CE: Approach to Respiratory Distress in Cats with Dr. Beer

It, I know it's a busy time, so if people aren't here, they can always watch later. Hi everybody, thanks for coming. Um, what was I gonna say? I don't know, I lost it. Uh, we're a small group, so that's kind of nice. So obviously, as you guys know, if you have questions as we go through, please just maybe we can type them in the chat, Caroline. Um, or if you want to unmute yourself and ask a question, that's totally fine. I always like to make things more of a discussion, if we can.

Um, and so today we're going to talk a little bit about cats in respiratory distress, which, you know, are a special situation in that they tend to be more sensitive sometimes than dogs when they come into the hospital. And so I think this is a nice lecture to do separately in terms of dogs and cats. Um, and I originally did this a few years ago when I was in Philly, so some of the pictures are a little bit old, but I think everything else still applies. Um, so Caroline was just like laughing about this picture as I was going through things as we were getting started. And, you know, obviously in an emergency situation, the team is really important. And you guys already know this, but triage, um, and stabilization are really tasks that fall mostly to the tech and assistant team. And so being aware of some of the common cases that we see and how to handle them and how to address them right away, especially if one of your doctors is busy or something else is going on, um, is a really nice thing. And in the picture, um, the second guy from the right side here is Caleb, who is the guy who started Instinct. Um, so you can thank him for all the chaos that's happening in the hospital today.

So one of the first things that we want to think about anytime we see any patient come into the emergency room is figuring out what's wrong as quickly as we can so that we can get the patient stabilized as quickly as we can. And so using the skills that you already have as a technician or assistant are really important here. So triage and a brief physical exam are the first things that we're going to focus on. And we always want to think about stabilizing patients first before we move forward with doing diagnostics. So a lot of the time in the emergency room, I think I see patients who come in who are clearly having some element of respiratory distress or have some element of shock and are not necessarily stable. And people are asking for diagnostics to be done, like patients to be taken down to x-ray, um, blood work to be drawn, that kind of thing. And we really want to focus on getting these patients stabilized and out of pain first before we do things. And so don't be afraid, you know, to ask your doctor and say, "Hey, can we do this first?" or "Can we give this patient a break?" or "Can we give some oxygen or a pain medication?" You know, we really count on you guys to recognize that those things are necessary, especially when we have a lot of things going through our mind and, you know, it's hard to keep all of those things straight. So don't be afraid to speak up.

Some of the first things that we want to think about specifically in animals that have respiratory distress are obviously oxygen support, which we'll talk about, medications, which may be medications to help them breathe more easily, medications for sedation to take away some of that anxiety of breathing, pain medication, um, sometimes a diuretic right away if we think that they're a heart failure patient, and then also in some situations, thoracocentesis, so tapping the chest to remove air or fluid if we think that that's going to be something that's going to help to stabilize them. We'll talk a little bit about ultrasound and then lastly, we'll talk a little bit about some of the common radiographic findings that we see in cats with different causes of respiratory distress.

So one of the things, you know, that I really try to stress to people in in patients coming into the ER and in patients that we're doing CPR on and patients that are really critical is, "Don't panic." You know, we have an amazing team at OVRS. You guys are extremely skilled in dealing with these patients and trying to stabilize them as quickly as possible. And I think it's really important to, um, have kind of a calm demeanor going into these situations where we can make ourselves feel better and make the patient feel better by staying calm. Cats especially, we want to try to be calm and minimize stress. And using fear-free techniques in the last few years has made a huge, huge difference. And I don't know if some of you who have come into the profession more recently have appreciated this, but looking back to maybe five or 10 years ago in the way that we used to handle patients with things like scruffing and, um, restraint techniques compared to what we do now is honestly night and day in terms of the difference that's there. Um, and so this is, this I think is really, really helpful for cats alone. And so if you're not up onto your fear-free training, I would definitely encourage you to do that or talk to other people in the emergency room about how we can do that more easily and make these patients a little bit less stressed.

Cats especially have to go about a lot of stress just to get to us. You know, if you've ever had to put your cat in the carrier to bring him or her to work, you know how challenging that is for us and for them. And so we really want to try to be as fear-free and stress-free as possible for them initially when they come in. We always want to think about triage. And I know that we've talked about this many, many times before, but the idea of triage is that we are trying to sort patients and determine which patients are the most critical and need to be dealt with the fastest compared to which patients are maybe a little bit less critical or which, which patients are stable and we can wait, um, to deal with those patients after we stabilize the most critical patients. And really, your triage should be a very brief, you know, kind of 60 to 90-second instrument-free assessment of these patients. So you don't need a stethoscope, you don't need a Doppler, you don't need a thermometer to do your triage exam. You really are visually and just physically kind of briefly examining the patient to determine if you think that they need to come back to the ER right away.

And there are nine classic components of triage that we think about. So two of them are part of the oral history. And so the first is presenting complaint. And so I, I think a lot of us will kind of go upfront and talk to an owner when there's a call for triage and say, "What brings you in today?" or "What's going on with your pet today?" And then the other thing that we want to know along with that is, "When was the pet last normal?" So is this a kitty who has had some increased effort over time or some coughing over time that has been going on for weeks to months, or is this a kitty that is acutely open-mouth breathing today and was totally normal last night? And that's important for us to think about not only progression of disease, but also potential differentials for what might be causing some of the things that we'll see in terms of cats with respiratory disease.

In addition to that, there are these physical exam findings. So we want to look at their mucus membrane color, which should be a nice normal pink. And in addition to that, their CRT, the capillary refill time, which should be less than 2 seconds. A prolonged CRT can tell us that they have impaired perfusion, so they're having trouble getting blood and oxygen to their peripheral tissues. And a really rapid CRT can tell us about, um, things like vasodilation and sepsis. So the refill time is really fast because the blood vessels are dilated and there's kind of a hyperdynamic response there in terms of the circulatory system. We also want to feel a heart rate or a pulse rate. In cats, a lot of times you can kind of put your hand just right on their chest to feel what their heart rate is, or you can palpate a femoral pulse, um, whatever is, is easier for you and less stressful for the patient and get an idea of what their presenting heart rate is, realizing that in kitties, they do have fairly normal high heart rates between about 180 and 200 or so. So a low heart rate can actually indicate significant disease, as well as an elevated heart rate. And then in addition to feeling the pulse or the heart rate, you also want to feel pulse quality. So does their pulse, is their pulse easy to find? Do they feel like they're weak? Do they feel like they're bounding? Those are things that we want to make note of.

And as I'm kind of doing these things and briefly looking at the patient, I'm also watching them, right? So we're looking at their mentation or their level of consciousness. Do they seem like they are oriented to you? Do they seem like they're neurologically or mentally appropriate? And are they breathing fairly comfortably with a normal rate and effort? The last thing that we kind of tack on to triage for kitties especially is palpation of the bladder. Not necessarily for cats that present with respiratory distress, but for all kitties, we like to make sure when they come in because sometimes people won't always appreciate that they're not urinating at home, especially those male cats, to make sure that they're not blocked. It's a good idea to just do a brief palpation of the abdomen and make sure that they don't have a really enlarged, firm bladder.

And then if you determine that this, that this cat needs to come back to the emergency room to be assessed by the doctors and the team, like we said, this initial assessment and stabilization, we want to be quick and minimally stressful. So if you can get a full TPR, that's great. Hopefully, you kind of already have an idea of what their pulse or heart rate is. You can get a quick respiratory rate if they will tolerate it. You can get a rectal temperature. That's definitely something for me that I am usually okay to wait on in cats that are in respiratory distress unless we have a specific reason to get that right away. Hopefully, a brief auscultation by the doctor to listen to their heart and lungs. And if we feel like they're okay, we can move forward with a further physical exam or at least a brief exam, you know, brief palpation, um, that kind of thing. If they need a break, don't be afraid to take a break. Um, and so if they need to be triaged to oxygen in the ICU, you know, let us know. We can always move them in there to give them some time to take a break, or there are other ways that we can supply oxygen, which we'll talk about too.

As we're doing that PE, and kitties that have respiratory distress, we really want to think about some of the abnormalities that we should be watching for. Um, and so a kitty that is open-mouth breathing is never normal, as we know, compared to a dog that, you know, dogs will commonly pant because they're excited when they come into the emergency room. Cats can sometimes open-mouth breathe just with stress, but that's definitely something that we want to be aware of and can be a sign of really severe respiratory distress. We can also look for more subtle things like nasal flaring. So when they're breathing, they will kind of open up their nostrils every time that they're taking an inhalation to try to move more air and decrease resistance to air movement. And in conjunction with that, we sometimes will see something called orthopnea, which means that they are taking a different orthopedic stance to try to decrease resistance to air movement. So they kind of will stand or sit with their head and neck extended to decrease resistance to air movement through the upper airway, upper airway, and through the trachea. And then in dogs, sometimes we'll actually see them kind of sit or stand with their elbows abducted, so pulled away from their body, to kind of decrease resistance within the thoracic cavity to air moving. So that's called orthopnea.

Um, one of the things that I think is really classic for kitties that have especially pleural space disease is they will get this rapid, shallow respiratory pattern. So they kind of look like they're breathing with significant effort, but they're not taking really big, deep breaths. And that can be an indicator that there is something going on within the pleural space. We also can see that in kitties that are easily stressed. Um, so auscultation is important along with that, but that's a good pattern to watch for. And then inspiratory or expiratory effort. So depending on where disease is localized, a patient may have more trouble inhaling, like they're having trouble getting air into their thoracic cavity around something, like if they have an upper airway obstruction, or they're having trouble expiring, um, if they have lower airway disease. We can see that in conjunction with things that we're looking for. We're also listening, right? So not all of these things require a stethoscope. So things like stertor and stridor, we can hear in a patient usually without a stethoscope. Stertor means that they have kind of a, um, a snoring or a low-pitched, um, kind of sound. So stertor, I think about like Bulldogs or brachycephalic dogs and the way that they breathe with their upper airway noise. Stertor is really common for them. Stridor means that you are trying to breathe through a very narrow airway. So it sounds like trying to breathe through a straw. So dogs with laryngeal paralysis would be the classic example of an animal with stridor.

We also want to be aware of coughing. Coughing is pretty uncommon in cats. Um, but if you do hear coughing, we want to know, you know, is it a wet cough? Is it, is it a productive cough? Does it sound dry? Those kinds of things. And then with a stethoscope, we want to listen to both breath and heart sounds. So in terms of breath, breath, breath sounds, excuse me, um, normal breath sounds, I say to people, should kind of sound like air moving through the leaves of a tree. So in a normal chest auscultation, you should be able to hear some air movement, but it should be kind of quiet and gentle. If you're listening to an animal's chest, especially if they have significant effort and you can't hear breath sounds, that's what we would call dull breath sounds. You can't hear air moving even though they look like they're working really hard to breathe. That can be a sign of pleural space disease. Muffled heart sounds can also be a sign of pleural space disease or pericardial effusion. So there's something kind of in between the heart and where you're listening on the outside of the chest. We want to listen for heart murmur and arrhythmias. Some of you are great at picking up those things, um, and it's always good to practice. So, you know, for patients that we have in the hospital, if you have a stethoscope and you're doing treatments, it's always good to listen to patients just to get more practice listening to them because even we sometimes have difficulty picking up on murmurs or arrhythmias. And those are things that you guys will pick up during your exams. And then crackles is fluid within the alveoli. So crackles kind of sound like Rice Krispy Treats or Rice Krispies, um, when you add milk to them, or like Pop Rocks. They kind of, it kind of has that like crackly sound. I don't know how else to describe it, but if you haven't heard crackles before and you'd like to listen, you know, come find one of us during the day when we're working and we'll try to find you a patient that has some nice crackles to listen to. Um, and then wheezes usually sounds kind of high-pitched, like a squeaking noise, and can be really classic for animals that have asthma or lower airway disease.

All of those things that we're doing, so watching these patients breathe, um, listening to these patients breathe, scaling them, are helping us to localize the problem, right? So just because they have respiratory signs doesn't necessarily mean they have respiratory disease. They could have heart disease, they could be stressed. Um, and so we want to kind of put all of these pieces of the puzzle together to try to localize where the problem is coming from. So as I mentioned, upper airway disease would be disease that focuses outside of the thoracic cavity. So we're thinking about, um, the larynx, the upper airway tissues, the oral cavity and the tongue, um, and kind of the cervical part of the trachea. And these are things where you might hear stertor or stridor, like we said. They might have inspiratory effort. You might actually appreciate that they have lack of air movement, um, so they look, they're trying to breathe and they're trying to move air, but when you listen kind of over the upper airway, you don't actually hear air moving. Or sometimes in kitties, if we think that they have some kind of nasal obstruction, you can put like a little piece of, um, like break apart a cotton ball or a Q-tip and hold a little bit of that in front of their nostrils, and you should see that move right when they breathe. And so you can diagnose decreased air movement through the nasal cavity by demonstrating that that movement isn't happening. Um, and things that we would think about in any of these situations would be things like nasal polyps, masses, or stenosis that are affecting the upper airway, really severe upper respiratory tract infections, so if they have a lot of inflammatory debris or mucus up there, it can be difficult for them to move air, and you'll also kind of see them do that hard swallowing thing like they have like a postnasal drip. And then laryngeal and tracheal masses too. So those would be the most common things that we would think about in terms of upper airway diseases in kitties.

And then let me just see if I can get this video to play. So this is a kitty that obviously has really significant, um, effort and you can see he's breathing with his mouth open. He's obviously fairly obtunded, but he has pretty big excursions of his chest cavity. And if you listen to him at the same time, we really could not hear a lot of air movement moving, um, or breath sounds moving in his upper or, or lower airway. So this is a kitty who was hit by a car and had tracheal trauma and was not actually able to move air into his lower airways.

When we think about lower airway disease, some of the common things that we might see are coughing. Again, we said, you know, coughing is pretty uncommon in kitties. And so usually if we're talking about a coughing cat, we're thinking about either feline lower airway disease, um, or heartworm disease, which is pretty uncommon for us. You may hear wheezing when you listen to them, and you may hear what we call increased bronchovascular sounds, um, which is basically just kind of harsh lung sounds that air moving through the trees is more loud than you would expect it to be and sounds a little bit more, um, enhanced. Big things we think about in those situations are feline asthma or other lower airway pulmonary parenchymal disease, and that could affect any of the, um, lung lobes. You may also hear things like crackles. They may have rapid, shallow breathing. And other differentials for things in that area would be things like pneumonia, which could be an upper airway infection that progresses to an infectious pneumonia, a viral pneumonia, or congestive heart failure. And crackles, I would say, are more typical of things like congestive heart failure and pneumonia because we're thinking about fluid in those very small cavities, those little alveoli in the lungs, and so you're hearing that fluid move around, which is either inflammatory fluid or pulmonary edema.

Usually, in terms of pleural space disease, I think pleural dis space, pleural space disease, I think is one of the really interesting diseases that we see in dogs and cats. And I, I think I find it really interesting because it's really satisfying to be able to help these patients by performing thoracocentesis. But they do have these classic physical exam findings where they sound dull when you listen to them. So that cat that was in the video, if you listen to her, she really didn't have any audible lung sounds. And so pleural space disease was one of the things that was on our list of differentials because we weren't hearing that normal air move through her lungs. Muffled heart sounds, you can also pick up on. We talked about them having this rapid, shallow breathing pattern where because there's something in the chest cavity, in the pleural space, excuse me, around their lungs, they can't necessarily expand their lungs as they would normally do. And so they're breathing more rapidly and shallowly to compensate for that. And then one of the things that we talk about commonly, um, especially in cats that have things like a cranial mediastinal mass, so a mass in the front part of the chest, is lack of chest compressibility. So if there is actually some kind of physical structure or tumor there, their chest will not compress like a normal cat. And this is something that I think we do so uncommonly that I usually don't pick up on it until we diagnose the mass. Um, and then I have to go find like a normal cat that has normal chest compressibility because it's not usually something that we palpate for really specifically. But it, it is something that you will notice in those cases. Um, and it can be helpful if you're aware enough to think about that when you're doing your initial physical exam, which I'm not. Um, so in these cases, you know, pleural space disease, we're thinking about pleural effusion, pneumothorax, so air in the chest in the pleural space around the lungs, a mediastinal mass, or something like a diaphragmatic hernia.

Okay, this gets a little, a little bit sciency and researchy here, but there have been a couple of papers out there that look at what is the actual evidence for certain respiratory patterns in dogs and cats that have pleural space disease. So like I mentioned, disease in the pleural space reduces your functional residual capacity, that's your FRC. And so the lungs have to operate with less compliance. And so you can see what we call a restrictive breathing pattern. So they increase the rate of breathing because they have basically less room to breathe. Um, and the inspiratory muscles, the intercostal muscles, which are between the ribs, have to actually work harder to move the chest cavity against this increased intrapleural pressure. So they have less space and they elevate during inspiration, and the abdominal contents will actually kind of get sucked into the thorax because of that increase in pressure and decrease in pressure within the chest cavity. And so they get what we call asynchronous breathing, where when they breathe, their chest expands and their abdomen contracts because they're actually using some of those abdominal muscles that are getting pulled into the chest cavity. So as the chest is going out, the abdomen goes in, and as the chest is going in, the abdomen goes out. So that's called asynchronous breathing. This short and shallow pattern that I was talking about, and that I really associate with pleural space disease in cats, based on the papers, they say it actually is more common in cats without respiratory disease. And in this paper, they found a lot of cats that had basically just stress coming into the hospital that are tachypneic, um, and that kind of skewed their results towards saying that cats that have the short and shallow respiratory pattern do not necessarily have pleural space disease. I still think it's a good reason to look. Um, and certainly we have tools in the emergency room to help us look for those things, which we'll talk about. They did find that pleural space disease was associated with this asynchronous pattern, so increased abdominal effort, um, expanding the chest and contracting the abdomen, those kinds of things were indicative of pleural space disease and were more specific for that type of disease. Um, and that was true in both dogs and cats. So if you're seeing that, if you're seeing that asynchronous breathing in a dog or cat that comes into the emergency room, that would be a good reason to maybe look with the ultrasound for pleural space disease, escalate the patient, and see if you hear dull lung sounds.

Basically, the research says, you know, any atypical breathing pattern should prompt us to look for disease, but not every patient's going to have it. So I think it's to be aware of this. If you see a patient that has really short, shallow respirations, maybe think about that. Um, but patients may not have it, or some patients may have pleural space disease without having that. And a lot of that depends on how quickly that air or fluid or tumor is developing, if they have other problems so that they can't compensate as readily, and how much is there. So patients that have kind of a long history of developing pleural space disease, like a kitty with pleural effusion, can really get quite a large amount of fluid in there if it's developing over time because they compensate for it as time goes on, right, until they get to that kind of critical point where they can't compensate anymore. So they may or may not display some of these classic breathing patterns that we talk about.

Um, one of the last things that we're going to talk about is radiographs. Um, and the reason for that is because I really feel strongly that any patient in respiratory distress should not be going down to Radiology to have radiographs performed immediately. This is obviously stressful for them. You know, we've all had those experiences where we take a patient down and they decompensate rapidly or they arrest when they're in radiology. And so we really want to make sure that we are trying to get these patients as stable as possible before we take them down to perform any kind of imaging, um, that may be stressful for them or put them at increased risk.

So coming back to stabilization, um, you know, as I've said, don't be afraid to take a break with these patients. So there are a lot of different ways to provide oxygen. This is not a way that we have, but this is something that we demoed, um, during my residency. So this is like a little astronaut helmet that you could use for kitties, um, which really was not very fear-free for them. I don't think they appreciated being in this kind of little globe to provide oxygen, even with a little bit of sedation. Um, so the things that we use most commonly are obviously an oxygen cage. I will say oxygen cages are hard to use and to utilize appropriately when we're trying to stabilize patients, right? Because you turn the oxygen cage on, you get it up to 40 or 50%, and then we put the cat in there, and then within a few minutes, you know, your doctor is going in to do another assessment, or we're opening the door to give an injection. And so it, it's not ideal in terms of initial stabilization, only because we're doing a lot of opening the door, and every time that we do that, the oxygen is going to go right back down to room air. I think too, for kitties, the oxygen noise can be really stressful for them. And so we sometimes have have kitties that come into ICU and get put in an oxygen cage, and they're already worked up, and then the sound of that oxygen blowing on them just really, really, really elevates their stress. And so initially, I think if we can, um, we want to think about things like an oxygen mask for initial flow-by. So, um, this dog obviously has some significant cyanosis, his tongue is fairly purple. Providing some flow-by, if you're using a fairly tight-fitting mask, can provide about 40% oxygen, so about twice what we're breathing out here in the real world. And you do want to make sure in these initial stabilization settings that you have this mask pretty close to their face, ideally kind of around their oral nasal cavity, but you also want to provide for them to be able to blow off their CO2. So you don't want it to be a tight-fitting mask in the sense that it has, um, a rubber seal on it and they can't exhale and blow off that CO2 because they're going to get hot, it's going to be stressful for them. So we want to apply it as close as possible, um, and then not in cats necessarily, but, um, nasal cannulas are something that we can think about for dogs, especially big dogs that can't go into the oxygen cage. This is just a kitty that is getting initial flow-by. I really feel like if you can put a mask on the end of this, um, oxygen line, that is really going to help to concentrate your oxygen flow more readily around the cat's face. And so I, you know, I see people holding up kind of lines like this a lot in the emergency room, and this is not going to be as helpful as putting a mask on the end. The mask is really going to cone that oxygen to the patient's face, and you can kind of hold it more easily over their nose and mouth. And so I would encourage you to do that and to have those readily available in the ER because it is going to help provide more oxygen to them, a higher FIO2 than you'll be able to with just the line alone.

So how do we know if the oxygen is helping? Um, I, I mean, you guys all know the pulse oximeter is a pain in the butt to use. Um, it's something that I tell people, you know, if, if it's working and you're getting a matching heart rate and you're getting a number that you think is accurate, wonderful. I think the most important thing about the pulse oximeter is don't let it change your plan. So if you, well, hold on, we'll go back to that in a second. So the way that it works, um, is that the pulse oximeter assesses oxygenation in a patient's blood by measuring the amount of hemoglobin, the percentage of hemoglobin that are saturated with oxygen. So ideally, you want to have your little probe on some kind of non-pigmented skin or mucous membrane. Um, so some of them we can use within the oral cavity, within the non-haired part of the ear, in the inguinal region, sometimes they work really well on a toe. Um, and the probe is actually sensing the wavelength, um, of oxygenated hemoglobin in the blood. So they basically need to find a pulse, they need to find an area where the blood is flowing, and then they can tell us how much hemoglobin, um, is saturated with what, with what percent of oxygen. So normal should be about 95 to 100%. And if you're getting that, then great. Um, the important thing to know about the pulse oximeter is that the curve that assesses oxygenation in conjunction with your pulse oximeter or your oxygen saturation is not a linear curve. So what we're looking at here is your PaO2, which is the concentration of oxygen in your blood, um, and your SaO2, which is basically your pulse oximeter reading. So we say normal, a normal PaO2 is about 80 to 85 or higher. Um, 85 to 100 reading on your arterial blood gas would be normal for a patient not on oxygen. On oxygen, that number is going to go higher. But a patient on room air, we're looking at about 85 to 100, and that would correlate, like we said, with a pulse oximeter of about 95 to 100. Right, as we kind of dip below this arterial oxygen concentration of about 80, this curve really starts to drop off. And so a PaO2 of 80, which is kind of the upper limit of hypoxemia, or the upper limit of what we consider significant, a significant decrease in your oxygen in your blood, is a pulse oximeter of 90. So if we're getting down to that 92, 90, 89 reading on a pulse oximeter, and you think that that is an accurate number, we want to know that because that really means that this patient's oxygenation is suffering. Um, and the cutoff for what we think about in terms of mechanical ventilation or now things like high-flow oxygen is about a PaO2 of 60, which is a pulse oximeter of about 88, 86. So this, this drops off really steeply, and that's important to realize when we're getting these numbers because sometimes I'll hear people say, "Oh, you know, the, the pulse oximeter is 90 or 91," or, you know, "I won't get a call if there's an issue and the number is reading around that overnight," because we're not thinking about how steeply that curve drops off. So those are things that we want to know if you think that it is a real reading.

That being said, it's super finicky, right? So I think at least 30 or 40% of the time when we use the pulse oximeter, we feel like the reading is not necessarily accurate. If their pulse rate is not matching, if their pulse rate is not reading the pulse oximeter is likely not accurate. And so we really can't use that number to legitimately say this is how well the patient is oxygenating. And if you can't get a reading, don't let that change your plan. The gold standard for measuring oxygenation is an arterial blood gas. And so, oh, that's my cat, sorry. Um, if you need help getting an arterial blood gas, any of the technicians in the ICU are always happy to try to help you. And that number, looking for that normal on room air oxygenation of a PaO2 of 85 to 100, will tell us if the patient is truly oxygenating well. And we can help you calculate an A-A gradient, which looks at how well oxygen is being exchanged in the body. So if your pulse oximeter doesn't read and the patient looks like crap, don't let that change your plan. You know, this cat is obviously in respiratory distress, she obviously is open-mouth breathing and needs some kind of support. So, you know, if you put the pulse oximeter on her and it's reading 99, I think none of us are necessarily going to trust that and all of us would agree that this cat needs some kind of support or sedation or both in the short term. So don't let the pulse oximeter change what you think you should do based on how the patient looks.

There are a few different medications that I think we all kind of think about classically for stabilization for cats and dogs that are in respiratory distress. Um, one of the first one, first ones we commonly will reach for is Lasix, or furosemide. And Lasix is what we call a loop diuretic. So that means it works in the loop of Henle in the kidney, specifically in the thick ascending limb, and it inhibits a certain pump. So it inhibits this sodium-potassium-two-chloride pump. And by doing that, it helps to, um, basically cause diuresis of fluid. And so water in the body will follow these electrolytes as they are basically lost from the system, and the patient will develop a diuresis and hopefully urinate within about 20 to 30 minutes of getting a dose of Lasix to try to decrease some of the fluid in the circulatory system. We use it for pulmonary edema, um, so mostly when we suspect congestive heart failure in dogs and cats. And those cats are usually tachypneic, meaning that they're breathing fast, or dyspneic, meaning that they're breathing with effort. They have those increased kind of harsh bronchovascular sounds or crackles. They may or may not have a heart murmur or a gallop, um, and they may or may not have dull breath or muffled breath or heart sounds if they also have some component of pleural effusion. We usually tell people when we're talking to clients, you know, fluid helps to, or sorry, Lasix helps to pull fluid out of the body. That isn't necessarily true. Really, what it does is it helps to dilate the pulmonary vessels. And so in letting those pulmonary vessels relax a little bit, it decreases the amount of pulmonary edema that is going out into the lungs. And then eventually, the body will resorb that fluid that is already in the lungs. Um, but I think that that's a little bit of an easier way to think about it, and people understand that when we talk about it that way. I cannot stress enough, and you guys know this, that Lasix can be given IM. It works very fast IM, very similar to how quickly it works IV. And usually in kitties, we're giving one to two milligrams per kilogram. So don't be afraid to give an IM dose of Lasix and then just put a cat in oxygen or provide flow-by oxygen while we try to get them more stable. Um, if we can't stress them too much to get a catheter in initially, that's okay. There are still stabilizing medications that we give in combination with that.

We're also usually thinking about some kind of sedation. I really like butorphanol for animals that have respiratory distress, and I think that's what we commonly use as a hospital. It is an opioid medication, but it is a little bit of a less stronger opioid. So it's a partial agonist-antagonist, and it's really nice for mild sedation. It does not have, um, good pain control effects, and so we really don't want to use it for pain, but we can use it for animals that have respiratory distress and especially for that anxiety component of respiratory distress. You know, not only are they having difficulty breathing, but they're also in the hospital out of their normal element, and they're anxious. And so those two things definitely compound on each other, and this can be a nice way to take away some of that anxiety. Again, it can be given IM, usually for Torb, we're thinking about 0.1 to 0.2 milligrams per kilogram, or sometimes even a little bit more depending on how stressed the patient is.

In cats who are having difficulty breathing, and we may think that they have some bronchoconstriction, um, or narrowing or collapse of some of the airways, we also will think about terbutaline. And this is a beta agonist, and so it affects beta receptors that are in different parts of the, in the body, in the tissues, but we're mostly using it for its bronchial effects in these kitties. And it can cause bronchial relaxation, um, and reduce some of their airway resistance and make it easier for them to breathe because it does also have some effect on the smooth muscle, um, and on the heart. It can cause tachycardia, so it's just important to be aware of when we're using it that way. It's usually fairly mild, but we're using it in kitties that have respiratory distress, usually when we think that they have asthma, to try to take away some of that bronchoconstriction and make it a little bit easier for them to breathe. Um, this is one that we give IM, so we don't want to give it IV because it can have more cardiac effects if we give it IV, and the dose is very, very small. So usually we're giving 0.01 milligrams per kilogram IM one time.

And then the last thing that we think about also in kitties that have, um, asthmatic or lower airway disease is some kind of steroid. Usually we're using dexamethasone, which has some anti-inflammatory and immunosuppressive effects, but it can also cause some bronchodilation. And so we're using it at usually a 0.1 milligram per kilogram per dose, and you can also give it IM. So all of these medications are things that do not require an IV line and can be very effective when given, um, intramuscularly for patients who are unstable. In situations where we are really in a pinch, um, you can actually give all of these things, which I don't necessarily advocate for, but you can give Lasix, dexamethasone, and terbutaline, um, and you actually can put them all together and give them as an injection. And some ER doctors call this "LADEX-a-balene." So if you have a patient who's in really severe distress, one dose of all of these medications is not necessarily going to be very harmful. Um, and that's something that we will consider in really, really extreme situations, although I will say I haven't done that in a long time.

So what about when there's pleural space disease? Like I said, this is one of my favorite things to treat and diagnose because I think it can be really satisfying and we really can make these patients feel better. We want to think about doing thoracocentesis pretty rapidly in these guys. Um, and one of the things that all of us learned in school is it's therapeutic, so it's going to make the cat feel better, and it's also diagnostic, right? So even if you do a tap and it's negative, um, that can tell us that there isn't air or fluid there. And if there is fluid there, then getting a sample of that fluid is really going to be helpful in terms of helping us guiding us in terms of further diagnostics and what we think is going on with the patient.

In terms of setting up for chest taps, many of you guys know this and are great, great at grabbing all of these things for us, but we want to have oxygen supplementation readily available. Ideally, we want to have an IV catheter in. Um, usually these taps go fairly smoothly, but we want to be prepared with supplies for intubation just in case, and we want to have IV access, usually to give some sedative medications, but also to provide support if the patient needs it. Um, sedation if needed, usually things like butorphanol can be really helpful in these situations. And then supplies for tapping. So we're going to clip and scrub. You need sterile gloves. Um, different doctors have different preferences for the tools that they like to use for for tapping. In kitties that aren't super, super fat, I usually like to use a butterfly catheter. Um, you also can use a regular needle, you can use a peripheral catheter. It really depends on doctor preference and kind of how they learned and what they're comfortable with. And then an extension set and three-way stopcock, some kind of collection syringe and collection containers, and then tubes to collect your samples. So these are some of the different setups that you can use. Um, I don't necessarily always like to do the catheter setup only because it adds an extra step, right? So if you've seen us tap with a catheter, you have to put the catheter in to the chest, and then you have to pull the stylet out, and then you connect it to the collection system, which is your extension set here, your three-way stopcock, and your syringe. Um, I usually like to tap with either a needle or a butterfly where I have my whole closed system set up from the beginning, and so there isn't a step where I have to take things apart and then reattach. But any of these ways are fine, again, just depends on doctor preference. Sometimes the type of fluid that you think is in there, if it's like a really thick, viscous fluid, sometimes using a catheter and making an additional fenestration can be helpful. Um, and also the size of the patient. When we're going about tapping, most of these patients are going to be in sternal recumbency. Sometimes if we're tapping for air, especially in dogs, we will tap them in lateral, but ideally you want to prep these kitties in sternal. And don't be afraid to shave a lot. Um, usually when we're tapping, we're thinking about tapping kind of mid-chest to more caudal chest, so rib spaces about six or seven to 10 or 11. And you can count from the back, you can count down from 13 and kind of see where that is if you can palpate on the kitty. But don't be afraid to tap, um, I'm sorry, to shave a large area and to clip and scrub a large area so that we have a good sterile space available. And then we're going to sterile glove, put together our collection system, um, and usually I'll pull my little glove, um, wrap kind of right up to the kitty's chest so that I can use it as a place where I can stabilize my hand and still be sterile. And then we're going to palpate the chest. So you want to feel, um, for the ribs. And all of the important stuff in the chest runs on the caudal side of the rib, the back side of the rib. So the way that I remember that is if a dog or cat is running through the woods and they get stabbed with something, they run into something. Um, evolution has kind of protected them to be at less risk for having some kind of really traumatic life-threatening injury because everything is behind the rib, not in front of the rib. So the nerves and the large blood.

Vessels run on the coddle side of the rib, the back part of the rib. So we always want to try to tap on the front part of the rib, the cranial aspect of the rib. So usually I will palpate with my left hand, kind of feel that rib and walk my finger kind of off off of that rib and then go on the cranial aspect of the rib. And if the kitty is really fat and you can't necessarily feel that, sometimes we'll kind of go in till we kind of bump the rib and then kind of slide cranially or forward and walk off of the front of the rib that way.

So here we are palpating with our left hand and then going in with our right hand, kind of right on that cranial aspect of the rib. You want to remember to go in really slowly. I think I see a lot of doctors kind of go right in there very, um, excitedly. And I, I really like to go slowly because you don't always know when you're going to hit that aor fluid and you don't always know that you're in exactly the right spot. So obviously there are sensitive tissues in there, there's blood vessels in there. We want to be careful about how we're tapping. So advance really slowly. Sometimes you'll feel this pop when you go through the plural space. You may not necessarily feel it and then hopefully you will start to aspirate air or fluid.

So this is a little butterfly catheter, um, that is all the way in, kind of up to the hub. And then we're aspirating using the line of the butterfly connected to a three-way stopcock. We always want to talk to people about risks or think about risks of chest hat before we do it. So it is not unusual that you will introduce a little bit of air when we're doing a tap. And so if we take X-rays after a tap, don't be surprised if you see a little bit of air. Um, obviously we don't want it to be a large volume, we want to be aware of it, but that is something that can happen. They can have bleeding secondary to lacerations. It's pretty uncommon that you'll see a severe arterial laceration and development of a hemothorax, but it is a complication that we think about. And if you're removing large volumes of fluid or air, they can sometimes develop some hypotension. So it's always good as they're recovering to check a blood pressure. And in really severe cases, usually chronic plural space disease cases, they can get this interesting condition that's called reexpansion pulmonary edema. So because the lungs have been collapsed for so long and kind of compressed by air or fluid, when those lungs rapidly re-expand, they actually can get severe inflammation and they can develop pulmonary edema in the lungs because of that. It's not something that we see very commonly in dogs or cats, but it is, um, pretty well reported in human medicine. And so I think I have a CT image of that coming up next. And then little things like hematoma or caas at the puncture site, kind of depending on how we're doing our tap, if you hit a small skin vessel, something like that, that can develop a little bit of fluid or bleeding there. And sometimes applying some compression can be helpful to minimize that.

So this is a case of reexpansion pulmonary edema, um, that was imaged with CT. And basically the idea here is that there was a large volume of, I believe, plural affusion, um, on this patient's left side, um, and they, sorry, right side. And they, um, developed an acute inflammatory response in that lung as it re-expanded. And so they can get, as it re-expands, the Alvi can basically rupture and they can get pulmonary edema because of all of this inflammation that occurs. The lymphatics are affected, surfactant is affected, and it usually resolves with time, but can be really severe in people and does sometimes require things like mechanical ventilation. So we just want to be aware of this. We think about it more, kind of when patients are having thoracic surgery and we're taking things out that have been in there for a long time and we think about the lungs re-expanding. But it is something that we try to monitor for, usually in the, the first kind of 24 to 48 hours after a procedure like this. And if they go into respiratory distress, we want to know about that, um, and see, does it look like there's air fluid coming back? Is there something else going on? These are good things to check for.

Um, ultrasound is something obviously that you guys know we use a lot in the emergency room and it can be really helpful in terms of evaluating the chest and looking for changes there. So it should not be a substitution for physical exam, um, triage, and your history. Those are really the strong skills that all of us have to diagnose these problems, but it can be really complimentary. It's nice because it's rapid and non-invasive. We don't have to take a patient down to Radiology to do any kind of Imaging and you can be kind of brief and good, a, get a good idea of saying, yes, there is plural Fusion, yes, I think there's a pumo, yes, something's going on in the lungs, especially in those patients that we can't get stabilized right away.

Um, there are some different methods for doing this, but the classic method, um, is with a patient in sternal or lateral recumbency, Imaging five different sites on the chest. So ideally you'd like to shave a patient, that's not always possible. If you can't, you want to part and wet the fur and apply alcohol and ideally gel as well. And then we look at these different sites. So on both sides of the, the chest, we look at what's called the chest tube site, which is kind of dorsally and codly between ribs 7 to 10, where you would put in a chest tube. And there we're looking for changes in the lungs or evidence of a numo thorax. And then you want to look at the paracardial site, which is basically over the heart on both sides to look for things like paracardial diffusion and also plural diffusion, which you can see around the heart. And then you want to look kind of, um, at the cranial aspect of the abdomen ventrally near the diaphragm. A really nice view sometimes is to look kind of through the diaphragm into the chest and we can sometimes get a good view of the heart that way and also evaluate for things like plural diffusion.

Um, this is just a depiction of where those sites are. So the chest tube site is kind of up here on the chest, rib spaces 7 to 10, 7 to 11. The per, paracardial site is down here by the heart. And then that last diaphragmatic site is going to be kind of up here, um, through the coddle part of the chest, looking into the chest, um, through the abdomen across the diaphragm. The really classic things that we talk about watching for, and I know some of us have talked about this in the ICU, um, in terms of a pneumothorax, we are looking for what's called a glide sign or loss of a glide sign. And a, a still picture is not very helpful here, but the idea is that when you're looking at an ultrasound image, if we look at this image on the right, these shadows that we're seeing that say RS, um, are the ribs. So these are shadows from the ribs. And then in between is the lung tissue. And in a normal patient that is breathing, you should be able to see kind of the plura or the chest wall move against the lung, right? So when we breathe, our chest wall and our lungs kind of move like this. And so if you're looking and you can see that in a patient, it means there's not anything in that interface that's preventing you from being able to see that. Whereas if you look and you just see those structures, but they're not moving, that indicates that there's something that is there that is preventing you from seeing the glide sign. So that would be really classic for a numo thorax.

Um, things like lung rockets or beines are things that indicate disease within the lungs themselves or fluid within the lungs themselves or inflammation. And so seeing these kind of increased shadows or increased, what we call comet tail artifacts, can indicate disease within the lungs themselves. A step sign can tell us about, um, basically kind of extensiveness of how severe a disease is. So sometimes you'll see a glide sign partially, but then you won't see it in the rest of the chest and that can indicate that there's a partial pneumothorax. It'll kind of look like this step that you can see here. And then the last thing is the la, loss of glide sign, which like I said, in a still picture looks just like, um, a glide sign, but you're not seeing that movement happen. And these are all things that are good to look for in general in patients in the emergency room, in ICU. And so if you know, if we're looking and you guys are helping us, always ask us questions and we're happy to kind of look at things together so you can get a better idea of what we're looking at because I think that this is really helpful.

Um, so this is just an example of using T fast, um, which is thoracic focused assessment with stenography for trauma or or triage, sorry, I didn't mention that, to look at a chest cavity. So we're looking here at the paracardial site. So this is the heart in the middle, um, and then around the heart, you can see that there is fluid. And so this is a patient that has plural affusion that's pretty significant, um, and so there's fluid within the chest cavity in the plural space.

Okay, lastly, we're going to talk about radiographs. Let me see, how am I on time? Okay, I think we're good. Um, so I just wanted to go through some of the really classic things that we will see with radiographs in cats for the more typical diseases that we see. And the first one is pneumothorax. This is a pretty cool one because it's, it has really classic radiographic findings. And if anybody from Radiology is on here and you want to add anything, please do. Um, but classically when we think about pneumothorax, we think about retraction of the lung lobes away from the chest wall. So if you look at this image and you look at kind of the periphery of the chest cavity, you can see kind of in between the lung lobes and the diaphragm here, there's just kind of black and then ventrally here, there's kind of black. So that these are areas where the lung lobes are actually kind of smooshed up because of air. And you'll also see sometimes that the heart looks like it's floating off of the sternum because there's air in between the heart and the, um, body wall within the plural space. So those are really classic things that we see. Oop, sorry, with pneumothorax in these, in this area of the periphery where there's retraction of the lung lobes. You also won't see the normal vasculature of the lungs. And so if you look there, it'll look like you won't see these normal, um, blood vessels, pulmonary vessels, those kinds of things that you would see within the lung lobes or around the lung lobes. And so that can be a good indicator too.

Pleural fusion, so fluid within the chest cavity, is also going to look like retraction of the lung lobes away from the body wall, but it's more scalloped. So you'll kind of see these rounded lung margins that kind of look like the lungs are floating in fluid. And then ventrally on this radiograph, you can see kind of loss of detail, fluid opacity that indicates that there is some fluid in there. And in this patient, actually, the trachea is kind of dorsally deviated. So instead of kind of tapering down normally to the heart, you can see that it's kind of pushed up. And this would be a case where I would also be suspicious of something up here in the mediastinal space that's kind of pushing it up. So a mediastinal m, m, with secondary fluid or something like that.

Congestive heart failure in cats can be tricky, as you all know. Um, but things that we think about are evidence of cardiomegaly, if you can see it, especially on VD views. We kind of talk about cats having that Valentine shaped heart, which can be really indicative of biatrial enlargement. And then an increase in pulmonary infiltrates around the heart. So in what we call the periler region, which is kind of just coddle, um, to the main stem bronchi, around the dorsal aspect of the heart. And then we also will sometimes try to look at the pulmonary vessels, which are a little bit hard to see here, but enlargement of the pulmonary vessels, especially the vein, can indicate that there's congestive heart failure. And then this is a VD view of the same patient. This patient, these patients are tricky, right? So this, this pattern you can see in the lungs looks a little bit patchy. And this could also be concerning for something like some kind of infiltrative disease, but I do feel like heart failure in kitties can look like this. And so reassessment after we treat them with some lasic is really important because if we're seeing improvement there, that's going to give us more information about what's going on too.

Feline asthma has some really classic findings. The most significant of which is flattening of the diaphragm. So instead of the diaphragm kind of having that normal rounded shape that you would see, and let me just go back here so you can kind of see what this one looks like. So you can kind of see this nice slope and rounding of the diaphragm in this kitty. And then if we come back to this asthmatic kitty or chronic lower airway disease kitty, you can see the diaphragm is really flat. That's something that we'll see classically in cats with feline asthma. And then also what we call a bronchiolar pattern, where they have, um, increased opacity around their small bronchioles, which is a little bit harder to see in this x-ray. I don't think I enlarged it. We'll see in a second when I click, but they kind of look like these have, they have these little donuts and sometimes tram lines where there's increased opacity around, um, the small bronchials or small airways.

And then this one, just for fun, is obviously a patient that has a diaphragmatic hernia. So if, if you take X-rays, if you, for example, hear dull or muffled lung or heart sounds and you're like, oh, they probably have fluid or, you know, maybe they have paracardial fusion or something like that, and the patient is stable enough for us to go down and take an x-ray, and you see intestinal loops in the chest, obviously we're dealing with something different and thinking about either a traumatic or some kind of congenital diaphragmatic hernia, um, that based on the presence of intestines in the chest would be surgical. Less common, but definitely something that we see.

So I think that that is about all I have. Um, you know, like I said, I, I think one of the most important things as a takeaway here is don't be afraid to take time with these patients and to go stepwise and stabilize them first before we do other things. We have a lot of tools, um, to our advantage, manage in the emergency room that we can use to try to help these guys get more stable before we do more diagnostics and think about common things that happen commonly. You know, these are going to be the most common causes of respiratory distress that we see in kitties. And so there definitely are other things that are unusual, but these are the things that we're dealing with on a, on a common daily basis. I think that's all I have. If anybody has any questions, I am happy to answer. Let me peek in the chat. I think I can't. Oh, here we go. Okay, Heidi. Heidi, are you still here? Is she gone? Um, it does look like she is gone. Okay, so Heidi is talking about looking at, um, the wavelength on the pulsox to see if you're getting good accuracy. And I think that's something that Dr. Cummings is going to talk about too, next month when she talks more about anesthesia monitoring. On our little handheld machines, it's not as useful, um, because sometimes we don't, we can't see a great wavelength on there on all of them. I can't remember if they all have wavelengths that we can see or not, but that can be something that can be helpful too. Anybody else have any questions? Mary Beth and Britney, thank you guys for coming. And I just wanted to mention too, Mary Beth sent me an email, um, the other day. I think I just replied to her, but there's some interest in talking about high flow. And it's definitely on my radar. I've been waiting because we, Dr. Snow and Dr. Hollahan and I are also just learning about high flow. And so I wanted us to get a little bit more comfortable with it before we do a lecture. But it's definitely something that we'll try to do probably in February or March. But in the meantime, if people have questions, come find us if we're using the machine, which I think has been in use this week, it sounds like, you know, don't be afraid to go and ask the team if you have questions about it, especially if they're not looking like they're super chaotic in there.