So thanks very much for the opportunity. I think this is a great way for us to kind of dive in right initially here. So today I'm going to talk on technical advances in the goal-directed therapy space. So I have some disclosures, none of which should really influence this topic. So in the next maybe eight, 10 minutes or so, I'm going to talk a little bit about the concept of goal-directed therapy and talk more about the rationale for why it's applied to the cardiac surgical space in particular. And then I want to dive a little bit more into goal-directed therapy, but through a different mechanism, and that's the cardiopulmonary bypass circuit. So these are not unfamiliar concepts to most in the room. What we have done in the past, and you might say, you've always done this, is we've always been doing goal-directed therapy of some sort. And that's really been through a couple of mechanisms. Two that are shown here, of course, the Swangan's catheter, and then transesophageal echocardiogram. And whereas these do provide lots of information around resuscitation and can be key features of how we think about fluid management, vasopressor management in cardiac surgery, they obviously have limitations, whether it's because they're highly invasive or because they require kind of a unique brand of technical expertise to be able to master. And the central concept here is that we're attempting to find a sweet spot of sorts around resuscitation. This is not unique to those of you in the room who have done this for quite some time, but the idea is that you want that balance between having excessive fluid administration on one hand and the organ injury that comes with it versus the hyperperfused state or the under-resuscitation on the other hand. And so that sweet spot, of course, is considered goal-directed therapy. And more recently, what we've seen is kind of a smattering of opportunity here in terms of monitoring techniques that can help to guide you in the way you think about fluids. On the left-hand side, one of the examples is that you can use ultrasound technique in the periphery, so this is at the blood vessel level, determine what waveform analysis might look like, and there are algorithms that can then guide that therapy. But what it all really tells you at the end of the day is where do you exist on Starling's curve? So one of the poor man's versions of this, which I've used for most of my career, and there are obviously limitations to it, but you can look at things like respiratory variation and volume responsiveness, and they suggest, of course, where you are on that curve. Now, these are theoretically basic concepts, but they are very difficult to master. And in fact, now, because we have a number of commercially available products that can help to guide these therapies, there's an opportunity here to step beyond some of the more invasive techniques and think about more surface-level techniques, whether that's using plethysmography or slaving off of your arterial line. And ultimately, the promise of this technology is that you have goal-directed therapy that can be very specific to your patient. One of the reasons this is particularly helpful in the cardiac-surgical setting is not only do you have algorithms that exist, and this is one that's popularized from a recent publication, but these can guide you a little bit either on intravenous fluid administration. It can tell you very specifically, based on that algorithm, if you are no longer responsive to those various fluid techniques, then perhaps vasoconstrictors are the goal. And then ultimately, again, for the cardiac-surgical perspective, those patients that might have low cardiac output states might benefit alternatively from inotropy. And it's these algorithms that might be able to do that for you, or at the very least, you can participate in the monitoring technique and understand where to go with your patient. This has been studied, I would say, in a modest fashion. More recently, there was a publication from the mid-2000 teens that showed, and again, this is a small cohort, but what's interesting is these are patients that are high-risk for heart failure, and what they found was despite the fact that we might, kind of as an ad hoc strategy, limit our resuscitation efforts, at least when it comes to fluids, that they found when they applied goal-directed therapy to the cardiac-surgical setting that they, in fact, gave more fluid to their patients than what they might have expected, and despite more fluid be given to those patients, they actually had lower complication rates. So this is a little antithetical to how we might think as a pretest probability for this patient. Interestingly, you'll see at the bottom here that their low cardiac output syndrome state was significantly reduced through the use of goal-directed therapy. And if you look at this on a more population-based level, and there's a couple of different meta-analysis devoted to this topic, patients, generally speaking, have enjoyed shorter lengths of stay as a result of using goal-directed therapy, probably associated with lower overall fluid burden administration and organ injury as a result of it. But there are alternative options for us to apply these same principles outside of just either fluid monitors or your arterial line or what have you, and one of the areas that we, I think, have under-focused over the course of the last several decades is in the perfusion area. So obviously for all patients undergoing cardiac surgery, or I should say most, we have this revolutionary option of managing them on cardiopulmonary bypass. This is an area that I think we have failed to understand the opportunity for goal-directed therapy. This is a study from the early 2000s that showed, and this is not of surprise to anybody in the room, that the more fluid you administer on bypass, the more hemodiluted you become, perhaps the lower your overall hemoglobin, you're gonna have a lower oxygen delivery value. And so that's gonna lead to organ injury. However, the alternative to that, where you can go on bypass and take as much fluid off that patient as possible, leads subsequently to a similar level of organ injury, but for a different reason. And what we set up there is that same paradigm that we just envisioned in goal-directed therapy, where you might, on one hand, see a hemodilution or ultrafiltration on the other, and somewhere in the middle is an opportunity for a more goal-directed perfusion approach. In this particular case, that same group suggested that perhaps it's the delivery of oxygen threshold that we should be looking to achieve. What is the threshold at which, if I deliver enough oxygen to that organ system, that I'm going to reduce the subsequent injury? What they found was, here, their DO2 of 272 is perhaps that threshold. And what spawned from this was this opportunity to create a goal-directed perfusion algorithm, and this is directly from that group. What they found was that perhaps you should, of course, limit the excess, the excessive hemodilution or ultrafiltration, maintain delivery of oxygen at a certain threshold based upon certain calculations, and then you should modify the way you think about flow on bypass and modify transfusion thresholds to step beyond thinking about just a transfusion trigger, a hemoglobin level, but perhaps it's a delivery of oxygen level that you're hoping to achieve that might dictate some of those practices. What has then come from that are a couple of different smaller trials, randomized prospective trials. This is a pilot study, actually, from our organization that showed when you use this same algorithm, you can significantly reduce the rates of AKI after surgery. Similarly, that same group, Renucci et al., performed a larger randomized control trial published just a couple years ago where they did the exact same thing. You'll see there the intervention is the delivery of oxygen to threshold and avoidance of some of these excesses. And what they found was that, again, those patients enjoyed a much lower rate of at least stage one AKI and overall incidence of AKI after surgery. And what's important to note is that these concepts, this goal-directed perfusion, goal-directed therapy concept is starting to become a larger part of some of the guidelines that have been put out as well. This is an example from our organization several years ago, the Guidelines for Perioperative Care, where they issued a grade one recommendation to utilize goal-directed fluid therapy. There's a whole host of ways you get at that endpoint, but the idea being, of course, that we aren't indiscriminate about how we think about that therapy. But just as interestingly, there are guidelines now put out by a number of organizations for the same concept but applied through the cardiopulmonary bypass circuit. And this extends, of course, beyond the circuit in the operating room, but to things like ECMO management in the post-operative setting. And so, honestly, we've got lots of opportunity going forward. We're still at the early stages of understanding how this applies specifically to the cardiac surgical setting, but the opportunities exist. And so I thank everybody for the chance to speak here a bit today. We'll get into some question and answer, I'm sure, as the session continues.

goal-directed therapy

cardiac surgical space

fluid administration

monitoring techniques

cardiopulmonary bypass