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S2D: The Symptom to Diagnosis Podcast - Episode 07: Hypotension
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S2D: The Symptom to Diagnosis Podcast - Episode 07: Hypotension
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Language: EN.
Segment:0 .
DR. CIFU: I'm Adam Cifu.
DR. STERN: And I'm Scott Stern.
DR. CIFU: And we're back with episode 7 of the Symptom to Diagnosis podcast. This podcast teaches evidence-based strategies for diagnosing common medical symptoms. Each episode is divided into four parts. We begin each episode with a case unknown to one of us. We then discuss five high yield features that help to accurately diagnose the cause of the symptom at hand, we then return to our case, before finishing up with a discussion of fingerprints, common misconceptions, pet peeves, and other random pearls of knowledge pertaining to the week's symptoms.
DR. CIFU: The cases that we discuss are drawn from our clinical experiences but, because protecting patient privacy is part of our oath, we never discuss actual patients and most cases are composites. Our topic today, or this week is hypotension. Scott, you're the expert of the day. Do you have a case to present today?
DR. STERN: I do, are you ready?
DR. CIFU: I am ready and raring to go. Let's hit it.
DR. STERN: Okay.
DR. STERN: So this was a complicated case you would be happy to know. An 18-year-old woman who presented to the emergency room with hypotension and feeling quite poorly and in a lot of distress. Her story actually started about three weeks before this when she presented to the emergency room with fevers. She was admitted to the hospital at that time and had multiple blood cultures that were positive for staph. Must've been every single blood culture that we drew was positive and she ended with an evaluation to see what the source of this was suspecting that she might have endocarditis because of the frequent positive blood cultures, multiple echos were done, and they revealed that the valves look normal.
DR. STERN: And at one point a CAT scan was done that revealed actually contrast in the thorax that wasn't clear where that contrast was.
DR. CIFU: Whoa, that sounds concerning.
DR. STERN: Careful auscultation at that point actually revealed a very soft, continuous murmur in the chest. And with a very careful echocardiogram we were able to eventually discover that she had a PDA. Furthermore, the CAT scan also discovered a lesion in the pulmonary artery which turned out to be a massive vegetation. So she had had a PDA at birth that had never been discovered and had become infected, and then formed the vegetation on the downstream side of the PDA and it was in the pulmonary artery.
DR. STERN: So a very unusual start to this case. So she was treated for several weeks with antibiotics and had a surgical resection of the infected pulmonary section of the pulmonary artery and PDA to close that. And after another week of antibiotics, went home to complete her therapy at home. She was doing well initially but after four to five days came back to the emergency room feeling horrible, weak, tachypneic and hypotensive and presented at that time.
DR. CIFU: Well, this is obviously a patient who would worry me a lot.
DR. STERN: [chuckles] Very good.
DR. CIFU: But I think actually and I'm sure this is why you chose the case, it's sort of a nice case for me to think about hypotension, because when I think about hypotension, the kind of the big picture things that I always think about is hypovolemia, right? Really common. I actually think that's probably the least likely possibility in this patient, but who knows, maybe she's just been feeling crappy.
DR. CIFU: Maybe she's got to receive different antibiotics that you haven't told me about, something like that. Distributive shock hypotension usually related to sort of peripheral vasodilation is a possibility in this lady, maybe she's got persistent infection which is not yet adequately treated or maybe something's gone wrong with her antibiotics, and so she's still sick.
DR. CIFU: You usually think about that sort of hypotension with gram negative organisms rather than gram positives. You get an exotoxin from grand positives, but usually not staph. So that's a possibility, but I think a little less likely, and then cardiogenic shock, it's kind of the third, I don't know, big category that I think about. And in this lady hearing that she's got infections around her heart, she's had recent cardiothoracic surgery at a time that maybe she had bacteremia.
DR. CIFU: I think I'd worry a lot about something creating cardiogenic shock and whether that's pericardial effusion, maybe that's vascular rupture, maybe that is now endocarditis with a failed valve. I'm not sure, that's kind of as far as I'd go, I think.
DR. STERN: Well, that's actually a really good approach. Uhm... Let me just ask you a question and we'll come back to the case, what would you do with her now?
DR. CIFU: Yeah so topic number one is she's hypotensive, we need to start fixing that. So I'd get IV access, I'd start tanking her up with fluids, whether it'd be saline or lactated ringers, and then I'd really want to get a look at her heart. I think I'd start with an echocardiogram. That's definitely where I'd start. She's going to be so complicated that I'm wondering if that's going to be enough and we're going to need some more advanced imaging but that's how I'd begin.
DR. STERN: That's great, so I think that's a really good start and I'll leave you hanging here and we'll come back to her in a little bit.
DR. CIFU: And I will get back to you about that case. [both doctors laugh] Okay, so let's leave the case for a few minutes and take a real deep dive into hypotension. Scott, since you're the expert today you're going to go through the five key points about diagnosing the cause of hypotension.
DR. STERN: Sure, well thanks Adam. Well, the first key point is actually to determine whether this hypotension is clinically significant and that is whether it's shock or not. And it's worth emphasizing that shock is not a blood pressure number but rather it's characterized by inadequate organ perfusion. You know, a blood pressure of 90 over 60 could be normal in a young pregnant woman, but could be shock in an older patient who normally has hypertension that's not well controlled.
DR. STERN: So we actually have to do something relatively unusual in medicine when we see this, we have to look at the patients and think about it a little bit and see whether or not there's signs of inadequate organ perfusion. So what do I mean by that? Well, inadequate organ perfusion of the brain might manifest itself as a patient who's confused and lethargic and unresponsive, in the kidneys it might represent itself as having a patient who's no longer making urine and is oliguric, cardiac inadequate profusion can result in cardiac ischemia and either EKG changes or troponin elevation.
DR. STERN: And finally, a global measure of inadequate tissue perfusion can be a lactate level which can be very helpful in this situation.
DR. CIFU: Right, yeah I think probably every intern has had the experience of being called, woken up in the middle of the night. "Somebody is hypotensive" and you burst into the room and there's someone like sitting in bed reading the newspaper, watching TV, looking like a rose. And it's not until you look back at their blood pressures that you realize like, "Oh, 88 over 50 that's where this person lives."
DR. STERN: Exactly, well once you've decided that there is shock then at one point, the second key pivotal point you've actually already mentioned which is treatment and diagnosis have to go hand in hand, like GI bleeding that we talked about previously, you can't really dilly-dally around and say take four hours to think about the diagnosis and then start treatment. You do have to get, regardless of the cause, you're going to want IV access right away.
DR. STERN: If there's obvious dehydration you want to start fluids right away. If there's obvious hemorrhage and shock, you're going to want to start packing red blood cells as soon as you can. And if there's obvious sepsis you really have to start anti-microbial therapy as quickly as possible because that saves lives. Do not wait for confirmation from blood cultures or other sources.
DR. STERN: And then if the source, if the etiology is not clear, one has to immediately begin the diagnostic process to decide whether this is distributive shock, hemorrhagic shock or cardiogenic shock.
DR. CIFU: I think that those are all great points and positioning the patient is something that I don't know if we have any sort of data on. Right? But if someone's hypotensive, they're kind of out of it, putting them in reverse Trendelenburg to get a little bit more oxygenated blood to their brain, I've certainly seen people who like sort of perk up when you do that. It's certainly not a solution but I think probably perfusing someone's brain as much as possible while you're working is a reasonable intervention.
DR. STERN: Well, it's so funny you say that because last week I was on the GENS and a lady with COVID passed out in front of me, I literally had to put her in Trendelenburg and then manage my own chest pain that she passing out as I was in her room. Well the third key point then is how do we distinguish distributive shock from hypovolemic shock and cardiogenic shock when it's not obvious.
DR. STERN: Distributive shock is when patients are vasodilated and the most common cause of this is sepsis and sepsis is indeed the most common cause of shock, overall, about 60% of all cases. The hallmarks of that are often, not always, often patients have warm extremities and they have bounding pulses because there's a big difference between the systolic blood pressure and the diastolic blood pressure or a wide pulse pressure.
DR. STERN: They often have tachypnea and tachycardia. On the other hand in hypovolemic and cardiogenic shock patients tend to clamp down. And so often they have cool extremities and a narrow pulse pressure. Cardiogenic shock may or may not be accompanied by JVD and S3 gallop. But if you saw that in a patient such as this you'd certainly have a clue that was cardiogenic shock and hypovolemic shock may not be diagnosed until you do orthostatic blood pressures.
DR. STERN: [bell chimes]
DR. CIFU: The orthostatic bell.
DR. STERN: I feel better now having said that.
DR. CIFU: I just want to kind of underline those are great points and the differentiation of warm and cool extremities is just one of those things that you actually need experience to get good at. It's not like being taught to hear a murmur. It's not like being taught to hear rales. And so what I do with sort of every patient I see I check their pulse, I feel what they feel like, and it just gives you a baseline, what do people feel like?
DR. CIFU: What does sick people feel like? So then eventually when someone comes in and they're clamped down and cold, you're like, "Oh my God." Or when they're sick as a dog, but they're really hot everywhere, it lets you know, what's going on.
DR. STERN: Or even just their hands are warm you walk up to them and they're shocky and their hands are warm. That would strike you as being peculiar, right?
DR. CIFU: Agreed, but we don't shake hands anymore in the age of COVID, so---
DR. STERN: I don't know how well this works with clubs.
DR. CIFU: Yeah.
DR. STERN: The fourth key point I would say is in patients who have distributive shock without an obvious infectious etiology you have to evaluate the patients for other forms of life-threatening distributive shock. One that's always surprised me is how much adrenal insufficiency looks like sepsis including the fact that patients can have fever with it. So when you're not making progress with this, in addition to covering patients for sepsis and evaluating them for sepsis, you need to cover them for potential adrenal insufficiency, start that workup and think about hepatic failure, anaphylaxis, and pancreatitis is another cause of distributive shock.
DR. STERN: So those are relatively easy things to check for, with a lipase, LFTs and eventually checking cortisols while you treat, again I'm going to say, while you treat, you can't be too academic about this or the patient's going to die.
DR. CIFU: [chuckles] I love that. We've never been on service together, but I feel like we probably echo each other sometimes. And when you think about distributive shock I think most of the diagnoses are easy. It's usually when someone's septic, they're septic, hepatic failure, anaphylaxis, pancreatitis, they're generally not subtle diagnosis. And so when I'm confused adrenal insufficiency shoots to the top of my differential, because if someone looks shocky for no reason, that's got to be high up there.
DR. CIFU: And I think maybe the one thing I'd add is you got to think why would this person be adrenally insufficient? Because there's often a reason as well.
DR. STERN: Absolutely, right.
DR. CIFU: I'm not sure I've ever seen someone who like "Oh, this person has just idiopathic cryptogenic adrenal insufficiency." Right?
DR. STERN: Right, totally. But they look terribly sick, I mean, until you've seen it you don't understand how frightening it is.
DR. CIFU: Right.
DR. STERN: Well, and then the fifth point is what do you do with patients who look like they have hypovolemic or cardiogenic shock and that they're clamped down and you don't get it. And like you said, normally it's obvious, but when it's not, there's a couple of tests that can be very helpful. You've already pointed one of these out an echocardiogram can be very helpful. It can show you an acute valve rupture, for instance in the aortic dissection and aortic regurgitation.
DR. STERN: When it's acute, you won't hear a murmur you need to echo that patient. Tamponade can be very hard to diagnose clinically and the echocardiogram can make that obvious. Right ventricular failure if it was present and unexplained would make you think about a pulmonary embolism. So an echocardiogram is really useful especially if it can be done quickly.
DR. STERN: And hypovolemic shock of unclear etiology, a CT scan of the abdomen or a fast ultrasound can reveal an unsuspected retroperitoneal hemorrhage and be invaluable.
DR. CIFU: Right, and retroperitoneal hemorrhage is another one, sort of like adrenal insufficiency that sometimes surprises you. I've had people who come in with fall and hypotension and you find nothing on the exam, at least initially until imaging shows you that retroperitoneal hemorrhage and explains everything.
DR. STERN: Right, you're not going to see bruising in the first day or two and on the back. I mean that's not going to happen till blood is dissected through. And if you haven't diagnosed it, the patient's dead. It's too late.
DR. CIFU: Okay, so let's get back to the case. I think more than ever before I'm kind of dying to hear what happened to this person.
DR. STERN: Well, I think that you did a really great job actually. So you were wondering what the cause was. The emergency room was very set on sepsis. They had early closure on this and continued, because of the history of bacteremia, continued to treat for sepsis and give fluids and the patient wasn't responding. And it wasn't until very late in the course that actually an echocardiogram was done at the bedside, which revealed life-threatening tamponade.
DR. CIFU: Wow, interesting. And was that thought to be a surgical complication or an infectious one?
DR. STERN: It was so, I don't know this, not being a surgeon but they don't do a complete pericardiectomy when they do these procedures, they remove what they need to remove and leave the rest in place. She had had a small amount of bleeding into the pericardial sac and it was enough to have created tamponade for her unfortunately.
DR. CIFU: Amazing, and we always say this about tamponade, right? I mean if you're putting fluid into your pericardium slowly you can have a huge pericardial effusion with very little in the way of symptoms that you can see on a chest X-ray. But if you do it quickly it doesn't take a whole lot of fluid to make you very sick.
DR. STERN: Right, exactly.
DR. CIFU: That's great. That is a really interesting and of course, pretty scary case. So let's move on to fingerprints, common misconceptions, pet peeves, and other random pearls of knowledge. Scott, you want to start us off with some fingerprints?
DR. STERN: I do, and I hope you have your bell ready.
DR. CIFU: I'm ready.
DR. STERN: So I want you to do orthostasis in these patients because many patients will be normotensive when they're laying down but an increase in pulse of over 30 when you stand them up has a positive likelihood ratio of 48.5 for large volume loss. [bell chimes]
DR. CIFU: A little late on the bell there, but whatever, orthostatic hypotension. And probably we should have a separate bell for anything with a likelihood ratio over 40, because that's ridiculous.
DR. STERN: [chuckles]
DR. STERN: It could be a horn you know.
DR. CIFU: So for my fingerprint I'm actually, for this entire section, going to go deep into cardiogenic shock. I have no idea why, but just as I was thinking about these, that's kind of what I wanted to talk about. So a specific finding for fluid overload is JVD, some experienced hands or maybe an experienced set of eyes. The likelihood ratio of JVD for fluid overload is 11.1. Okay, let's just say 11.
DR. CIFU: Thus, if you have a patient who comes in with hypotension, cool extremities and JVD that person has cardiogenic shock. There's no question. Yeah, you're going to do other tests but you don't even need other tests.
DR. STERN: And that was true even looking at the external jugular, wasn't it?
DR. CIFU: Right, that was true, that was true. So if you're not great at the internal jugular the external jugular can help you out too.
DR. STERN: Right, that's really interesting. All right, let's go into common misconceptions. The one that I find shocking and I want to emphasize, because every time I read this I'm still surprised, is that infected central lines, when they're infected, often look normal. In one study only 27% of patients, who had infected central lines had signs of inflammation at the site. So you need to assume if they have a central line in, and they look like they're septic that they're infected no matter what that looks like.
DR. CIFU: That is so true. I think it it doesn't mean that you shouldn't examine the line, right? You should still get all over it, you should milk it. You should see if there's pus coming out of it, but even if you find nothing. Yeah sure, whatever the tip's infected, right? It shouldn't surprise us, but it does. So my common misconception, and this is a real one for me, is that there needs to be a really severely reduced ejection fraction for the cause of the hypotension to be cardiogenic shock.
DR. CIFU: I looked this up and it turns out that the average EF, in patients with cardiogenic shock is 30% and that's surprising because we're seeing patients all the time in clinics with ejection fractions of 20-25% who are doing fine with it. But again, if it's a rapid drop from an EF of 60% to 30% that person's going to be in shock.
DR. STERN: Right and that wouldn't be the case of course, if it was valve problem.
DR. CIFU: Absolutely.
DR. STERN: Great, and my last misconception is again another finding that one would expect and it's often not there, which is fever. Particularly the elderly, they can have serious infections and not have a fever and in one study 18% of elderly patients who were actually bacteremic had either a normal temperature or a low temperature. So we have to be careful when we make assumptions that someone's not septic because these findings are not universally present.
DR. CIFU: We've done enough of these now that I forget when, on which one we've talked about what, but at some point I made fun of you for making the point that sick people can be sick without a fever or something like that. [chuckles]
DR. STERN: Well it's okay.
DR. CIFU: So how about pet peeves? Give me a good one.
DR. STERN: All right, well my pet peeve actually stems a little bit from this case, which assuming that all patients who have shock have sepsis. What we tend to see time and time again in diagnostic errors is that we tend to assume that our next patient has what our last five patients have. And so when something's common like sepsis, we tend to assume that every hypotensive shocky patient has sepsis.
DR. STERN: And if we miss these other causes whether it's adrenal insufficiency that looks like sepsis or cardiogenic shock that doesn't look like sepsis, we're going to kill people. So we need to be careful. Yes, assume it's sepsis, yes, treat the patient, but don't stop your diagnostic workup and your evaluation there.
DR. CIFU: That's great, it's funny as I reflect on a lot of the pet peeves that we've had I think a lot of them really speak for availability bias, right? It's that idea that like, "Huh, I've taken care of a lot of cases, most cases of acute kidney injury is ATN, and so that's where I'm going to go all the time." As you said, 60% of hypotension is sepsis. So I'm always going to go there, and it's great to sort of have an understanding of the prevalence, but if it overwhelms your diagnostic reasoning, it's a mistake.
DR. STERN: Absolutely.
DR. CIFU: So my pet peeve and every house officer who's ever worked with me knows this is the lactate level. So lactates are very useful. You mentioned it a little bit earlier and I think you're going to mention it a little bit later looking over the notes here, but what drives me crazy is that lactate has, to some extent, replaced evaluating the patient.
DR. CIFU: And so what often happens is you're dealing with a really sick patient and someone draws a lactate and tells you like, "The lactate's high!" You're like, "Of course it's high, the person's sick." Or on the other hand, you have a perfectly normal patient maybe who came in sick and keeps on getting lactate drawn and people keep on telling you the lactate is 1.4 and you're like, "I don't care.
DR. CIFU: The person looks perfect, leave me alone with that." And I think it's a little bit timing because when I was a house officer to draw a lactate it had to be a green top on ice, run to the lab. And so we never used it. And now it's almost a little bit too available.
DR. STERN: Yep, agreed.
DR. CIFU: You have one more?
DR. STERN: I do have one more pet peeve and that's the whole skin turgor thing. I love when people tell me their skin turgor is good, their skin turgor is bad, and I look at everybody who's 30 to 40 years younger than I am and I think to myself, your skin turgor is always going to be better than mine. I could drink four quarts of Gatorade and my skin turgor is never going to look like yours again, it's actually useless. So people should give up doing skin turgors.
DR. CIFU: Neither of us are quite at the point now that we could just like pull up our skin at the beginning of rounds, and says that doesn't move the whole time. And yet we're doing fine. Okay, let's finish up with some clinical pearls. What do you got for me?
DR. STERN: The first clinical pearl is if you have a central line and the patient looks septic you have to start MRSA coverage. Again, you have to keep evaluating that patient like you said, but MRSA coverage has to be included.
DR. CIFU: Great, great point. So my first one is, if you have a patient who has fever and hypotension in whom you're either considering sepsis, or you've diagnosed sepsis it really helps to undress the patient and take a good look over their skin. Maybe, this is the husband of a dermatologist speaking but you can actually find real clues to the underlying cause of their sepsis. Sometimes really bad things.
DR. CIFU: Rocky Mountain spotted fever, meningococcemia come to mind, but also maybe it just helps you a little bit with your risk stratification right? If you see petechiae and you're thinking, DIC, boy this is a patient who's sick, and maybe sicker than you think, just seeing them for the first time and maybe even sicker than, the God-given lactate level tells you.
DR. STERN: Yeah, that's really great. Rashes and fever are scary phenomenon. My next clinical pearl has to do with appropriate antibiotic choice. So there's been lots of studies have shown that appropriate antibiotics, reduce mortality by 50%. So even if you start empiric broad coverage initially when you see that patient you really want to think, as you move through this diagnostic process, of what are the likely organisms, and make sure you cover them, because that's going to reduce mortality by 50%.
DR. CIFU: Yeah and I think, we like to be elegant and parsimonious, which is one of the reasons we're doing a podcast about this but this is one of those places that maybe you throw a lot of that out the window. And you go broad early, you make sure you're not missing anything, and then sure, as soon as there's data that allows you to narrow, use it. But yeah, that's a great point.
DR. CIFU: My next one will be just that not all cardiogenic shock is related to an MI. That is the textbook. That is sort of the fear thing. But maybe as in your case, you know, there are a lot of other things which can cause cardiogenic shock. I think about myocarditis, tamponade, PE, an arrhythmia even, you know, crazy causes of heart failure, like Takotsubo's can have people coming in in cardiogenic shock with normal myocardium, I guess, Takotsubo's not normal myocardium but you know what I'm saying?
DR. STERN: So my last pearl will have to go one more time to lactate level. Where it is useful, is the patient who's not feeling well, who's normotensive but your intuition is they might be sicker than you think. And a lactate level there that's elevated can be very helpful. There's a study, that looked at normal types of patients, who had a lactate level of over four who are being evaluated.
DR. STERN: Their mortality was 15% compared to only 2.5% of patients whose levels were less than four. So that's a good place to use it I think. You're not really sure, they look sort of sick, you're trying to make the argument "Do they belong on the floors?" "Do they belong in the intensive care unit?" "How sick are they?" A lactate level can be helpful.
DR. CIFU: Just cause I can't leave this with lactate being spoken on well at the end, I think one of my other problems with lactate is that, when we look at the end points in those studies, lactate is very good at identifying people who will do badly. And most of the intervention studies show us that, using lactate does get people to the unit faster. I'm still unaware of any studies that using lactate show that people actually do better.
DR. CIFU: And it may be that we respond a little bit later, but I don't know.
DR. STERN: You're big a curmudgeon. I would say, look, if the mortality is up and you can identify that, especially for learners who have less experience than you Dr. Cifu, it might be particularly useful.
DR. CIFU: I know but you of all people know, that that's a surrogate endpoint right?
DR. STERN: I do. [both laugh]
DR. CIFU: And that identifying a group that's of higher risk is great, but that doesn't mean that our interventions are going to help them.
DR. STERN: That's true.
DR. CIFU: You may actually put a right heart cath in and you might injure them with the right heart cath.
DR. STERN: Oh my goodness okay.
DR. CIFU: Okay so--
DR. STERN: There we go.
DR. STERN: [both laugh]
DR. CIFU: Let's cut things off. So we hope you found this episode of the Symptom to Diagnosis podcast useful and a bit enjoyable. As a reminder, our textbook, "Symptom to Diagnosis: An Evidence-Based Guide" takes a much deeper dive into how to think about, and reason through the diagnosis of medical presentations. The book is available in print, through all the usual places, on your mobile device, and also available and fully searchable via the Access Medicine website available worldwide from McGraw Hill.
DR. STERN: Thank you. The music for the S2D Podcast is courtesy of Dr. Maylyn Martinez.