Good evening and welcome to tonight's webinar with the webinar vet. My name is Sophie McMurra, and I'll be chairing tonight. So before I go on to introduce our speaker, I'd just like to point out that you can ask questions throughout the webinar.

To do so, just hover over the toolbar either at the top or the bottom of your screen, and you'll see a Q&A box. Click the Q&A box, type your question, and that'll come through to me ready to ask Becky at the end. OK, so tonight we have the wonderful Becky Robinson.

Becky is an RCVS specialist in veterinary anaesthesia. She graduated from the University of Liverpool in 2008. She passed her European diploma in Veterinary anaesthesia and analgesia in 2013, and subsequently became an RCVS recognised specialist in veterinary anaesthesia.

Becky joined the anaesthesia team at Davies Veterinary Specialists in November 2016 and takes an active role contributing to in-house staff training and enjoys working in the multidisciplinary environment with its varied case load. So I'm very excited for tonight's webinar and I'm sure you all are too, and I'll hand over to you, Becky. Perfect, thank you very much.

So thank you all for joining us today. The talk tonight is, on the principles of anaesthetic management for the critical patient. And I've put this caveat here in the title that, this is not all about the drugs.

And you can see from our outline that actually the vast majority of the talk is, is going to be about how we approach these patients and how we can stabilise these patients and, and having a holistic view and management of them. With just a little bit on the, the anaesthesia at the end, because actually, what's really important for these patients and to have successful management of these critical and sick patients is actually caring for them throughout the whole process and not just focusing on the anaesthesia. So anaesthesia and analgesia, they are essential aspects to modern ethical medical practise.

And unfortunately, a lot of our emergency or critical patients will require sedation or anaesthesia, and usually this is fairly rapidly once they're presented to us. Now, our job, certainly when you're acting as an anaesthetist, needs to, is to, we have to minimise the anaesthetic risks that these patients have. And also hopefully we can optimise their anaesthetic experience.

Now when it comes to critical patients, the type and severity of compromise can vary massively. They can have huge amounts of different things wrong with them. So, in terms of how we approach these patients, it's often helpful to consider the potential underlying reasons for the patient compromise from a body systems approach.

And this can help us to start mentally preparing what equipment and treatment might be needed for patient stabilisation and their ongoing anaesthetic management. So for example, we can split our body systems down into the cardiovascular, respiratory, neurological, hepatic or renal systems. These are probably the, the major body systems that we need to think about.

And we can see that depending upon what potential compromise the patient has, we can already start planning what we need to do to stabilise that patient, whether it be provide analgesia, provide fluid resuscitation. Provide oxygen, airway management, and we can kind of target our, our approach and our preparation and management of these patients depending upon what the underlying problem is. When it comes to considering anaesthetic management of the emergent or critical patients, it's often really useful to assign a grade to their physical status.

And we often use what's known as the American Society of Anesthesiologists or ASA status and the scale that the this group of an anesthesiologists came up with. And this was originally a scale designed for humans. But we do commonly use it in veterinary patients.

And the idea is, is that we assign this physical status to the patient based upon a combination of their history and physical examination. And this table kind of gives a brief overview of what we would class various different patients, in terms of their ASA status. And the scale goes from 1 to 5, with 1 being a completely healthy, normal patient.

So this would be, for example, a patient coming in for an elective, ovarian hysterectomy or castration. All the way down to an ASA 5 patient. And we can see that that is a patient who is defined as being moribund and they're not expected to live more than 24 hours without having any surgery.

And then we've got all of the the scale in between. Now when it comes to critical patients, or emergent patients, we often define, sick patients as being those with an ASA status of 3 and above, with ASA 1 and 2 patients being classed as healthy. Now, being able to assign an ASA status to our patients is quite useful because we've got numerous studies which actually show that this ASA status of our patients has a predictive value for patient outcome.

And one of the biggest epidemiological studies which has been performed, that is the confidential inquiry into a small animal peropive fatalities or the SEPSA study, has shown that patients with an ASA status of over 3, so those are our sick patients, do have a greater risk of complications and death when it comes to anaesthesia and sedation compared to those patients who are of ASA status 1 or 2. When it comes to anaesthesia, I really quite like this, quote, which, comes from the 1950s. And this is a quote that, is, it's someone trying to actually describe what anaesthesia is.

And they say that anaesthesia is a process of controlled reversible intoxication of the central nervous system. And the reason why I like this quote is that this term intoxication kind of gives us the idea and reminds us that yes, while, while anaesthesia and sedation is often necessary in a lot of cases, we are actually giving agents to the patient, which is depressing the whole cardio their whole central nervous system. Which, if we give too much of it, we are actually going to cause intoxication, and we're often walking a fine line, particularly in our critical patients, between what, the amount of anaesthesia we need to give and providing too much that can cause an overdose.

In terms of absolute figures for anaesthetic risk, these figures come from that SEPA study that I've just mentioned. And when we look at all cases, so these are, ASA grades 1 to 5, so including healthy patients and sick patients, we can see that the overall canine and feline mortality is 0.17% and 0.24% respectively.

However, when we look at our sick patients, so that is those that are ASA 3 and above, we can see that that's anaesthetic risk and the risk of mortality jumps massively. So that jumps to 1.33% for dogs and 1.4% for cats.

And I think it's useful to just spend a couple of minutes to think about why this is so. I mean, it makes sense that sicker patients are at greater risk, but, but why? So when it comes to looking at factors which affect anaesthetic risk, they can be broadly split up into risks which are associated with the patient's signalments.

So that can include things such as age and body weight. And unfortunately, we can't influence these. But also, unfortunately, many of the identified patient risks are actually associated with our critical patients.

And then we have management factors, and these are important to know and understand because management factors are the things that we can influence. And therefore, if we can influence such management factors in a positive way, we can hopefully reduce the anaesthetic risk for our patients. And finally, what these big epidemiological studies have also shown is that actually drug-related effects are much less important in terms of anaesthetic risk.

So while we often hear things such as drug A is safer than drug B, actually, what we find is that that this effects of these drugs isn't that important. And what I take from that is that we really should be using familiar techniques, because if we use a familiar technique in these critical patients, we know what to expect, and therefore, we know, when or are more able to recognise when something is going wrong, and we can pick it up sooner because we know what should happen. So while theoretically one drug may have more benefit over another, if you're not used to using it, then the theoretical benefit of its safety, is likely to be much less important.

So we talked about the fact that many of our critical patients do have factors associated with them that are associated with an increased risk. And that includes things such as extremes of body weight, patient age, so either younger or older patients, how urgent the procedure is and whether a procedure is classed as major or minor. A further explanation as to why, compromised patients are particularly at risk during the anaesthetic period is to do with their physiological reserve.

Now compromised patients have a reduced physiological reserve. Also, when we anaesthetize any patient, whether that be healthy or sick, that anaesthesia will depress many homeostatic mechanisms within the body. And we know that anaesthesia can induce hypothermia, hyperventilation, hypertension, and reduced cardiac output, for example, and that can happen in both our healthy and our sick patients.

But in our sick patients, the combination of having a reduced physiological reserve, so being less able to cope with these changes in homeostasis, make our patients particularly vulnerable in the peri-anesthetic period. So when it comes to anaesthetic management of these patients, There's often I feel a focus on what is the best drug protocol, and this is often misplaced. And this kind of comes back to what I was just saying in terms of using familiar techniques.

So there is actually no single correct recipe to use in these critical patients. However, what we do need to make sure that when we're coming to select a technique or an anaesthetic protocol, is that we have an understanding of the physiology and also understanding of what the disease is that the patient has, having a knowledge of the drug pharmacology and the effects that are gonna happen with the drugs that we're planning on using and reiterating again, having a personal familiarity with the technique that we're planning on using, so we know what to expect when we're using it. Whenever we're presented with a critical patient that is likely to need you the sedational anaesthesia.

I, it's, I find it useful to, to have a logical approach to the case. And that includes, as I said right at the start, having a, a holistic approach to it. So ensuring that we have a patient history and physical examination, ensuring that we perform any diagnostic tests that are deemed necessary, and we'll come on to, this in a bit more detail in a little while.

Ensuring there's appropriate stabilisation of the patient, consideration of likely potential complications and risks, and then finally putting all of that information together to have consideration of anaesthetic or a sedative plan. Now, in reality, we often don't have that much time with our critical patients. So often these steps need to occur simultaneously, or at least, some of the steps happening, simultaneously, in order to, to speed up the process, but also making sure that we're doing it in a safe manner, and covering everything that we need to do.

What is really important to remember is that we have to have active management of these patients throughout the entire anaesthetic period. And I said this right at the start, it's no good just simply thinking about what our anaesthetic protocol is going to be unless we've considered. Everything else before that, including getting what sort of state the patient is in by performing physical exam and diagnostic tests and ensuring that we are stabilising the patient so that they are in the best possible state to undergo anaesthesia.

So starting with patient history, obviously, if we have an emergent case, we're not often afforded the luxury of having the time for a full patient history. So in these cases, I often get what I call a capsule history. And sometimes I even delegate the history taking to somebody else so that we can stay with the patient, and manage the case, next to the patient and ensure we're doing everything we, we can for them.

Pertinent information that we need to get from the patient history includes species and breed, which hopefully is pretty obvious from looking at the, the patients. Having an idea of what their temperament is, trying to, to gain an assessment of whether we think they're going to be painful. What their sort of age range is, and importantly, and what is often forgotten, ensuring we, get the information of any pre-existing diseases that these patients may have and therefore what might, impact what we need to do.

It's very important that we perform a physical examination on our patients and perform an assessment. We have to have a patient assessment in order to form and implement plans. And now as I said, a physical examination is a crucial part of our patients assessments, but it will also include looking at monitor parameters such as blood pressure, and also looking at a variety of appropriate laboratory data which is specific to that individual case.

What I will say is that we just need to be a little bit careful that, we don't miss the woods for the trees. Very often we get hung up in looking at the monitored parameters, and laboratory data, and just looking at, taking blood samples and, Doing ultrasound scans and, and looking at all of these diagnostic tests, but actually it's important to remember that we can get a huge amount of information about our patient from a basic good physical examination. So it's really important that we don't miss this out.

In terms of our physical examination, we need to make sure we're performing it efficiently and effectively, but we really need to make sure that we don't cause any further undue patient stress. As a priority, if we think a patient is painful, we must provide analgesia because this is going to automatically make the patient feel better, calmer, and it's going to also make our lives a lot easier because, it will often make patients much more amenable to performing a physical examination. When it comes to looking at a physical examination, in terms of what's important for consideration of anaesthetic management, we really need to be focusing on the cardiovascular system, the respiratory system, and, to some extent the neurological system.

So we're gonna go through each of these systems in a little bit more detail and kind of picking out the sorts of things that we need to be looking at when performing a physical examination on these patients with relevance to going on to perform sedation or anaesthesia. Obviously, whenever we're performing a physical examination on our, critical or emergent patients, we need to be doing this, thinking about triaging them. We need to, ensure that we have a, a, a basic, idea of what our patients' airway breathing and circulation status is.

And obviously, if that, highlights any significant immediate problems, we need to deal with that. And I also put, in here disability. So this is kind of where I'm starting to think about the neurological status of the patient as well.

So starting with the cardiovascular system, obviously, we're all aware that the cardiovascular system is responsible for circulating blood throughout the body. It delivers oxygen and nutrients to the tissues and removes waste products. Many of our emergency and critical patients, can have conditions which can affect the cardiovascular system, whether that be through affecting the autonomic function, vascular tone, heart rate or contractility.

And we have to have an idea of how compromised our patient is in order to try and minimise the expected impact that we're going to have during anaesthesia on our cardiovascular system. The most obvious thing to look at first when it comes to thinking about the cardiovascular system is the patient's heart rate and rhythm. And this can be assessed in a number of different ways.

So for example, auscultation, pulse palpation or a variety of monitoring equipment. But what I will say is that we always should assess our patient's heart rate and rhythm in combination with their pulse rate and rhythm. Because this can give us additional information such as what the patient's peripheral perfusion may be and whether they're suffering any pulse deficits.

And also another really important point to remember is that if we're assessing a patient's heart rate and rhythm via an ECG, which of course is the gold standard way to assess a patient's rhythm, having electrical activity on an ECG doesn't necessarily mean that the patient has a contracting heart. It simply means that there is electrical activity occurring within the heart. And if we think to what one of our arrest rhythms is, pulseless electrical activity, we can see that we can have, what sometimes can look like a relatively normal ECG, but actually our heart isn't doing anything and actually that patient has arrested.

So this is just something really important to remember. In terms of heart rate, we need to appreciate that it's actually a relatively non-specific indicator, and it's got to be taken in context with what else is happening in that patient. So, for example, there are multiple reasons why a patient may be tachycardic.

And these are just some of the reasons why I came up with, with why a patient may be tachycardic. And these are gonna have to be differentiated, and we might have to do a little bit of detective work to actually find out what is the problem. Now, in most cases, tachycardia is usually down to no deception or the patient is painful, the hypovolemic or hypotensive.

But if we've ruled all of these things out by giving the patient analgesia and volume resuscitation, then we actually need to then start working through the list and thinking of other reasons why the patient might be tachycardic, to try and, and solve the problem and treat it. I've already said it's really important to assess pulse quality when we're assessing heart rate and rhythm. I said it allows us to assess full pulse deficits and gives an indication of perfusion.

But what we need to appreciate is that when we're assessing pulse quality, what we're assessing is what's known as the pulse pressure, and that is the difference between systolic blood pressure and diastolic blood pressure. What it is not telling us is the absolute blood pressure. And there's been various studies in both humans and veterinary species, which indicate that this is True.

So, some people will tell you that if you can feel a pulse in the metatarsal artery, then the patient's blood pressure must be above, mean blood pressure must be above 60 millimetres of mercury. This is not true. We cannot tell blood pressure based upon pulse quality.

We are simply assessing the difference between systolic and diastolic blood pressure. So, moving on to blood pressure, this is something which, as an anaesthetist, I often get really quite, hung up about. I'm, I'm often really quite worried about blood pressure.

I'm monitoring blood pressure and making sure that it is an adequate blood pressure. And this is because, we do have to have a minimum blood pressure in order to perfuse our tissues, provide the nutrients and oxygen, and remove waste products. And our critical patients can often suffer derangements of blood pressure, whether that be hypertension or hypertension.

And obviously, when it comes to blood pressure, we can measure it in a number of different ways. In emergency patients, it'll usually be via a noninvasive method such as a symmetric blood pressure monitoring, or the Doppler. But in some cases, particularly cases who are, in ICU, for a prolonged period of time.

Who have or are likely to suffer from derangements in blood pressure, we may use invasive blood pressure measurement with an arterial catheter. In terms of critical patients, most often we're gonna come across hypotension rather than hypertension. If we do come across hypertension in our critical patients, most of the time it's because, they're painful and they need some analgesia.

When it comes to hypertension, we can often split this up into either mild hypertension or severe hypertension. Both of which do need treatment. Obviously, if we have a patient with severe hypertension, this requires really quite prompt treatments, and management.

And this, if we can provide this prompt treatment and management, we're hopefully going to minimise the morbidities which may occur, for example, reduction in renal perfusion. In terms of blood pressure, we, as I say, as an anaesthetist, I often get really hung up about it and wanting to make sure that I'm, my patient is not hypotensive. But actually, in reality, it's not the thing that really matters.

The thing that really matters, which we'll come on to, in the next couple of slides, is perfusion. But we use blood pressure because actually, it's really hard to assess peripheral perfusion. Whereas blood pressure is actually relatively easy to easy to measure, especially if we're using a non-invasive technique.

It gives us an objective measurement and we can track it over time. And while it maybe isn't as important as peripheral perfusion, as I said, maintenance is important because we do have to have a minimum blood pressure in order to, perfuse the tissues. And blood pressure can give us a crude indication of cardiac output and perfusion.

But as I said, blood pressure doesn't equal perfusion, and we can have a patient who has a relatively low blood pressure. So if we, look at, these equations here, blood pressure is made up of cardiac output. So, how much blood the heart is pumping around the system in any given time, which is in itself is made up of stroke volume, so cardiac contractility, and heart rate.

And also systemic vascular resistance. So how vasoconstricted or vasodilated our, blood vessels are. So any one of these factors can actually influence our mean arterial blood pressure.

You can imagine, for example, that if we have a high systemic vascular resistance and our blood vessels are vasoconstricted, our blood pressure is going to go up. We will have a good looking blood pressure, but actually, it might be really hard to pump that blood through that really vasoconstricted blood vessel as opposed to if it was vasodilated. So this is why we say that blood pressure doesn't equal perfusion, because we might have a good blood pressure because we have a high systemic vascular resistance and, a lot of vasoconstriction.

But actually, we're not necessarily perfusing those tissues because we can't get blood flow through that very constricted blood vessel. Whereas if the blood vessel is vasodilated, we may have a lower blood pressure, but actually, we still have perfusion. But perfusion is actually really difficult to assess, and we rely on having subjective parameters, including looking at the patient's mentation, the mucous membrane colour and capillary refill time, heart rate and pulse quality and extremity temperature.

But as we've already seen for heart rate, and we will see for mucous membrane colour and capillary refill time on the next couple of slides, these really are subjective and are influenced by a number of different things. We can use markers of anaerobic metabolism and increased oxygen extraction to assess perfusion, and these have been shown to be a little bit more objective. In practise, what we will most often use is looking at a patient's high lactate levels, or whether they have a negative base success.

And this is all well and good, but taking repeated blood samples in order to, continuously assess these markers of anaerobic metabolism just isn't practical. We can't keep repeating, blood samples over and over again on the patients. And also it becomes really expensive for the owner.

And it also is something that we can only do intermittently. It's not that we can, get almost continuous measurements. So actually assessing perfusion is quite hard, which is why we default to blood pressure.

Assessment of mucous membranes is always useful in a critical patient or in any patient, but we do have to understand that it's limitations. Obviously, we can gain quite a lot of information from mucous membranes, depending upon, the colour that that we see. So, we can get an idea of whether the patient is synotic, if they have, other diseases, in other body systems such as liver disease, .

But we do need to understand the limitations surrounding looking at mucous membranes. With the, the primary one being that the colour that we appreciate in the patient's mucous membranes will differ depending upon the light that we look at them under. The best example I can give you is if we are ever looking at a patient's mucous membrane colour when the patient is under a heat lamp.

In the red lighting of the heat lamp, it's pretty much impossible to tell anything about mucous membrane colour. And our ability to interpret the colour of the mucous membranes, can differ under different lighting. So, what it may look like in, the prep prep room may look completely different, to the theatre, depending upon the lighting that is used.

Depending upon the circumstances of the patient, there are some expected changes that we may see with mucous membranes. So if we have drugs or states which can cause vasodilation, then our patients are going to have pinker mucous membranes. Whereas if we have drugs or states causing vaso constriction, this can result in paler membranes.

The best example I can give you of this, is the original coloration for the meatomidine and the Attipamazole bottles when these drugs were first licenced. So, the Meatomidine bottle was coloured blue because meatomidine causes vasoconstriction and our patients became blue. Whereas the Attipamazole bottles was coloured red because when you gave it, you cause vasodilation and the patient became pink again.

We can also assess patients capillary refill time, and this can give us another indication of the patient's perfusion. So if the capillary refill time is prolonged, the patient may be suffering from vaso constriction. If it's shortened, the patient may be vasodilated.

However, it's important to appreciate the capillary refill time is actually not very sensitive. So we can see in this video here what is actually a relatively normal looking capillary refill time. But actually, this patient was euthanized, 5 minutes before this video was taken.

So this patient has no perfusion at all. The patient is, has died. So it just highlights how, insensitive capillary refill time can be.

Moving on to the respiratory system, it's important to assess the respiratory system prior to interaction with the patients because any interaction with the patient is likely to affect the respiratory system. And we can look at the patient's respiratory rate, effort, and pattern. One of the main reasons a patient may be presented to us as an emergency associated with the respiratory system is for dyspnea.

Now we all know that dyspnea means an increased breathing rates and efforts. And this can either be due to upper respiratory or lower respiratory tract disease. And by simply observing the patient, we can get an idea of what is the underlying cause of the dyspnea.

Additionally, if we can look at the patient's breathing pattern, if we think that this is associated with lung disease, again, depending upon the patient's breathing pattern, we can get an idea of what might be causing it. So, for example, patients who have an effortful exploration. Likely to have an obstructive disease with the best example being asthma, whereas patients who have an increased ventilation and rapid shallow inspirations have what's known as a restrictive pattern, and that can occur with pulmonary edoema or plural space disease.

So as an example, here we can see this cat with rapid, shallow breathing, who is quite obviously dysneic, and this is due to plural space disease because they have a diaphragmatic rupture. So from simply observing the patient from a distance, we can actually get quite a lot of information. Obviously, if we have a disic patient, we need to first and foremost make sure that we avoid stressing these patients.

Because if we stress them, we're going to increase demand for oxygen when they're already struggling. We need to provide oxygen and this can be done through a number of different ways, with the, the key thing being that we are, we don't cause stress to the patient. And in some of these patients as well, it can be useful to consider giving them a light sedation because being dysic is actually quite scary, and these patients get quite anxious, which again is going to increase their stress levels.

Increase their respiratory drive when they're already struggling. If we can sedate them slightly, for example, using something such as a low dose of phenol that can remove the anxiety for the patient and can actually vastly improve their breathing. In terms of how we assess the respiratory system, we can obviously perform a thoracic auscultation, which can provide us with a huge amount of information.

We can use pulse oximetry. We can use capnography, and a lot of people think capnography is just when for when the patient is anaesthetized. But if we have a patient, who, for example, has a face mask, a tight fitting face mask on, and we have side stream capnography, we can use, A an intravenous catheter with the stylelet removed, attached to the end of the side stream catnography, put inside the the face mask, and we can actually get a pretty good trace from that.

So we can use catography in a relatively noninvasive way, to gain an idea of the patient's ventilation. And then finally, we, we can also think about using arterial blood gases to assess the patient's respiratory system. But as we've already mentioned, using arterial blood gases or, or blood samples of any type, doesn't necessarily provide us with continuous information and performing repeated blood samples may not be practical.

I'm gonna very briefly mention brachycephalic breeds because, these are patients which, are likely to be presented to us, as an emergency case, for respiratory disease. And brachycephalics have, a number of different conditions which, could cause us problems. Now, I'm not gonna spend too long on them because I could probably talk for a whole hour about management of brachycephalic patients, under anaesthesia.

But it is important to be aware that, obviously alongside their respiratory tract disease, they can have, gastrointestinal disease which can predispose them to regurgitation and aspiration, and also ocular problems as well. Because of all of their airway problems, these patients are at high risk, and these, their airway problems are often worsened by stress, or anaesthesia. So it's really important that we take care of our brachycephalic patients, whenever they're presented to us for anaesthesia, whether they're healthy or sick.

But our sick brachycephalics, just have that additional, risk, associated with them. Briefly looking at the patient's neurological status, now I'm in when I'm talking about a patient's neurological status in terms of, particularly in terms of the the critical patients. I'm talking about assessment of the patient's mentation.

I'm not a neurologist. I would probably struggle to do a full neurological examination on a patient. That is often is not required in most emergency cases.

What we need to know is what the patient's mentation is. And there are multiple different causes of, patients having altered mentation. That could be primary neurological disease.

It could be that they have electrolyte imbalances, maybe they're septic, painful alterations in, in body temperature, or just generally some form of systemic disease. It's not always as obvious as, the case in this picture, where this dog was unfortunately kicked in the head by a horse. .

But in terms of assessment of mentation, we're basically simply looking at whether the patient is alert, whether they're, depressed, or they're, in a coma or stuporous. And this is pretty much, the level of my neurological assessment on patients. And it is important that we do this for every patient.

Coma scales can be used as an objective form of measurement, and if we have a patient who has specific neurological problems, or they do have an altered mental status, then use of objective coma scales can be really can be really useful, particularly for monitoring a patient over time. The most commonly used coma scale is the, Glasgow Coma Scale. And I would recommend this, and using these, for patients who do have an altered mental status.

In terms of diagnostic tests, most emergency patients will require some form of an emergency database. We, we use our emergency database and our laboratory tests to detect any derangements in our patients and also to, to some extent to allow ongoing monitoring. However, it's important that we appreciate that we have to be able to justify which tests we're using.

And a monitored variable is only useful if the alteration that we detect is linked to an interventional therapy that will affect the outcome. It's really important that we don't just start doing tests for the sake of doing tests. We have to be able to justify why we're doing them.

In terms of what sort of tests might be needed for an emergency database, this can include performing PCV or and total proteins, looking at patients' electrolytes, glucose, lactate, potentially looking at, urea and creatinine. Potentially looking at blood gases, or blood smear evaluations. And depending upon the patients and what they're presenting with, depends upon what tests we will need for that patient.

I don't have time, tonight to go through all of these tests in detail. But in the accompanying notes, there are details, about when we would be using these tests. So patient stabilisation is probably one of the most important aspects to anaesthetic management of our critical patients.

It's important that we prepare our patients as best we can for the anaesthesia and the procedure. However, if a patient has a condition, where surgical intervention can be life-saving, the anaesthesia shouldn't be delayed, . Because no matter how much stabilisation we're going to be able to do, that is not going to cure or treat the patients.

What we need to be doing is providing ongoing stabilisation, as we're preparing stuff for the procedure. And then when we get the patient in what we think is going to be the best possible state that we can get them in, performing anaesthesia and surgery at that point, because that is what is going to cure them. It may be that we have to perform ongoing stabilisation during the procedure itself.

The first aspect of patient stabilisation is analgesia, and I've already said that analgesia administration is a priority. Generally speaking, for most of our critical patients, a drug from the opioids class is, is usually quite appropriate. It's good for moderate to severe pain, and these drugs have a favourable safety profile.

However, where possible, we should try and consider using multimodal analgesia. And we can see from this diagram that there are a huge number of different drug classes that we can use. However, we do need to remember that some drug classes may not be suitable for compromised patients.

Probably the best example being non-steroidals, where we shouldn't use them until a patient has a stable cardiovascular system. Fluid therapy is another aspect which is really important for patients stabilisation, and compromised patients will often require some form of fluid therapy. And this is usually to treat either hypovolemia or dehydration.

In terms of what sort of fluid we can use, if we have a patient who's presenting with hypovolemia, which is probably one of the more common presentations where fluid therapy will be needed, we can consider using isotonic crystalloids, hypertonic crystalloids, or, or, More controversially, colloids. Usually we will use, be using isotonic crystalloids and we're usually recommending a rapid bolus of between 10 and 20 mL per kilogramme, over, for example, 10 to 15 minutes. .

And reassessing the patient. Gone are the days when we would use what we would call shock doses of isotonic crystalloids, which was, often quoted to be 90 mL per kilogramme and for dogs and 60 mL per kilogramme, for cats, which, these numbers came about because that is the volume of the circulating blood volume. We don't do that anymore.

What we tend to do is give incremental doses. So we tend to give a fluid bolus to the patient, assess for their cardiovascular response, and repeat the flu bolus if it's required. In some cases, we may need to assess a patient's oxygen carrying capacity.

So that is whether they're going to need blood products. Now again, this is another topic which I could talk for a whole hour just on blood products. So, this is the only slide really that I have on blood products.

And it's just to kind of prompt you into thinking that some patients may need oxygen carrying carrying support. In terms of when we need to think about giving blood products, to some extent, it depends upon the patient. In an acute setting, we often use what's known as transfusion triggers, which can either be, having a PCV, of less than around 20%, tachycardia unresponsive to fluids, resuscitation, or indications of anaerobic metabolism.

But if you have a patient who has a chronic anaemia, say, then these transfusion triggers may be slightly different. Some critical patients will present to us having arrhythmias, and it may be that we have to think about managing these arrhythmias. However, what I would say is that while arrhythmias are common in our emergency patients, not all of the arrhythmias are pathological.

And actually, we should only really be thinking about treating arrhythmias, if they're causing hemodynamic effects. And usually what we mean by this is whether the arrhythmias are affecting the patient's blood pressure. So if the patient is hypotensive and has an arrhythmia, I'm much more likely to treat that arrhythmia than if they have an arrhythmia but are normal intensive.

And how we treat the arrhythmia depends upon what arrhythmia they have. We need to be thinking about temperature management of our patients. Most, critical patients will be suffering, if anything, from hypothermia, due to immobility or poor circulation and metabolism, and we might need to be thinking about passive or active warming in these cases.

But we also need to remember that hypothermia can occur. This may be due to opioid-induced hypothermia, particularly in cats, often doesn't require much treatment. .

Or down the line to large breed dogs with thick coats, brachycephalic patients or patients who have suffered from seizures. These patients may end up being severely hypothermic, and this really does need treating with some urgency. We've already talked a little bit about blood pressure management, and thinking about the causes of the alterations in blood pressure, and therefore hopefully trying to, direct our blood pressure management, towards what we think the underlying causes, whether that is providing, on restoring circulating blood volume, providing vasopressor if necessary, and treating arrhythmias.

Generally speaking, a lot of our emergency and critical patients may require some form of oxygen therapy, particularly if there's respiratory or cardiovascular compromise present, and oxygen therapy can obviously be life saving. However, just remember that if a patient is needing longer term oxygen therapy, particularly at high concentrations of oxygen, we need to kind of be thinking about why this is the case and trying to do something about it because, such longer term, high concentration oxygen therapy is not recommended because of the risk of re reactive oxygen species formation, and ultimately oxygen toxicity. So once we've considered what's going on in our patients, thinking about stabilising them, it comes to anaesthetizing them.

We need to think about creating a problem list for the patient's anaesthesia, procedure and ongoing management. Because if we can anticipate problems, we can adequately prepare for them, rapidly identify them and hopefully treat them successfully. Being prepared is, is absolutely vital, particularly for our critical patients who can rapidly deteriorate.

And a lot of people think that, knowledge and experience are the most important things to dealing with the crisis, but actually, what's probably more important is being prepared, because we can then react a whole lot quicker. Obviously, we want to avoid adverse events and nemesis, but it's not always possible. But as I say, if we can prepare and anticipate these potential problems, then we're gonna be able to deal with them a whole lot easier.

And this is where the idea of using checklists come in, because if we can develop routines to perfect our preparation for each patient, then we're going to hopefully minimise the problems. Checklists have been shown both in human and veterinary medicine that they, they will they do reduce perioperative complications. And in human medicine, in both, elective and critical cases, checklists have been shown to reduce morbidity and mortality by around about 40%, with similar benefits also being shown in the veterinary field.

And there are checklists available free of charge online from the Association of Veterinary anaesthetists. So it's worth worthwhile looking and thinking if it's something you can instigate in practise. We can also have specific crises checklists.

So these are checklists for emergency situations. And again, they've been shown to reduce error rates. The best known example in veterinary medicine, are those included in the recover guidelines for CPR.

When it comes to our anaesthetic protocol for our critical and emergency patients, as I've said, a focus on what is the best protocol is often misplaced. And hopefully, as I've highlighted already, patient assessment, management, and stabilisation is much, much more important. However, I am gonna give you a couple of general principles.

Firstly, as I've said multiple times, we need to use agents and methods that are routine and predictable, and we know what we're doing with them. Most of our patients will benefit from premedication. That premedication may only be an opioid analgesic agent, but that is still premedication.

I personally am careful with the use of benzodiazepines. A lot of techs will say benzodiazepines are good for critical patients because of their cardiovascular safety profile. But be aware that benzodiazepines can cause disinhibition and can cause excitement in a patient.

They have to be pretty sick for them to not cause, excitement, which could make a situation much worse. So just be careful when using them. I've already said that modest sedation can be very beneficial for patients with respiratory compromise.

Whenever we're giving drugs, we should be conservative with both their dose and frequency because it's easy to give more if we need to, but it's very hard to take drugs away. Administration by the intravenous route is preferable where possible. When it comes to induction of anaesthesia, pre-oxygenation can be very useful, providing it doesn't cause patient stress.

Anaesthetic induction with inhalation agents is not recommended because that has been shown to increase morbidity in patients. However, for maintenance of anaesthesia, inhalation agents are useful because generally speaking, we're used to using them, we know what to expect. When we have our patients anaesthetized, patient monitoring is really important.

If we use anaesthetic records, we can easily spot trends, so we can see if something is starting to deteriorate sooner. And also the anaesthetic records provide legal documentation. Again, we have resources available free of charge from the AVA online.

So if you don't use anaesthetic records, it's worthwhile having a look at them. In terms of patient monitoring, we need to make sure we're covering, assessment of central nervous system, cardiovascular system, the respiratory system, patient's temperature, and other things which may be relevant, for individual patients, for example, glucose monitoring. When it comes to anaesthetic recovery, it's really important not to forget that our job has not yet finished.

The majority of anaesthetic deaths, whether that be for healthy patients or sick patients, tend to occur in anaesthetic recovery. It's a period which is often neglected, and it's really important that we have appropriate observation of our patients during this time. Things that we need to monitor in recovery include the patient's consciousness and reflexes, ensuring that the patient is not left alone until they are alert and able to lift their head.

We need to monitor a patient's body temperature. I've put a relatively conservative, 30. 6 degrees here.

But really most of the time, we're monitoring patients until they're over 37 degrees, and or even 37.5 degrees and making sure that we're providing some form of warming technique to allow them to achieve this temperature. The patient has to be able to maintain their own airway and have their endotracheal tube removed.

Their circulation has to be, stable, and I've put to having a heart rate and blood pressure close to pre-anesthetic levels, but that is obviously close to pre-anesthetic levels once they're stabilised. And we need to make sure that the patient has appropriate postoperative analgesia, have provided that and have a plan for it moving forwards. There are multiple problems which can occur during the anaesthetic recovery period.

Some of the most main examples include upper respiratory tract obstruction, hypoxemia, having an inappropriate temperature, having either a rough or a delayed recovery, or postoperative bleeding, and these are all things, which are much more likely to occur in our emergency or critical patients. And so we need to be aware of them and monitoring for them, because we're not going to detect them unless we're monitoring for them. So to conclude, critical patients obviously, are commonly require anaesthetic management, but they do have, this increased risk that we've talked about.

. I've hopefully highlighted to you on multiple occasions now that specific anaesthetic protocols are much, much less important than taking a holistic management approach, which is why probably 2/3 of this talk has been on assessment of our patients and stabilisation of our patients rather than just looking at specifically the anaesthetic management. And what is really important for our patients, for any patients, let alone our critical patients, is having an appropriate preparation for them with patients assessments and stabilisation. So if anybody's got any questions, I will be happy to take them.

Otherwise, hopefully, this is managed to give you an oversight of, the sorts of things to be thinking about when it comes to dealing with, emergency patients who require anaesthesia. Thank you very much, Becky, absolutely brilliant webinar packed full of lots of useful hints and tips. So if anybody does have any questions, just hover over your toolbar, click the Q&A box and send them through and I can read out to Becky if you do have any.

So it was interesting to hear that we often think that knowledge and experience is the safest thing if anything goes wrong, but actually it's just being prepared. Yeah, I mean, obviously we do have to have an understanding of what we need to do, but if it's no good having that knowledge if we don't have the things to hand what with With what we need in order to treat the problem, we can save vital minutes by having everything there. So for example, brachycephalic patients having, an array of endotracheal tubes, can save, can save minutes if it comes to when we induce anaesthesia and, we find that the tubes we've got are too big, for example, and that can make the difference between a respiratory tract obstruction and not.

So, just simple thinking ahead can make a massive difference. Yeah, it does make sense. I know some practises for brachycephalics, especially in recovery, and they go back to the kennel, they often have an airway kit just like a sealed box with laryngoscope and the ordinary.

Cafeter and things in case there is difficult airway. Definitely and I think that's a brilliant idea because it's then right there to hand that you can can have the equipment that you need should a problem arise. Yeah, definitely.

So on that note, I will say thank you to everybody for logging in and joining us tonight and thank you so much, Becky for a brilliant webinar.