Good evening, everybody, and welcome to this Tuesday night webinar, proudly brought to you by the webinar vet and proudly sponsored by Chanel Farmer. Huge big thank you to Chanel Farmer for the sponsorship tonight. If it wasn't for their generosity, we would not be able to bring this to you for free.

Little bit of housekeeping if you're new to the webinar vets. If you've got any questions, just move your mouse over the screen. You'll see a little control bar.

It's usually a black bar at the bottom pops up. You'll see a Q&A box in there. Just type in your questions in that.

They'll come through to me and we'll hold those over to the end. Our presenter tonight is live with us, but he's not going to be doing the presentation live. We've pre-recorded the session as we did with Jonathan last time.

And it worked incredibly well. So, but be assured he is on and happy to answer any questions that you may pose throughout the presentation. So Jonathan graduated as a veterinary surgeon from the University of Bristol in 2003.

After 10 years working in equine practise, he then completed an MBA at the University of Southampton before joining Ilanco Animal Health. He was with Elanco for 6 years working in sales, technical, and marketing roles across multiple species areas. He then returned to equine practise for a further 2 years at B&W Eine before joining Chanel Farmer as the UK product support manager in 2022.

So, we're going to play the recording now. And as I say, Jonathan will be with us throughout the recording and at the end to answer those questions. Kyle, if you would start the video for us, please.

Hello and welcome to this Chanel CPD session. My name is Jonathan Moore. I'm a veterinary surgeon and a product support manager for Chanel UK.

Today I should be talking about inherent anaesthetics and companion animal practise. I should be focusing on the use of sevoflurane and isoflurane in canine and feline general anaesthesia. This presentation is designed for veterinary professionals and is part of Chanel's ongoing CPD series, which covers disease states relating to the products in our portfolio across both companion animal and equine practise.

More information on additional CPD content is available at the end of the presentation. These are the topics we should be covering. I shall begin by discussing a, a general overview of anaesthetics before moving on to inherent anaesthetics in more detail.

And in relation to inherent anaesthetics, we'll discuss factors to consider when selecting gas type. Look at MAC or Mac. We'll examine some of the adverse effects which you might see when using these gases.

And we'll look at patient factors and how these relate again to the choice and the use of, of the gases for maintenance of anaesthesia and how health status can affect the situation. And finally, we'll finish by discussing monitoring of patients under general anaesthesia. It should be noted that these products use off licence in other species.

However, in this presentation, we'll be focusing on the licenced species only, i.e. The dog and the cat.

If you wish to discuss off licence indications, please contact either myself as the technical support vet for Chanel, or speak to your territory manager who will point you in my direction. So what is an anaesthetic? Well, the term anaesthesia comes from the Greek word anaesthesia, which means without feeling, without sensation.

Anaesthetics can be divided into two types, general anaesthesia or GA and local anaesthesia. General anaesthesia is defined as a reversible loss of consciousness, whereas local anaesthesia is a reversible loss of sensation from a localised part of the body without necessarily affecting the consciousness of the animal or patient. So let's go on to think about inherent anaesthetics in a little more detail.

Well, with general anaesthesia, both induction and maintenance of anaesthesia can be achieved through either injectable agents or inherent agents. In general, the injectables are used to induce anaesthesia due to their rapid onset of action, and then the switch is made to an inherent agent to maintain the anaesthetic, especially for medium to long term procedures. Why is this switch made?

Well, when using insolent anaesthetics for maintenance, we reduce the risk of administering an overdose. With injectables once that agent is in the animal's body, the only way it can leave is through metabolism or use or possibly through the use of an antidote reversal agent. But with inherent agents, changes can be made to anaesthetic depth relatively quickly because the agents are expelled primarily from the body via the respiratory tract.

And essentially, if we have any adverse effects, we can hopefully deal with these more quickly. And again, we can have a more fine-tuned control over anaesthetic depths. Finally, with the inhalants, once the procedure is finished, we have a faster recovery from the general anaesthetic with inhalant agents.

So the way in which inherent anaesthetics produce their effect is still not fully understood. There are a number of things that are believed to play a role. They may act on the lipid matrix of neuron membranes.

They are also believed to activate inhibitory central nervous system receptors such as chloride channels, GABA receptors, and potassium channels. They're also also thought to suppress CNS stimulating neurotransmission pathways such as cetylcholine, glutamate and serotonin. However, despite not fully understanding the mechanisms of action, what we can see is the overall effect is a down regulation of all activity in the central nervous system.

So as we've said before, the maintenance of general anaesthesia is primarily carried out using inhalation anaesthetic agents. The most commonly used types in the veterinary market, certainly in the UK are isofluorane and Sivafluorane. Indeed, these are the only two products that are currently licenced in the UK for this purpose, and both come from the halogenated ether group.

So of these two agents, isofluorine and Sufluorane, how do we choose which one to use and what are the differences between them? Well, these are some of the things that come into play when making that choice. At the first of which we will go to next is the Mac or MAC.

There are also other practical aspects involved with the two products, which we will look at. There's also the speed of induction and recovery. There are differences between the two agents in this regard.

And finally, because we live in a, in the real world situation, price is often a consideration. So what is Mac or MAC? Well, MAC stands for minimum alveolar concentration in oxygen.

And it's the percentage concentration of a vapour in the alveoli of the lungs that is needed to prevent movement in 50% of patients in response to surgical stimulus. And this is at one atmosphere of pressure, so essentially sea level. A Mac is used to compare the potency of anaesthetic vapours.

If an agent is reported to have a lower Mac, it's therefore more potent because less of the agent is required in the LVA of the lungs to have the desired anaesthetic effect. Conversely, the Mac is higher for an agent, the agent is considered to be less potent. So Mac remains fairly stable in healthy patients.

So for isofluorine and Siva fluorine, and indeed all the anaesthetic inherent agents, there are quoted Mac values that appear in the literature. For isofluoran in dogs, this is reported to be between 1.3% and 1.4%, and see the flurane in dogs, 2.1% to 2.4%.

In cats is fluorine 1.3 to 1.9%, see the fluorine in cats, 2.6% to 3.4%.

So there is slightly a slight variation depending on which literature you you get this from. But I think what you can see quite clearly there is that the difference between the two agents is that the seed of fluorine requires a greater concentration. Essentially, it's, it has a lower potency than is fluorine.

So how are these marked figures used in surgery and general anaesthesia? Well, remember that MAC is defined as, as the, the level of agent where 50% of patients will not show response to surgical stimulus. This is obviously not really what we want.

We want every patient to not show a response to surgical stimulus. And this brings us on to thinking about this ED 95 number. This is the effective dose where 95% of patients will not show a response to surgical stimulus.

And this is quoted to be between 1.2 to 1.4 times by the Mac value.

In addition, deep anaesthesia is said to be around 2 times the mac value. So somewhere in between these figures, this brings us to the idea that we can achieve the necessary surgical anaesthetic depth for hopefully the vast majority of patients at 1.5 times by the Mac value.

So remembering that the Cedar fluorine has a higher Mac value than isofluorane, higher vaporizer settings will be required when using Siva fluoran when compared to isofluorane. And this means that moreeverflurane will be used to ensure that the patient remains at an adequate surgical depth during anaesthesia. So let's bring these pieces of information together and think about Mac and the vaporizer settings.

So, remember, we have Max 1.5 that is going to give us the adequate depth of anaesthesia for the vast majority of patients undergoing surgery. So if we look at the lower part of the table here, we can see max 1.5 isofluorine.

The dogs is 2 to 2.1%, and for cats, 2 to 2.9%.

And see fluorine 3.2% to 3.6% for dogs and 3.9 to 5.1% for cats.

And again, we can see that the vaporizer settings are going to be higher with see fluorine when compared to isofluorine. Unfortunately, dating is not quite as simple as this, because patient factors will play a role and alter the Mac value, which will come onto this further in the presentation. Please note, these values are taken from the literature, and they differ slightly from the values recommended in the SPCs for Siva Hill and Iovet.

However, these differences are minor and largely sit within the ranges suggested in this slide. So let's think about how anaesthetic agents enter the body and how these agents are dispersed throughout the body and enter various different body tissues. Obviously, we have a keen interest in the agents entering the central nervous system, because this is where they're having their desired effects.

On the graphs here, we can see alveolar partial pressure on the Y axis and time on the X axis, where 0 here is the point where the vaporizer is turned on. So when we look at how the concentration of inhalation anaesthetic agent changes in the lungs after we turn on the vaporir, we tend to see this distinct curve on this graph. The initial rise represents the period when ventilation moves the anaesthetic agent rapidly into the lungs and into the alveoli.

Following this, the knee stage shows when the concentration increase starts to slow. The slope of this is determined by the rate of uptake of the anaesthetic agent in the vessel rich tissues such as the heart, brain and liver. The tail section is where the concentration stabilises in the lungs.

The slope of this section is determined by the rate of uptake and tissues with relatively poor blood supply such as muscle and fat. How quickly the agents are taken up and therefore the the specific shape of the curve for each inhalation anaesthetic agent depends on how soluble the agents are in various body fluids and tissues, most importantly, blood. So the solubility of these agents in in blood is really critical to the speed of onset of their action.

And this solubility in blood is defined as the blood gas partition coefficient. And forever flurane, this blood gas partition coefficient is 0.6, and this compares to isofluoran, which has has a blood gas partition coefficient of 1.4.

This means that sevofluorine is less soluble in blood than isofluorine. So only small concentrations of sevofluorane in the blood are required before equilibrium with the alveolar gas concentration is reached. Sevofluorin is therefore rapidly removed from the lungs and is then able to have its effect in the central nervous system.

So when we look at the alveola partial pressure against time graphs for sevofluorine and isofluoran, we can see a key difference between these two anaesthetic agents. So as you can see on the graph here, see the fluoran's curve is steeper, meaning it's reaching its effects faster than isofluoran. So why is this?

And it's all down to that solubility. The the see the fluorine is reaching its equilibrium point between the dissolved gas in the blood and the gas within the alveoli of the lungs more quickly than isofluorine. It's therefore transferred to the central nervous system more quickly than isofluorine to have its desired effect.

And then importantly, because these inhalation agents are primarily expelled from the body in the same way they came in, i, via respiration, the same applies in reverse. So when the vaporizer settings are turned down or turned off, the changes to the anaesthetic depth occur more rapidly with Cfluoran because the agent is able to leave the blood and leave the body more quickly than isofluorine. So the difference between the two agents in terms of their solubility and blood and how that relates to those curves that we've just looked at.

As you say, this gives rise to the key difference between the two molecules. Induction and recovery is more rapid with sevofluoran and gives the potential for finer control over anaesthetic depths when compared to isoflurane. It also means that any adverse effects that you might see during the anaesthetic process can be reversed more quickly with sevoflurane.

Conversely, it also means that changes can occur rapidly with see the fluorine. So, obviously anaesthetic depth is monitored carefully in all cases, but even more so we see the fluorine, you have to be very much aware that the changes can occur quite rapidly. So, again, very careful monitoring is required with this, this gas.

This brings us on to talking about the vaporizers. So isofluorine and sevofluorine require different vaporizers, they're not interchangeable. You can't just have one vaporizer and switch between the two agents.

In addition, some products require adapters to use with certain vaporizers. Indeed, we supply an adapter to allow the use of our see fluorine see hail with some see fluorine vaporizers. Please contact your Chanel territory manager for more details on this.

Let's go on to look at another difference between isofluorine and superfluorane and how this has an impact on the practical aspects of an anaesthetic. This difference is smell. Isofluorine is a very pungent smell, whereas Siva fluorine has only a light odour.

This difference makes see the fluorine really useful for mask inductions because the patient is less able to detect the anaesthetic agent that it's breathing in. A lot of animals will react adversely when they when they smell the isofluorine in a mask, whereas this is less likely to happen using see fluorine. And this is very useful in these situations where mask induction is required.

It should also be remembered that, that this difference is very useful in small furry or exotic inductions using a mask or, or chamber. But remember that this indication in these species is off licence. So the fact that isofluorine has a stronger smell than see fluorine can be useful in certain situations.

For example, is there a leak in the in the circuit? This might be more easily detectable with isofluorine when compared to see the fluorine. However, we really should remember that breathing in these agents as a result of the leak is not ideal.

We don't want the personnel in the immediate environment, surgeon, the anaesthetist, anyone observing to be breathing in. Anaesthetic, gas. So, ideally, it's not a brilliant way of identifying a leak and other methods should be considered and leaks avoided wherever possible.

Finally, when considering which agent to use, it should be mentioned that cost is often a consideration, and has an impact on the decision made. So see fluorine does cost more and you need a greater volume. However, generic Sevafluorane products such as our Sivahale makes the use of see fluorine more affordable.

This allows practises and patients to benefit from the practical advantages of Cflurane, which we just talked through, especially for those more challenging clinical patients where finer control of depth and recovery are required. Remember, isofluorine is still a great anaesthetic agent and can be very readily used in clinically well animals and and in routine surgeries. So it's, it's often just finding, you know, which situation is right for you and your practise and which 1 may be right for this specific patient that you're dealing with.

So let's consider the adverse effects that you might observe when using these anaesthetic agents. The list here is taken from the data sheets. So you might see respiratory depression, depression of the central nervous system, hypotension, muscle relaxation, vasodilation, myocardial depression.

Depression of body temperature regulating centres and gastrointestinal effects. Some of these indeed are actually the desired effects of the of the general anaesthetic inherent and essentially the effects become adverse when an excess of agent is used. So all of these adverse effects are are to be expected with drugs that cause central nervous system depression.

The other adverse effect which was worth considering is malignant hypothermia. This occurs rarely in predisposed patients, and these patients are usually dogs. So isoflurane and Siva fluorine pose similar risks of an adverse effect due to their similar modes of action.

And as we've said before, adverse effects are essentially dose dependent. There may be less chance of adverse effects occurring with superfluoran when compared to isofluoran because changes to anaesthetic depth can be made more quickly. There is essentially less risk of going to excessive anaesthetic depth when using this product, because you have that finer control over the anaesthetic.

So as we mentioned earlier in the presentation, the correct vaporizer setting for a specific patient is not, unfortunately gonna be as simple as 1.5 times the max value for the anaesthetic gas you're using. Patient factors are gonna come into play.

Some of these patient factors will cause the Mac to increase, and some of them will cause the Mac to be decreased. So the list here, we have ageing, pregnancy, anaemia, hypoxia, hypothermia, hypertension, metabolic acidosis, hypothyroidism, premedication use, and the concurrent use of analgesics. These will all decrease the Mac value and therefore you will need a lower dose of inherent anaesthetics as the agents will be essentially more potent in these cases.

Conversely, there will be factors which will lead to an increase in the Mac value. And patients with any of these factors will need a higher dose of inherent anaesthetics as essentially the agent will be less potent in these cases. So these factors include increased body temperature, hyperthyroidism, concurrent use of central nervous system stimulants such as doxopra and hyponatremia.

Finally, there are some factors which have no effect on Mac. Which is good to know. These include the sex of the patients, the type of pain that, that is being experienced during the surgical procedure, such as visceral, peripheral, etc.

The length of the anaesthesia has no effect on Mac. Finally, hypertension has no effect on Mac. So what does this all mean practically for our anaesthetic?

As we've stated before, it means that essentially you can't just take the max value of the anaesthetic agents and sometimes by 1.5 to give you the required vaporizer setting for your anaesthetic. You've got to consider the patient factors.

And and what impact this will have on the Mac value. And it's worth actually just running through these all before the surgery starts, just so you're kind of aware of of the situation and how the different patient factors might impact that surgical procedure and the anaesthetic procedure. At the very least, patients will have been pre-medicated and this reduces the amount of agents that will be needed to achieve surgical anaesthesia.

Let's now bring the impacts of these patient factors into the real world and discuss some, some actual cases. First case here is case one, Lord Edard. Lord Edward needs to undergo a dental.

His cat He's male, he's 18 years old, he's got hyperthyroidism. He's got high blood pressure. We plan to pre-medicate him before the procedure.

And he's on meloxicam for arthritis. And he only has one eye. What will these factors mean to the Mac value in his case?

I'm gonna give you a couple of moments just to have a think about this. OK. So the fact that Lord Edard is a cat is going to have no effect on Mac.

The fact that he's male has no effect. That he's 18 years old, this means that the Mac is going to decrease. That he's got hyperthyroidism.

This is gonna increase the Mac. That he's got hypertension. This is going to have no effect.

The fact that we plan to pre-medicate him, this is gonna decrease the mark. And also that he's on meloxicam for his arthritis. This again is gonna decrease the mark.

And finally, the fact that he's only got one eye, this has no effect. So overall in Lord Edard's case, Mac is going to be decreased. Let's move on to our second case.

This is Indy. In the, it's planned to, it's planned to undergo an exploratory laparotomy. So let's think about the patient factors for Indy.

Indy is obviously a dog and a Labrador. She's female and neutered. She's 11 years old.

We plan to pre-medicate her. And her pre-op bloods have showed, showing that she's got a hyponatremia. Again, I'm gonna give you a couple of moments to just have a think about what these patient factors mean in terms of the Mac.

OK, so the fact that Indy is a dog has no effect, the fact that she's a Labrador has no effect. The fact that she's a female neutered canine Labrador has no effect on Mac. However, The fact that she's 11 years old, more geriatric, this is going to decrease the Mac value.

And that we plan to premedicate her again, this is going to decrease the Mac value. And those pre-op bloods showing a hypernatremia. Well, this is going to increase the Mac value.

However, overall, we're gonna have a slight decrease in Mac in Indy's case. So I think the obvious question now creeps in. Now that we know that we have these increases and decreases, how much of the increase and decrease is going to impact Mac?

And I think that that's a reasonable thing to ask. Unfortunately, I think it all comes down to the individual cases here, and it probably depends on the severity of of the each of the individual patient factors. So I think in order to quantify things more, you probably need to go into these factors and look at more detail.

But I think overall, we can see that adding all these patient factors together gives us an overall indication of an increase or decrease in mark for an individual patient. And critically, the thing to do is to respond to the patient in front of you, treat each case as an individual, and make the changes necessary to the anaesthetic based on that individual's needs. Finally, we're gonna go on to look at monitoring of anaesthetic depth.

And this is irrespective of which agent you're using, whether using isofluorine or superfluoran, the same is going to apply for, for both of these anaesthetic agents. So, these are the 5 factors that are gonna come into play when assessing anaesthetic depths. The first here is palprebral reflex, and this is typically absent at surgical anaesthetic depth.

Second here is I position. As anaesthesia deepens, the eye moves from a central position to a ventromedial position, with mainly the scle of them being visible. Essentially, the patient's going cross-eyed.

However, it's worth remembering that if anaesthesia deepens even further, it's possible for the eye position to move back to a central position. And this is, this is really worth being aware of because if you're just looking at that to monitor anaesthetic debt, people may erroneously assume that the the depth of the anaesthetic is becoming less and and turn up the vaporizer settings, and this would be obviously be a terrible thing to do in this situation. Third thing here is pupillary dilation, with increasing depth of anaesthesia, the people will become more dilated.

Fourth factor here is jaw tone. This loosens as the as the depth of the anaesthesia increases and can be assessed by gently manipulating the jaw. Finally, we have the pedal reflex, firmly squeezing the webbing of the skin between the toes shouldn't cause the limb to be withdrawn.

If anaesthetic depth is insufficient, then the the reflex will cause the limb to be drawn away from the, from the painful stimulus. So this should be abolished once you achieve the correct anaesthetic depth where surgical stimulation is not going to be felt. As well as monitoring the signs of anaesthetic depth in the ways we've just discussed, careful and regular monitoring of the following are also required for every anaesthetic.

Respiratory rate, blood pressure. Indicators of cardiovascular functions such as heart rate, capillary re full time and partial pressure of 02. And the temperature of the patient.

It's very useful, I think, and I, I'm sure most people will do this in their anaesthetics to keep a record of these on the chart. And this allows you to see the changes and trends over time during the anaesthetic. Should be looking out for signs of respiratory, and cardiovascular depression, along with alterations and decreases in blood pressure.

It's important to provide thermal support early in the procedure and keep an eye on the temperature of the patient throughout the anaesthetic and during recovery. Remember that lowering of the body temperature can cause the mac value to decrease. It should be noted that this presentation is targeted towards non rebreathing circuits.

Rebreathing circuits will complicate things as the percentage of the inherent agent will change over time. We're not going to go into this in detail in this presentation. Suffice to say that if you are using or you want to use a rebreathing circuit, you may want to get more information on the use of these circuits if you're unclear or before you start using one.

So when will you need to alter the dose of the indolent agent that you're using for maintenance of anaesthesia? When do you need to change the vaporizer settings? Well, as we've said before, always respond to the patient in front of you, and respond to the situation you're in.

Through those monitoring tools that we've just discussed, watch for early signs of any adverse effects. And if you are starting to see these, make small changes and monitor the patient for the effect of those changes. Remember, changes in depth of anaesthesia can occur more quickly with pseudoflurane due to its physical attributes.

So keep an eye on this and monitor these patients carefully during the anaesthetic. So when might you need to turn up the gas? When might you need to increase the amount of inhalation agent that has been delivered to the patient?

Well, the obvious answer here is that if the patient is becoming too light and is starting to respond to surgical stimulation, It's worth noting that if you've taken the time to ensure that you're at the correct anaesthetic depth before surgical simulation has started through all those monitoring signs that we've talked through, then this is unlikely to be the case, as long as you're continuing to monitor those signs and ensure that the correct depth of anaesthesia is being maintained throughout the procedure. It may, however, that there is a problem either with the equipment, maybe the gas has run out or there's a kink or something like that, that is meaning that the agent is not being delivered adequately to the patient. Check the circuit you're using, check the equipment you're using, top up the vaporizer, all those kind of things.

But as you say, you really shouldn't be in a situation where you're needing to turn up the gas dramatically during a procedure. Conversely, when might you need to turn down the gas? When might you need to reduce the amount of anaesthetic agent being delivered to a patient?

Well, it can be tempting to turn the gas down if there's a drop in the respiratory rate or blood pressure. However, just take a moment to interpret these changes with hyperventilation. Is the ET tube OK?

Is there a kink in the circuit or the tubes all functioning as they should be? And if you've got hypertension, is something else occurring? Is there a bleed, for example, that the surgeon needs to be made aware of?

If the answer to all of these is no, and everything is, is OK in these regards, then it's OK to turn down the gas a little. Essentially, you're turning down the gas if you feel that the depth of anaesthesia is going too high, through those monitoring signs that we've talked through earlier. Finally, let's talk about the situations where you'll need to make a dramatic change to the vaporizer setting, I turning the vaporizer off.

So the first of which is part of the normal process of an anaesthetic. You're going to turn the vaporizer off when the procedure, the surgical procedure is over and you're ready for the animal to move to recovery. The second situation is if you're in an emergency situation.

So true emergencies that require immediate discontinuation of inhalation anaesthetic agents come in two forms, hypersensitivity reactions and cardio pulmonary arrest. Anaphylactic or anaphylactoid hypersensitivity reactions usually occur after the administration of a drug, but can also occur during some procedures, such as mast cell tumour removal. Severe and sudden hypertension.

Tachycardia, arrhythmias, pulmonary and portal hypertension and cutaneous changes can occur. With cardio pulmonary arrest, as the name suggests, this is characterised by cessation of ventilation and circulation. As far as the inhalation anaesthetic agent is concerned, in these emergency scenarios, the vaporizer should immediately be turned to 0, circuit fluster with oxygen, and appropriate life-saving treatment initiated.

So after that last dramatic slide, we're going to bring everything together in a summary and finish off now. So a thorough understanding of anaesthetic inherent agents, the Mac associated with those agents, your anaesthetic equipment, patient factors involved with individual cases and how that impacts the Mac, adverse effects that you might see during an anaesthetic, and excellent monitoring of an anaesthetic. These will maximise the likelihood that an anaesthetic procedure will be successful and stress free for all involved.

Please note this presentation is designed to give an overview of some of the factors and topics to consider when using see the fluorine and isofluorine. It's not designed to be a comprehensive guide to anaesthetics and companion animals. If you require further information on this topic, there are plenty of sources out there.

Indeed, there are whole textbooks that have been written on, on the subject, and I would refer you to these for further information. So in terms of support for Chanel products, we have a wonderful team of territory managers, and these territory managers are probably our greatest practise support resource. We have Dish, who's based in the Midlands in North Wales.

We have Susan, who covers Northern Ireland and Scotland. We have Kelsey, who's in the north of England, Matty in the Southeast, and finally Matthew Oaks, who covers the south, southwest and South Wales. You also have myself as the product support manager, and our contact details are available on this slide.

Please reach out to us for any support that you may require or questions that you might have. This is a list of references which relate to this presentation. The only thing left for me to say is thank you so much for listening.

I very much hope this presentation has been useful and interesting. More information and further CPD is available at vet. Chanelfarmer.com.

To receive a CPD certificate for completing this training, please email [email protected]. Once again, Thank you so much for your time, and we look forward to seeing you on one of Chanel's CPD sessions in the near future.

Jonathan, thank you so much for recording that for us and for being with us here tonight. Before we go over to the questions and that, I'd just like to say, we understand that some of you have been having problems with the sound. Just a reminder that we have recorded the session.

And it will be live on the webinar vet's website in the next day or two. The technical guys normally have it up by the next day, but if it's not there by tomorrow, just give it a day and then go back and check. And then you'll be able to pick up any bits that you have missed.

But also, you can then Stop and rewind and look at some more of those facts and everything else that Jonathan brought up. So, once again, Jonathan, to you and to Chanel Farmer, thank you very much for your time and for your generous sponsorship tonight. Thanks, Bruce, much appreciated.

Let's pop over to some of the questions. Bev was asking, can you just remind us what MAC means? Yeah, sure thing.

That's the minimum alveolar concentration in oxygen for an anaesthetic agent. So it's just the, the kind of catch-all term that that's used to to basically define the concentration of, of agents and, and really a measure of its potency. I suppose that's the best way of thinking of it.

Excellent. Then we have a question that is coming from, Miriam from Algeria. Why can you not mix, the two ISO and SIO in the same, inhalant canister?

Hi, Miriam, that's a, that's a really good question, and I think it's something that comes up quite a lot, because it is a barrier, potentially for practises switching between agents. And I think essentially it comes down to safety. It's a bit like you're filling up the car at the petrol pump, they're now designed that, that you can't accidentally put diesel in a petrol and vice versa, I believe.

And, and I think it's kind of the same kind of thing. What they don't want to happen is is people using different agents in one machine and not possibly realising that that is the agent that's in that machine at that one time, because obviously, it has an impact on the concentrations you're going to be using as we've talked about. So my understanding is a lot of that has come from human medicine and human anaesthesia, where again, you know, safety is, is critically important.

So we've, we've, I think followed on from that in terms of the machines. It's like I say, it does obviously cause a bit of a barrier. I'm, I'm not sure we can help you out in Algeria, but certainly from a UK and Ireland perspective, if people want to reach out and contact us, either myself or or the territory managers, there are things that we might be able to do to help you over that barrier.

So, as I say, just get in contact. Fantastic. Couple of questions about CPD certificates.

First one was in from Alexandra. So Alexandra, as you can see up on the screen at the moment, you just need to pop an email through, to that address, vet updates at Chanelgroup.ie, and they will be able to supply you with that CPD certificate.

Rachel wants to know, do you know the Mac of Sivo and rabbits? And would you use SIO or ISO in rabbits? That's a really good question.

I don't have it off the top of my head in front of me, because obviously, as we talked about with this presentation, we just wanted to focus on the licenced species, just from a Really a communications point of view. But that's something that again, reach out to me separately or we can get your email address off the system and we can talk through that, that particular situation, in a vet to vet basis. Excellent.

Alexandre has got two questions. The first one is, how long can you keep a patient on inhalant anaesthesia? And the second one is, he has heard that, Io can be a little bit irritating on the respiratory tract.

How about SIO? Not something I've, I've come across, personally, in terms of irritation and, and certainly the sorts of people using it without encountering that, that, particular issue. In terms of how long a patient can remain under anaesthetic.

I think that's possibly a little bit like asking how long is a piece of string. I think I think it's very much dependent on how the anaesthetic is going. If everything long as it's stable, exactly that, Bruce, I think as long as the patient is stable, then.

Yeah, then, you know, things are progressing as they should. It's a slightly different situation in equine anaesthesia where longer anaesthetics have other potential complications in terms of myopathies and and things like that. But small animals, certainly cats and dogs, we don't, we don't tend to have those kind of issues.

I think things like, you know, temperatures we mentioned in the presentation is, is a factor, you know, the longer an animal's under anaesthetic, potentially the temperature can drop. . But the key thing, as we said there is, you know, respond to the patients in front of you.

If you're seeing, if you're seeing changes that are unwanted or or worrying, then obviously you're gonna have to . Adapt, I think, under those situations. I think to add another aspect to your saying, which I love by the way, I use it all the time.

How long is a piece of string? In this case, how long is the string and how thick is it? That's that's great.

I like that. . Oh, I'm gonna mess this name up.

I apologise before I even tried. John Luca, I think it's pronounced, says could you shortly list or list short list of pros and cons of ISO and CIO? That's another webinar.

I was gonna say, I, I, I think we've, we've covered a lot of that during the presentation, I think, you know, I think, you know, for me, the big advantage with, with Civo is that, that you can rapidly change the anaesthetic depth and, and recovery is faster. So you have that fine tuning of, of the anaesthetic. Obviously, conversely, the, the, the fact that the depth of anaesthesia can change quickly with Civo means that you've got to really pay very close attention to that, to that anaesthetic depth throughout.

But it can be very, very useful in terms of, you know, the control you have over an anaesthetic. ISO is a very, very good agent, nothing wrong with it. But again, the key thing with, with both of them is just being aware of the differences and what you might see with them.

I think if a lot of practises, when I talk to them, will tend to go one or the other, and they'll tend to get used to whichever one they're used to using. Some practises will switch between the two, but again, it's just being aware of all the issues involved. The big one historically that that has stood against Sevoflurane has been cost, because obviously you're using more of it and and you require a higher .

Anaesthetic percentage on the, on the vaporir as we've talked through. But the nice thing now is, is with the generic products that that cost factor has become less significant and it's become more cost effective, essentially. But yeah, if, if I've missed anything, then no, please rewatch the video.

Hopefully it's all in there. Yeah, that's, that's the beauty of watching the recording is you can rewind and stop and have a look at all these things. Here's one to put you on the spot, Jonathan.

Rachel wants to know, if we prep a patient on a Sio vaporizer, can we then move it onto an iso vaporizer? That's a really good question. I've never heard of anyone doing that.

No, me neither. I don't see why not. I mean, the only, the only situation I could see where that would be necessary is if you run out of agent, one of the agents halfway through or or something catastrophic happens to the machine, the vaporizer.

But In theory, I, I should imagine you could switch between the two. I mean, certainly that's a very off licence question. It might be one, it might be one for an an an an anaesthetic specialist, but.

Yeah, I, I don't see why not. Again, I think the key thing, as we keep coming back to is just, you know, that monitoring and responding to the patient in front of you. And I think that's, yeah, that's an important one is that your patient reacts differently, differently.

Yeah, you're gonna, if you did it, you'd have to let One, you'd have to be very careful in that transition period because there'd be differences in the time that they reach the concentration. If you think about those graphs, you'd want to make it so the graphs didn't overlap. So there's a potential that you might either go too deep or, or too light, I think in that transition period.

I, I would be, I would be cautious about thinking about doing that. It, it's an emergency situation only, I would have thought, yeah. We have an interesting one here, from Emma Fisher, who says, I am actually a human ICU doctor with a background in anaesthetics.

Clearly, she wants to upgrade to being a vet, but we won't hold that against her. In humans, this is becoming more popular as a method of measuring depth of anaesthesia alongside other clinical monitoring. Is there any use of this experimental or clinical in veterinary medicine?

Sorry, say that again. Bruce, I, I lost what, what the parameter was. It's, I don't know what it stands for, but it's the monitoring activity.

As far as I'm aware, it's not yet commercially in veterinary. I don't know if it's. I haven't heard of anyone doing that.

And I think, you know, a lot of the time in veterinary, as we know, we get a trickle down from human medicine. So I would imagine if that becomes more common in human anaesthetic monitoring, then it, it might become more prevalent further down the line in veterinary. But yeah, as far as I know, no one is doing that at the moment.

So maybe there's a research opportunity there for someone. Yeah, it would be an interesting one. Leanne wants to know, does the induction agent play a difference in, the sort of follow on of with either ISO or or Sio?

No, I don't believe so, because essentially what you're doing is you're, you're getting the patient to, to, a depth of anaesthesia with the induction agent and then taking over that anaesthesia with the inhalant. So it doesn't really matter what is being used to get you to that point. It's what you then, you know, follow on and and have a nice smooth transition between the two.

I think that's, that's the, the key thing. Yeah, yeah. Antoinette poses a very good question.

If SIO has a more rapid onset of action and return to recovery, would this mean that Sivo has more smooth recovery as well? A lot of people say that, when you talk to, to clinicians that are using it a lot, and that's one of the things they really like about Civo is the smooth and, and, more rapid recoveries from it. .

I think it, yeah, it certainly seems to be an advantage that people like in practise. So yeah, I would say yes. Question from Catherine.

She says, why is Iso safer in guinea pigs than Sio? Have I got this right? Again, that one I think we'll take offline, contact me, we'll, we'll talk about it, if that's OK.

Only because it's obviously we're talking about off licence indications. Yeah. Yeah.

Cool. Alexandra's come through with another question. Which one of these gases do you personally prefer for neutering and which one for more elaborate surgeries such as orthopaedics or neurosurgery?

I think given what we've talked about for in terms of the benefits of the two and all the, the properties of the two, A lot of people, if they have access to both, will choose sevoflurane for the more complicated cases. So that second example there, neurosurgery, etc. Those are probably ones they're going to be usingivvolu, whereas more routine neutering operations, certainly if the patient is fit and healthy, people might be quite comfortable just going down the IO route.

And again, A lot of that will be down to things like, you know, the cost considerations between the two. But certainly, when I've been talking to people, a lot of clinics will have one or the other, and the opportunity to have both in a practise is, is maybe less common. But if you do have that, then fantastic.

But I think most people, as we talked about, will reserve the ISA or keep the ISA for the kind of more in inverted commas, standard, normal, anaesthetics. Fit and healthy patients and then maybe use the CO on stuff that's a little more complicated, maybe has a, a few more complicating patient factors involved. So yeah, I think that's very much what I hear when I talk to people.

Excellent. Flora has come through with a question. You briefly touched on it earlier, and Flora says, are there any special considerations when using re-breathing systems?

Yeah, I mean, with, with the rebreathing systems, you get a a change in the anaesthetic levels within the, within the circle system over the course of the anaesthetic. I, I think, you know, those systems, why we didn't go into a lot of detail here is you could basically do a whole CPD session on, on rebreathing circuits. They, they can be quite complicated and tricky to use.

So, I would probably say. Dive into that topic in a little more detail, but essentially it's because the concentration of the gases changes over the course of the anaesthetic. So you're constantly having to make adjustments to the, to the vaporizer settings during the anaesthetic.

Yeah, I think it's one of those ones where, as you say, it's quite complicated, and you've got to really just look into it and study it and, and, and get trained on it. And once you're comfortable, that's great. But, it's not just a, a willy-nilly sort of jump into it.

I think that does actually bring me quite nicely onto one of the other topics that I was kind of thinking about discussing in this kind of Q&A session. And, and one of the things that obviously is such a hot topic and a buzzword in the not just the veterinary world, but, you know, the world in general is sustainability. And this is something that that people have approached us to discuss regarding anaesthetic agents.

. The rebreathing circuits and circles are considered to be sort of low flow systems. So you are potentially using less anaesthetic agent in those systems, which is good because obviously you're venting less gas. The other thing that I think it's worth considering is that you can get specific scavengers now that will remove these gases from from the vent, from the exhaust vents, essentially from an anaesthetic circuit.

So those are things that might be worth looking into if if that's a priority. And I think like I say, sustainability is such a, such a big topic at the moment. Yeah, yeah, anything that helps the green situation, especially with the inhaling gases, I think it's a good thing.

Yeah, yeah. It's, it's one to, you know, just look into in a little more detail. It's only something that that we've been talking about quite a lot recently.

Yeah. One more question, Jonathan, before we let you go. Adele has asked, would be a good choice for C-sections given its rapid recovery?

Yeah, I think, I think that arguably yes, you know, you're, you're not gonna have a. As big an impact on, on those, those newborns, and it's going to leave their system faster. So yeah, I, I, I think that that would be the case.

I would, I would Possibly reach out to to and this just to confirm that, but, but, you know, just thinking off the top of my head. Yeah, I don't see why not. I think that would fit into the category of slightly more complicated procedure that might be useful to use CO4, as we talked about previously.

Yeah, yeah. There's lots of comments that have come through and messages that have come to me to say, fantastic webinar and very insightful. Thank you very much.

So, I'm passing those on to you, Jonathan. Thank you for your time. Thank you for doing the recording and making it available to us.

Thanks so much, Bruce, and thanks, thanks so much to everyone for listening again. It's been, it's been a lot of fun. Yeah, and to everybody that attended, thank you very much for your time.

Remember that the recording will be up on the webinar vet's website in the next day or two. So if you have missed anything, or if you want to go back and look at something again, it's real easy to get onto the website and you can pause and rewind. It's, it really is a great facility to have.

To Kyle, my controller in the background. Thank you for making everything run nice and smoothly. And last but not least, to Chanel Farmer for their generous sponsorship, which made tonight possible for everybody.

So from myself, Bruce Stevenson, it's goodnight.