All righty. Well, the last talk of the day, I'm glad everybody's sort of staying with us, is talking about plural space disease. So it's something that doesn't often get a sort of as much attention, but in terms of treating the treatable our theme for today, given this is something that we can stabilise relatively easily, I thought it'd be worth just covering a little bit more how we sort of deal with these patients a little bit.

So that's our, our focus for the last hour today. And in terms of, of common causes of plural space disease, this isn't really an exclusive list. I, I realised, as I was just reviewing this before we, we started today, is that I've missed off diaphragmatic rupture on here, but it goes to show there's lots of different types of floral space disease, there's lots of different causes.

So, you know, pneumothorax, it might be traumatic or it might be a ruptured bulla. Hemothorax might be a trauma or a coagulopathy or some kind of horrible cancer. Lots of different things in there that can all cause really quite significant respiratory distress to these patients.

The bottom line basically though, is, is if you suspect there's tra space disease again, we're going to proceed with our thoracentesis very, very quickly. And it's my experience, maybe I'm shooting myself in the foot for saying this, but I'd say the vast majority of cases you can do this without any sedation. There's always the odd fractious patient or the patient that is genuinely too distressed to be able to handle this, without some sedation, but generally speaking, I'd, I'd say it goes pretty well most of the time.

And people are, are often fearful about doing this because, I mean, at the end of the day, we are sticking a needle into a chest. When you put it like that, it's something that sounds like we should be concerned. But actually it's good techniques that we're likely to have, we're not going to be too gung ho sticking needles in places, not using the technique.

Complications are really quite rare and as you said, before, it's, it's really diagnostic as well as therapeutic, so it's sort of win-win, basically. I thought I'd mentioned sedation protocols if it's needed. As I said, typically I find if we've got, you know, calm people and that includes sort of us and, and our staff around us, a a quiet place, I often sort of take the cats off somewhere, a little bit quieter to be able to do this.

Oftentimes nothing is is needed, but If I do need to give something, then again, it depends on the patient in front of you, but I'll tend to go with low doses of drugs I'm familiar with and typically I'll think about opioids or combining that with another drug if, if I need to, again, using sort of low doses to affect. If I do need to sedate for thoracentesis, I, I kind of break my own rule a little bit cause normally I have no IV catheters for a patient in respiratory distress kind of rule unless I've got a convincing reason to, to deviate from that. I feel like if I'm sedating these patients, I, I, I feel more comfortable having IV access so I can top up drugs more quickly, if, you know, I'm, I just feel more prepared.

So I do think about getting an IV in these patients and quickly if I am trying to give them sedation, then I can just proceed with things a little bit quickly. And if there's an emergency that happens, then I can feel like I can handle that a little bit better. But as you said, hopefully not that common, you'll have to use this and certainly Hopefully you won't get patients where you're down at the bottom of the list here necessarily too often.

In terms of, of complications, I, I appreciate that I'm probably very gung ho about doing this and I may be encouraging people to do serracocentesis before they might otherwise be comfortable with. I'm talking about doing it almost sort of to follow on from the, the triage of these patients in terms of the, the timings. So I want to present a balanced view and say, well, actually, what are the complications, what are the risks or the benefits?

And There are some complications, but they're very rare. But to be balanced, there is a risk of a nitrogenic pneumothorax that we create. Typically, it's most likely to happen because we didn't have a close collection system that we'll see, in the, in the next slide.

Really due to our estrogenic injury to the lung, people really worry about sort of lacerating the lung and, and things like that during thoraccocentesis, but The nice thing by definition about having plural space disease is that there's a barrier between your chest wall and the surface of the lung because you've got this air or fluid in the way. So the lung should not be the first thing your needle touches. And you can It doesn't sound great when you say this, but as you take out the air or fluid that's in there that shouldn't be in the lung expands and comes up towards you, you can feel a sort of scratching sensation on the needle as that happens.

So you, you get a heads up that, that the lungs coming towards you. So that's unlikely with sort of good, good technique, I would say. There is a risk of haemorrhage and this figure shows quite nicely, just to as a note for all of us to remember that behind each of these ribs there's this little neurovascular bundle.

And so simply by doing arthracocentesis off the cranial edge of each rib as the pictures showing here, we'll lessen the likely of any haemorrhage and with, with good technique again, infection is going to be quite rare. So, Not that common, thankfully for any complications. With regards to contraindications, if you read the textbooks and, and so on, you'll read that having a thrombocytopenia or a severe coagulopathy, so, issue with our plotting factors, is, is a contraindication to this.

And I've, I've put this with a question mark because It all depends on clinical context. So, let's say I've got a patient with horrible thrombocytopenia, it's spontaneously bleeding everywhere, and it's not doing well and there's a sliver of pleural effusion. I'm probably not going to go chase that by doing strachocentesis because I don't have that much to gain as opposed to I've got a lot to lose with that.

Versus if I've got a young dog, 8, anticoagulant rodenticide 3 days ago, now comes in with a hemothorax, severe respiratory distress, I'd probably need to address that pleural effusion to be able to stabilise the patient, not necessarily emptying it all out completely, just taking off enough to stabilise the patient. But that by itself is, isn't necessarily an absolute contraindication. So, so the clinical context and clinical judgement, It's gonna sort of impact whether that is an absolute contraindication or not.

In terms of equipment, it's pretty simple stuff, thankfully, just to sort of review. So we're getting stuff ready to, to clip and scrub the patient and I always wear sterile gloves for this, just so I'm aware of sort of where my hands are. So I'm, I, I know that I'm more careful about using the appropriate clean technique.

And it's a way of creating, so the equipment is to get a closed system of something that's gonna work. So there needs to be something that's gonna poke into the chest, whether that be a butterfly catheter or a regular needle, an over the needle catheter. And then I prefer to have some extension tubing immediately downstream of that before we have a three-way tap and a syringe to collect it.

The extension tubing just providing me a distance between the person doing the collecting over here and making sure that they're not accidentally sort of pulling at . Where I'm trying to, trying to sample. I'd say I like using butterfly cats for cats, but let's say if we have a particular cat who might be over-conditioned, and it may simply not be long enough.

So if that's the case, then that's not really gonna work, but we can use those in dogs too if they're small enough. I do quite like using an over the needle catheter or something that's been a little bit longer, and you can use that with or without a stilette. I quite like taking out the stilet cause I just feel a bit less nervous about having some giant stilet inside the thoracic cavity.

But then if you do that, you just have to be really aware that that catheter can be very prone to kinking at the, the side it enters the skin, which isn't really going to help you evacuating the claw space. So just kind of thinking what do we have, what are we familiar with, having some kind of close setup, that we, we can drain the chest and collect a sample from. In terms of performing it, I'm sure people have done this many times before, but I think historically we've always said what the landmarks have to be.

But in all honesty, I can't remember the last one of these that I didn't use the ultrasound guidance for. So if we have it, absolutely, let's use it and find a sort of a good pocket of where we, where we think the fluid is or having identified where the lung point is and the pneumothorax to make sure that we're kind of getting into a nice pocket of air there. That said, if we don't have ultrasound, you know, it's not working, we haven't done it, whatever the case is, and we still suspect plural space disease, then it's still 100% appropriate to do this so-called, it's termed blind, but that's seems a little unfair, maybe.

We're using specific landmarks that we, we know to be the, the right spot. So, If we're doing it blind in sort of inverted commas there, then we'll aim for around the 7 to 9 inch coststal space over here. A nice spot because it's basically caudal to where the heart is but cranial to where your diaphragm is gonna come in, so you're less likely to get liver aspirate, which is always a good thing.

So around that sort of spot. Going off the cranial board of the ribs we talked about, so we're not poking that neurovascular bundle, causing bleeding or, or pain to the patient as we sort of disturb one of the nerves there. And then in terms of location up and down the chest, generally speaking, I'll divide the chest into thirds, so I'll sort of draw an arbitrary line in my mind's eye here and an arbitrary line down here.

And then if I think I'm draining fluid, I'll go at the junction of the top and the, sorry, of the middle and the bottom third, so I'll put my needle round about here. If I'm draining air, then I'll go at the junction of the top and the middle so so somewhere, somewhere around where the cursor is pointing to now. So thinking about that in the patient internal recumbency.

If I have a patient who's in lateral recumbency for some reason I'm trying to get air, then I'll just go at the deepest part of the chest of the rationale that's where the air will all have collected. So again, sort of judgement as to what's going on and what we think is the right thing to do. But in a true emergency, you know, maybe the patients on the pose of respiratory arrest like we need to do this immediately rather than faffing around counting ribs, a sort of easy cheat is just to find the sternum and trace upwards and basically on the right line to, to do your thoracocentesis.

That could be a nice, a nice shortcut to use, save a bit of time as well. In terms of the actual technique, then we can kind of see that our, our willing to volunteer here getting clipped and prepped, us finding that, that location either with ultrasound or, or there and, and going off the, the cranial border of the rib. Something that I find quite helpful to do that I thought I'd mentioned at this point is rather than just having us just holding completely onto the needle and having it just going into the, the chest and risk having the patient move and our needle fall out.

I almost like to, to hold the needle and, and steady my hand against the chest wall. So if the dog does move, I and the needle move with it, if that makes sense, so that the needle isn't just sort of falling out with the, the slightest movement, especially if we're not sedating our patients really heavily to do this, that can be something that just makes things a little bit easier, as well. And then in terms of needle track, what's the best way to do this?

Initially, I'll angle the needle in perpendicular to the chest wall, so I can anticipate I'm going to go through the skin, I'm gonna feel going through the intercostal muscles, and then I'll feel almost like a little pop or sort of a loss of resistance, and at that point, I should be in the po space. I do say that the only exception to that is if we have a particularly over-conditioned patient again, let's say. Sometimes you can feel a little pop as you go through layers of fascia with, with significant amounts of fat tissue.

Then the average patient, as you feel that pop, you'll be into your, your paw space. Once I'm in, then it's a case of angling the needle down, so it's aligned more parallel with the body wall. And again, that allays some of the fears that people may have about poking the lung or causing lung lacerations, etc.

And I'll deflect that needle based on whether I'm trying to go ventrally for, for fluid or more dorsally for for air as well. But generally speaking, at that point, as soon as the needle pops through, we can have whoever's operating the three-way tap to aspirate, and we'll, we'll know if we sort of need to, to redirect the needle as well. And as we go, we can figure out, are we getting enough volume off to explain the clinical signs and do we predict that this is gonna be a, a, a therapeutic procedure as well?

Something that's really important to do is you could be forgiven for doing a thracentesis and thinking, job done, all sorted. But something that's really useful to do is to basically reassess the patient just straight, straight after the procedure is finished. So in terms of auscultation, for figuring out if there's still any, any dullness there, and potentially repeating ultrasound to see has the, the lung point changed?

Have we removed all of the air, how much fluid is left behind. And the rationale behind that is that if the patient then has a change in condition later, and we knew where we were up to. And we'll talk about if we did have, for example, a pneumothorax as a complication later, we knew what things were like before that happened.

So it can be useful just to have a sort of new time zero for how this patient's doing. Cytocentesis is one of those procedures I, I really like doing because you get an immediate improvement in how they look, assuming that you're, you're removing a significant amount and It's safe to say typically these patients will have quite a rapid breathing pattern before you do the thoracocentesis, and as you remove enough of the air or fluid for that lung to expand, you can actually see them take a deep breath or, or make a kind of sigh. And it's really satisfying to see that obviously, if there's more air or fluid that that will come, then we'll keep going, but at that point, you know that you've made a sort of clinical improvements to these patients and I had a case as a resident, I still remember now where I was doing thoracentesis on a cat, but in, in West Philadelphia, we often saw patients quite late, let's say in the course of their disease process.

And there was a cat that had been in respiratory distress for probably 3 days on sort of talking to this owner who'd been trying to sort of put off coming in. And we did thoracentesis and we drained a large volume of this cat. And partway through the cat took a, took a deep breath and I was quite happy.

And then the cat literally went to sleep with no sedation on board and could literally probably just breathe again. So you can see this immediate improvement and in terms of getting a respiratory distress patient stable, that's basically the, the sort of the gold standard, if you like. We said it's nice to see what's, what's left in terms of, has it been effective.

So maybe if I remove some air, but not all of it, can I expect this to kind of be a problem again later? What am I left with? Thinking about how much has come off and is it significant.

So, for example, if we look at this radiograph of this cat with phile allergic airway disease, it's actually, it's got pretty bad disease radiographically at least. And we can see that there's a mild pneumothorax over here as well, probably from sort of ruptured, ruptured distended lung. If this cat comes in with severe respiratory distress and I do serracentesis and I get off 20 mLs, I know that that isn't really the, the problem at the end of the day, that there's, there's something else.

So putting that volume in context to tell you if there's likely another problem left behind is important. So, for example, if it's a trauma patient that had a pneumothorax, is there, are there contusions that are now going to become evident. If a cat with heart failure, does it have palm edoema too?

Is there a cancer, you know, some, something else as well. So it's worth kind of thinking about what we're sort of leaving behind. And probably one of the most frustrating things that comes up when you're dealing with this procedure is it can be immediately life-saving.

It can stabilise them very quickly, but sometimes it just doesn't go how you want it to. And what can occasionally happen, and I imagine that this has happened to many of you as well, is that you get blockage of the needle. So you, you know that there's a whole bunch of fluid in there.

You can hear it, you've maybe seen it. You know you're in the right place and you just can't, you just get negative pressure, you get nothing else. And if you were to look, with the ultrasound, what you sometimes see is these sort of floating strands of fibrin up here.

And you can just imagine that you aspirate with a needle and this just gets sucked straight into the end of that needle and stops you getting all of that fluid. And there's some things that you can do to try and troubleshoot that rather than sort of, you know, repeatedly going with different sized needles, coming up with the same sort of problem, patient, you know, losing tolerance this understandably. Is potentially doing things like changing into a smaller syringe, so we're not applying too much pressure, so we're less likely to actively suck these sort of strands into the end of the, the needle that can help.

But something that can make a big difference is, let's say you do strachocentesis and you drain off 10 mL of fluid, or maybe 8 mL of fluid, and then it stops, and you know there's a lot more than that. If if you if you've got a closed system, it's all clean. You can safely flush back one or 2 mLs of that fluid back into the chest without without opening the system, I should say.

And if that has got something stuck in the needle, it will often clear it a little bit, and then you can maybe try repositioning or sucking slightly differently and try and get some more off. So if I'm doing chocentesis on one of these more challenging slash annoying patients. Then I'll, when I'm emptying out my, syringe between sort of aspirates, I'll maybe leave one or two mLs in the syringe, so I have this in-built flush to be able to sort of clear that needle if necessary.

And sometimes that helps, but sometimes you might just need to place a chest strain to sort of empty these ones out and it's worth just getting a sense as to when the thoracentesis should be a simple, straightforward, quick procedure to do. If the situation's evolving and it's not that, then thinking about changing strategy is important. And just making extra sure that if you are using an over needle catheter, it's not kinked at any site, especially if, you know, it's a, a smaller catheter.

It's really worth exploring that, especially if you maybe been repositioning it because that's an easy thing to, to troubleshoot as well. It's really, really, really important if there is fluid in there that it's collected, and it's analysed. Because we've been focused on the therapeutic aspect of thoracentesis, but really it should be diagnostic too.

And so it's not to say you have to send every fluid off for everything. What I typically do is I'll collect samples into EDT and plane tubes, and then I can sort of choose at a later point what I want to look at. So if I, I generally will send these off to the lab as well, so they'll come back with, fluid analysis and cytology and then decide if, if culture's necessary, but having samples available to culture if we do think it's an infectious process.

But more and more I'm, I'm a big fan of doing in-house cytology of these samples, because from an emergency standpoint, I need to know if there's something that will change my plan for what I want to do. And one of those things is if there's a pyothorax. So this is a, a beautiful cytology here, lots of intracellular bugs.

I really want to know about this right now because it is gonna change what I do. And so I feel confident doing in-house psychology to look for that, and then I'm just sort of a day ahead of, depending on how quick your lab is, you're, you're sort of getting the heads up as to what you need to do. In the balance of being fair though, I, I'm a big, I, I generally encourage people to sort of do their own cytologies to find sepsis.

It's one of my sort of my, my, my big missions, if you like, to try and sort of get people to think sepsis earlier on. But in the spirit of that, I think, and I have to be careful with this myself, not to overinterpret the findings. So, You might want to do cytology on some pleural effusion and you see a bunch of lymphocytes in there.

And the worst case scenario in me saying, well, this could be lymphoma. And it was interesting as, again, a study that came out just last year that looked at pleural effusion in cats that were lymphocyte rich and whilst many of us may well think lymphoma, it was interesting that, sort of 70% of these cats actually have cardiac disease, . And you know, there, there are other diagnoses that go with that.

So, This is just one example of where just being really careful not to interpret things, definitely having a look, looking for things that is going to change what we do from a treatment perspective. But just bearing in mind that in terms of analysis of this fluid, unless you're very confident with all kinds of cytology, it's always worth submitting that to an external lab and getting their input on what they think as well. As well as being on the lookout for, for pyothorax and finding sepsis early on, another type of fluid that I'm particularly interested in is if the patient has a Pyothorax and This is probably one of my least favourite types of plural space disease, in terms of how easy it is to fix and how well patients can end up doing with it.

But in an emergency standpoint, it also is relevant to me because although we said for average thoracentesis, the risk of complications was low. Kylothorax is maybe the one I have more of a healthy respect for in this regard, where I, I do believe that there is a higher risk of us getting an iatrogenic pneumothorax after a straightforward thoracentesis and We've probably all seen these kind of thorax effusions. They look like this sort of awful milkshakes, sometimes strawberry flavoured, sometimes vanilla.

And if you did cytology, you'd see sort of like a, a mix of, of neutrophils, and macrophages, small and, and small and sort of medium lymphocytes quite a sort of mixed mixed but probably chronic inflammation. And the reason that you can get a pneumothorax with these is that it, because it's such a sort of chronic effusion, it's been there for a long time and Kyla's fluid is very inflammatory, it's very irritating to the flora. And you can end up getting a, a sort of a fibrosing colitis.

And if you do serracocentesis and you completely evacuate that plural space, you get them back to sort of dry in there. You're asking this for the fibros slightly shrunken lung to expand very rapidly and fill a space that it's not really used to doing, and that can cause a sort of a tear in this this fibrous tissue, which causes immediate air leakage. And so generally speaking, I'm, I'm wary of these.

I don't know for sure it is a Kylothorax as that fluid starts coming out because it could be pyothorax, that, you know, we mentioned that it could be something else. But if I'm concerned it could be a kyothorax, what I'll do is I'll only do syracocentesis until clinical signs have been improved. I won't necessarily try and get every last bit out as the temptation might otherwise to be.

Because if pneumothorax does happen, it tends to occur as you completely drain the thorax as opposed to just get some off. So I'm, I'm just wary, I think in summary as to how I deal with these. And the degree of pneumothorax can be quite mild, but I have seen cases where they've had a continuous pneumothorax and and needed a chest strain and can recall one very unfortunate cat that needed a lung lobectomy because it had persistent air leakage, which with a kind of a rubbish underlying disease process anyway, it's the last thing you kind of want to enforce on these as a complication of something that we did that was trying to help.

So just to kind of have an awareness of that. And to kind of demonstrate that in a, in a different way, these are radiographs taken from a cat with from a patient with a pylo pylohorax. You can see the significant amounts of effusion, but if you really get the sense of the rounding of these lung lobes, they almost look kind of scalloped, and that's that really sort of fibrosing nature of this chronic effusion, and that's just really doesn't have any give if you suddenly ask that lung to expand.

So that's the kind of the, the reason that we run into problems in some cases, I should say with this specifically. So strachocentesis is the, the first line in treating suspected pleural space disease. But there are some cases that we might think actually you, you're gonna benefit from having a chest drain placed.

And some of those that I've listed here. So in the context of a pneumothorax, it's really for persistent pneumothorax. So, This is a patient whereby maybe it's a, a patient that's come in with a spontaneous pneumothorax and we're doing strapocentesis and we're still doing it half an hour later, the air is still coming.

We just never get to that point of getting negative pressure. And we checked the system, there's no leak. It's definitely not us, it's definitely coming from inside the patient and it's just the system that's coming.

So that's kind of one of these criteria for thinking about a chest drain. The other one might be a patient with a pneumothorax who you do thoracentesis and you do get negative pressure, and you assess the patient and you get your new baseline and then 30 minutes later, your ops are done and the respiratory rates back up again and you're back to square one and you scent them again and you get a bunch of air out, you get negative pressure. And you just, you just end up with this kind of air building up more frequently than not.

And There's not really a hard and fast rule as to say, well, when do you have to place a chest drain in those. I tend to have a 3 strikes rule, so if I've drained them, twice in a relatively short period of time, the third time I have to do it, or I'll say let's just get you stable, and let's place the drain right now, assuming that, you know, the owners are on board, etc. As to what that short period of time is, it really depends.

So if I'm draining them once a day, then, you know, that's not that big a deal. I can do that. But I'm doing it every few hours or I've, you know, done it twice since I started my shift sort of thing, then I might think about is this the right decision to place a chest drain.

And then other times might be if there's pleural fusion, so to be able to medically manage yothorax a little to drain out all of the infected material to be able to lavage and, and sort of break down any, any chunks or anything that might be in there. And for managing yothorax is a sort of more, more chronic space disease as well. So those are probably the, the most relevant decision-making points as to when you might face a chest strain or not.

To go through the technique briefly, to make sure people are happy with that. There's lots of different types of chest drains out there, lots of techniques available. So, traditionally, there's been this sort of trocar type drain, which, typically, is a little bit larger bore, and slightly firmer material, and has this metal tyle running down the middle of it sort of aid in placement to sort of get that size of drain placed in the patient.

That can be placed with using the trocar or with a tunnelling technique we'll talk about. All these other smaller, drains that are typically placed, using a so-called modified singer technique, which basically involves using a wire as a guide to insert that drain into the claw space instead. So quite a few different options out there.

If we start with these trocar type drains, so you can really see all these sort of metal spikes really look like and they have the, the little point of it protruding from the end to sort of help you gain access into that little space. We can see on the image over here what the ideal pathway of one of these drains is. So we want it to enter the skin, probably over here, a couple of rib spaces, tunnel under and then enter the chest cavity about your sort of 7th and 9th intercostal space.

So exactly the chest tube site we were talking about with ultrasound earlier on, and then aim to go forward, ending up around the sort of 2nd or 3rd tetebrae and right over here. So that's kind of what we're aiming for. You can appreciate if you or I were having one of these placed, I think I probably would like to be unaware of that.

So the recommendation is that these our patients are under the general anaesthesia for this to, to make this a sort of safe procedure since the movement at a critical point in time would, would be pretty devastating potentially. The question comes, what sort of tube size should you pick, and that is gonna vary a little depending on if you're trying to drain air with a pneumothorax, you can get away with a much much narrower tube, versus if you have a pyothorax and you're trying to get sort of quite a lumpy textured fluid out. And there's lots of stuff out there to say you can look at, you know, if you have pre-existing radiograph for these patients, you can compare the bronco size and go with the tube that size.

And you can feel the intercostal space and say what can actually fit. There's tables out there as sort of one reproduced here to say what do you pick for the average size of the patient. But in all honesty, you might just look and see what you've got in your cupboard that you can sort of get into the patient.

So there's obviously different factors that, that go into this. Although most commercially available tubes have got some fenestrations, already, some little kind of holes for excess drainage, you can make additional ones in these tubes, if, especially if you had a sort of very, you know, like a pyhorax, for example, where you anticipate difficulty draining. But it's really, really important that you, if you make these additional holes that you're not compromising the integrity of that tube as you can appreciate.

So as a general rule to try and stop us getting an extra problem, the individual holes should be less than 25% of the tube circumference and What's probably a good tip is if you put, if you do put any additional holes and if there is a radiographic line on the tube, you put the last hole on that line so you can make sure that all of the holes you've made are actually inside the plural space, so you're not tracking, tracking fluid from inside the chest to potentially your subcutaneous tissues, as well. So you can make additional holes, but just to make sure that that's going to be a help rather than a hindrance. In terms of preparation for these chest tube placements, and we said about anaesthesia with a protocol including some analgesic as well.

Stabilising the patient in advance as much as possible. Sometimes if, you know, if you're placing one of these for a persistent pneumothorax, so you can't get negative pressure, it might well be that you, you have to have somebody doing thoracentesis simultaneously, not ideal, but just whatever sort of clinically indicated. And in terms of positioning, then I, I would really struggle to place these in a, in with the patient in a position of a lateral recumbency affected side uppermost, given the sort of the, the nature of the tube placement as we'll see.

So in terms of the actual details, then we'll do a, a wide hair clip and preparation basically of the entire side of the chest, and finding out exactly where we want to go as well sort of seeing the, the next slide and then doing a little local block, I think really helps these patients as well. In terms of landmarks, we've mentioned that we want to create some kind of tunnel in these patients so that we don't have the tube going straight in, the patient going straight into the clawal space for the risks that we don't want to have things tracking in and out of the plural space. And also when we hopefully get to take this tube out later on, we don't want to create potential complications for things that might easily go into that chest directly from the, the skin wound.

So I typically make an incision at about the 10th intercostal space here in the skin, just that little bit larger than the tube, and then aim to enter the, the chest a couple of rib spaces forward as we've said. In terms of how we actually get that chest rain in, I think the, the way that was previously done, and I think this is the way I placed my first chest tube, was to use this so-called roar or force technique whereby you, basically you put the chest tube and through that skin incision, you tunnel forward a couple of spaces and then you elevate the chest tube up to 90 degrees above the patient. Have your fingers resting a couple of centimetres and just above that, and then they say with a a sharp thrust and to basically use that spike on the end of the chest drain to go down in the intercostal space and hopefully, fingers crossed, your fingers holding onto your drain here will stop it going all the way through.

And I'm very thankful to say that the times that I've placed strains like this, I haven't caused major injury to intrathoracic structures, but it, I think I was lucky and it, it can and does happen, and this is an image showing just that of it's an inerative view showing where a chest strain has been placed and right through a lung lobe or you could potentially hit vessels as well. So. Whilst it has been done like this, and I think a lot of people feel very comfortable doing this, there is a significant risk of, of injury and so there's probably better ways or preferred ways, but I would probably do this now.

And although it may seem like more of a faff, to be perfectly honest with you, this is, is a safer way to do it and with a bit of practise, this can just be sort of like the, the new normal. So. With this, we create a tunnel and we're, we're using some hemostats or similar to kind of assist us with this placement.

So again, we've got our skin incision made at the point that the skin, the drains going in the skin, and we're using these instruments to actually make that hole through the intercostal muscles. So we can tell whoever's handling our anaesthesia to say we're about to enter the chest just so if they are giving any breaths, they don't choose that exact moment to do this. Pause any assisted ventilation just for a second and use those instruments to pop, pop down through that intercostal muscle to get into the plural space.

And then what you can do is basically use that as a, as a guide to place your, your chest right in. So it's a lot safer and as I said, with a bit of practise, it can become a lot easier. And when we're placing that drain in, basically, we'll, you can do it with or without the stytin, whichever sort of feels easiest, but we want to be aiming the tube for the, the opposite, opposite shoulder basically.

So we're trying to aim that tube, that nice cranial ventral pattern that we saw in that cutaway image earlier. And some people recommend twisting the tube a few times once it's in to try and avoid any kinks. I'm not aware of any evidence base at all to say that works, but, I, I can't say that it doesn't either.

So just thinking about getting that tube in sort of its optimal place so it will work as possible. Instead of creating a tunnel and having your instrument kind of running one way before entering the plural space, you can actually create your tunnel in advance. And so this kind of image is showing that if you pull the skin forward a couple of rib spaces, you can basically make your skin incision and then place your, make your hole straight down just immediately below that place your drain and then as you relax the skin, you create the tunnel retrospectively.

Which I find a little bit easier but does require having sort of more helpers around. So it potentially depends on on the given day as to how practical an option that is. Regardless of how the drains placed, then we're gonna want to secure it.

So thinking about using a, a purse string suture at the site of insertion and then something like a finger trap to sort of cinch around the tube to prevent that going anywhere. And then it's often a case of getting as creative as as you can or want to create a closed system that's gonna stay genuinely close so you don't get leakage of air, so. Often these drains will come with little clamps on them, and having those clamps on rather than other ones that you might have around is important just so we're not damaging the tube.

Have a three-way tap over here, often with valves kind of on the, the ends of these, these other parts of the tap. And then you can see here some, some cable tie and just cinching that Christmas tree into the drain just so it's unlikely to just fall out and and cause a problem. But regardless of how, how much hardware you put on this to secure it in, these patients still need really close monitoring, .

Because it seems like they can get interfered within a second. I really like these patients to have these covered, to wear a string vest or have a t-shirt or, or something to stop them rubbing up against the cage door, making sure that they're not going crazy and aren't going to sort of, you know, tear this out, and making sure they're comfortable, especially if one of these bigger drains has been placed as well. Pose placement as well.

The recommendation is that radiographs are taken and to include a couple of views once the plural space has been evacuated and partly to check that the drains in the correct location and this time I'm always a little bit iffy on because I feel like if I've placed it and I've evacuated the floor space completely, then it's kind of working, so I, I have to think really carefully if I was going to start fiddling around with that drain in future, but at least we kind of know how it's located. Making sure that all of the holes are in the floral space so that for example, if we had a pyothorax that we're not sucking some of the pyothorax fluid out and then it being unfortunately deposited in the subcutaneous tissues en route to the outside, so we're not setting up complications down the line. Looking for anything else that we should be aware of, but I'm looking to see if there's any clues as to what's going on with the underlying cause once the floor space has been evacuated in terms of is there a mass there is there something else that we should be aware of.

And it is amazing what you find with these chest post drain placement radiographs. So I think one of the first drains I placed was when I was a resident, and it wasn't an overconditioned patient. I'd felt a pop.

I placed this drain. It had all been textbook, but it just wasn't really working, and I'd taken radiographs and I'd probably placed it between two fascial planes in the patient. I hadn't actually got into the chest, so that was an easy thing to sort of troubleshoot and figure out what was going on.

But there can be all sorts of things, that can be, the tip might be sort of misplaced with the, the tip exiting the chest inlet is sort of shown by the red arrow here. There might be sort of kinking of the tube and, and various other bits. So it's always worth kind of spotting if there, there is a problem just sort of early on in proceedings.

I will confess I can't remember the last time I actually placed one of those sort of more trocar type drains. I've become a much bigger fan of the, the sort of a miler type chest strains or this I should say like the over the wire technique in general. And for me the advantage of these is that they, they tend to be smaller catheters but still clinically effective, which is important, but they're well tolerated.

You can place them with a light sedation as opposed to having to anaesthetize them, and you just tend to, you have a few different sizes and that tends to kind of meet the requirements of most of the patients that you'll have. So it seems like it's more of a practical option and The cats, and dogs that tend to have them, I find just tend to eat eat once they're in. I'm having to sort of analges them less than if they have this sort of giant tube in there.

So I feel like clinically, I feel like these patients are easier to manage with this sort of smaller time training. People worry that, you know, they're, they're kind of smaller bores, so can they be used in dogs? And I appreciate this dog isn't exactly looking very clinically well, with its various other bits of instrumentation going on.

But, I find clinically we can manage dogs with kyothorax, with pyothorax, and with these, these smaller bore drains. Obviously, if, if there's something with really concreted, Soral space secretions, then maybe not, but I, I would question whether or not a sort of a, a more standard drain would be effective anywhere in those. But generally speaking, I'll feel very comfortable using these in, in canine patients as well.

And in terms of some means of how it actually looks if people haven't used these before, I think they are becoming much more popular and, and, people are sort of buying into them as a better alternative, and it's the same kind of preparation, but the difference with these is, these can be placed with the patient internal because they're just technically easier to place, so it can be quite nice for a patient with ongoing respiratory distress to not have to fully anaesthetize and put them in lateral recumbency, etc. And it's basically a case of we, the actual chest joint itself is, is quite soft. It does soften even further typically once it exposed to body temperature, explaining why they can be quite so comfortable, for want of a better word.

But they're soft to begin with anyway and so we need to sort of help that in. We can't sort of poke it in as we did with the other rigid ones. And so to do that, we'll get an open the needle catheter, place that into the claw space where we want the drain to be inserted.

I don't typically create a tunnel for the smaller bore, drains like this. I might do for the slightly larger ones, the same principles as we talked about apply, in which case I'll typically have someone pull the skin forward and then put my, my catheter in where I want it to go. And then we'll basically put the catheter in, take the style out, briefly cover over that sort of open catheter with, with a thumb or a digit to stop any lots of air creeping in, but very quickly to put the, the guide wire in through that catheter and then we can take that catheter off.

We've literally got a wire sticking in the side of the patient. It's imperative if we're using these sort of wire-based techniques that at some, at every point in time, somebody is holding that wire because there are reports of wires being accidentally lost inside the patient. So it's, it's almost like a sort of Chuckle Brothers sketch of I've got the wire, I've got the wire sort of thing as we go with this, but making sure somebody has the wire at all times.

And then we can basically use that as the guide to insert the chest drain over and again, critically making sure that we're not inserting the wire simultaneously as the chest drain goes all the way in. But once the drain's in a little bit, we can start pulling out that wire as the chest drains advancing. So, pretty easy to do.

This image shows quite nicely that there's a little butterfly, at the site of the drain here. So there's a nice suture opportunity, little holes that we can. And place a suture into, so typically one here, one here, and then a little dent around this bit, and so easy to secure in which is, is quite handy.

And you can drain as soon as it's in. So if your patient wasn't as stable as you wanted, then once it's sort of in and secure, then it's a good time to drain and again, you get that immediate feedback if your, your drains like this be in the right place or not as well. Complications of chest tra placement in general are pretty uncommon.

Some of them listed here. Again, less likely, I would say if, if you have a patient with plural space disease, there's a bigger complication of being less left with ongoing plural space disease that's clinically significant than you are from placing a chest ring well. So.

Apart from what we said about, you know, the risk of yothorax, completely emptying the chest of that, which would stand for thoracentesis too. The rest of it is, is less likely, and the bigger issue is if you're just not draining as much as you wanted to and, and making sure there isn't any, any leakage, but they can generally stay in as, as long as they're being functional. In that time though, they do require 24/7 observation in case, you know, their, their condition worsens, so there's a progression or there's a, an issue with the drain checking insertion sites and Just being mindful when they are removed, the size of the hole should be pretty small, but making sure that we, we don't suture that because there is a risk that you can get quite significant subcutaneous emphysema if you try to.

So against what might be your better instinct, just leaving that to heal by secondary intention, typically covering it with a primapore or something similar, just to prevent any bacterial invasion there. Most of the time we test strains they will just drain them as needed, in terms of the patient has clinical signs, if there's a pyothorax will typically drain them quite regularly to try and get some source control on the infectious process. And in very rare cases, more so for the persistent pneumothorax cases, you might have to consider that they need continuous drainage, .

In which case, this may be something that you, you have in, in practise, it may, may not, but there are various machines that are available for, for set and drainage of persistent floor space disease of which my personal favourite at the moment is this Topaz machine on the right here, which is, is basically as easy as it gets. The machine does it all. It even tells you how much air it's taking at any given point in time.

And stops you with this, setup of of trying to count bubbles and various things we used to, with the older ones. So lots of options out there, but do require, you do require to have them in at the time you need them. So a potential other option to have in stock for kind of your worst case scenario need continuous drainage is one of these homelick or otherwise known flutter valves.

And it basically looks like this. So in terms of sorry about that in terms of sort of general size, and you're talking about sort of 10 centimetres or so, something in that region. And it's basically a, a one-way valve that you would insert this, this blue end here into the end of the chest tube, and this would be the entire apparatus that was there.

So it's more portable, you know, if the patient was moving between clinics, this would be a good way of transporting them. And the way it basically works is that you have your chest drain attached where the, the blue bits are on the, the right here. If there is air coming out of the patient, then this rubber sleeve inside is open and the air can come out and escape into the environment, so out the patient if they breathe.

But as if air tries to get in and tries to access the, the chest, then that sleeve actually closes and prevents any backflow. So it's, it's a one-way system and, and for larger patients, it's a, it's a good way of keeping that chest empty. In terms of what else could be done in, in plural space, in management of these sort of continuous pneumothoraxis, this is a relatively newer thing I wanted to, to mention, so.

This was published in 2014 in, in JEC, this technique of this autologous blood patch treatment, but I think this particular procedure has been around for a long time in human medicine, and I believe is, is used for blood patch for people that have persistent problems after epidurals and CSF jacks and, and the like, to try and kind of create seage. And what this, this, kind of, this case series did was it reported what happened if, if people did this in, in 8 dogs with a persistent pneumothorax and I mentioned this because this is something that's quite practical that you know, if, if we have a patient who's been on a continuous plural drainage device and it's still not sealing, then we're pretty much looking at saurootomy as the next step, which is a pretty big step in, in, in my eyes. So this is a technique that isn't necessarily, isn't advocated for a first-line treatment.

It's more for a what if I've got this patient that I can't do a whole lot with? Is there anything else I can try that's it's it's sort of niche in my opinion as to when you might use it. And what these dogs had in common is they had a persistent pneumothorax that they defined in the study as persistent leakage of air that didn't respond to two days or more of conservative treatment.

So these were the ones that had been on sort of continuous drainage, just weren't really improving. And what they did was they took blood out of the jugular vein, and they basically without anteregulating it, without doing anything else to it, they inserted it into the floor space. So it seems pretty crude and indeed it is.

They took between, I believe 5 and 10% of the patient's body weight, and collected in sort of 20 to 50 mL increments until they sort of achieved their, their total dose, and they basically put it into the floor space, either by a drain if they had one shown here, but potentially by a strachocentesis needle if not, so a sort of other alternative. They took radiographs in 6 of these. Right, here we go.

Yeah, you're back. Hello, sorry, I don't think like that. I don't think the system reviewed that that technique very well.

Sorry about that. Hopefully you heard most of that. I think where we're up to, we were saying that we'd taken the blood out, we put it into the floral space, and I, I think, yeah, we were just about to say that, all of these dogs did receive a short course of antibiotics following the procedure, which is, is something just for us to, to bear in mind when we're sort of thinking about applying this to our patients because The results seemed like they were pretty promising.

So the procedure was deemed as successful in 7 of 8 of these dogs. So, by successful, they meant that the pneumothorax resolved in one of those dogs, it was resolved immediately, which is pretty impressive. And some of the dogs needed this repeating, but overall success rate went up to 87%, which is, is pretty good for dogs that had been failing treatment, .

I guess it's hard to know what would have happened if you'd have just left these dogs for an extra day, but I suppose if nothing had worked in 2 days, then why would it miraculously have have happened then? So, Indications are this procedure could be successful and my clinical experience and that of kind of others in my field is that this can work. In order to present a balance for you, I should say that they did know infections of a quarter of these dogs, so 2 of the 8, despite the fact they'd all received antibiotics.

So I guess that's something that I, is a reason for me not to use it in everybody, just in case, just kind of keep it for those patients that, that really need it. But I thought it was interesting to note, and something to potentially get people out of a tight spot that they might find themselves in. And the very final thing I wanted to say just to finish up is in terms of plural space disease in cats, again, we've been saying common things are common, but I guess we don't necessarily know.

We know in our mind's eye what's common, but actually is, is there any numbers on there as to, you know, what are we up against? And so to finish off that Konig produced a study last year in JFMS, just retrospective you're looking at causes of pleural effusion in cats. So I thought that was probably topical for us to finish on today.

And it turns out that if you were a betting person and you wanted to know what was common in, in cats, you should vote for cardiac disease as being most common. So in, in this study of the cats that they looked at, 306 are a pretty decent number. 35% of them had cardiac disease, neoplasia eczema is common, Pyothorax next, SIP, yothorax, and then other.

And notably in, in 8.5% of the cats, there was more than one disease. So, I guess for me, this is useful in terms of I'm always thinking worst case scenario, but potentially cardiac disease being one of the, the better prognostic things that we can find in here.

So maybe I should be a little bit more cheerful when I, I meet a cat with plural space disease but be on the lookout for that potentially being more than one thing. So. That is all I have for today.

So if anybody has, any questions, then, then please let me know. Lindsay, that was absolutely fabulous and and well done on picking up that call again that it can be a little bit flustering when that happens. So thank you for that.

No worries. We have a couple of minutes. We have some interesting questions coming through.

Dan asked, is the cytology that you done, that you do in-house done on a centrifuge or an un centrifuge sample? Great question. And usually, well, oftentimes both, so.

I'm, I'm by no means pathologically minded. I, what I tend to do is I'll make a, a direct smear of the fluid that I've got and then stay in that in this quick. And this sounds very unscientific, but if it looks quite purple, I'll imagine I've got quite a decent cell count on there and I'll look at that directly.

If it isn't or if I look at the direct one, I'm not seeing a whole lot, then I'll typically make a spun the centre reviewed sample, get my credit, put that on the slide and have a look, . As a general rule, I think if most of the time if there is something that you're, you're gonna want to know about like a pyrex, for example, it's typically quite cellular and you'll generally see something on a direct, but I wouldn't want to say just do that because I think there are ones you'd miss. So I'd start with the direct and if I didn't get to enjoy that, I'd go ahead and do my sun sample.

But, but great question. I'm really glad you asked that. Excellent.

I think Jill's got a fabulous question as well. She says, do you advocate placing a feeding tube at the same time if reasonably appropriate when you have the patients under anaesthesia already? And it was when you were talking about cats, obviously.

Mm. I love the fact that you asked that because I, I think there's, there's very few things worse than kind of wishing you had a feeding tube. So I think it's definitely something to think about.

It probably depends on patients stability, but hopefully with sort of stabilising and pre-chest tube and then having the draining that you can use immediately, hopefully that's less of an issue. I guess, to be honest, I, I suppose if you're placing the sort of the miler or the over the wire drains then typically they're sedated, so I'm using sort of fairly light sedations to do that on local, so I probably would need to deepen them to sort of go ahead and place an Otube, for example. So I guess if I, if I thought nutrition was a, a, a really significant issue at that point in time, then absolutely that'd be a good spot to do it.

I do use a lot of nasoesophageal nasogastric tubes, because I'm hoping that a lot of these disease processes should cause sort of temporary inadottence. So, you know, I can get away with using an NG tube that I can pull within a few days and they should be eating by that point, which can be placed under a sedation. So I think that would probably be my preference unless there was a sort of a reason I thought.

A nasal tube wasn't tolerated, in which case going ahead with an old tube at that point in time or an esophageal tube, I should say, it'd be the way forward. But it makes me happy to hear that you're thinking of nutrition at this point in time. I think that's a really great thing.

Excellent question. I think Alina's also got a really good question. She wants to know, would you always place bilateral chest tubes in cases of pyothorax in both dogs and cats?

Good question. Do you know, the funny thing about pyosaux, and the thing that first clues me in that it could be a pyothorax if I'm just presented with sort of chest X-rays of a patient with pyral space disease, is if it's unilateral, because most other causes of chest al space disease, sorry, are typically bilateral if it's, heart disease, if it's Pylosaurs, etc. Whereas pyosaur can be bilateral, but it can be unilateral, whereas the others tend not to be.

And I think the sort of the rationale behind that is there seems to be sort of mixed evidence out there, lots of different opinions, but whilst there should be communication between the two sides of the thorax in dogs and cats, I think if you've got this sort of big viscous, effusion, like a, like a piousothorax, it can kind of seal those off and end up on one side. So I'm basically going with this is if, if it does seem like it is unilateral based on assessment, based on ultrasound, imaging, whatever you've done, then I'd feel comfortable just placing on that one side. If it's on both, then I think bilateral chest strains are the way forward, but I'll typically place the, the affected, the worst affected side chest strain first just in case the patient isn't doing well under sedation or, you know, just, you know, it's all done and we just get a chance to do one or something.

So it probably depends on distribution of the, what I think, but if there's bilateral disease, I will place bilateral drains ideally because I don't think that just one side will be completely drained by it through the other side necessarily. But yeah, that's really good question as well. Thank you.

Excellent. Folks, once again I'm really sorry. I'm sure like me you would love to listen to Lindsay for hours more.

I'm sure she's quite tired and fatigued now, but we are under time pressure, so I'm afraid we cannot answer any more questions. Lindsey, once again, we have loads of comments coming through of how fantastic it was, how much information has been gained over such a short period of time and just generally verbal thunderous applause. So thank you so much for your time.