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Recent studies suggest that patients undergoing surgery might do better postop if BP is kept greater than a MAP of 65.
This is prelim data (see references below) and correlation doesn’t equate to causation, but could we have become too complacent about intraoperative hypotension?
Edwards Lifesciences reached out about sponsoring a show to talk about these issues (they make real time BP monitoring devices and are working on machine learning algorithms to predict hypotension earlier), and after researching it more I agreed. And Dr. Neal Fleming, Professor of Anesthesiology at UC Davis, happens to be just the right expert to help school us! Check out the full transcript below, and hit us with your comments and questions on Facebook!
- Salmalsi, et al. Relationship between Intraoperative Hypotension, Defined by Either Reduction from Baseline or Absolute Thresholds, and Acute Kidney and Myocardial Injury after Noncardiac Surgery. Anesthesiology 2017
- Bijker, et al. Incidence of Intraoperative Hypotension as a Function of the Chosen Definition. Anesthesiology
- Wickham, et al. Care of elderly patients: a prospective audit of the prevalence of hypotension and the use of BIS intraoperatively in 25 hospitals in London. Perioperative Medicine 2016.
- Bartels, et al. Blood Pressure Monitoring for the Anesthesiologist: A Practical Review. Anesthesia Analgesia
- Maheshwari, Sessler, et al. A Randomized Trial of Continuous Noninvasive Blood Pressure Monitoring During Noncardiac Surgery. Anesthesia Analgesia 2018
- Hatib, Cannesson, et al. Machine-learning Algorithm to Predict Hypotension Based on High-fidelity Arterial Pressure Waveform Analysis. Anesthesiology 2018
ZPac, check out the original video here on Facebook and let me know what you think!
– We live?
– We’re live.
– We’re live, look at that. What’s up Z family? It’s your boy Dr. Zubin Damania, and yes, I said Dr. Zubin Damania and not ZDoggMD because I am in the presence of a professor of anesthesiology, Dr. Neal Fleming, who is professor of anesthesiology at UC Davis right here in Cali. And it’s interesting ’cause we’re here in Irvine, California in the OC keepin’ it real, at Edwards Lifesciences because they kind of talked to me and they were like do you know about hypotension, low blood pressure, in the intraoperative setting? And I said I’m a hospitalist, I know that I take care of patients who have complications after the intraoperative setting and I pre-op patients before they go into the OR, and I’ve rotated through the OR, but I haven’t thought about managing blood pressure and low blood pressure in the OR in a long time. And I learned a lot, which is low blood pressure in the operating room actually could be more dangerous than we thought. And we’ve been complacent about it, and the question is now, is there something we can do to better recognize it, to maybe predict it a little bit earlier and be more proactive in our management of it. And that’s why I wanted to talk to you.
– So that’s like everything done, right there.
– We’re done, the show’s over, thank you guys. See you guys later, no. So first of all, let’s back up from first principles for a second because I have to learn a lot to understand, relearn a lot to understand the physiology here. A lot of our fans work in the OR, either as surgeons, anesthesiologists like yourself, or scrub, you know, OR techs, nurses et cetera. In the operating room, as an anesthesiologist, the way that you would often measure blood pressure, in say uncomplicated patients, is you’d have a cuff, just like on the floor, that inflates every three to five minutes and checks your blood pressure.
– But it turns out, you know, you’re missing obviously a lot of data points, but who cares, right, if the blood pressure’s a little low and you catch it five minutes later, and maybe you do something about it, and you check it again in five minutes. Why is that not the best way to think about blood pressure?
– I don’t know if it’s the best way, but it’s the way we’ve done it forever so it should be okay, right?
– Of course, right? ‘Cause we know the status quo in medicine is the bomb.
– Change is hard.
– Change is really hard. Like for example, they have wired me up to this thing and it is a real-time sensor called ClearSight that they’re using to measure blood pressure in real time, non-noninvasively. And even though my finger looks like it’s going to fall off.
– It won’t.
– It won’t. Why won’t it fall off?
– We’ve seen this.
– You’ve seen this? So yeah, I’ve seen a guy impaled through the chest and he didn’t die, so.
– It’s disconcerting, it’s a little bit of venous congestion, it’s what happens with this system.
– So it’s venous congestion, not arterial?
– That’s correct.
– Got it. So it’s venous blood pooling, but actually you can feel, there’s still cap refill, and it feels fine. Now, back to the main premise though, why does low blood pressure in the OR matter at all?
– Well, it used to be like the standard admonition, any time we didn’t know what to do with an anesthetic we’d ask a hospitalist or an internist, what should we do to take care of this patient and they’d tell us avoid hypoxia and hypotension.
– That was like the classic advice.
– And the reason we say that is well, classically, hypotension is bad. It leads to bad physiologic outcomes in patients outside of the operating room. but it turns out now there’s data that inside the operating room.
– Yeah, ’cause I think for a while we used to think that there was some sort of, maybe even protective sort of stuff, I mean you’re anesthetized, you’re kind of, it’s not really hibernation, but maybe it’s okay that your blood pressure’s a little low because the demands aren’t’ as great, maybe it’s okay, but I think what’s happened over time is the, well one we’ve got a whole bunch of information now. All of the operating room data is streamed in to all these servers and computers are looking at all these numbers, these huge numbers, and now we can see things that we couldn’t see before. ‘Cause we used to just think that if the patient survived, we’re cool.
– Yup, keep ’em alive till five. That was our motto.
– But now what we’re seeing is there’s a whole bunch of other bad things that happen afterwards, and then by looking at all this information we now have available, we can see that there’s associations between bad outcomes and low pressure in the operating room.
– So, and again physiologically, this isn’t that surprising, although you had mentioned, we thought well if you’re in this hibernated, sleep state, you know again, your physiologic demands aren’t that high, maybe you can tolerate a lower blood pressure, but it turns out that’s probably not the case.
– Probably not the case, and probably relatively limited amounts of low blood pressure can really have an impact down the road.
– Even for a short period of time according to some data out of Cleveland Clinic and other places.
– Cleveland Clinic’s really good ’cause they have, they’ve accumulated this huge pile of information, interoperative data, and they’ve been able to really leverage what they have learned there and I think give us some really more objective guidelines and targets that are more manageable other than just avoid.
– Right, right. So the targets that they’re sort of thinking about are something like a mean arterial pressure of 65 at the lowest.
– And it’s interesting because in other settings we’ll be like, oh you know, keep his MAP above 60, if it drops at 50, you know, for a while, who cares, it’s okay.
– Who cares, that’s right.
– But increasingly, when you actually look at the data sets, there are associations with bad things. And so then it becomes a question of well, in the OR, if we’re gonna actually prevent too much hypotension, ’cause it seems like it’s an area under the curve. The more hypotension you have–
– Deeper, longer.
– Deeper, longer hypotension, the more potential bad outcomes you can have. So then the question is, is that cuff that’s inflating every three to five minutes sufficient to allow you to manage hypotension in a proactive way?
– Probably, you’re missing, well you’re missing four minutes out of five worth of data.
– So, if we had more information, we then can decrease the overall time that the pressure’s lower. If we have more information coming down the pike, we can follow trends that we couldn’t before so that there’s basically more dots in the graph. So I think you can see the trends more easily. So for both those reasons, continuous data is, I think consistently shown to give you better guidelines.
– Better guidance, I guess.
– Now assuming that it’s not just throwing all the data at you, like every second you see what the blood pressure is. Like for example, right now, I’m on this ClearSight monitor and I have a full stream of blood pressure, 137/84 up to 161 as I pointed up there, up to 177 as I watch it, and then I stop watching it and it goes down. And that is an accurate blood pressure when I do a show, guys. If I stroke out in front of you now, you need to know, okay. Love you Z-Pac, I love you. I don’t wanna die Logan Stewart. All joking aside, so this real time data is fascinating. So for me it’s fascinating ’cause ever since they plugged me in, right as I started the show, my initial blood pressure was like 120. The minute I started looking at it, it creeps up. That is like a type of white coat hypertension and I’ve always had this, it’s an adrenergic response where I get sympathetic overdrive. Not only that, but we’re live on a show with someone much smarter than me.
– Don’t put it on me.
– It’s all on you, Dr. Fleming. Don’t put it on me. Don’t you put that evil on me, ZDoggMD! But the idea then that now we know in real-time, beat to beat variability, and how does this thing work, by the way?
– It’s pretty cool.
– I’m not flipping you guys off. This is just where the probe is.
– It shines a light through your finger.
– And measures the light that comes out on the other side.
– So kind of like a pulse ox.
– Like a pulse ox, the same sort of thing. And then it has, and you know how when you whack your thumb with a hammer?
– I do it all the time.
– And you can feel it just throbbing?
– Well that’s, that happens normally, you just feel it more after you hit yourself with a hammer and finish swearing. And so what it does is it has a blood pressure cuff that basically inflates every time the pulse comes down the finger. And so that’s basically an exact reflection of the blood pressure.
– Exact in real time. But it’s a peripheral measurement, so it affected by pressors, agents we use to raise blood pressure, is it affected by peripheral vascular disease, things like that?
– Math is involved because your pressure is different from your pressure there and is different from your pressure here.
– Got it.
– So they do some corrections for that.
– Got it.
– And there are sometimes when it’s not gonna work well.
– If you have really bad peripheral vascular disease, sometimes it doesn’t work well. But in general, works pretty good.
– So what we have here then is a non-invasive way to measure blood pressure in real time that gives our anesthesiologist and our OR team a real-time wave of what’s going on with blood pressure. If blood pressure’s important, which we’re positing the data is suggesting that it is.
– Blood pressure’s important. It also gives you a whole bunch of other information that we didn’t used to have.
– Like what?
– Which is amazing. Well, it measure your cardiac output.
– Oh, cardiac output, which is stroke volume times heart rate, if I recall from physiology.
– Very good.
– So you can calculate based on what parameters would you do then? The machine does it?
– The machine does it, basically it looks at the size and the shape of the pressure, calculates the stroke volume multiplies it by your heart rate and measures cardiac output.
– Got it, so okay, so you can check cardiac output now. To me, this brings us to management of this. Because the only reason you wanna know any measurement, and this is important right, why measure something if you’re not gonna do anything with it? And the reason I came to Edwards here, we flew out here to talk about this, is there’s compelling reasons that knowing this information in a real-time way, without having to stick an art line in, that’s something invasive, which you can do for very sick patients.
– We do it a lot.
– But what about our routine patients, our mom who goes in for the gallbladder? Like if you can know in real-time, the question is, what are you gonna do with the data? If you’re gonna do something that’s not gonna cause harm and over treat, but you’re gonna do something that actually prevents bad outcomes, or can help us more proactively manage this, then it’s worth doing. In this case, it is. Because what can you do in the OR to manage low blood pressure? What are sort of some of the things you would do?
– Well you remember.
– Well, I remember. Well I remember this, the cuff inflates, the anesthesiologists go, it goes,, makes a little alarm, the anesthesiologist boredly looks up from their paper and goes, mmm, Zdogg is 157/97, let’s pretend it’s not, you know a MAP of 50. Anesthesiologist goes cycle the cuff again, maybe we’ll give a bolus of 250 cc’s of normal saline that’s hanging here.
– IV fluids.
– IV fluids. So some volume in the vessel that will raise the blood pressure, or it could be what like a blood? You could give blood as a volume?
– We hope not, but yeah. Anything, we could give albumin, we could give, you know, salt water, anything in the IV fluid.
– That increase blood volume.
– Just expands blood volume, get the heart going, in more push, more preload.
– Right, which allows it to better perfuse the tissues. Which is, yeah, with the badness we wanna avoid. What about like a change in the anesthesia agent? Could you do that?
– You could. It’s kind of important though, you don’t wanna take it away. And we do, now we add a bunch of monitors, actually we’re starting a whole nother world, that’s maybe another show.
– Anesthesia awareness.
– And monitoring your brain stem, have you done that one yet?
– I haven’t, will you come on and do that with us?
– Uh, it depends. We could put some probes on see, maybe on me.
– You don’t wanna probe my brain, Dr. Fleming. There’s nothing there, it would be a flat line.
– So you could do that, so there are guidelines for that. And then there’s also drugs.
– Vasoconstrictors, so things like phenylephrine, or inotropes, dopamine, dobutamine, epinephrine, norepinephrine, all those.
– Got it, so drugs, volume, tweak the anesthesia agents. And in order to make those decisions, you have to know what’s going on with the cause, or suspecting why. And there are parameters that can help you. So cardiac output obviously can help you and maybe stroke volume, stroke volume variation, different measures that you can check. CVP, different monitors.
– Not anymore.
– Is that just not a thing anymore?
– I don’t think it’s a thing anymore. I mean, if you look at the data, CVP’s not really, it’s not gonna tell us what we have been taught it will tell us.
– Which is volume status.
– Volume status, it just doesn’t work, and so those sorts of relationships, they look like shotgun blasts. And so that’s this whole other world with these dynamic monitors of function that have replaced CVP. That’s what these things are bringing us now.
– See that’s what makes it really interesting to me. Because I trained in the world of you put in a Swan or you put in an IV catheter.
– Get CVP and you check CVP and that’s how you resuscitate, and now we have again, and because we have the ability to analyze large numbers of data points, we can actually start to do things like create algorithms that can predict hypotension.
– That’s a whole nother world, yeah, there’s computers.
– But just sticking with this for now, so this device, the ClearSight then, in real-time will look at my blood pressure, which is still quite high, it’s also that they probably put the probe on my back in the wrong position so I can sit properly, and it’s artificially inflating it. Either that or I will stroke out in front of all y’all. In which case, we’re gonna get a lot more views.
– Oh cool.
– A ton of views. I hope you’re ready to be famous, Dr. Neal. So in that setting then–
– CPR certified.
– You are?
– I guess he’s an anesthesiologist, if I’m going down, practice the right place. Right, right, right. So you can then use the other parameters that you would measure in real-time and say okay, I’m gonna give fluid, no I’m gonna back off on the anesthetic, or no, I’m going to maybe give Lasix even. What if I’m volume overloaded and that’s why my cardiac output’s low?
– Could be, could be.
– So there’s lots of different things that could happen.
– Yeah. Can I?
– Oh yeah, get up there. Save my life.
– [Neal] No, I won’t save your life, I’ll just give you your numbers.
– I’m dying Z-Pac.
– [Neal] No you’re not, you’re fine. Your index is 3.8.
– [Zubin] My index is 3.8, cardiac index 3.8, that’s good.
– [Neal] Yeah, so you’re good.
– That means that you know, when I, those years of crack binges that I was doing.
– No damage.
– No damage at all.
– You hear that kids, smoke that crack. No I’m kidding. So this piece is actually can be quite transformative in terms of how you operate as an anesthesiologist. Is it something that really has transformed your practice?
– Yeah, I mean this is all new stuff. I mean, there’s that whole world, we still use Swan catheters, but we use it in, you know, cardiac surgical patients, so that’s about it.
– Yeah so–
– But there’s this whole other world of folks that are, they’re not really healthy, they’re having surgery, they have a whole bunch of other stuff going on, you know, the Swan-Ganz catheter is pretty invasive, it’s expensive, it’s complicated, but you know, you’d like that information, but you’d like to not take the risks associated with putting that catheter in.
– This opens up all of that patient population to the information that we used to get just from the Swan.
– See and–
– go ahead.
– See, this to me again, when I was training, putting in the Swan was the apex of your line placing skills. And I remember being under the drape and doing this whole thing, and I remember also when I did my anesthesiology rotation at UCSF the anesthesiologist said look, this guy probably needs an art line, we were middle of the case. Go under the drape and put that in, don’t worry, you can’t hurt him, he’s under anesthesia. Well, turns out I could hurt him, because I poke, poke, poke, poke, poke, poke, till I got it in. When the guy woke up and I saw him post-op, he had pain in the wrist and a bunch of little puncture wounds like a vampire came. And that’s how we learned to do these procedures, but I was forever traumatized because I felt like I did harm, although we needed that art line. Here’s the thing. Look at this, all it’s doing is turning my finger blue, but it’s warm and perfused. It’s just venous pooling. And this can actually do what, you know, a lot of what that was doing. And again, it’s not a replacement, necessarily.
– No, but it comes pretty close.
– Comes pretty close, so for the little old ladies having the gallbladder removed, if you can avoid low blood pressure in that patient, you could avoid outcomes. And some of these problems that you get downstream are nationally problematic.
– So, yeah. That’s when I get called as a hospitalist.
– Yeah, I mean, well, ’cause you stay in the hospital longer.
– And they have more problems when they go home.
– Exactly right. So, this could be a way to fix it. Now, what’s even more exciting to me, and I think this is really cool, and actually would be interesting is if we could ultimately downscale this and put in it in CVS, ’cause then you’d, instead of getting that snapshot, you could get a real time, sit there and think yourself into hypo or hypertension and see what affect it has on you. It’s remarkable that–
– Well the feedback.
– The feed, this biofeedback for me, doing a show, I’m 153/97. And it makes me wonder, I need to do less shows. ‘Cause the area under the curve, if I, I’ll say that the probe is in a low place, but all that, oh I hope. Otherwise, me and Neal are gonna have some talking after. The other interesting thing about this is with these data points, there are algorithms that Edwards is working on.
– That are, they’re calling the hypotension predictive index.
– It sounds like they looked at a ton of data points and said could we actually start to anticipate hypotension based on patterns.
– Well, what’s the deal with that?
– It seems to work.
– Robot apocalypse coming.
– It’s coming. Well I think they took a lot of the data from a monitor like this, so they looked at the shape of that blood pressure waveform, they look at how broad or narrow it is, they look at the cardiac index, so how well the heart’s working, they look at things like the stroke volume variation, and they they kind of break it down to a bunch of other, I think they have like millions of different parameters they looked at, and they just dump it all into a big computer and say figure out the best way. And then they took, again, data like they had from the Cleveland Clinic and from some other institutions and said, here’s a patient who’s hypotensive, what happened before? Could we see it coming? By looking at all these millions of different parameters, they developed an algorithm which, you’re from Las Vegas, it’s an odds thing. Yeah, exactly. It tells you that the chances that the blood pressure will be below 65 five minutes from now. That’s kind of cool.
– Let me summarize that, because that is something that to me is absolutely indicative of the transformative power of what they call artificial intelligence. Really, just algorithms. You can look at all this data from real-time probes like this and then build a model that will say, you know we see patterns. I bet you based on this pattern it’s 99% of 95% likely, whatever the numbers are, that you’ll be hypotensive in five minutes. And if you can alert a clinician to that, they can proactively look at the trends and go, you know what, we may wanna give that bit of fluid now, or we may wanna turn back this, or we may wanna give that pressor, or we may wanna dial up the epi, whatever it is you’re doing, or the neosynephrine, in real time. You guys like neo don’t you?
– It’s become pretty popular.
– Yeah, in the OR.
– Yeah, but I think the one important thing is that it will fix the primary problem, it’ll always make the blood pressure better, but the nice part is the extra information ’cause sometimes you can make the blood pressure better and the output worse.
– Right, right, right.
– And so this information tells us there’s more than one answer. I mean, bringing the blood pressure up is cool, it makes the surgeon happy, everyone goes away, they don’t stop bothering you, but if you’ve hurt the patient, that’s not so good. And so the extra information from these is critical.
– So the AI actually is more patient centric than we might otherwise be able to be.
– Well the AI.
– We’re blood pressure centric.
– Yeah, well the AI is predictive of problems before they happen.
– Right, right, right. So then you can be proactive in managing.
– And then also, additional information as to most appropriate management.
– Excellent, so better tailored management of hypotension earlier in a way that maybe hopefully we do good for the patient. See again, that’s exciting. You know, we just did a show on Apple Watch and how they’re tryin’ to predict, or catch falls after they happen, catch a-fib after it happens. What if you could prevent the fall, prevent the a-fib, you know, hey, you’re sounding a little stressed, this pattern’s gonna lead you to a-fib in three, two, okay. I’m gonna meditate stat! Right now, okay, now we have to clarify that this is ClearSight, this is available now, and that it’s FloTrac, which is a different device that is gonna use the hypotensive, hypotension predictive index, but that index, that algorithm, is not yet available. So this is actually going to come in the future, but it’s exciting.
– The predictive algorithm needs the invasive monitoring, needs the arterial pressure waveform.
– Got it, so and that they, I think Edwards calls it FloTrac, it’s an actual–
– That requires the arterial catheter.
– Arterial catheter. Which makes sense because you need the fine grain to–
– Little bit.
– Yeah, yeah.
– But this is pretty close, so you know, if you dream.
– Right, yeah.
– I don’t know if we’re allowed to say that or not.
– We don’t dream on this show, okay.
– If you are.
– Something we do.
– Currently the predictive algorithm just comes from the more robust monitor, the arterial catheter.
– Yeah, so folks who work in the OR, folks who care about their patients, floor nurses who have seen bad things that happen from intraoperative hypotension, all of this really matters. Which is why I was happy to be taught about it. Because I didn’t realize that just even, you know, that first of the way that we might measure intraoperative hypotension may not, may be a little outdated. That there may be better ways to do it and that managing it might lead to better things, and the physiology of how to manage it is fascinating.
– So it’s good to know about in general for me as a hospitalist as well.
– Yeah, and it’s a new world. It’s not the world I grew up in and it’s not the world I trained in. This is all new information, new data, new approaches.
– What’s the biggest change you seen in anesthesia in your career now? You’ve been doing this for a while.
– You mean since I started with open drop ether, or?
– You had open?
– No I did not.
– Since you made ’em bite on the bullet, Dr. Neal. How’s it been since then?
– Well, it what I tell, actually, it’s what I tell everyone. I mean, the drugs are all different, but I think the monitoring is probably the key difference. The ability to get all this information without puttin’ in Swan catheters or arterial pressures, and then the subtleties of that information that the additional things, like not using stroke volume variation and figuring how to do that. I mean, that’s what, the last 10 years? And it really, I mean, and a lot of it hasn’t really, this is all OR stuff and it hasn’t really crept out yet, but I think there’s huge potential if it ever gets out. But for life in the OR it makes what we do so much fun.
– This is why I kind of like technology, even though I hate it. ‘Cause there’s some technology like the EHR that’s just wrecked our lives, but also made it safer for patients, but then there’s technology, and that’s why, you know, when Edwards and I connected, I said we should talk about this because it’s really cool.
– It is pretty amazing.
– And I wanna talk about it with someone way smarter than me, so I asked Logan to talk, no, Dr. Neal. Dr. Neal Fleming, I am hoping to have you back on the show in the future so we can talk more about stuff. Because you know stuff that us hospitalists don’t know. That frightens me.
– It shouldn’t frighten you.
– It does.
– No, being on this show frightens me.
– Are you scared?
– That’s on you, not me.
– Look at my blood pressure.
– I know.
– 140, 154/90.
– I’m a little scared how you’re gonna go for a little bit.
– Well I gotta fly to Orlando to do a talk, that’s gonna jump my blood pressure to 300.
– Jaws of the storm there?
– Yeah, right in to the storm. By the way, mad love. Oh, and check this out. So what is this, Dr. Neal?
– [Neal] This is the demo from the software that runs the predictive index.
– So okay, so the hypotension predictive index.
– This isn’t you.
– This is not me.
– But this is basically the chances that this demo patient is gonna get into trouble. And then… It’s a little bit, yeah, so you can do this, can’t you? There, and then this is all the background information for the prediction. So what happens is you end up, you’ll end up seeing the predictive index will start to creep up. And the crazy thing is, I mean, we started using this and the mean arterial pressure kind of looks okay, and the other, the index, I mean this is kind of marginal, looks okay, and then this will slowly start to creep up. And then you just kind of scratch your head and you try and figure out why it’s going up and what to do and then you look at, in theory then you look at this other screen that tells you where the output is going and the stroke volume variation, which is the CVP equivalent. And then it has this other measurement that I don’t know, maybe it tell you how well how the heart’s doing. So that’s like the, this would tell you if you needed to give an inotrope. Or and another measure here that supposedly tells you how compliant the vascular system is, this would tell you if you have to give a vasoconstrictor or not. And by looking at how these numbers change, tells you if you should give more volume, you should give more inotropes, or you should give some afterload increase. And so supposedly it puts you in the right category for treatment so that you fix the pressure but don’t hurt the output. So that’s what this is supposed to do.
– That’s dope. I hope that happens. That’s really cool, that’s actually putting data to work. By the way, how many Z-Packers felt like Dr. Neal looked like the dopest weather man on the planet there? There’s a 22% chance of low stroke volume. We have a low MAP front, MAP front coming in from the north with 102 millimeters of mercury, Bob, back to you. Actually, show Bob.
– [Neal] Sorry.
– That was tremendous. By the way, you know, when I was learning about stuff for this show, ’cause I always have to learn about stuff ’cause I’m not so bright, I remember tryin’ the read about stroke volume variation and trying to wrap my head around it. And just for the Z-Pac who care, ’cause we’re just going deep for a second, stroke volume variation is, stroke volume is how much blood you’re squeezing out of the ventricle with each beat, yeah, or over time? And so it–
– Over time.
– Over time. So it relates to cardiac output, how much blood you’re pumping out of the heart, and it varies beat to beat based on whether you’re breathing in or breathing out. And for those in the know, who when you breathe in, you create negative pressure in your chest and that brings a lot of blood to the right side of the heart, it dilates the pulmonary capillaries and arteries. And so you actually pull blood away from the left side of the heart a little bit, right?
– Little bit.
– And you maybe bulge a little bit into the left side from the atrium on the right?
– And so, see he’s like no, that’s not what happens.
– It’s close.
– It’s close, and then the blood pressure actually drops a little bit, and that’s normal with deep breath, and when you breathe out the opposite happens, it goes up a little bit. So in people who have dysfunction, like severe COPD, cardiac tamponade where the sac around the heart is full of stuff and it won’t allow the chambers to dilate, you get something called pulsus paradoxus.
– Which is a greater than 10 millimeter of mercury change in blood pressure between breath and exhalation.
– Kussmaul sign if you will. And he will, okay. So that was strictly for the nerds, pulsus paradoxus. Go on rounds today and you’d be like, yeah, did anyone check a pulsus paradoxus? And they’ll turn to the weakest link in the team and be like, yo, did you check pulsus paradoxus? And he’ll be like I don’t know what that is. And you can just watch the fun. Anyways, that’s medical bullying 101 guys. What do you think Dr. Neal, did we do this?
– I don’t know.
– Is there anything else that you think is important to talk about?
– Nothing comes to mind right off.
– Yeah, man, this guy. He knows stuff, I learned stuff. How’s my blood pressure?
– [Logan] You’re going down, Z.
– I’m gonna die.
– You’re in trouble. You’re in trouble.
– Welcome to my world, people. Early onset vascular dementia, it’s on. All right guys, I wanna thank Edwards Lifesciences for letting me play with the ClearSight, for telling us about the hypotension predictive index on their FloTrac device, and the exciting things that are happening, and it’s fun to be in Irvine. It’s humid, it’s humid here. You people have this thing called water in the air. I don’t like it, and yet I do. All right guys, I love you, hit share, hit like, leave questions in the comments, and we’ll see if we can get you answers. And we out, peace.