Thanks for the introduction, Stacey, and good evening everyone. So this evening we're gonna look at catography as one of our monitoring modalities, and I'm going to go through understanding the benefits of catanography to you. So as an overview, we're going to start and look at identifying and describing some normal catagrams.
We will gaze through. Few bits of troubleshooting using your capnograph. I'll explain some waveforms that we see associated with specific problems and I'm sure you'll probably have some recollections of cases that you've managed, and certain traces that you may need a little bit of help with.
I'll explain to you some of the case examples how Calography integrates with other monitoring modalities. And I hope by the end of it that you'll be able to leave this webinar able to demonstrate the benefits of Caography to your colleagues in practise. So this is the.
Question that we're gonna start off with, which one of these describes you? Are you totally new to this. Have you got a cameo graph, but you never use it?
Do your colleagues use it and you're not quite sure what's going on, you could do with a bit of help. Are you happy with using Canography day to day, or are you totally proficient? So let's see who's out there.
OK, Matt, I've launched that whole question for you, and people are busy, busy voting away, so I'll just give people another 10 seconds or so. OK, and, and that poor question. So, we have 38% saying that they are totally new to this.
19% say they've got one, but they never use it. 12% saying colleagues use it, but I need help. 27% saying happy with the day to day, and 4% saying totally proficient.
OK, that's brilliant, we've got something to work on there then. Excellent, so. 19% of you have got a capnograph, but you never use it.
That's one of the most expensive pieces of equipment in your practise, so. The less we use equipment, the more expensive it actually is, so my advice to you. Is use catography, use all of your monitoring equipment on every single case you deal with on a day to day basis.
I hear on a regular basis the argument, well, it takes as long to put the monitoring equipment on as it does for me to do the procedure. I haven't got my the video in this presentation tonight, but I do have a video of one of our nurses, and that demonstrates her ability to put all the monitoring equipment on a dog within 60 seconds of induction of anaesthesia. So, with well-trained colleagues, we can debunk that myth that it takes longer to put the equipment on and it does for us to do the procedure.
That's experience, that's using the monitoring equipment every day, and obviously having the confidence that we know what that equipment is actually telling us. So you just bottom right hand corner here, so those of you that are totally new to this, got one never use it. It's this trace at the bottom here, this is our capnogram trace.
This is a, a fairly normal trace on that machine there. Just on the right hand side you can see that ET figure of 36, so that's our end tidal carbon dioxide concentration. To the right of that, the FI means fractional inspired, so it's a measure of the inspired carbon dioxide, which should be zero.
And just below that we've got RR respirate 11 per minute. So that's the typical information that a knograph will deliver you in practise. You have a waveform, you'll have the actual the CO2 number.
Most will deliver a fractional inspired concentration of CO2 and you'll get a rest rate as well. So which answers are true to this question? Canography tells us about oxygen saturation, ventilation, metabolism, circulation, depth of anaesthesia and cardiac output.
So you can choose multiple answers here. OK, Matt I've launched that whole question for you and we've got some early voters. I just give people a little bit more time with that.
OK, I'll end that poor question. So, oxygen saturation, 23% of people chose that option. 92% said ventilation.
Metabolism, 42%. Circulation, 23%. Depth of anaesthesia, 15%, and the last option in cardiac output, that was 27%.
OK, so you may be surprised to learn the answer to this question. Actually, all of those are correct apart from one, which is oxygen saturation. So when we're looking at carbon at entitled CO2 and Cainography, we're purely looking at carbon dioxide.
And carbon dioxide has nothing to do with the way, well, nothing to do with the saturation of haemoglobin with oxygen, so there isn't any oxygen measurements going on with Caography. And I think by the end of this webinar you appreciate. The role of capnography in telling us about ventilation, metabolism, circulation, how we use catography to assess our depth of anaesthesia, and the information that catography can provide us about the adequacy of our cardiac output.
So we've got some good cases to illustrate all of that. Just a bit of terminology, you've already heard me say Caography and capnogram. So capnography is the measurement of carbon dioxide in respired gases, and when we say respired gases, we mean inspired and expired.
And I've already used the term end tidal, so end tidal means end of expiration. And we all already talked about fractional inspired, so when we breathe carbon dioxide in. Carbon dioxide concentrations in room air or in an anaesthetic breathing system should be close to zero.
So you shouldn't be breathing in carbon dioxide. And you can see in the monitor screen on the right hand side here our fractional inspired carbon dioxide is 0 millimetres of mercury, but our expired is 36 millimetres of mercury. It's a continuous measurement, so of all of these parameters we measure, yes, our ECG is a continuous parameter.
If we have invasive blood pressure as we have on this monitor here, that red trace there, that is a continuous measure. If we take non-invasive blood pressure measurements, so our oscillometric measurement in the bottom left-hand corner here, you can see there's values for systolic diastolic mean, but that little counter there tells me that this is running every 3 minutes, so that's not a continuous monitor. Our carbon dioxide is a real time, .
Breath to breath monitor. Capnogram, that is terminology for the actual graphical wave form. So Caography is the measurement.
And the catnogram is the actual graphical waveform. You might see the term capometry or capometer, and capometry is the display of entitled CO2 values without an associated wave form. So you may well have a capometer in your practise that tells you what the entitled CO2 value is.
I think what you will appreciate from this webinar tonight is there's a lot that we can gain from assessment of the actual waveform, rather than just looking at an entitled number. But I hope this webinar if you, if you do have a a capometer, I hope this webinar gives you the confidence to understand what that cappanometer tells you without the associated countgraph. If you are sitting here again, never use this, need to go and buy one, then I would strongly suggest that you, you buy a camera graph that has a a wave form.
Just on that note, if we're looking at spending our, our, our precious capex budget on equipment, the camera graph is the bit that pushes up the cost of the monitor. It's the, the technology in that analyzer is the expensive bit, but I would, really encourage you not to skimp on that and to always add capography into your monitoring purchase. It's probably one of the most valuable peak modalities of monitoring that we have.
There's some good work from the SEPSA study, which was conducted in the late 90s and reported in the early 2000s, looking at. Monitoring modalities that reduce risk associated with anaesthesia in dogs and cats. And one of the things that came out of SEPSAF was the pulse oximetry and pulse monitoring have been demonstrated to reduce mortality.
Now I think if that work was repeated again, we would be able to document convincingly that catography also helps reduce mortality in small animals. That's just my opinion, that's not been proven in the literature yet. So what's it telling us?
It is telling us about metabolism, circulation and ventilation. So all of the cells in the body produce carbon dioxide, and that's what we're measuring. Once it's been transported to the lungs in the circulation, and once it's been ventilated from the blood across the blood gas barrier into the alveoli and into the airways.
So right from the production of CO2 through meta metabolism, right through its excretion out of the body. So, capnography tells us about those three things, metabolism, circulation, ventilation. And when we're trying to analyse whether we have any abnormalities on our catnograph, these are the three things that I have right at the front of my brain when I'm thinking about this.
What's going on with the metabolism? Is my circulation what it should be, and what's going on with my ventilation? Normal values of entitled CO2, and these are fairly consistent across species, 35 to 45 millimetres of mercury.
You may read in cats that the normal values forentidal may be a little bit lower, maybe sort of 30, 32, up to 40 maybe. But just the ease of, of memory, I have 35 to 45 in my head. If our entitled CO2 is more than 45 millimetres mercury, that's hypoventilation.
So our patient is not removing as much CO2 from their lungs as they should do. If the CO2 is less than 35 millimetres of mercury, we talk about hyperventilation. So the patient is blowing off more CO2 than they would normally do.
Knowledge of the normal catnogram can get you out of a lot of difficult situations when you're looking at a catnogram going, I, I just don't know what's going on here. So one of the things I would do is just encourage you to print out a copy, either copy. This, I'm quite happy for you to print a screenshots of this diagram here, probably the one on the next slide because I've actually made it bigger for you.
We're just looking in any textbook and get a reference of the normal phases of the cameragram. It's really important that we differentiate what's inspiration versus expiration, and the whole concept of this is that expired gases contain CO2. Inspired gases should contain no CO2 at all.
So slightly bigger version than that. This is a pretty normal shaped cameragram there with 4 phases, phase 123 and 4, we have those divided into expiration and inspiration. So that's the start of expiration.
When we first breathe out, the gases coming out of our airway are the first gases coming out from the conducting airways. So from the trachea and the main stem bronchi where they haven't undergone any gaseous exchange, so CO2 concentrations are quite low. During the process of expiration, we start getting some of the gases coming from deeper within the lungs from tissues that have undergone gaseous exchange.
Obviously they're coming up to the main conducting airways and then out to where we're measuring and they're increasing the concentration of CO2. What we then see is between phase 2 and 3, just 6 arrows on here. So from phase 2 where that arrow is, is there, we see an increase in the concentration of CO2 right up to the end of expiration.
And this point, this peak here is where we measure our end tidal CO2. So it's the end of expiration, where we have the highest concentration of CO2. You'll see from the shoulder of that curve up up to 0.3 we have.
What's called the alveola Plateau, and it can be on a diagonal like I've drawn here, or you'll see on a lot of the cattograms that we're going to look at in this webinar, you can see a flat, more of a flat plateau to that. After that point, once we've reached maximum concentration of CO2 being expired, that's when we change from expiration to inspiration, and obviously the sampled concentration of CO2 decreases as we inhale those fresh gases that contain very low levels of CO2. What should then happen is.
Once we are halfway through inspiration, the CO2 levels are falling. And we should then get to a point where we're inspiring fresh gas with no CO2 in it at all. So the trace should always, always go back to baseline.
If your trace is not going back to baseline, then we have a problem with rebreathing, so rebreathing of CO2, and we'll look at the causes of that. So these are these 4 phases of the ketogram, which is fairly simple to remember, that's a fairly normal shape. We'll look at some variations on normal and we'll also look at some abnormal shapes of curves as well.
Some of you, I know will be familiar with Capnography.com. This is an incredibly extensive resource.
It's a, a human, written from a human perspective by a couple of medical anaesthetists. Some people say it's maybe a little bit too much for what they need to understand. So yes, there are some human examples, but there are also some simple examples that are analogous to things we see in the veterinary context as well.
So by all means have a look, don't get too overwhelmed by it, then you can spend, you can spend the whole weekend on the. So let's talk about measurements. I've really talked about where we measure as far as phases go.
There are two different types of measurements, points at which we can measure. Are inspired and expired CO2. We either have side stream, monitors or mainstream monitors.
So in the side stream monitor. You have the machine which contains the analyzer and it has a pump in it. And that pump is aspirating a continuous sample of gas from the patient airway, and you can see here on the left hand side of the screen, it's between the ET tube and the Y piece of the breathing system.
We've got this extra connector here with our gas sampling line. Now this gas sampling line is impervious to gases in the, the, the immediate environment. So it's not going to affect the concentration of, of your sample during that aspiration phase.
So all the analysis in that case takes place in the machine which is remote from the patient. The other alternative on the right here is a mainstream option whereby you have the, the analytical chamber actually within the breathing system. So you'll see on the right hand side we've got the ET tube on the left hand side we've got the work of the connector, you're actually increasing the dead space in that patient's airway fairly significantly.
So actually in our small venue patients that can make a real difference. Just on the top left here, this is the type of connector that we would commonly use for connecting between the patient and the breathing system, or you can use a heat and moisture exchange or an HME with the Capnograph port here shown in the centre of the screen. It's quite important to note I've been to quite a few practises and they just seem to reuse the same HME for sampling, it's probably not such a great idea because they do get saturated, and you're more likely to aspirate more water into your tube.
Just here, the, the next picture along, you can see we've got two different types of connector on our smaller ET tubes. So this is a low dead space connector, which means that you don't have to then add another additional piece of kit in as far as sampling goes. So if you've got cats and small dogs, these low dead space connectors for your side stream monitor are a really, really good option.
And just on the right hand side of the screen here we can see the other, the machine end of the that component. And you can see this chamber here, this is called the called a water trap. And it's really important not only from a machine longevity point of view, the water doesn't get into the machine because it damages the machine, but actually water vapour itself interferes with the infra infrared analysis within that monitor.
So actually the brains of the monitor inside, you have 22 chambers, there's a sampling chamber and a reference chamber, and there's in infrared light transmitted across those two chambers, and you have a comparison of the sampling chamber versus the reference chamber and the photo detector picks up the difference between those two. As I say, that can be influenced by water vapour, which is the whole role of the water trap to take the water to vapour out of there. And it can also be influenced by nitrous oxide, and if you are doing any large animal work, it could also be influenced by a methane produced by cattle, although not to a huge, huge degree.
I can't think of doing cattle work, having my CO2, I'm hugely influenced by methane production, but methane production doesn't really happen in dogs and cats, so it's not something that we have to really be concerned about. A mainstream stream option. We have the little analyzer with the infrared light as you within in the breathing system.
And bottom right here you can see those components whereby the, the beamer of light is transmitted across this special adapter. These are, and this particular machine, from Masson, these are really, really lovely, it's a lovely piece of equipment. Unfortunately, with lovely pieces of equipment, people tend to drop them.
You can see it's a very expensive analyzer on the end of a long wire. And what happens when we move the patient from an anaesthetic machine, you could just drop the breathing system on the floor. Now, these little guys don't take much to damage them, so.
I think for me in veterinary practise, I would actually prefer the side stream option. It's very rare that those side stream tubes get damaged, but they cost probably 50% to replace, whereas this is a 2000 pounds piece of kit, so. I would be quite cautious about spending your, your hard earned capex budget on a mainstream option versus a side stream.
So all of our components in Northwest are side stream because I've seen too many, damage, trapped in cupboard doors, run over by trolleys, it's a little bit heartbreaking, so. Few rules with capnography. Just remember that the Kanograph never lies, but.
You have to ensure that it's serviced and calibrated, and you can buy calibration gases, so your machine will have a calibration mode that you set it to. Or you just have your machine serviced once a year and that will include calibrating the counter graph. So obviously with measurement, we need to rely on the numbers that we're actually measuring.
If you have a side stream option, if the line's been trapped in a cupboard door or a drawer under the anaesthetic machine, then it will interrupt the sampling of that gas from the airway and you'll get an unreliable reading, so just make sure your lines aren't trapped. Just when you need them, some of these monitors have a habit of going into a zero mode, which is a real pain when you really, really want your camera graph. They take a while to warm up as well, so when you turn a multi-parameter monitor on, it's the camera graph that takes longest to warm up.
So if you're going to use it for induction of anaesthesia, and I'll talk you through the advantages of doing that, make sure it's on or warmed up, and the warm up message has gone, or you, you know how long it takes to warm your monitor up. There's one machine, one type of machine that we've got that for some random reason just flicks from measure mode back into standby mode, which again can be quite irritating. So just watch for the quirks of your anaesthetic machine, your anaesthetic monitor, sorry.
We need to make sure that there are no leaks in our system if we're going to rely on what our camera graph tells us. And so that's right from the cuff of the ET tube to the ET tube itself, all of the connectors and the breathing system and the sampling line as well. So just make sure there aren't any leaks.
For those of you that maybe don't use cuff DT tubes in cats, we're going to get a lower end idle CO2. Because of the leak around the cough, and a lot of the time I don't cough E tubes and cats, and I just accept that my entitled CO2 for my cat is going to be lower, but I know exactly why it's lower. And also check that your catnograph hasn't come disconnected.
So I said before that this is a continuous monitor and you have that lovely trace that's displayed on the bottom right hand side of the screen. If your patient is under the drapes and the camera graph in the ET tube, the camera graph and the breathing system become disconnected from the ET tube, your trace is gonna go to zero, and it's gonna alert you to the fact that the patient's been disconnected. Perfect for dental work when we're moving patients around.
However, I've been in a situation before where the ET tube's fine. The camera graphs still attached to the ET tube, but the breathing system has come disconnected from the camera graph. And you're looking at the monitor going, well, the patient's connected, so why are they waking up?
Why can I smell is so? It's because your breathing system's kind of disconnected from everything else. So, just one of those who've been there and done that, so I'm just warning you, to make sure that your connections are always tight.
It's fine when it's a dog, it's not so much fun when it's a horse. Other things to check for, check about moisture in your lines, so obviously our exhale gases from our patients are warmed and humidified and we do have a habit that they have a habit of of the moisture condensing in the line. I would suggest you have a couple of sampleling lines cos you'll find that they fill with moisture and then you just need to hang up and dry them out and then switch to the other one.
One of the things that I do do, those side stream ET tube connectors that I showed you before, you can hook the ET tube connector and the sampling line up to the common gas outlet on the anaesthetic machine and then use the oxygen flush to flush all the moisture out of that oxygen line. It works. We need to ensure that our water trap is actually connected.
This is a little quirk of the mind drain monitor that we, we've got a few of these at Northwest, and this is really temperamental, it just pops off quite easily, so you just need to be careful that your water trap is connected and it's dry as well, because that will interfere with the sampling of the gas going into the machine. So at night, I would recommend you just disconnect your water tract from your machine and just open them out just to dry them overnight and then they're fine to use again in the morning. Well it's a caution.
When do I get really worried? If I see a sudden loss of trace on my camera graph, that is not good. Remember we said 3 things to think about when we have a problem with the cameo graph, metabolism, circulation, ventilation.
If we have a sudden loss of trace and it's not because the camera graph is zeroing, you can see in this bottom right hand corner, we've still got a little bit of CO2 but we've only got 11. There's no. Zeroing message going on anywhere on that monitor, so that's when we need to get worried, a sudden loss of trace.
Has our patient become disconnected? We're gonna check that. We're gonna check whether or not we can actually feel the pulse, and we're gonna close the valve, squeeze the bag and give the dog or the cat a breath and see what happens.
Because sudden loss of trace is is an impending sign of doom. If we've got no trace at all, that generally means that we've become disconnected at some point along that that connection between anaesthetic machine and the patient. A progressive decrease in CO2.
I think by the time you see this happening, you generally know something serious is going wrong with that case. So it's gone from, OK, I've got a sick patient I'm dealing with to, oh actually this patient is deteriorating in front of my eyes, we're going bradycardia, there's no trace on the pulse oximeter. You can see on the right hand side of the screen here, we have complexes on the ECG.
But we don't really have P waves going on there and the QRS that that ST segment is a little bit slurred and we don't have any decent camenogram going on there with an entitled CO2 of 11. So this, this was actually taken from a patient that was in the process of crashing. So that is a typical sign that you would see in a patient under anaesthesia connected to camera that is crashing in front of your eyes.
And persistently high CO2 is obviously we should be concerned about persistently high CO2 is an indication for for ventilation. Hypo and hyperventilation, we already said that hypoventilation means we're not eliminating enough CO2 from our lungs. Most common causes in day to day clinical practise are drugs we use and depth of anaesthesia.
So we would quite commonly see hypoventilation with a pre-med of methadone and medoomidine in dogs. So the deeper our patients are, all of the drugs that we use trend towards hypoventilation, and we should always expect hypoventilation under anaesthesia. We're reducing the ability.
Of our dogs to maintain a decent minute ventilation, so we're reducing the volume, we're reducing respiratory rate with all the drugs that we use, so we're gonna see some hypoventilation. And in those cases where they have muscular disease, where they have an inability to actually ventilate neuromuscular disease, this would be good examples of hypoventilation. Hyperventilation, CO2 of less than 35 millimetres mercury, generally associated with an increased respiratory rate.
Common causes of increased respiratory rate, pain, pyrexia, hypoxia. And we said before, didn't we, that the other reason we could see a low entitled CO2. So perhaps let's pretend that you're using a kinometer and you don't have a trace to, to look at.
Obviously we're gonna look at the patients and we're gonna look at how they're breathing, how rapidly they're breathing, that's probably gonna give you the answer. And therefore you, that's going to help you decide whether this is hyperventilation causing my low entitled CO2 or whether I actually have a leak in my system. So again, like all monitoring, whenever we talk about monitoring, one of the things we always say is any abnormalities go straight back to the patient, check that they're still breathing, you can feel the pulse, assess their depth of anaesthesia.
So I always go back to basics whenever I have a question like that. I guess something that's useful to address at this point is looking at these two. Situations What are we gonna get worried about?
Entitled CO2 in this situation, you can see on the left hand picture, it's the bottom blue trace that we're looking at, our camera graph there it's very very square wave. Entitled CO2, there's 51. It's reporting an inspired CO2 of about 2 millimetres of mercury.
You can just about see that that trace isn't always going back to baseline, but it does actually touch baseline, at that point. So I'm not too worried about the inspired there. The end title 51, I wouldn't get too excited about that.
We said normal 35 to 45. For an anaesthetic, say, 1 hour duration, 1.5 hours duration, a patient can cope with an entitled CO2 of 51.
What I would do in this patient is just give them a breath every every now and again, close the valve, squeeze the bag. But I will have already checked their depth of anaesthesia because we said that is probably the most profound influencer. Let's just see, does this patient really need to be on this inspired concentration of isofluorine or C fluorine.
So entitled CO2 can help you assess the patient's depth. It's often one of the first things that you see that you go, oh, actually that CO2 is quite high, let me check my patient depth before I do anything else. On the right hand side here, if this.
Patient doesn't have a leak in its system, we're just gonna check that we're gonna close the valve, squeeze the bag, just see if we can hear any gas escaping at any point along that that system. If they don't have any leak detected, we're going to think about depth of anaesthesia because that's another reason why patients can have a very rapid respirator inappropriate depth. Have they just experienced a painful episode in that procedure?
Think about checking temperature, and are they likely to be hypoxic. If they're under anaesthesia and they're on 100% oxygen, they're pretty unlikely to be hypoxic unless there's an underlying reason going on there. We mentioned rebreathing before, how.
In that phase transition from phase 4 to phase 1, we want to see our baseline go back down to 0 because effectively when we inspire, we shouldn't be breathing in any CO2 at all. We see rebreathing when we have exhausted soda lime. And I know I've got a, I've got a picture of this cycle flow.
Circle system at the bottom of the screen here. It's very rare that you see rebreathing, that side line's gonna be pretty exhausted. Those of you that use the hamster wheel circle systems, you're much more prone to seeing rebreathing with those cos they are prone to channelling whereby you don't get efficient, transport of that exhale gas through the soda line, and it's just the, the gas floats along the top.
So you may well see rebreathing with more often with the hamster wheels rather than the cycle float systems. Faulty circle valves, obviously those valves in that circle system are there to promote unidirectional flow. If the valves are either stuck or missing, then you don't get unidirectional flow, so you don't get proper removal of CO2 from the gases that are then going to be inhaled again.
So just check your valves. If you are using a non rebreathing system, so something like alacrity piece, if your fresh gas flow is inadequate, then you're going to see rebreathing. So the whole point of the fresh gas though.
Yes, we use oxygen in the UK. We deliver 100% oxygen to our patients. The litres per minute, we use X number of litres per minute based on the breathing system we're using, simply to flush out, to carry our volatile agent into the patient and then to flush the CO2 out of the breathing system.
So if your fresh gas flow is inadequate, it's not going to remove that exhaled CO2 out of the breathing system to the scavenge. And we can use catography to perfect our fresh gas flow as I'll show you in one of these case examples. So, if you're trying to convince someone, right, I want to spend 4000 pounds on a multi-parameter monitor, and I'm gonna show you how we can save money in doing it, one of your targets has got to be addressing fresh gas flows.
So getting your oxygen, fresh gas flow that you use right down to the minimal amount that we need. Yes, you're gonna save money on oxygen. But you're also going to keep your patients a lot warmer as well.
So this isn't low flow anaesthesia, this is appropriate flow anaesthesia. Low flow refers to closing the valve when you're using a rebreathing system like a circle, closing the valve. Matching your ins with your outs as far as oxygen goes.
This is just sensible flow anaesthesia. Our valve remains open, but we are just using only as much oxygen as we need to eliminate CO2 from the breathing system. Sounds like a good New Year's resolution, doesn't it?
Let's get our flows as low as possible, keep our patients warm. Save are actually the way to do it is calculate how much time it saves on nursing resource in recovery, warming those patients up again, because your staff costs you one of your biggest, well your biggest cost in practise. So we've talked about measurements and we've talked about certain troubleshooting problems.
Let's look at the normal variants because I want you to be able to look at these and go, well, actually, yeah, that's normal, and I'm quite happy about that. Also you need to be able to say to your colleague that's normal and this is why it's normal, this is what it is. Cardiogenic oscillations, and there are examples on each of these three pictures are entirely normal.
You will see that that's pretty different from that normal cameragram trace that I put up. You can see there's a baseline. You can see there's exhalation.
You can't see that alveola plateau, can you? So we're not hitting that really nice alveola plateau. Apart from the bottom screen there, we might just be getting there and then we've got something going on.
What's happening here, the, the kind of. I don't know, I don't think traditional classic are actually the right words. The previous explanation that people gave were.
That it was the beat of the heart within the chest influencing the exhalation of gases from the lungs. Now there's more work that shows that it's not actually the, yes it is related to pulsar flow. But it's the, the pulsar, a reflection of pulsatar flow through the, the pulmonary tissues.
I guess we can argue academically about what the underlying mechanism is. What I want you to take home is this is what a cardiogenic oscillation looks like and this is entirely normal. The important thing to note, and you'll see on all of these pictures, that that entitled CO2 looks fairly normal.
Depending on the sampling rate of your monitor, so how fast that gas is being aspirated through into that size stream monitor, depends on where exactly on that trace your monitor is. So you may well get breath by breath readings. Your camenograph might might produce a value of 37 1 time, then it might say 21, then it'll say 25, then it'll say 38, then it'll say 25.
It's because it's measuring at different time points on this curve. It's measuring a set rates because the gas samples are either 70 or 150 mils per minute. That's a fairly typical sampling rate.
So that's just a time-driven rate. The important thing if you're monitoring the anaesthetic, obviously monitoring, when we're monitoring, we're looking at changes over time. It's important that the change that you're monitoring is consistent every single time, so write down the highest number that the machine spits out at you.
Because you can progressively see your depth increase and then think, oh no, actually, just be lured into a false sense of security with those numbers. So just make sure we know exactly what we're writing down. All of these monitors here on the top left-hand corner, you've got 37, and then to the right it's got AWRR so it's average rest rate that it's calculating, it's telling us it's 23, which to my eyes, that does look like a rest rate at 23.
Bottom here, we've got an ent total of 36 and rest rate at 17. Sometimes with cardiogenic oscillations, the machine will inaccurately count the rest rate, so again, if you've got that, it's important to just look at the patient or look at the rebreathing bag and work out the rest rate manually. This is a typical example of surgical manipulation, either pressure on the abdomen or the thorax, just influencing the, it's making it look like we've we've got a dip and an inspiratory dip in between.
But that's just the surgeon pressing on the abdomen, which, of course, if I put this picture in front of you you may, you may not be able to tell that, but actually when you're in theatre, you know exactly what's going on there. So, and that's just surgical interference with the entitled reading, so nothing to really worry about that. This is something you don't see this very often and when I was planning this webinar, I thought, oh, I don't have a picture of this.
I'm not sure I'll actually see that this week. And then I did see that one of our patients did this on Monday, so I was there quickly with my phone snapping away. So it's not the most beautiful picture and the monitor screen doesn't look very clean, does it?
But, it's all for your benefit. When we We talk about the concept of lung units, OK, we know our anatomy of the lungs, but different lung areas of the lungs empty at different rates. And so you can see in this trace where I've got the arrow, we haven't got that really nice plateau.
We, we've got a plateau, so we think, oh look, OK, we've got to sort of the maximum level of CO2 empty out of our lungs. Oh look, then there's a bit more, we've got that peak. At the end of expiration.
That's just late emptying, which is attributed to the different rates of emptying of lung units. Now, It's most likely to be associated just a normal variation, so if you see that, I wouldn't get too concerned about it. What it may be an indicator of is if your patient's been anaesthetized for a while and they're in they've been in a certain position for quite a while, that's probably where that becomes a bit significant.
You could have a talactosis in one area of the lung. And my advice in this situation would be just to give the dog a manual breath, a dog or the cat, I don't know if they're saying cats, it's more likely dogs that get lepticis. It's just to give the dog a manual breath every now and again just to expand those lungs.
Not a big huge chests. Expanding squeeze, because actually when we give a patient a breath, we shouldn't really see their chest move very much cos actually to move the rib cage, it takes quite a lot of pressure to do that. So we just want to gently expand the lungs inside the thoracic cavity when we do that side breath.
So that's what I would recommend if that happens. Let's move on now to look at some case examples focusing on specifics of airway and circulation because these are two really big areas where your camera graph can prove very useful. Trace on the bottom, OK, we haven't got that.
Alveo, well, we haven't got a, a, a textbook alveola Plateau, but this is a fairly normal looking trace for dogs and cats to see that very commonly. So I wouldn't be worried if you get that monitor out of the cupboard that you've never used tomorrow and you see this on your first case, I go, well, yeah, that's normal, quite happy with that. Huge advantage to kenography is documenting tracheal intubation.
And this is a standard of practise in in the NHS and we've incorporated that as standard practise in North West. So once the patient's been pre-med is, everything's ready, we've done our checklist. Part of the checklist is, is the monitoring equipment turned on and ready to go.
This is fine when we've got normal patients and there will be those of you out there going, well, I never need to use your laryngoscope cos I always get it in the right place and you're probably going, oh, do I really, I don't need to use a camera graph, I get my tube in the right place every time. You do get those situations where they're just a little bit stressful and you think, oh, is my tube in the right place? Well, how am I gonna test that?
If you've got a camera graph, you've got an instant answer. This is the quickest thing that will tell you that your ET tube is in the right place. So that hideous brachycephalic, and I haven't, I should have put the video in of a hideous brachycephalic intubation I did, it took me about 8 minutes to get a tube in this dog.
But capography was my saviour in that circumstance, cos you can use it to guide your way towards the larynx and the airway. You can actually attach it onto the ET tube as you're intubating. So when you get really close, and I'm sure some of you may do this in rabbits as well, when you get really close, you can see just a whiff of CO2 there and you know you're in the right place.
So ET tubing, turning around, looking at the monitor, look, we've got CO2, we're happy. Then we're gonna go and test the patency of our cuff, see if we need to add any air to that cuff to get that airway seal. So on the left, that's immediately after intubation that I took this shot.
On the right here, this is an illustration that shows what happens when the ET tube backs out. So you have a beautiful trace, normal, normal, normal. Your ET tube backs out, there you go, you know you're in trouble.
Hang on, there's something going on with my airway. I need to reassess this. If you then close the valve and squeeze the bag, you're gonna hear.
As gas escapes in the pharynx that ET tube just hanging in the pharynx or dangling somewhere near the larynx. So we need to immediately reintubate that patient. I'm sure you'll all recognise this emergency situation.
We've got a lot of air in this patient's chest. How's our catography going to perform? How's it gonna help us in this circumstance?
I think we naturally think, oh. Air in the chest, let's see what the patient's saturation is. That's gonna really, really help us.
But I would suggest adding catography in alongside that modality to improve our ability to recognise when problems are happening and our ability to document how effective our treatments are. So this is the readings from that dog. You'll see our pulse ox is telling us saturation of 99%.
We've got a lovely signal strength there so we can rely on what our our pulse ox is telling us, rate is 132. So we think, oh look, we're happy. Then we look on the right hand side and we look at our camera and go, look, that's OK, 36, we can convince ourselves that 36 is normal, this dog's doing a fairly good job.
It does look like it's hyperventilating and respirator's giving us 44. So this dog is working really hard to maintain that saturation. So yes, the saturation's normal, but the dog's having to work really, really hard to do that.
What we can do with both of these monitors is use them to document how effective our drainage has been. So once we've drain that chest, OK, there's gonna be some atylactic lung there and it's gonna take a while for that lung to expand normally. But what we should see is that arrest rate slowing down and the trace on our countergram just coming back to more of a normal trace.
I don't normally expect that immediately because these patients, when they're in this situation, there's hypoxic respiratory drive going on, and that's just the brain saying, breathe, breathe, breathe, to maintain, oxygen saturation and flow to those tissues. So it's a nice thing to document with time. If you drain the chest and then you get back to normal, you're back in a state of normal.
One of the things that we'll often say is right, we'll, we'll do a one-off needle drainage once, if this patient refills, then that's when they need a chest drain. You can use your catography in that patients document if anything changes rapidly with that patient. Obviously we're talking about an anaesthetized patient here.
You can also use capnography on a nasal catheter to measure entitled CO2 as well. If you've got a nasal oxygen tube, you can attach the catnographs to that as well. That's reports in the literature.
I mentioned before about using our counter graph to get our fresh gas flow absolutely perfect. And this little case here, this dog was less than 1 kg. So you can see he's got a big bandage on his leg, he's got, a, a, a stifle fracture there.
It's gonna be a fairly long surgery. We're quite concerned that this dogs can get really, really cold. So that's our main driver to using catography to reduce our fresh gas flow.
You might be surprised to see us running 0.5 litre per minute. That's a bit low.
I think probably most veterinary nurses would be quite stressed if I said we just turn your fresh gas flow down to 0.5 litre per minute. And we know we can do that because we've got a cameragraph and this, you've seen this picture before on the cardiogenic oscillation screen, but you can see this trace is going back to baseline every time, so we know that we are delivering enough fresh gas flow to flush the CO2 out of that breathing system.
I talked before about the importance of having a sealed system and no leaks. One of the things that does happen, not uncommonly, is that we might have a decent cuff on our ET tube to start with then. Either the cough is faulty and we didn't inflate it before the anaesthetic can check it, or maybe the pilot balloon gets snapped when we remove the patient, have that happen fairly often.
Or perhaps when we move the patient position, that sealed tube all of a sudden starts leaking because we've changed the position of the patient. So one thing to watch out for, and for me, this is something that I will walk into a room and spot. I, I know this is the same picture I used before.
I did try to reenact this this week for for your benefit, but I couldn't make it happen. If you've had a beautiful trace like this kenogram on the top here, lovely, lovely, lovely, you move the patient, something happens and you get what's on the bottom screen here, you just get a sharp spike instead of your lovely square trace. It's probably because your ET tube has started leaking.
And the first thing I would do, close the valve, squeeze the bag, listen for a leak in that patient. Surprising the number of times you can walk into your room and spot an abnormality based on that. This is my next question, and some of you may have come to BSAPA last year and been to the lecture where I showed this.
This is a relating to a breathing system I was sent. I, on a CPG course I was teaching, as in a nurse come up to me and say, I've been sent this breathing system, it just doesn't work. The patients keep waking up on it.
Can we send it to you to look at? I'm not gonna tell you which one it is on this pitch, but one of these breathing systems is incorrectly assembled. See which one is it?
Which is, oh, I can't see the thing with poles over my screen. What's the question? And which assembly is correct?
Is it the one on the left or is it the one on the right? My, I launched that question maybe a little bit too early in my keenness. And you can drag the poll question window around the screen.
So if anyone else is having that problem, just drag the window out of the way and then you can see the photograph. Apologies. Oh yeah, there's a lot more people voting now that I've said that.
OK, cool. Superficially, these both look the same, and actually I looked at it and I thought, what am I gonna do? Right, I'm just gonna put this next to a normal breathing system.
OK, I'll end that whole question now. And so, oh, it's fairly close actually, which assembly is correct. OK.
So 40% of attendees said left and 60% said right. OK. Right, I'm not gonna tell you the answer yet, so let's look at this video on the next slide.
OK. So, this is me testing two breathing systems to document which one is abnormal. Actually I'm just gonna turn the sound off because you don't need to hear me.
There you can see the end title was 33. This is a mini like breathing system, so we're using a fresh gas layer of 1 litre per minute, which is appropriate. That trace is going back to baseline.
In Spiritually 0, end title's 37. That's on the normal breathing system. We're putting this faulty breathing system on there, switching over, connecting it to our.
Guinea pig of a patient. Looking back, Trying to work out why the report was that. They can't keep dogs asleep on this breathing system.
Can you see instantly that trace isn't going back down to baseline. Going up, up. Inspire's gone to 2.
Inspire's now gone to 6. Still got my fresh gas flow on one as I had before with my breathing system that I know works. So there's something going on in this breathing system preventing the CO2 being flushed out of it.
You can see the entire CO2 is going up as well. It's 37, it's now 46, when Spi is 14, I'm there going that well actually we need to stop this experiment. That is the consequence of that breathing system being incorrectly assembled.
The scary part of that is that's how it was delivered to that practise from their supplier. I'm gonna stop the video there, cos I think you've probably seen enough as to what can happen when we. I know I'm not.
Do I turn the fresh gas flow? Oh yeah, I do turn the fresh gas flow up and see if it makes a difference there. Oh, sorry about that.
So we've gone to 6 litres per minute to see if turning the fresh gas flow up does actually flush anything out of that breathing system, yes it does. So you need to use a really high fresh gas flow to try and get any CO2 out of that breathing system at all. It's not really working for long.
So very faulty. Previously we were running that on 1 litre per minute and now we're having to use 6. Back to this picture here.
If we look at the the system on the right, this is the one that is correctly assembled. So where the blue arrow is here, this is where it fits to our anaesthetic machine. So you've got your fresh gases, your oxygen and your Io or your Cvo.
Kevin's back And then going to the patient along the green. So green is generally the inspiratory limb on most breathing systems, if they're correctly assembled. Then, coming from the patient down the white limb towards the scavenge, and then to the outside world.
Well, not the outside world, to the, yeah, to the scavenger. If we look at the blue system, the sorry, the, the small system on the left, you can see that when these gases come from the anaesthetic machine. They just go straight out of the scavenge.
They don't necessarily go to the patient. Those that do go to the patient end up in the expiratory limb and then in the bag. So those gases that get back to the bag just contain CO2.
So when the patient breathes in, it's breathing equally from both of these limbs. It's taking all these gases laden with CO2 from the bag, so it's that one that's incorrectly assembled. You can actually pull all these components apart and reassemble it correctly, but unless to the experienced eye, the inexperienced eye, that's really difficult to tell.
So actually I think this is quite a dangerous breathing system to buy. It's probably cheap, but I would advise if you are buying a mini lag, then buy a properly assembled one, rather than one where there's danger of misassembly. Cos that's why the poor, the patients weren't being kept anaesthetized, .
This practise didn't have any capography, so they didn't weren't actually aware of the fact that OK my patient's not anaesthetized, but equally their CO2 levels are sky high as well, which is not good for them. Nice example. Talking of sky high CO2 levels.
If we are going to deal with hypoventilation, or we are going to perform intrathoracic procedures or use neuromuscular blockade for ophthalmic surgery, for example, we need to use automatic ventilators. And entitled CO2 is essential for understanding what we're doing with our ventilator, knowing how effective our ventilation is. So if you're thinking about using ventilators for whatever level of surgery you're doing, you definitely need entitled CO2.
Those are the indications of hypoventilation, thoracic surgery, and neuromuscular blockade. And you can clearly see this patient on the bottom right hand side of the screen was definitely in need of automatic ventilation because his entitle C2 was 88. This patient was just being prepped before it went into surgery, .
And that CO2 was fairly positional, so it was very high in lateral recumbency and when we moved the patient into dorsal recumbency, the CO2 was better. However, if we hadn't ventilated this patient, and that entitled CO2 long term would be certainly detrimental to that patient. I'll go through this in a little bit more detail in your notes that we're measuring entitled CO2 at the junction of the ET tube and the breathing system.
That's gonna be a little bit lower because of dilution than the CO2 in the alveoli, which in turn, depending how effective our ventilation is, will be a little bit lower than the CO2 in the blood flow to the lungs. So whatever we're measuring in tidal, we can always assume that our partial pressure of arterial CO2 in the blood is going to be slightly higher, maybe 234 millimetres of mercury higher than the normal patient. If we've got a patient that has lung disease or it's been for a long time and developed a elect the cyst, that difference between the tidal and the, the arterial CO2 will increase further.
So you should always think about it in the context of where we're actually measuring. Clinical practise guidelines for ventilation suggest that we should use CO2 to evaluate the efficiency of our ventilatory support. We can use it to verify the integrity of our ventilator circuits.
It will assist us in monitoring the adequacy of blood flow because we have no blood flow, we're not gonna get any CO2 measured. We can use it to monitor the severity of pulmonary disease as well. So in those patients that we, the sicker patients that we're ventilating perhaps in an ICU manner.
We can use our ventilatory parameters to assess when that lung disease is getting worse. That's a whole another webinar topic. When we start ventilating, you can see here the traces in the bottom, the more square traces are the ventilator breaths, but our patient is still trying to breathe as well.
This is not a huge problem and in dogs and cats it's really easy to override ventilation, their their ventilatory efforts. You don't have to use neuromuscular blockers to paralyse these patients to override their ventilatory drive. We just start a ventilator and that's what the trace looks like eventually, but then you end up with a beautiful ventilator associated trace on our countergram.
However, when we get to the other end, if your ventilator's got a weaning function, then that will help you wean the patient off the automatic ventilator back onto their spontaneous or manual efforts. The CO2 is always gonna go up when you turn the ventilator off, so accept that your CO2 will always go up. We're not gonna stress about it.
We're just gonna close the valve, squeeze the bag, give our patient a breath to support them back to their transition from the ventilator back to spontaneous respiration. Moving on to circulation, we know if you've got no cardiac output you're not gonna have any entitled CO2. And in that circumstance, let's just think about it, this isn't a poll question, just chuck this in here.
What will the PACO2, so the partial pressure of alveola CO2 be? If we've got no cardiac output, will it be high, will it below? Initially, the PACO2 is gonna be high because we're not effectively removing that CO2.
And if you've got a crash situation and you may have a patient that has a really low end tidal CO2 cause there's no cardiac output, but if you were to do a blood gas and sample, an artery, you're gonna see a really high CO2 because that CO2 has built up and it can't move out. Metabolism may have maybe trying to continue in that crash state. But the minute that patient crashes, that CO2 has just not been removed for the lungs, it's gonna be definitely high.
You can see this patient here, this is a patient that that has crashed. You can see from the ECG that we've got a bradycardia, we've got abnormal complexes there and our end total CO2 is 8, so we have no effective circulation. So internal CO2 we know is really, really useful for using in CPR.
Another example where we've got ventricular fibrillation on this ECG we have very low output, so an entitled CO2 of 12. That's only because you can see those look fairly uniform, those traces. This dog was actually a dog that crashed in theatre and was still on the ventilator.
So an entitled CO2 of 12 is definitely not a good number. We know from the human literature that when we're doing CPR what we're looking for when we do chest compressions is return of spontaneous circulation. And if our entitled CO2 is above 15 millimetres of mercury, then prognosis is actually fairly good for that patient to survive that that CPR episode.
We know that from the human literature, we don't always know that in dogs, but if you have an entitled CO2 when you're doing your CPR we consider that a good prognostic factor. See the difference in these two cases on the left, the one on the left, the one on the right, you've seen the one on the left before, the one on the right, we've got nothing going on from an ECG point of view in this patients and our own total CO2 is 0. The other advantage if your patient has crashed and they're not anaesthetized, obviously you know from what we talked about before that you can use your, your entitled CO2 to document whether you've intubated the trachea or not.
In the early stages of crash, you will get some entitled CO2. You, if you get 4 or 5, that means you are in the trachea, you're not in the oesophagus. We all know how easy it can be to intubate the oesophagus during a a stressful crash situation.
This is that case before, so this is a patient that we had given some alpha 2buorphanil to. We were just sedating this dog. It's a, it's a healthy dog that's just having a routine sedation.
He went profoundly bradycardic and so we intubated, quickly. You can see that we are breathing for the patient, but our entitled CO2 is really low, so. There is something going on here, we need to deal with that bradycardia.
We gave this dog adrenaline, adrenaline does exactly what it says on the tin and it's increased our heart. Heart rate to 227, it did then go higher. At that exact point in time, we've just stopped breathing for the patient to see if he has any spontaneous efforts, so you can see that the the CO2 is saying apnea there.
And indeed, he did start ventilating for himself again. So we've got good return spontaneous circulation. This is one of those crash situations where it's totally unexpectable, most crash situations are unexpected.
It's totally unexpected. It was a profound bradycardia that was a problem with this dog, so we've got serious reduced cardiac output, therefore we have no CO2. The minute we restore cardiac output, we see CO2 on that trace, and we've got an entitle of 29 here and a spontaneously breathing dog.
OK, that was an extreme example. Our catnograph can help us determine when we should treat a bradycardian. The first thing I normally think of with a bradycardia, and OK, this one probably is about 38, that machine is telling us the right number.
My first response is, well, what's the the blood pressure doing? Is the blood pressure OK? In this case I'm thinking, well, 30, yeah, you look a bit slow actually you may maybe your blood pressure, I mean of 85, probably happy with that.
Can we be a bit more accurate with how this bradycardia is affecting this patient overall? Let's look at the CO2. CO2 should be 35 to 45.
In this case, that bradycardia is definitely affecting the cardiac output because our entitled CO2 is not normal. So one of the questions I asked you right at the start was what can we use cameography for? What does it tell us about ventilation, metabolism, circulation.
I put cardiac output at the bottom there, didn't I? I know we don't Typically use cardiac monitors in our veterinary patients, but our carography can tell us about the state of that cardiac output and how other parameters are influencing our cardiac output. So you can see here this bradycardia, cardiac output we know is heart rate times stroke volume, that bradycardia is having a severe impact on our cardiac output.
When we fix it, when we give an agent to increase our rate, we get a normal entitled CO2. And that's quite nicely illustrated in this case here. He was This case just a little bit slow at 40.
And you can see his entitled CO2 is 34. When we give an anticholinergic, and I use glycopyrelate in this case, when we give that to increase his heart rate. We get back to more normal heart rate, this was a small dog, I think it was, I think it was a shih-tzu.
We've just increased his heart rate back to something a little bit more normal, and you can see the entitled CO2 is increasing. So that heart rate was affecting his cardiac output. We've now, well, we've now got a slightly high CO2, but I'm not gonna get too excited about, an entitled CO2 49.
You can definitely see the difference there between correcting that bradycardia and how it influences your cardiac output. One thing we always forget is the impact of our volatile agents on our circulation and our cardiac output. Isofluorine, sevofluorine, they're both massive vasodilators and they both decrease cardiac contractility.
So by that mechanism, the effects cardiac output. They reduce our preloads. And they reduce our, our cardiac output from contractility decrease point of view.
Bottom right hand corner here, we're measuring how much isofluorine we're delivering our patients, so our inspired and are expired. So an entitle of 1.6 is fairly high, and you can see our entitled CO2 is only 28 then.
We don't have bradycardia. What happens when I turn that iso down? On the right hand side of the screen there we've gone from an N tidallier of 1.6 down to 1.1.
You can see that our ntidal CO2 has increased by 6 millimetres of mercury. This is a lovely case example as well. People commonly use, we, we do commonly use two agonists.
We don't often have all of our monitoring equipment on when we're giving our Alpha 2s cos we're using them for sedation, but this is a case where we wanted to top the dog up. It's a little bit light, so we topped it up with some alpha 2 during its anaesthetic, and the screen on the left is immediately after we gave that alpha 2. We know that the alpha 2 agonist we give them, the initial effects we get are quite profound, so we get a really profound vaso constriction, we get a really profound bradycardia.
On the left hand side of the screen here, we've got a rate, the rate is reporting at 72, although that does actually look slower than 72 to me, so I'm not necessarily believing that. You can see the shape of that camera graph and the title CO2 the minute, I, I'm afraid I don't have the job before we gave the picture before we gave the alpha 2 because I looked at the screen and go, right, I need to take a picture of that. I didn't expect it to to be that dramatic.
You can see that our end title is only 29, and it had been more normal, it had been high 30s before we gave that drug. And if you compare the shape of the kenogram between the left and the right, you can see, certainly see the difference in having that higher end tidal on the right. So picture one on the left was 1 minute after we gave that Alpha 2 agonist top up.
Picture 2 on the right was 5 minutes later, once that vas constrictive bradycardia effect of the alpha 2 have waned a little bit, and we have better cardiac output. So great example that our alpha 2s do affect our cardiac output, but that effect is quite short-lived. I think what I would summarise this presentation with is if you've got a counter graph, if you get out of the cupboard or if you're about to go out and buy one, use it for every single case, get familiar with it.
It's such a valuable piece of equipment. Switch it on before induction. If anything goes wrong, think metabolism, circulation, ventilation, provided you've dealt with all of those troubleshooting points about can I rely on what my camera graph's actually telling me from a sampling point of view.
So it's one of the pieces of equipment that I really love, I really rely on it. I talked before about decreasing mortality from a pulse ox point of view. If I could choose one piece of monitoring equipment, it would be my capnograph versus any of those other things that I have.
OK. Brilliant. Thank you very much, Matt for yet another brilliant webinar, and I'm sure people watching found it very useful.
We've had quite a few, questions and comments come through, but just before we go to the questions, the webinar vet team really appreciate your feedback. So if you could spare, a few seconds to complete the feedback survey that should have popped up in a new tab in your browser, that would be fantastic. I think Dawn will add the link to the survey in the chat box as well.
The feedback survey is anonymous unless you provide your contact details. So if you would like a response to your feedback, please include your name and email address. And I know depending on which device you're using, the survey doesn't always pop up, so as I said, Dawn will add the link to the chat box.
You can also email the office, office at the webinar vet.com or provide feedback in the comments section on the website if you're listening to the recording as well. This webinar was actually requested via the webinar vets members Facebook group.
So if you have any requests, please do let the team know using the Facebook group in the feedback survey I've just mentioned, or by emailing the office at office at the webinar vet.com. And also due to popular demand and expertise series on anaesthesia is being delivered by Mats, which will be starting in April, consisting of 4 webinars on the topics of human factors in anaesthesia, including safety culture and dealing with risk, new drugs and new ideas on all drugs, anaesthetic monitoring and controversies in anaesthesia.
So watch out for that series in a few months. OK, Matt. So the first question that we had was submitted quite early on in the webinar.
The person said, I'm not sure if I understand. Does Matt use Capnograph in cats? Yes, absolutely.
Caography, dogs and cats, both, and you. You just consider 35 to 45 your normal, but accept that maybe in cats you may get a slightly lower value, because cats are, slightly different to dogs, and if your ET tube is not coughed in the cat, you will get a slightly lower value as well. Yeah.
Great. Thank you for clarifying that, Matt. And the next question, in your opinion, what is the best make of multimodal anaesthetic monitors?
The one that I'm about to buy is the Cardell Touch. Why do I like those, . There are the one, the other one I mentioned was Mind Ray, which we've had for years and they were very cost effective.
They're still quite nice monitors, but they just got a lot more expensive and I think you, with the Cardell. From a multi-parameter point of view, the Cardell blood pressure algorithm is in my opinion, the best blood pressure algorithm out there. So if you're looking to spend your money most effectively, it's got a lovely pulse ox, it's got a lovely blood pressure algorithm.
And the capography component's really good as well. If you want if you want mainstream, they'll do mainstream, but I'm gonna order side stream because of all the things I said to you previously. But get one on trial, and, as I said in that disclaimer slide at the start, I don't get, don't receive any financial incentive for saying that, so.
Great. Thank you for that, Matt. What is the catnograph in COPD cases and could it be used as a diagnostic tool?
What you can, one of the things that you, you don't commonly see this, you can see changes with broncho constriction on your camera graph and it becomes a kind of shark fin shape. That's quite nice if you just look on Caography.com, you'll find a picture of that.
So if you've got expiratory resistance, so that could be general airway spasm and COPD or it could be bronchoconstriction for something like anaphylaxis, you will see a shark fin appearance, so quite an angular, sharp change in your camera graph. That could also be if your ET tube has become dislodged, let's say your tube has dislodged up against the edge of the trachea and your ET tube doesn't have a Murphy's eye, so you've got resistance to exhalation, that's the kind of pattern that you can see as well. From a diagnostic point of view, if you do see that in, and you think it's bronchoconstriction and you give a bronchodilator, you will see the cat graft go back to a really normal shape.
Where I, one thing I've done previously is asthmatic cats. If you do see that bronchoconstriction. Half a mg of ketamine IV ketamine is a bronchodilator, so you can see that in front of your eyes, the way the counter graph improves once you give that ketamine as a bronchodilator, but you could use tibutyle to the same effect, yeah.
Thank you, Matt. The next comment, as an examiner, I have to tell students that the bag is always attached, to the tube with the rim on. I was never taught this and I also found my students usually are not aware of the rim.
I'm not quite sure. I, I, I don't quite understand that, sorry. The bag attached to the rim.
I think it was around about the time that you were asking whether the left or the right set. Oh yes, OK, . I touch.
I'm just trying to think about that, man. It's confusing me. Yeah, I would have to think about.
Assembly of the breathing system. The, the problem, the problem with that one in particular is it's made up of different components that can be used for a lot of other things. So you can assemble that breathing system however you like, and it's wrong.
So I think it's, that's, it's a fundamental problem with that particular breathing system. OK, thanks, Matt. We've had a lot of people saying thank you, I know that it was a fantastic webinar, but I'm very conscious of time, so, just to say thank you so much again, Matt, and, thank you to the member who requested the webinar on this topic.
It was clearly a very, popular topic. Thank you to everyone who attended the live webinar. It's always great to have you online with us and providing feedback and also getting involved with the poll questions.
And, last but not least, thank you to Dawn for co-hosting with me on the webinar today. Next Thursday, Danielle Gunmore will be discussing feline lower urinary tract disease. So I hope you can join the webinar next week too.