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Hi, good evening, everybody and welcome to this um six evening education update. Um We're delighted this evening to have Doctor Alistair Han joining us um to talk about management of the patient following complex vascular surgery. And I know that many of you may have been to these six education updates before. Um But for anyone who isn't a sex member and just to tell you about 66 is an organization which aims to improve the care delivered to critically ill patients throughout Scotland and has focused on three main areas. So education, research and audits and, and there are a number of membership categories available for all sorts of different healthcare professionals and number of benefits to being a six member including reduced delegate rates at our meetings, comprehensive travel insurance, and then access to various travel and education bursaries which can fund you do some pretty incredible things if you're interested to have a look at membership for our website. And so to introduce our speaker this evening, Dr Rough is a consultant anesthetist at the Royal Infirmary of Edinburgh and is one of three anesthetists in the Scottish National Thoracic AAA and complex aortic service. And this service assesses patients with aortic pathology from the arch distally and performs a wide range of open endovascular and hybrid procedures. He has been involved in the update of all of the postoperative aortic guidelines, Edinburg and has a specialist interest in spinal cord ischemia and its management. And then finally, he wants to stress to us all that he is not an intent of this and he wants you to be kind to him. So, um Ali thank you so much and I'm going to hand over to you. Good evening everyone. And thanks J for the introduction and, and thank you for the invitation to speak. As he says, I'm Allie and I'm an anesthetist and I've been tasked with speaking to you for, I think about 50 minutes, hopefully 10 minutes for questions at the end about care of the patient following major vascular surgery, or at least that was the title I was given. And the first thing I did was sat, sat down and I thought, well, what, what patients will you be interested in that, go to your critical care units? And it probably varies around Scotland. Um certainly aortic patients, but perhaps carotid endarterectomy patients or um patients following lower limb revascularization or amputation. But really, I think that would be far too much to try and cram into an hour session and, and my sort of um specialist area, an area of, of interest is aortic surgery. So I changed the title and we're going to call it care of the patient following aortic surgery. And I thought, well, actually, aortic surgery is a lot of things and, and start surgery at the, at the aortic valve. And I don't do that. So I've had to change the title again to cure the the of the patient following aortic surgery, but not the kind that involves full card of pulmonary bypass. So, and potentially the clunks name for a title of this, this platform. But there we go, that's what we're going with. So I think before we get to post postoperative care, we have to consider the the conditions that affect the aorta and the type of patients that present with these conditions, then go through aortic procedures, which are certainly a source of confusion. And hopefully, I can help to, to explain the various things that we do to the descending aorta. Um We're going to chat about spinal cord ischemia and its management and then other elements of postoperative care and like all online um presentations, it does. It's quite hard to know that there's actually people listening. So if you do want to ask questions, please fire them into the messages channel. And I I'll try and keep an eye on that as we go along, happy to be interrupted and pick up on questions rather than leaving everything to the end. So, aortic conditions, well, when you think of the aortic patients coming to the intensive care unit or the h you probably first think about aneurysms and these obviously represent a large proportion of our aortic patient and the majority of aneurysms occur due to degenerative change in the aortic walls. Most commonly in the infrarenal aorta and the risk factors for that, as I'm sure you all know would be being male caucasian old. So over 65 um, hypertensive hypercholesterolemia family history, diabetes is an interesting one. Having diabetes actually reduces your chance of forming an aneurysm. But if you have an aneurysm and you're diabetic, you've got a higher risk of rupturing. Don't ask me why. Um So there is a small subset of patients who will have connective tissue diseases like Marfan's or Danlos or Lois Deutsch. That's a much smaller proportion of our aneurysm patients. And then you've got mycotic aneurysms and aneurysms develop at following dissection. Um Again, as minority groups. Next, we have acute aortic syndromes or the triad of dissection, intramural hematoma and penetrating ulcers, you'll be more used to seeing these patients coming. Um as type B dissections distal to the left subclavian artery for invasive BP, monitoring and aggressive BP control to um to try and prevent a need for intervention. Um In these patients, of course, if a patient develops malperfusion of organs or limbs, then they may need to, even with a type B, they may need to go for an acute procedure like A T var. And even with good BP management. They still are at risk of delayed aneurysm dilatation of the aorta and subsequent intervention. And we've got traumatic aortic injury. And then the most common site for this is that the aortic isthmus. So that's between the left subclavian artery and the ligamentum arteriosus, which is the remnant of the ductus arteriosus. So right at the top of the descending thoracic aorta where the aorta is relatively tethered. And therefore, if you have a significant deceleration injury, you can get shearing forces there and various grades of traumatic injury from um intimal tears, intramural hematoma, that's grades one and two to trans section or rupture, which will obviously require intervention and lastly, aortoiliac occlusive disease. So at the severe end of the peripheral vascular disease spectrum patients who um have blocked off their aorta and have invariably horrific claudication and really limited exercise capacity. And just always take these, take these patients very seriously and and be wary of them. If they've managed to block their aorta, they will, even if they don't declare symptom wise, they will have significant coronary and cerebral vascular disease and they are all high risk. We don't have time to go through all the associated comorbidities that our aortic patients tend to come with. Um And obviously, we should do everything we can to optimize these prior to any intervention. It's rare that you get hip athletes presenting with the Arctic conditions. Unfortunately, for me, so preoperatively, all of our aortic patients get a spectrum of basic investigations, blood CCG echo PFTs, chest x-ray, updated aortic imaging and CPET. Um in addition to you on the CPET front, we have a really great CPET service at the Royal in Edinburgh. So two vascular CPET clinics a week. And as I say, all of our aortic patients will be put on the bike. And um that's been happening for, for over a decade. And the great thing is that the surgeons speak CPET and it really feeds into a useful discussion at MDT level and, and sort of risk stratification really benefits from it. Our T AAA patients that also have a dobutamine stress echo and CT coronary angiogram to try and further delineate their cardiac risk. Everybody's seen by a consultant surgeon, an anesthetist and we discuss all patients at the MDT. So they'll obviously be people from around Scotland on this call. And um if you have a patient with a suprarenal aortic pathology, they will be discussed at the Pan Scotland MDT and surgeons you work with will contribute to that if you have an inf renal pathology that will be discussed at a local level. I forgot to mention of, of course, with aneurysms, we have the National Screening Project. So all males in Scotland in their 65th year are invited for an ultrasound and then um monitored if they have aneurysm dilatation of their abdominal aorta, we consider intervention once it, once it reaches 5.5 centimeters ap on ultrasound or is growing, expanding at more than one centimeter a year. So procedures before we discuss procedures, we have to have a brief overview of aortic anatomy. And this is how you would find it in an anatomical textbook. But as an anesthetist, I need to simplify a little bit and a stick drawing is much more easy to understand for me. So, starting at the aortic valve and we, the first major branch we have is the anin artery. I'm pretty sure I used to call it the brach of catic trunk at university. But and the surgeons all seem to call it the anin. So I've tried to teach myself to call it that too. And it gives rise to the right subclavian and right common carotid arteries. Next up the left common carotid artery and the left subclavian. And you can see I've not drawn any other branches until the diaphragm. But of course, there are lots of little branches coming off the intercostal arteries and then below the diaphragm, the lumbosacral arteries and these smaller branches are extremely important, particularly for spinal cord perfusion, which we'll come back to later. But in terms of bigger branches, the, the next one down below the diaphragm is the celiac axis, supplying the, the upper abdominal viscera. And then the superior mesenteric artery, which has a really important role in perfusion of the majority of the G I tract from the the mid juden downwards in the bilateral renal arteries and the inferior mesenteric artery which supplies the hindgut. But in almost all occasions when you're operating on the infrarenal aorta, you will sacrifice the inferior mesenteric, the IMA because the superior mesenteric is really well and collateralize with it and will take over. Yes, there is a risk of colonic erect ischemia. But that risk is low and last the aortic bifurcation into the common ili arter zones of the aorta are also useful for understanding the interventions that we do. So, the ascending aorta from the aortic valve to the ominate the arch encompassing the three branches of in left common carotid and le subclavian and the descending thoracic aorta and below the diaphragm, the abdominal aorta which you can further divide into the visceral segment and the infrarenal aorta. So um as we go through this, I just want to stress this general rule that it it it is obvious, but it's worth thinking about the greater the length of the art that you replace or you stent endovascularly, the higher the complexity, the higher the periprocedural risk, the higher the morbidity and the higher the mortality. So, keeping things simple at first with the infrarenal aorta. Um Here, we've got two types of infrarenal, open operations. These are open rep pairs of the infrarenal aorta and on the left, we have repair for an aneurysm and on the right and aortobifemoral bypass for aortoiliac occlusive disease. So as you can see on the left, there's a clamp that's gone on below the renal arteries. The aneurysm sac has been opened. And in this case, a tube graft is being a Dacron tube graft has been sewn in um replacing the aneurysmal tissue. So that's the kind of simplest inal aneurysm repair. There's also clamps on both common iliac arteries. Now, when you put that clamp on below the renal, you cause significant sequence of physiological events, you cause an immediate increase in afterload. And with that, you can get systemic hypertension, increased myocardial wall stress and potentially myocardial ischemia. So you have to have an anesthetic plan that can mitigate for that and monitor for it. There's then a period where the legs are ischemic and most patients don't really come to any harm from having ischemic legs. What you, what you're thinking about is the next step and aortic anesthesia is all about thinking about what's the next step in the, in the surgical process and what I have to prepare for. And the next step will be leg reperfusion. And in the case of an elective infra aneurysm repair, usually elective sorry, leg reperfusion isn't much of an event. There is maybe a modest drop in BP. So you would want to have a patient with a good BP with a bit of pressure to hand and volume available, but it shouldn't be, it shouldn't be terrible. And as you'll see, as we go through the, the bigger operations as that clamp goes higher and higher reperfusion events and get more and more challenging and more and more profound. And the the caveat to that is if you have a patient who has had ischemic legs for a more prolonged period of time, for example, a rupture, then leg reperfusion can be much more dramatic and much more problematic. And of course, that's due to um a load of metabolic nasties coming back into the systemic circulation, um potassium lactate acid load, and you get this triple whammy effect where you get an immediate drop. When the clamp comes off, the clamps come off, you get this immediate drop and afterload, you get uh um and you get the stuff back into the systemic circulation which is negatively endo and gives you vasoplegia. And that, that triple effect can really, really drop your BP and compromise the patient and on the right with their aorta bi femoral graft. Interestingly, when you clamp the aorta, you often see very little at all because the aorta is very already occluded. And also because this is a chronic condition, they will have collateralized to their legs via their celiac and their sme. So the legs are not truly ischemic when the clamps are on. So often the reperfusion um event is is is not particularly noticeable, not always. But um that now that doesn't, doesn't mean that these are all straightforward easy procedures as I said, said before, these patients are all high risk and they do cause problemss. Um I'd have to mention the, sorry, come on to the um ruptured aneurysms in a second. But, but the, the set up that we would use for our elective open inal procedures, um It would be a surgical laparotomy. Interestingly, we are an outlier in our surgeons will perform a transverse laparotomy and that there in the vascular surgical world, there is a, there is a belief that transverse incisions lead to poorer aortic exposure. And our surgeons would all argue vehemently against that. And the only reason why they do a transverse laparotomy apart from the fact that's what they've been trained to do and, and what they're used to doing. And the main reason initially was for analgesia, it, it makes your um it makes your epidural look really good when you only have to cover a few dermatomes to take a good chunk out of the postoperative pain. And in the majority of the rest of Scotland and the UK, people do up and down surgeons are doing up and down midline laparotomies, the blood loss is incredibly variable. Our medians about a liter and a half for an elective, obviously much higher for a rupture. And we set these up with a large bore drip, a thoracic epidural and it is one of few operations where there's really good evidence for improved morbidity and mortality with a thoracic epidural. There are plenty of people who feel uncomfortable, citing epidurals and then shortly afterwards, within the next couple of hours heis the patient. Um but um it is still recommended and that's what we do. Um We do not have a significant, we have a significant rate of epidural hematoma, touch wood, have a very low rate of epidural hematomas. And so it does appear to be safe to do and nice even recommend that you should do a thoracic epidural for your um in renal repairs. Patients obviously go off to sleep with an arterial line who pop in a central line. A urinary catheter use a single Belmont w rapid infuser and a single cell saver for these cases. And we do serial gasses and point of care coagulation tests to aid with our resuscitation and, and the Royal in Edinburgh, we're a clo pro user. You may use roam or um tag in your centers. We do use te if there's particularly if there's preexisting cardiac disease and most patients would be extubated at the end and return to level two care when they're elective. Of course, ruptured aneurysms are completely different kettle of fish and I could speak for an hour on, on er, facets of rupture, aneurysms and care rupture aneurysms. And so I just can't do that. But um here we see a really large aneurysms that with, with a retroperitoneal rupture, obviously, time, time to either cross clamp or time to stent deployment is absolutely critical in these cases and they will start off almost invariably shocked with on the on the precipice of multi organ failure. And they're much more challenging than the elective cases. But um the set up and the approach is similar and just that they're likely to have a much higher blood loss and be much more unstable. The nice recommendation is that where possible these, these patients should be managed with an endovascular approach under local anesthetic. That's you need to have AAA lot of planning to have that that in place. We actually don't have that in place for the majority of ruptures. Uh in, in Edinburgh, we most of us, most of ours would go to an open, an open repair and that is something we're looking at. Ok. So sticking with infrarenal and I talk thinking about endovascular approach. We have to enter um excuse me, the world, the clunky world of endovascular aortic nomenclature, starting with the Eva or endovascular aortic repair and endovascular aortic repair could be repair of any part of the aorta. But because it was the first thing to come along, it's usually applied to an infrarenal stent graft. So this is percutaneous or surgical access onto the femoral arteries bilaterally and in the Cath lab or in a hybrid theater suite, deployment of a stent graft with ceiling zones above and below the aneurysm. Usually there's not enough normal aortic tissue between the bottom of the aneurysm and the aortic bifurcation to seal. So most of these will be bifurcated or trouser type devices and this is a much simpler affair than an open aneurysm repair. So, percutaneous or surgical access, as I said, minimal blood loss, a drip tube and an a line and a catheter and level one or level two care after afterwards, depending on, on how you're set up. Some places in the UK do do day case Eva believe it or not. It is possible. And I watched a presentation on that on Vas Vas GBI I last year and my, I would have renamed the Presentation Day Case Eva just because you can, doesn't mean you should, but that's just my opinion. Um So when evar came along, um the, it looked like the death knell for open aneurysm repair, why would you choose a laparotomy blood loss? Um You know, all the risks of open repair where you can have this, as I'm sure you're all aware. Um The problem is longevity. So favorite of FCA examination rooms is EV R one trial and specifically the longer term follow up from the EV R one trial. And if you look at the purple and green lines, that is aneurysm related survival, purple being open repair and green being endovascular repair of an infrarenal aneurysm. And if we zoom in on those, sorry, it's a bit pixilated. But, and what you can see is on the purple line, if you have an open repair a small number of patients will have a major per complication and not survive the immediate perative period. But thereafter, things flatten out and the aneurysm is fixed and it tends to stay that way. Um endovascular repairs of of course, as a as a lower level intervention, not many people fail to leave hospital. So there's high survivorship at the start. But then there's this downward trickle as, as problems creep in and these problems are, um, endo leaks which I throw in the next slide. Um, issues with the stent graft, not fully excluding the aneurysm, ongoing sac expansion and reintervention, potentially rupture and death. If you look, it's about seven or eight years with the two lines crossed. I, if you had had an open repair at the start and you're still alive at that point, then you're, then you're increasingly more likely to stay alive than you'd have if you'd had an Eva. And then it's in simplest terms when you're considering a patient who's suitable for both. Um, obviously you have to take into account the patient's wishes and there's, there's lots of factors in this. But one of the key things is if you think the patient, er, considering their comorbidities, their functional capacity and all of their investigations is likely to live for at least seven years and they're so they're fit enough for an open, they should have an open. So these are all the types of endo leaks I won't bore you with what all different types mean, but stents can fail in all sorts of different ways. Um Type two is type two is interesting. It's not nothing to do with failure at all. It's back, pressure from, um, from a small branch of the aorta like a lumbar artery or sacra artery. Um, and sometimes you have to go in and embolize these and sometimes you can't manage it and the aneurysm continues to expand and these can be really problematic to deal with. Um the, the um the patients keep having to come back for attempted coil embolization or maybe even direct sac puncture. They, they sometimes inject the sack with the stuff called onyx. It's like a, a glue that's meant to solidify and stop the sack expanding. It doesn't always work. So what a nice see this a pretty controversial guideline when it came out in 2020 is worth a read if you're interested in vascular surgery and anesthesia. But um essentially to draw your eyes to this part of it, what it says is what, what I was just saying at the, at the last slide. Um If you're fit enough for open, you should be, you should be offered an open and you should be doing an open repair because of the longevity issues with evar. Evar definitely has a place with patients who have abdominal cope pathology. So hostile abdomen and people who will struggle to make it through an open repair. Um, but, um, when evar came along a lot of centers through the baby out with the bathwater and stopped doing open repairs and moved to almost 100%. And surprise surprise, there were, there were issues that weren't predictable when this all came out and now they're having to sort of re relearn, um, or re retrain almost in, in open aneurysm repair because, er, is not suitable for everybody. Ok. So that's an in renal repair. Once we move up to the visceral segment, things get more complicated because unlike the IMA which you can sacrifice with and you do sacrifice with in renal repairs, and we have to ensure ensure ongoing perfusion of the celiac sma and renal. If you have a Jugar pararenal aneurysm, which comes just up to renal, the surgeon may be able to do an inter renal, that's image B or a suprarenal clamp C. Um And I would package those procedures along with infrarenal in terms of how the patients tend to behave. Although there is a significant increase in afterload. Once you start excluding renal arteries, it's usually relatively straightforward to manage. The blood loss is fairly similar. The main difference between these and in renal is, is the postoperative risk of AKI and hopefully temporary renal replacement therapy requirement. But um with fast surgeons, the risk remains fairly low unless they have problems. Whilst in the top end anastomosis and there's, there's really prolonged renal ischemia. But if the aneurysm extends up further than that. And this is our first er touch on the, the modified Crawford classification of T triple, which I would say is probably the least intuitive classification system that I've come across of anything. Um perhaps endoleak are up there as well. And this is a type four T AAA and, and you obviously can't do a supernal clamp or a renal clamp. You have to do a celiac clamp and, and things will move up a gear. Um Sometimes it's not a full type four aneurysm but, but pathology, they just may require a type four approach or ie a suprarenal clamp. So in order to get a tampon um above, sorry, super celiac clamp, in order to get a clamp on above the celiac, you have to do some, some pretty wacky operating. So you can either do a laparotomy or a retro approach. Our surgeon does a transverse laparotomy, a rooftop incision and then performs a left medial visceral rotation, which is otherwise known, also known as a maneuver. It's a trauma surgery maneuver and it essentially involves flopping. I'm not a surgeon think I'm allowed to say that flopping the stomach, left kidney spleen across to the right side of the abdomen along with everything else, which gives you access into the left renal artery and the the left lateral side and posterior aspect of the abdominal aorta. And what the surgeon then does is takes down the left cross of the diaphragm because he has to put the clamp on the descending thoracic aorta, but having access it via the abdomen. So type fours are funny because although it's a type four T AAA, it is an aneurysm of the entire abdominal aorta. But it's in the T AAA classification predominantly because the clamping zone is actually in the thorax, albeit accessed from below. And the clamp looks like this called Cosgrove clamp whenever it comes out, I think of a certain Marvel and villain and it's poked up through that aperture with the left crust of the diaphragm is taken down and the the distal descending through aorta is clamped. That's your supra celiac clamp on. And when that goes on, it kind of unleashes physiological chaos on the patient. So firstly, there is a really huge increase in afterload at that point. If you can imagine excluding um the perfusion of your of your entire body below, the diaphragm causes a massive increase in afterload and therefore often extreme hypertension, significant increases in myocardial wall stress and a much higher risk of myocardial ischemia than whether an infrarenal or pararenal or even suprarenal clamp. You then have a patient who, who is un hepatic essentially and has turns out the patients don't like having ischemic liver guts and kidneys and rapidly develop profound acidemia, metabolic disturbance and coagulopathy. But the the real kicker is reperfusion. And when that camp comes off, um the there is this um all hell is kind of unleashed as everything is washed back in from the liver guts and kidneys. And um that triple whammy that I was talking about earlier on is, is um amped up much higher than if it was an in renal clamp. A pararenal clamp. To give you context, we prepare for a systolic BP drop of of about 100 millimeters of mercury. So surgeon will give you warning clamps shortly coming off. You try and with volume and pressure drive the BP to about 180 190 systolic can expect to drop of 100. It's very much dependent on cross clamp time. We like it when it's less than 30 minutes. It makes our job much easier between 30 minutes and an hour, things can get a bit hairier and after an hour we get the DFIB and, and mini jets opened because the chance of the patient arresting either with the clamp on or with when the clamp comes off as much goes up significantly as you get over an hour and it can be really quite unpleasant. So, um, I don't know why you would do that type of surgery or inflict that sort of stress on yourself. It is truly time critical um, surgery. When they do the top anastomosis in a type four or any, any visceral anastomosis, you'll see the other, the other t trips all involved some form of visceral anastomosis and it's always the um the highest risk to the pro um I think it's quite interesting. This is, this is how they do the anastomosis. So the clamps on above the diaphragm, the aneurysm has been opened, exposing the origins of the visceral arteries. The celiac is just hidden behind the top of the graft. The sme in the renal and the surgeon hand shapes a Daron graft into this sort of beveled top end and they then aim to encapsulate the four visceral artery origins with the top end of their graft. Sometimes the left renal is too far away and they therefore do a separate jump graft that's quite common to the left renal, but you would still having anastomose. The other thing you would, you would minimize the time. And that is the motivator here. If you were to do a multi brach graft and individually anastos on to the visceral arteries, it would all take much longer and your visceral ischemic times would be much longer. Sometimes they have to do that particularly with connective tissue patients. And that's a, that's a, that's a less favorable option because of the increased vis ischemic times and the sort of physiological consequences of that um There is an island of aneurysmal tissue between those those arteries potentially. Um but that doesn't tend to dilate these patients are, are monitored POSTOP with imaging and usually it's ok and the benefits outweigh the risks. So, as you can imagine the set up for open supra coli a clamp or type four repair is more elaborate than an infra repair. Um I've described the surgical approach, the blood loss is higher due to visceral back bleeding and um and sort of greater duration of procedure. And also because the patients develop are more prone to developing coagulopathy and because of the supren clamp, supra clamp rather aesthetically, we have a couple of big drips, an epidural or G A. We use bilateral radio arterial lines just so we can sample and monitor at the same time. Um a couple of central lines, a multilumen and also a white bore. And that has the advantage of being able to connect your belt with a splitter. So you can achieve a liter a minute it flows. But also if these patients do have a significant risk of acute kidney injury and requirement of filtration, so you can use the hopefully use the same line for filtration if required afterwards. So urinary catheter two bow months with big buckets on them, two cell savers and we do cool the patients to 34 for visceral and spinal cord protection and obviously do lots of gasses and clot pros to guide our resuscitation. And we always use a tee in these cases, find it invaluable in assessing filling status and and potential myocardial issues and um sort of have a lot of infusions to try and keep the patient alive through the whole thing. This is what it looks like. And this is last week in our, in our sort of cockpit at the top end of the 3 18. And you can see the monitoring and all the infusions and other bits are quite interesting. We use a noninvasive hemoglobin um monitor which is quite useful for, for trend and guiding resuscitation or minute by minute rather than supplemented by your serial gasses. Of course. And you can see the tu a machine there on the right. And that's at the end of a type four repair, that's a bifurcated graft. The patient must have had a bifurcation or proximal common iliac disease as well. So it's a, a type for the auto biel graft and you can see the smaller graft coming off the front of the main da is a jump graft to the left kidney. So big, big exposed area and a lot of bleeding and a lot of sort of physiological upset. And those patients have, have not insignificant risks of organ failure in the immediate postoperative period. We, we, we, I should say on the type four, we, we do try to extubate them. Um but we've got a fairly low threshold for bringing them back intubated just depending on what the blood loss is and what the gass are looking like. And, and we'd rather there was a slow, slower controlled wake up and into care unit, then we rush in theater and regret it. Ok. So hopefully you're still sticking with me on the visceral segment. Um endovascular repair, this I think is relevant to our centers other than, than Edinburgh, because so called complex endovascular repairs go on around Scotland. And here again, terminology is pretty, pretty awful but fever and BVA. So fever is fenestrated, endovascular aortic repair and BVA is a branched endovascular aortic repair. And these are custom made grafts based off of the patients. CT imaging in a fenestrated stent graft, there are apertures which are lined up with the origins of the visceral arteries. And then what they do is they go up and deploy little bridging stents between those those fenestrations and the visceral arteries to seal off the aneurysm. If your aneurysm is really quite large, that technology doesn't work. And you have to use a branched device like you could see on the right there and they're more complex. They take longer to put in, they're longer, which leads to more aortic coverage and therefore increases your spinal cord ischemia risk. Um So it's just kind of another level up even more confusingly. You do get some custom devices which have both fenestrations and branches. I'm not even sure what you call them bars or yeah, complex endovascular repair is a useful term which encap encapsulates all of these things. Here's another illustration of fenestrated versus branching. So on the left two images, the small bridging stents and on the, on the right where there's a bigger gap between the main, excuse me, main stent graft and the visceral artery, a longer branch. So we set these up there. Again, there's either percutaneous or surgical, bilateral femoral archey access. They're not really meant to bleed, they don't bleed from the aneurysm, but they actually can ooze quite a lot from around their sheaths and especially when they're heparinized and you do have to watch the hemoglobin and you have to watch the, um, the coagulation. But compared to type four, you know, there should be a walk in the park, a large, large drip ga we do use CS F drains depending on the extent of aortic coverage. And I'll come back to that in detail later, an a line and a central line and a urinary catheter. And when these came along, it was like history repeating itself. I mean, who would want a type four repair with all the, all the risks involved when you could have this not risk free. And certainly from a point of spinal cord ischemia and visceral ischemia, there are significant risks around complex endovascular repair. But compared to an open type four, you know, significantly less immediate perioperative risks. But, um, we're, we're kind of in the same boat and there is skepticism because of what happened with Eva about complex repair. We don't know the longevity of these devices. They've not been around for long enough and we wouldn't be surprised if you start to creep in down the line. Therefore, nicest stance is you have to have a really careful discussion with the patient about the risks of EV R versus open. And I think it's kind of funny that they say this, you have to discuss the uncertainties about whether complex EV R improves a per up to survival long term outcomes. How, how is the patient meant to decide based on that? I mean, it the kind of sta status in at the moment, particularly in Scotland is if a patient is, is fit enough for a type four and you do have to have a much higher level of fitness to to put a patient through a type four open then for an inal for example, but if they fit enough, you should, you should probably be doing an open operation because that is definitive. We have, we know that's definitive. We got a big case series about that. Um reintervention rates are low. Survival is good if you, if you get through the initial period, um and potential organ dysfunction at that point time will tell the role that complex endovascular aneurysm repair has to play here. Um But but it is a very attractive option because type fours are high risk. OK. So the descending thoracic aorta is simpler again because this is the domain of the thoracic endovascular aortic repair or T var. Most patients with isolated descending thoracic aortic and pathology would have T var rather than an open repair because here, you've got a relatively simple procedure compared to an open repair of your thoracic aorta. It involves one lung ventilation by aortic bypass, which you'll see. And when we get a bit further on, and the approach is quite similar to a complex endovascular repair, it's a big a big drip a tube, a CSF drain, if there's a significant risk of spinal cord ischemia and a and a central line worth mentioning when we deploy TVA really proximally. So for example, up against the, the left subli artery, the operators require significant hypotension to accurately deploy the stent. There's various ways of doing that. We use a pacing sheet and temporary pacing wire in the right ventricle to overdrive pace and drop the BP because we find that's literally on off. Um and er really easy to do and you don't get this long lasting hypotension like you do with pharmacological management. Some centers use adenosine or esmolol, we find the Esmolol just you're talking about 30 to 45 seconds of hypotension. And if you give a big bolus of esmolol, you know, it lasts a long, longer than that several minutes and you don't want the hypertension for that long. Another way of doing it is a IVC balloon, haven't any personal experience of that. We don't do it in our centers, but it is on our list of things to consider. If you have a patient who, who you didn't want to pace for some reason due to their cardiac history, once you have pathology involving both the descending thas aorta and abdominal aorta, this is the, your other T triple A's. So back to the modified Crawford classification, the 123 and five, I'm not going to go through them all in detail. Um Two and three are the, are the biggest and the worst one and five are not quite as bad, but they're all pretty bad. Um And just to breathe through this, I know it is super specialist and it only goes on at the Royal in Edinburgh. But hopefully you're interested to know what happens to these patients and they're in a funny position. So sort of hips are over to the right I be shoulders are, are over more and then they have a thoraco laparotomy or full fileting rib resection, diaphragmatic division and exposure of the entire descending aorta from left subclavian to aortic bifurcation. And this is a type two repair once it's been done and looks all lovely, clean and easy. In actual fact, it looks a bit like this, which which is a bit of a mess, but that's actually that actually looks quite dry, believe it or not. So, right on the right is the patient's head on the left is the patient's pelvis. The diaphragm is in the middle, the surgeon's retracting the left lung, which as you can see is not entirely pink, which is standard for our patients. And you can see there's been a a jump graft to the left kidney, that's a smaller, smaller graft coming off the main body. So huge operations, the the biggest one of the biggest operations, you can have really um massive exposed surgical area, massive blood loss to the tune of tens of liters. And obviously, with that massive physiological disturbance and the potential for serious or organ dysfunction. In the wake of all this, we use aortic bypass usually in the form of partial left heart bypass to facilitate these cases. And the excuse to really budget um diagrams that I have done. I thought you might be interested to see what that involves. So um there's a type two aneurysm and the surgeon will cannulate the left atrium using it accessing via an inferior pulmonary vein. That's because it's less arithmetic than going straight in through the left atrial wall. And that um blood is passed through an ECMO style pump with no reservoir, which does have an oxygenator on it. If it's left heart bypass, that is superfluous to requirements, but is a safety mechanism in case the patient's not tolerating one lung ventilation. Or you've inadvertently they, they have a PFO for example, and the, the drainage cannula has actually gone through that and into the right atrium. So there's always an oxygenator on, there's a heat exchanger to cool the patient and that blood is returned to the left common femoral artery actually via a Dacron graft with which the surgeons suture on because they could, they have the groin open and they can do that in a jiffy rather than like a percutaneous eal cannula. And that means you get really excellent antegrade and retrograde flow. So having done that, you have these parallel circulations and can then clamp above and above the aneurysm. And at the diaphragm essentially isolating the thoracic aorta but maintaining flow to everything that's important. So the heart continues to eject and supplies the brain and the upper body. The pump supplies the abdomen, the abdominal viscera in the legs. The surgeon can then um hopefully with relative stability to the top end anastomosis. Unfortunately, all those intercostals that he's now staring at tend to back bleed a lot. And you do often have a, a really significant amount of um bleeding at this stage, but at least there's no visceral ischemia yet because obviously, the next thing that has to happen is a sequential movement of the clamps down the way and, and a period of visual ischemia. And just like with the type four, the rest of the graft is completed and then everything's reperfus and we use the pump to rewarm the patients and then de cannulate. And this is a the old photo, this is what it looks like a patient in that funny position, rotated over to the right, lots of infusions. Um And one on ventilation you can see top left, it's a vis side tube. So it's got a camera looking at the carina and the left lung is deflated. You can perform an endovascular approach to the bigger aneurysms. So that would encompass a combined T var and branched and or ferate device um which is otherwise known as a full metal jacket. And these are often performed as stage procedures just to try and a little bit of collateralization and mitigate the risk of spinal cord ischemia. Um And that's more than enough on the, on the descending thoracic an arch um side of things. I'm not going to go through these in detail. I don't have time, but you can have open repairs on the left of an arch replacement of the frozen elephant trunk, which is a stent graft deployed into the remaining aneurysm for a subsequent endovascular open repair. And in the middle, the are hybrid procedures where the arch is de branched and then a TVA placed to cover the osteo of the arch vessels which have been Deb bra and then more recently, total endovascular your arch repair, which we've just started doing in Edinburgh. And the, the role for that is emerging. Ok. So it's taken um you know, the majority of the, of the session to actually go through all the repairs and I hope that's useful. And the last bit, I'm going to concentrate on the postoperative side of things and particularly spinal cord ischemia. And hopefully, well, in an attempt to check whether you're awake or paying attention, we're going to go through a little case and I'm going to try and do something which really says no one's bothered to attempt before. Um, so I hope it works in some poles to see what you, you would do. So, this is a real case from a couple of months ago in the royal, um, a 66 year old patient coming to HD following elective open infrarenal repair for a screen detected asymptomatic 5.5 centimeter aneurysm in renal aneurysm. He has uneventful surgery, a tube graft, a liter, blood loss sounds like a good day. Never seems to happen to me. Um, but he's doing really well. He's comfortable with his thoracic epidural just on a trickle of no a and with a map target of 70 there's a concern that he maybe has a bit of um coronary artery disease. And at two o'clock on POSTOP day one, he's having had a good morning, sat in his chair the n he's quite tired. He wants to go back to bed for a snooze. So the nurse goes to move him back into bed and he says he can't move his legs. So she sort of raises the alarm and a registrar comes over and assesses him and finds his legs to be warm, well, perfused with good pulses, but he has a significant asymmetrical weakness on the right. He can, he really can't move his leg at all on the left, he can flex his hip a bit, he can move his knee a bit and his ankle a bit, but it's not normal and he has total loss of sensation of both legs. So the first thing, the red thing is probably the epidural, so stop the epidural. But after an hour there's absolutely no change. So I'm going to try and launch a poll you can do, um, uh, is that you cannot do multiple options. Um, just one at a time. Uh So if you can, if that's working, I mean, sorry, I need to go back giving the answers away, see if you can click and I should see the results of that and hopefully you can see it. Yeah. Oh, great. It's working great. Ok. So it's not, it's definitely not unanimous. I know that you may do multiple things at once but you know, just humor me here. So wait another few seconds. If you can't find it, I think it is in the, and if it hasn't popped up, it'll be in the messages but, and you can see the results and the messages hopefully. Ok, so I'll stop it there. And yeah, so a spectrum of things, 46% of people are going to increase the map, map target and give fluids and press, try and achieve that. And um, but, but others have, you know, a significant number of people are thinking about doing other things imaging or, and even, er, 13% are thinking about just cracking on with the Lumbar CS F Train. So that's interesting. Um What the, what the team decide to do is they do start with increasing the map, they give a bit of fluid and up the no adrenaline and easily get them up to 90 but nothing improves somebody. There's actually a neurology registrar on an ICU placement and who says, oh, this, I think this could be a paraf sign bleed actually. Um So it suggests an urgent ct head and they think, well, while we're down there, you know, this could be an epidural hematoma. Why don't we just scan the back as well? So yes, it an urgent ct head and spine doesn't show anything at all. And, and of interest, his bloods are plumb normal and he hasn't had that low molecular heparin for ages. So, um what do you do now order an urgent MRI spine or insert a lumbar CS F drain. So let's see if I can launch the next pole. Hopefully that's gone live. Now, see if we get some. Oh, good. It's working again. Ok. So the majority, I'll just wait a bit longer. It looks like the majority of people are going for inserting a CS F drain. But a few people fancy doing a bit more imaging and ordering an urgent MRI. Well, it's actually even itself out. So it's about 50 50. Um split opinion should you just get on with the drain or order an MRI. Um, and this is difficult decision making. I'll come back to what I think or what we, we think is in the, in the royal, but there, there's no absolute right answers here. And in fact, the team decided to order an MRI. The weakness is unchanged and that takes hours to, to obtain, as you can imagine, a patient of no adrenaline. You're going to need a neuro anesthetist. Um You need the scanner to be free. You need the radiographer uh changing all the monitoring over pumps, infusion lines through the Faraday cage. You know, it's an absolute, I'm glad I don't do it. It's a total pain I remember from training. So it takes a while and then the result takes a while and it comes back as normal. No, no cause shown for leg weakness. No epidural hematoma, no evidence of spinal cord ischemia. Patients still got weak legs. So what do you do? Now? Do you as a as a critical care team get on with inserting lumbar CS F trade or are on the basis of the scan hasn't shown spin Corm seek advice for one earth is causing this. Um this patient's weakness. I'll try and launch this one. Hopefully that's available now. Ok. Responses are coming in. OK. That's just about everyone. So three quarters of people are going to put in a CSF gene, but one quarter would like to discuss it further. Ok. Well, what actually happened with this patient was at that point? Um, there are multiple, I've oversimplified, there are multiple discussions going on with vascular surgery, vascular anesthesia. And at this point, he gets a lumbar CSF drain and within a couple of hours, his neurology is back to normal and um that, that continued to discharge. So he did, he did have spinal cord ischemia, um and it was successfully treated and he had no long term neurological impairment, which is great. So why does spinal cord is ischemia happen? And then we'll come back to sort of its treatment and, and what I would suggest you do about it. Well, it comes down to the smaller branches of the aorta that, that we missed out from the stick diagram, the intercostal arteries and the lumbosacral arteries which all feed into the single anterior spinal artery and other important contributors come from the vertebrals, particularly the left vertebral via the left subclavian and the internal iliac. So, um you've got all these multiple levels of collateralization which which feed into the supply of the anterior spinal artery. And when you either stent or replace part of the aorta, you, you wipe out the the contributions at those levels. In the case of open surgery, you can reimplant really large vessels but but not always. And when you endovascularly stent someone you can never do that. So you're always going to be changing the flow to the anterior spinal artery. And what what that causes is this an excuse me anti card syndrome. And where all but the dorsal columns can become ischemic. And the classical picture is of a progressive symmetrical flaccid paraparesis, the paraplegia with a loss of sensation, but preservation of proprioception and vibration. That's the textbook in reality where you have probably because you have this dynamic ischemia um going on, it rarely conforms to that. It can be, it's often asymmetrical, it can be unilateral, they can and you can have bizarre sensory disturbance. So I think the take from home from that is in, in any aortic patient with any form of leg weakness, consider spinal cord ischemia. So the other things that contribute, we've talked about the loss of segmental arteries. If you do an operation and you cross clamp the aorta, you immediately disrupt the cord perfusion and then you have a reperfusion injury to the to the cord. When the clamps come off. Despite the best efforts of the vascular anesthetic team, you are likely to have some hypotension perioperatively, um especially if there's major hemorrhage and that can contribute. And due to all of the above, you can get spinal cord edema, which is likely to worsen for 48 to 72 hours before it gets better. And that can raise your intrathecal pressure, reduce your cord perfusion. And then this vicious cycle begins in terms of the risk of spinal cord ischemia and the incidence is vary hugely between case series. But for, for a case like that, that we went through an open inal aortic repair, it's very rare, but it does happen less than 1%. It creeps up for an open type four, obviously a greater length of aortas being replaced. So more and more of those collaterals are being taken out and, and for complex endovascular work and T bars, it can be really quite high and in some cases as high as 30% for branch grafts and it's also unsurprisingly high for, for the bigger open repairs. So you may well come across this if you're doing complex endovascular work. So what do you do about it? Well, you can plan to stage the intervention if possible and to allow some collateralization. Usually that's for the larger endovascular repairs. If you do an open procedure, we use bypass, which as well as I showed you that sequence where during the, the thoracic part of the operation, the abdomen was perfused. Well, of course, if you're perfusing the abdominal aorta with the pump, you're also perfusing the lumbosacral and the iliac and that will be really beneficial to the cord and we cool patients to protect their cord amongst other things. And the surgeons will try to reimplant intercostal or lumbo arteries into the graft. But for all procedures, the kind of mainstay of it is is map augmentation, ensuring good blood oxygen content and considering CS F drainage to lower your CS F pressure. And that's based on this, this equation, spinal cord perfusion pressure equals map minus CS F pressure. And so when do we put CSF trains in well electively, I prophylactically, we use CS trains for all of our bigger open repairs, type four repairs who've had a previous intervention on the thoracic like A T VAR because they've already lost some of those intercostals and any endovascular repair with high risk features. And there's lots of the of high risk features. But the key ones are whether it's a long stent and that's because you're just covering AAA lot of collaterals and um where you're covering the distal descending thoracic aorta like a distal T VAR or A B VAR. Because that area is often very important. There's, there's sometimes a really big art in cross artery there and anatomical text weeks will describe that as the archey of the DABI. It's not a term the surgeons tend to use. But the thorac, there's often a really important contribution in the distal thoracic aorta. And that is also a kind of watershed area that can be affected in the emergency sense. If ac sri blocks early in someone who we deem to be really high risk, we we replace it. But any, as I said, any aortic patient um who doesn't have ac sri already and has a possible diagnosis of spinal cord ischemia and their symptoms don't resolve with simple maneuvers like map augmentation. You should be thinking about doing a CS F train and different centers do things differently. We are very, we are very prophylactic. We put in a lot of CS F trains and other centers are much more reactive and, and just assess the legs. If you, if you're a reactive center, you need to have a really robust system whereby a CSF train can go in very quickly if weakness develops because this is a time critical situation and people are put off prophylactic drainage because they worry about the complications which will come onto. But I suppose it's a self fulfilling prophecy in the Scottish service in Edinburgh. We do a lot of CS F drains. We have very, very low complication rates, touch me and and therefore we're kind of not, not scared of CS F drainage. We do it all the time. Um We're very careful in protocols about how they go in. They, they're managed fantastically on the critical care unit. And I think therefore we have really low, low levels of complication. Um I'm going to, I know I'm gone, I'm speaking for too long, so I'm just going to skip through that. There is evidence, albeit a varying, varying to vary degree is evidence for CS F drainage. The Cochrane review has kind of said not great evidence, but you should probably do it. Um But international consensus guidelines are strongly in favor of doing it for me, significant aortic interventions. So if you have a patient with leg weakness, an aortic patient and that could be a POSTOP patient or in the pre op sense, any patient with dissection or um a big aneurysm with thrombosis. And that has happened recently, a pre op patient presented to the Royal infirmary with a big unknown aneurysm and leg weakness and it was spinal cord ischemia and it resolved with a drain um or aortic occlusive disease. Think about whether it might be spinal cord ischemia, it can be and postoperatively, it can occur early or it can occur weeks down the line up to. We've seen it three weeks down the line. Obviously, things to consider other things to consider would be a motor block related to an epidural and epidural hematoma and and everybody's incredibly fearful of them rightfully so, but they are epidural hematoma are, are much more rare than spinal cord ischemia. Um In intracranial pathology can cause leg weakness. Of course, um particularly if it's significant asymmetry or unilateral, you want to be thinking about that and leg ischemia, easy to exclude by just examining the patient and and what you have to do with any of these patients. Take a good history. Think about the context, examine the patient and thinking about imaging and there was obviously different differing in opinion on that on the polls and the issue of course, with MRI is the delay it creates with the best will in the world. If you've got a patient on no press, no organ support. The scanner is empty, the radiographer is free and someone's free to take them. Yeah, you can probably get that and that's quite unlikely to happen. Actually, all of those things, you could probably get that a result in a couple of hours, but it doesn't take much to creep in and you're looking 456 hours in line before you get an MRI result. And actually, even if an MRI suggests no cord ischemia, it can't fully exclude it like in that case. Um So the the mainstay of treatment um is the first three things. So simple things, map augmentation and the evidence is not fantastic, but most centers, big volume centers, we have 90 millimeters of mercury in their protocols. We tend to just advise increasing 10 millimeter mercury steps and then reassessing. You've obviously got to be careful that you don't over vasoconstrict the patient and just result in no flow and cardiac therapy monitors can be useful, obviously trying to resuscitate the patient with volume. So they're warm peripherally all the the IC basics and making sure they're well oxygenated and and have good hemoglobin. And, and again, it's not an area of great evidence, but some, a lot of big volume centers will use an HP target of 100 in anyone who they think has spinal cord ischemia to try and kind of boost blood oxygen content. If none of that works then you should have be putting in a CSF drain to drop CSF pressure. And from the best available evidence, we, we aim for under 10 millimeters of mercury and sometimes we will drain more aggressively than that if we, if we, especially if we show that that causes an improvement down to five or transiently zero. But you're always balancing that against the risk of the patient. And this is what, what it looks like when it goes in, it's basically coughing up an epidural on purpose. So you use a 14 gauge um two needle, a loss of resistance tech. But you can either do like a spinal where you just jab it straight into the fecal sac or like an epidural where you use a loss of resistance technique to, to access the epidural space and, and get close, put the stet back in and pop through and then you feed this this floppy catheter in while CS F is gushing everywhere and try not to lose too much. And you can actually, and what we'd recommend for people who are unfamiliar with the kit is just use an epidural kit obviously has to be very clearly labeled and there are safety implications there. And on the right scan showing how it should hopefully sit within the fecal sac, you feed about 5 to 10 centimeters in, they're zero at the level of the thoracic cord, that's where the evidence is. If you say to an ICU nurse, zero this device at the thoracic cord, they look at you funnily so you tell them to zero at the heart and it's near enough. Um We, you can either use a neuro neurosurgical style CSF drain or we use an active pump, got a liquid guard pump to aspirate off CSF and tend to start at 10, as I said or sometimes drop a bit lower and we limit drainage to 20 miles an hour to try and reduce one of the complications which is intracranial hemorrhage. And that's the liquid guard pump. And we have a protocol which has various um parameters which you set and then an advice of what to do if the patient's legs become weak and the most common issues are blockage. Unfortunately, we, well, we, we don't flush them, um, almost never flush them unless it's very early on in the process because it's unlikely to be successful. And there's a clear infection risk there. And so it usually means replacement and try and avoid an emergent removal does happen from time to time, unfortunately, but even despite them being well secured and patients will be patients, I suppose. And intracranial hemorrhage is the big worry. We reduce the risk of that classically. Subdural can be subarachnoid by limiting drainage. Um But the thing to think about here is patients who survive aortic procedures with paralysis almost invariably say they wish they were dead. Um And that's not hyperbole, they, that they they have said that to me. And um I think if you, you often do drain aggressively when the patient has a really dramatic er, neurological compromise, accepting the increased risk of intracranial hemorrhage because of how devastating the complication is. Um, as I say, we have low complication rates in the 22 year history of the service, we've had two intracranial hemorrhages and, and one infection and we hope that will continue. Ok. Sorry. I'm really stretching the time now. I do apologize but other elements of postoperative care, um These are our updated Arctic guidelines and if anyone wants to have a closer look, please email me my email address will be on at the end. I'll be glad to send them to you. I just wanted to zone in on a couple of things. Um Sorry, that's a busy slide. But in the cardiovascular side of things, the key things are we like patients to to be slow. So we like maintain beta blockade um at all costs basically. So even if they're on a bit of pressure, still give the beta blocker and turn the pressure up because that is so protective against myocardial ischemia um map targets if if you're not worried about spinal cord ischemia are, are kind of standard I would say. Um And ECG monitoring is really important. We like to continue aspirin statin for, for coronary plaque stability and obviously normally normalizing electrolytes to reduce chance of arrhythmias. These patients bleed and they do so for lots of reasons, they're on antiplatelets, they're heis in theater, they get cold acidotic. If they have a super celiac clamp, they get visceral ischemia and reperfusion, potentially massive hemorrhage and cell savage with a CD. Um And so they may well require coagulation management on return to the critical care unit. And the mainstay of testing will be lab based test, but we do use point of care coagulation testing in our critical care units. They are fantastic. A CCPS are able to do those for us. And then we have an algorithm which I'll show you in a second which guides treatment based on the point of care coagulation test. And we really stress that sort of aggressive management of coagulopathy in the immediate POSTOP period can significantly reduce POSTOP bleeding and risk of return to theater. And the sort of risks that come with that um There's some targets there um which we have sort of, there's not fantastic evidence. These are born out of sort of consensus statements and local experience where we like our patients to be. This is our clot pro guideline and written by Doctor Niel, um who is a sort of world expert in point of care coagulation testing. And again, if you want a copy of that, I'd be delighted to send it to you. It guides, guides people towards what to give in the case of abnormal coagulation. These are the, the worst clot pros I've seen in P 3 18. So on the left and profound hypofibrinogenemia and a type four repair. And on the right, we're quite unusual to see hyperfibrinolysis in aortic surgery. And I forgot to mention tranexamic acid, you know, is really big in trauma and obstetrics, but the evidence from vascular is not compelling and we only give it if we see hyperfibrinolysis on, on near patient testing and the rest of postoperative care is kind of icu um bread and butter, there's nothing particularly weird and wonderful about it. Um I, I don't think er, we use low molecular heparin in patients who were not particularly worried about spinal cord ischemia. We use unfractionated heparin if we are because it gives you bigger, better time windows for putting needles in the back and it's kind of slightly easier to assess and particularly out of hours and reverse. Obviously, with protamine, we don't routinely use protamine POSTOP in our patients. We let the heparin wear off unless there's significant bleeding. And your lab test or clot point of care. Coagulation test suggests a significant ongoing heparin effect. Couple of niche things when it comes to endovascular repair, they do use these closure devices and it took a while to get them to agree what they wanted the patients to do. So we lie them flat for an hour and then set them up to 45 degrees for six hours and they can do what they want and you do have to keep an eye on the groins for bleeding and swelling. And then some patients can get this post implantation syndrome where they get a serious response and potentially back pain thought due to be to be due to sac thrombosis is supportive, supportive treatment and analgesia. Um We've covered all the the spinal cord ischemia parts in detail. There is the potential for visceral ischemia with complex stents and um t trip a open repairs. And really what you have to do is just watch things like watch your surrogate markers, you output creatinine lactate LTs. Um try and ensure patients are well filled with good cardiac output and not over vasoconstricted. Um And if there is concern about visceral ischemia, usually you're going to be speaking to the surgeons and, and thinking about imaging. So again, apologies that I've overrun. Uh Julie will keep me right. Hopefully, we've got time for a couple of questions and if you do have any other questions or uh want any of those protocols, I'd be delighted to hear from you. You have my emails there, but thanks for the opportunity to speak. Thank you so much, Ellie. That was absolutely excellent. Um And I'm consistently in awe of the vascular anesthetists who managed to maintain stability whilst the patients being Replumbed like a washing machine, it's really very impressive. Um uh I guess if you want to try start popping your questions in for all into the chat. Um If you don't mind, do you mind if I ask a question? So, um just to start us off and obviously in the Royal infirmary, we've talked as your case really nicely illustrated. Uh I guess sometimes that there are delays to picking up potential spinal cord ischemia in this group of patients. And I guess in a unit where there are 300 nursing staff, 40 consultants, et cetera. And how can we make sure we're maintaining vigilance um for these patients and picking up potential signs of spinal cord ischemia as soon? Um as we can. Um, do you have any strategies, do you think it's an education thing? What, what do you think is that is a really good point and it is challenging. I think a lot of our patients who are in the highest risk cat have epidurals and the nice thing about that is the nurses are really tuned in to motor checks. Um So, so that's nice. But obviously there's a subset of patients who don't have an epidural and they're the ones that really worry about. Like how do you ensure and, and you know, things that we try, obviously the documented handover and safety brief, the verbal over on the critical care unit we've thought about, we never really implemented bed head signs. I think that's something we should think about. Yeah. Um and um yeah, it it is, it is challenging and I say that epidural patients do get, assess the other problem that we do see happening is legs go a bit weak and, er, or it's just the epidural and it's kind of like turn it down a bit. You don't want to totally compromise analgesia. The patients are going to be sore and, you know, it is really tough. Um, and yeah, I don't have any, an obvious answer for, for what we do about it. And I forgot to mention in terms of assessment, the gold standard is probably for, for ventilated patients, propofol, remi fentaNYL. That's what we used to do to facilitate up and assessment, but a sort of series of, of adverse incidents with remi fentaNYL due to we don't use that routinely in our critical care unit. So that's unfamiliar to our nurses. We felt that actually um well managed Remy was going to be the best, but actually well managed, badly managed Remy. So that's what that's what we use, but it's really, really difficult and it, and especially we turn over nursing staff and, and nurses who aren't used to looking after our patients with. Yes, it's a challenge. I'm just interested because with three of you, I imagine you end up being contacted a lot for clinical advice regarding management of these patients and it must be quite a lot in terms of your al call requirement. Um There's a question here from Doctor Bramley who's saying I'm interested to know an acute dissection, how do you balance the potential need for spinal drainage with the risk of rupture? What pushes you to delay surgery for a spinal drain? Hi. Hi, Gina. It's nice to hear from you. Hope you're well. And um yeah, you're probably thinking more about type a dissections but, but you know, it could be a, could be a type B dissection, the rapid rapid expansion or more perfusion that needs to go for A T bar where there is concern about immediate threat of rupture. We we just can the spinal, spinal drain and move to a reactive approach like often these things are happening out of hours. So actually having somebody who's happy to rapidly put in a CS F challenge. So um yeah, just get, get the, get the uh rupture risk dealt with and save the patient's life first and then rapidly assess them. And if you need to put in the drain, of course, the problem with that can be um especially if they're unstable, they might have lingering coagulation issues and it can be really, really difficult. You, you're not going to put a needle in the back until you've met safe parameters to do so. But I I would say in, in any dissection situation, what we do is we don't put a drain in unless we need to. Ok, thanks. Hey, are there any other questions for Allie? I don't need more. If not, I'm just going to take the opportunity to thank you so much aie for giving up um your Thursday evening to chat us through um a complex, complex aortic imagine of a complex aortic patient. I learned a lot from that. I thought it was a fantastic talk. Um I've just popped the link to feedback in the chat there. And so please follow that and that will allow you to generate a CPD certificate um as well. Uh We will be back on the 26th of October and our palliative care colleagues are going to deliver a session on palliative care and critical care. And so thank you all for coming this evening and, and thank you again, Allie for speaking. No problem. Thanks for having me.