do. And this is nothing new. I think we ran through the same problems when we're introducing capnography or pulse oximetry or depth of anesthesia monitoring.

You know, we as clinicians get very used to doing things a particular way, our own way. And anything that we're asked to change makes us a little bit uncomfortable because we're all about patient safety. And we know that what we do works well.

So we don't have a real impetus to change the practice. Interestingly, it's also been shown that the duration of uptake of new technology in medicine takes about 17 years. So I remain optimistic that even though the initial uptake has been relatively slow, more and more clinicians understand the need for quantitative monitoring.

And also with a recent development of at least four or five different quantitative neuromuscular monitoring that have hit the market, my hope and actually anticipation is that more and more people will start using quantitative monitoring, again, for the benefit of our patients.

Andrew Mortimore: 

Thank you very much. And that is a positive outlook to end your section on. So I'd like to thank you very much, Sorin, on behalf of GE HealthCare, the sponsors of this podcast, and the Association of Anesthetists for sparing the time to let us benefit from your wisdom and knowledge.

So thank you very much for that.

Dr. Sorin J. Brull: 

My pleasure. Thank you for the kind invitation.

Andrew Mortimore: 

This concludes the podcast on neuromuscular monitoring in 2024. Are we practicing to the highest possible standards? And we would like to thank all of the speakers who have taken part.

We'd like to thank the Association of Anesthetists and we'd like to thank the sponsors, GE HealthCare.

Thank you for listening to Clinical View Podcasts, brought to you by GE HealthCare. Expand your view at clinicalview.gehealthcare.com. Thank you.

Insights, interviews and best practices by clinicians for clinicians. Welcome to GE HealthCare's Clinical View podcast.

Andrew Mortimore: Welcome everybody to this podcast produced by the Association of Anesthetists and sponsored by GE HealthCare. On the subject of neuromuscular monitoring in 2024, are we practicing to the highest possible standards? The podcast will cover four main areas.

Firstly, the pharmacology of reversal agents and benefits and side effects. Then an overview of strategies for reversing neuromuscular block. Followed by an update on the latest American and European guidelines on monitoring neuromuscular block.

And then finally, techniques of quantitative neuromuscular monitoring, which is the best equipment to use. We hope you will enjoy this podcast and gain something from it. So thank you very much.

We're now joined by Dr. J. Ross Renew, who completed his medical school at the University of South Carolina School of Medicine. Dr. Renew completed anesthesia residency at Mayo Clinic, Florida, and his fellowship in adult cardiothoracic anesthesiology at Mayo Clinic in Rochester. Dr. Renew is currently an associate professor of anesthesiology and serves as the vice chair of research. His research interests involve neuromuscular blockade and monitoring, transesophageal echocardiography, and caring for the cardiac patient undergoing non-cardiac surgery. So thanks very much, Ross, for joining us.

And you've agreed to talk to us about the overview of strategies for reversing neuromuscular block. So thank you very much for that and welcome. On behalf of GE HealthCare, our sponsors, and the Association of Anesthetists.

So I'm just going to ask you the first question. What are the main considerations when choosing a strategy to reverse neuromuscular block, and how does the choice of muscle relaxant influence this decision?

Dr. J. Ross Renew: Thanks, Andrew, and thanks for having me. I think there's kind of two guiding principles when we start to think about reversal strategies and trying to really deliver the best care for our patients at a critical point in the operation. One of which is to, you know, these medications, these reversal agents have side effects, and so we've got to consider the side effect profile and obviously individualize based on patient factors.

And so kind of a one-size-fits-all approach is certainly not the way to go, and we really should be individualizing our care. But I think one of the bigger drivers is this idea that, you know, why are we giving reversal agents at all? And that's to avoid residual weakness.

And, you know, there's mountains of evidence demonstrating complications that are associated with residual weakness, and we really can't just rely on, you know, clinical assessment or even a peripheral nerve stimulator to say, wow, those look like four strong twitches, I think my patient's okay. All that to say, we need to be incorporating both monitoring and reversal agents to deliver optimal neuromuscular blockade management. Certainly the monitor allows us to determine the dose, which is an important strategy.

It lets us check the level of blockade, and our reversal agents are kind of triaged based on the depth of blockade at the time of reversal administration. And so they also allow us to have evidence that our patients have adequately recovered and ultimately not have residual weakness, and thus keeping them safe from the complications associated with it. You know, the part to considering what reversal agents would be best for our patients is certainly the type of neuromuscular blocking agents used.

As you'll remember, the Benzylisoquinoline agents, Atracurium, Cisatracurium can be reversed with neostigmine, whereas neostigmine is also able to reverse the aminosteroidals, in contrast with Sugammadex, which can only reverse the aminosteroidals, rocuronium, vecuronium, etc. And I'll show you a couple examples from our practice. When we had Sugammadex introduced to our practice, it had kind of a downstream effect on the kind of neuromuscular blocking agents that were chosen.

You know, Sugammadex has a high affinity for particularly rocuronium, and so it's interesting to see is once our group got a hold of Sugammadex, our Sugammadex use went up, but also our rocuronium use went up. And really the times that we use the Benzylisoquinoline now would be things like if they had allergies to aminosteroidals, or if there was some contraindication, maybe severe renal impairment. And so this gets back to factoring in patient considerations.

All these things kind of tie in and trying to help you develop an individualized, safe reversal plan for your patient.

Andrew Mortimore: Thank you very much for that. So secondly then, in what situations would a clinician opt for a pharmacological reversal versus allowing spontaneous recovery, and what are the pros and cons of each approach?

Dr. J. Ross Renew: Great, good question. So I mentioned earlier in my prior response that one of the factors, strategies that goes into picking a reversal agent is to consider and trying to minimize the potential side effects that could come with them. Certainly when we give neostigmine, we have to co-administer an anti-muscarinic to avoid some of the side effects associated with neostigmine administration.

And so is there a path where we can avoid reversal altogether and avoid some of these potential side effects? Certainly it's unlikely to have major side effects from these drugs, but when we start expanding out into large populations, the chances of this happening are not zero. And so eventually some subset of patients will have complications related to the reversal agents in and of itself.

And so spontaneous recovery is something that can be accomplished, and certainly there is a role for it in modern anesthesia practices. But I like to emphasize that the pathway to safely omitting reversal is through monitoring. I would feel very comfortable omitting reversal and avoiding the potential side effects if I had a quantitative monitor on that demonstrated adequate recovery.

And the conversations I've had with colleagues before would be something along the lines of, well, I gave an intubating dose of a neuromuscular blocking agent to facilitate intubation. The surgery went on one to two hours, and I probably don't need to give reversal in that instance. Well, there's a lot of literature that demonstrates tremendous variability in how patients metabolize these drugs, how they respond to them.

And so just relying on some arbitrary time interval and some expected pharmacokinetics, pharmacodynamics, and when you think the duration of action has stopped for these medications is unreliable. And so really if you elect to utilize spontaneous recovery, I think it's a safe fashion with the caveat that you have a quantitative monitor to confirm that you actually have restored neuromuscular function.

Andrew Mortimore: Thank you very much indeed. And then the third question, can you explain the importance of timing in the administration of reversal agents and how it impacts the recovery of neuromuscular function?

Dr. J. Ross Renew: Yeah, so timing is important. I think timing ties into production pressures. And I know my practice is not unique in this aspect, but we've got a lot of patients who need our help, who need our care, and we're trying to get them in in an efficient manner without sacrificing safety.

And so when we start thinking about the differences between our two reversal agents categories, the acetylcholinesterase inhibitors and Sugammadex, there are some differences that are important. And it's not that one's better or more applicable than the other, but we just have to individualize based on each scenario. And for instance, neostigmine has to be given at shallower levels of blockade versus Sugammadex, which can reverse at deep levels of blockade.

That neostigmine administration, if you're going to give it when you have a patient with a train of four, count of four, and starting to approach spontaneous recovery, that means you're going to have to really have your finger on the pulse of where the surgeon is in that operation. And so if they're closing, let's say they're closing fascia and they need that patient paralyzed, depending on the time from closing deep fascia layers to getting to skin, if that's a short duration, a short period of time, you may not achieve a train of four count of four, a shallow level of blockade that lets neostigmine be an option. However, in other circumstances where those scenarios don't pop up, if you're able to allow that patient to gradually recover to a moderate and shallow minimal depths of blockade, you can use neostigmine with the caveat that you should be guided by a neuromuscular monitor.

But then I'll point to the ASA guidelines in one of their last recommendations that recommend waiting at least 10 minutes after neostigmine to extubating, again, still guided by a quantitative neuromuscular monitor. It just takes a little bit longer for neostigmine reversal to work, so you have to have a little bit more planning in when you're going to give it, whereas Sugammadex is going to be a little faster recovery. But nonetheless, whichever one you're using, you still need to be using your monitors because funny things happen at emergence.

Patients are getting transferred over from the operating room table to a stretcher. IVs get pulled out. Medications forget to be flushed in.

Medications forget to be given altogether too. I mean, when you do enough cases, there's tons of scenarios that can pop up. And so, again, the way you confirm that you've got your timing right with your reversal agent and the drugs have actually worked and you've restored neuromuscular function, you've heard me say it before, is using your monitors to ensure they have the desired impact.

Andrew Mortimore: Okay, thank you, Ross, for that, for allowing us to benefit from your knowledge and your wisdom and your experience. So on behalf of GE HealthCare, our sponsors, and the Association of Anesthetists, I'd like to thank you for taking part in this podcast.

Dr. J. Ross Renew: Thank you for having me.

Andrew Mortimore: This concludes the podcast on neuromuscular monitoring in 2024. Are we practicing to the highest possible standards? And we would like to thank all of the speakers who have taken part.

We'd like to thank the Association of Anesthetists. And we'd like to thank the sponsors, GE HealthCare.

Thank you for listening to Clinical View Podcasts, brought to you by GE HealthCare. Expand your view at clinicalview.gehealthcare.com.