Bedside Ultrasound Quiz Part 2: A 50 yr old man with dyspnea, acidosis, hepatitis and leg edema. #FOAMed, #FOAMer, #FOAMus

So I was glad to see some great answers on twitter about this case, so let me fill you guys in on the management and the details.

So my diagnosis was of a (likely viral) myocarditis as a subacute process over the last weeks, with a superimposed pneumonia causing the acute deterioration and presentation to ED.  I didn’t think that his elevated lactate represented shock, but rather a reflection of adrenergic activation and reduced hepatic clearance due to congestive hepatitis.  He also had congestive renal failure. Of course, the LV had a 4 x 2 cm apical thrombus, which is likely secondary to the dilated cardiomyopathy.

So the management was diuretics, antibiotics, and anticoagulation, which resulted in a gradual improvement of the respiratory status and renal/hepatic dysfunction. He had a coronary angiogram the day following admission which showed two 50% stenoses deemed to be innocent bystanders.

Bottom Line:

I think the learning point in this case is that, without POCUS, this could easily have been treated as severe sepsis with multiple organ failure (potentially rationalizing away the BP of 140 as a “relatively low” BP due to untreated hypertension), and as such, may have received fluids… Especially south of the border where they are mandated to give 30 cc/kg to anything deemed “septic.”  This would have been the polar opposite of the necessary treatment.

The scarier thought is that he may have then progressed to “ARDS,” been intubated and then the debate between keeping him dry and giving fluids for the kidneys may have ensued.  Though a formal echo likely would have been done, it may not have happened in the first 24-48 hours… If MSOF progressed and he succumbed, the rational may have been that he was “so sick,” and died despite “best care…”

The reality is that he is not yet out of the woods today, with an EF of 15% and afib, but he is off O2 and sitting up in a chair. Fingers crossed he falls in the group of those with myocarditis who improve…

Love to hear anyone’s thoughts!

 

Cheers

Philippe

Hepatic Portal Venous Gas (HPVG): a Less Ominous Sign than We Thought? A Case of HPVG associated with massive PE… #FOAMed, #FOAMcc

So a few years ago I had a patient in the ICU, post op for some abdominal surgery, and, using POCUS, I detected a hyper echoic area in the liver, in a wedge shape.  I scanned the patient and, lo and behold, there was a matching area of air-filled hepatic venous sinuses on CT scan. Well, my surgical colleague and I were very concerned and proceeded to inform the patient he would be needing exploratory surgery for what was likely ischémie bowel. He essentially – though in more polite words – told us we were idiots and that his belly felt fine and he didn’t think surgery would be needed at all.

His belly did feel fine. So were his labs. So we worried, but, given this whole thing about free will and consent, etc, couldn’t very well force him into what we felt was necessary surgery.

The next day he was fine. On POCUS, the area of air had shrunk. The next day, it was gone altogether.

We thanked him for his keen clinical acumen and for teaching us a good lesson.

However, we were a bit perplexed, because traditional teaching equated portal venous air with a severe bowel disorder, usually ischemic or inflammatory, with exceedingly high mortality. At least that is what we had been fed. We are both grads of 1999. Hmmm…

So over the next few years we saw a few of these cases, sometimes bad, sometimes not, and a review of the literature (see below)  showed an interesting evolution of the disease. Described in the 1950’s on plain films, hepatic air was a bad omen indeed, with mortality in the 75-90% range. In the CT era, the mortality started to “drop” to the 35-60% range. Now you can find quite a few reports of “surprisingly” good outcomes with conservative management. So this evolution doesn’t represent a change in severity so much as the technological capability to detect smaller and smaller amounts of air in the venous system – just increased sensitivity. And now, with POCUS – ultrasound is the most sensitive detector of air in a vascular tree – the associated mortality is likely to take another drop, not only because of our ability to detect very small amounts of air, but also because we are actually looking at the area, and also in a wider range of patient’ pathologies that those commonly associated with HPVG.

 

Clinical Case: HPVG and PE!

So a couple weeks ago I saw a patient in the ED who’d recently broken an ankle, had her foot put in a boot and managed conservatively and came back dyspneic and tachycardic. Here are a couple of clips:

As always, I start with the IVC:

Big & fixed.

Hepatic veins:

Biphasic flow.

Femoral veins:

So here the source of the problem is pretty clear, a large common femoral DVT.

She wasn’t very echogenic so I don’t have great clips of the heart but she had a dilated and hypocontractile RV with a McConnell’s sign (preserved apical contraction), small and hyper dynamic LV with septal flattening.

Now here is where it gets interesting, the portal vein:

You can clearly see bubbles traveling up the portal vein. Ominous, or not?

So clinically, her abdomen was normal, she had no abdominal symptomatology at all…

 

Pathophysiological musings:

So the severe RV obstruction resulted in significant venous congestion. Additionally, the decreased cardiac output – as manifested by a lactate of 4 and mild tachycardia/hypotension (110 HR, BP sys 90’s) was clear.

The etiology of HPVG in the literature isn’t clear – mucosal disruption, bacterial gas are all mentioned but as far as I could find, no definitive answer.

Is it possible that there is a “normal” inward leak of mucosal gas that is normally fully dissolved in the venous bloodstream, but that, in cases of low flow and/or venous congestion, the dissolution capacity (per unit time) decreases, and that gas comes out of solution?  Alternately, those who have increased intraluminal pressure (gastric distension, etc), the increased transmembrane gas driving pressure may overload an adequate blood flow…

This would explain the benign course of many patients, particularily those with gastric dilation.

 

Clinical course:

Based on hemodynamics, tachypnea and, to some degree, venous congestion, I decided to thrombolyse her using 1/2 dose lytics. Within a couple of hours her HR decreased to the 90’s and BP rose to 110 systolic.  Echographically, however, the IVC/RV findings remained similar, but the HPVG decreased. By the next day, HPVG was altogether gone, lactate had resolved and dyspnea was significantly better.

 

Take Home Message:

HPVG, although not quite as poor a prognostic sign as once thought, nonetheless warrants concern and investigation, even if the abdominal exam is entirely normal and without symptomatology, as correction of an underlying cause of “benign” HPVG (whether low-flow or bowel distension) would still need to be addressed.

In the meantime, I suspect that, reported or not, this has been noted by other POCUS enthusiasts, since we are now looking more frequently at this area, and are dealing with patients with low-flow states, congestion, bowel obstruction/ileus or more than one of these.

Hopefully some investigators will take a look at this phenomenon and delineate the pathophysiological mechanism!

Love to hear of your experience with this.

cheers!

 

Philippe

For those interested in POCUS, see here for a quick read primer on clinical applications of POCUS.

 

HPVG Review article 2009:

wjg-15-3585

 

The NYC Tracks with Jon-Emile part 2: a discussion on congestion, pulmonary and otherwise. #FOAMed, #FOAMcc, #FOAMus

So here is our second discussion, where we delve a bit into diuretic physiology, the issue of organ congestion, the myth of the “low-flow” acute renal failure associated with CHF (see earlier post), and a couple other things including a great way to determine if a patient isn’t respecting the low salt diet prescription!

I meant to, but forgot to discuss with Jon what I think is an important end-point in CHF management: the IVC. Yes, it is useful not just to make the diagnosis of congestion, but also target normalization of IVC physiology prior to discharge. It just makes common sense. If you decongest a patient just enough to get them off O2 and send them home, they bounce back a lot quicker than if you make sure you’re given them some intravascular leeway.  How do you determine this? Simple enough, make sure your IVC is down at least to below 20mm, and has recovered the classic acxvy and respiratory variation. I personally try to get into the 8-12 mm range, but that’s arbitrary. Here is some good data for 20mm:

06005

Without further due, here is the NYS Track 2:

 

Please share your thoughts!

 

cheers

 

Philippe

The NYC Tracks with Jon-Emile: Paracentesis and Volume Status. #FOAMed, #FOAMcc, #FOAMus

So I was in NYC last week and met up with my buddy Jon-Emile Kenny, (@heart_lung), intensivist-physiologist extraordinaire, and we recorded a few discussions on practical matters.

I always love to debunk myths and avoid dogmatic guesswork, and, more often than not, Jon, with his encyclopedic knowledge of the physiology literature, but more importantly a cutting edge understanding of it, can back up my vague ideas and empirically derived ideas, so that the next time someone asks me why this is so, I can have a semi-enlightened answer!

So here is the first, where we discuss the common question about the need (or not) of intravascular volume repletion during or following large volume paracentesis. Yes, there are some formulas out there as to how much albumin or crystalloid one should give, due to the worry of subsequent hypovolemia. Note how those formulas use no data about your patient’s volume status at the time of paracentesis, so as far as I’m concerned, they have no value whatsoever in an era where we can assess this. Yes, ultrasound is the base as far as I’m concerned.

Here we go:

Please share your thoughts!

cheers

 

Philippe

Fluids in Sepsis: An EmCrit Webinar! #FOAMed, #FOAMcc

Screen Shot 2016-04-27 at 2.00.28 PM

Screen Shot 2016-04-27 at 1.43.23 PM

So a few weeks ago Scott (@EmCrit) asked me to be part of a pretty cool webinar organized by the Greater New York Hospital Association about fluids in sepsis. The gang consisted of David Gaiesky, Emmanuel Rivers and moderated by Scott himself. And for some obscure reason, he asked me to be part of it – much to my honour (terror, also), naturally.  It was only afterwards that he told me it was to help stir the pot and be controversial, challenge the “old school” etc… He seemed to have overlooked that I am Canadian, and inherently and perhaps overly polite and considerate – at least live and in “person”!

We talk about a bunch of stuff around fluids, which, how much, how to assess, etc.

Anyhow, I hope I got a few ideas across, but it was really cool to hear that these gurus do use ultrasound – don’t necessarily strictly adhere to, for instance, EGDT, and also advocate that guidelines are guidelines and not necessarily gold standards.

Here is the link to the webinar for those interested:

 

https://t.co/dbL03Vuqlj

 

And here is the figure for the section where I refer to fluid responsiveness/tolerance:

Screen Shot 2016-02-21 at 9.25.50 AM

I further talk about this in a previous post here.

Scott and I also recorded a debrief which should be coming up in the next weeks on EmCrit – link to follow!

cheers!

 

Philippe

Cerebral & Somatic NIRS (Near InfraRed Spectroscopy) in shock states: tailoring therapy. (PART 1) #FOAMed, #FOAMcc

So I’d mentioned using NIRS to monitor and tailor therapy a few months ago, and promised a more in-depth discussion to come, so here we go.

For this not familiar with the technology or the concept, NIRS measures tissue saturation, predominantly venous. Hence physiologically it is akin to central/mixed venous gases, but localized. Cerebral NIRS found its foothold in the OR with carotid and cardiac surgery, but its use is now expanding. Given typical knowledge translation time of a decade, it should end up joining ETCO2 as a routine vital in monitored units, but probably not soon enough.

So in our unit at Santa Cabrini Hospital in Montreal, we’ve had this technology for about a year (the INVOS system), and have been studying its uses. In this time, three applications have stood out:

  1. Finding the “Sweet Spot” for vasopressors.
  2. Confirmation that therapeutic interventions are hemodynamically appropriate.
  3. Cardiac arrest: CPR adequacy, prognostication and detecting ROSC.

 

  1. Finding the “Sweet Spot” – I think (hope) that anyone reading this with professional interest understands that pressure does not necessarily equal perfusion.  With that in mind, adjusting vasopressors to a pressure makes little sense, and represents at best a guesstimate of perfusion, which is what we really are after. We can all agree, however, that a certain minimum pressure is required, but whether that is 65, 55 or 45 MAP no one can say for sure.  So the way I like to use it is to establish a baseline and watch the direction of the tissue saturation with vasopressor therapy. If the saturation begins to drop off, we may have reached a point at which excessive vasoconstriction is worsening tissue perfusion, and that inflexion point may represent the upper beneficial limit of the vasopressor – this may happen to be under 60 or 65 of MAP.  However, it is key to understand that this inflexion point is reflective of the current state of hemodynamics, such that a change in volume status or cardiac output, in one direction or the other, would likely change the position of this physiological point.  For example,  a volume depleted patient may reach a decreasing tissue saturation point at 55 MAP, but, once volume replete, may reach a higher MAP of 65 or above before a drop in saturation is seen.  Conversely, a patient whose best tissue saturations were around 65 MAP who suffers an MI and sudden drop in cardiac output may now see his perfusion compromised at that same MAP, which would now be achieved with a greater vasoconstriction, less cardiac output and consequently, poorer flow… I posted a case discussion which illustrates this.
  2. Confirmation that therapeutic interventions are hemodynamically appropriate – I feel this is really important. When a patient’s life is literally on the line, and knowing that our interventions are seldom without potential nefarious side effects, it is poor medicine to be introducing a therapy without having some form of monitoring – preferably multiple – that we are headed in the right direction, or at least not making things worse. Of course, we already do this – with BP, sat, lactate, CCO, ultrasound, ETCO2 – but I think using a realtime measure of tissue saturation adds to this. It is also my firm opinion that integrated, multimodality monitoring is necessary – at least until someone develops some form of mitochondrial monitoring which tells us that the cytoenergetics are sufficient to survive. Until then we are stuck with surrogate markers and many of them (e.g. lactate) are the result of complex processes that preclude them being a simple indicator of perfusion adequacy. For instance, when giving a fluid bolus/infusion – after having determined that the patient is likely fluid responsive AND tolerant – one should expect to see an increase in ETCO2 (other parameters being constant), an increase in CO, an increase in NIRS values. The absence of such response should make one reconsider the intervention, because without benefit, we are left only with side effects.

Here is a patient’s cerebral (top) and and somatic (thigh – bottom) and CO values. This patient had an RV infarct and was in shock.

IMG_7948IMG_7946

 

Following initiation of dobutamine, this is what occurred:

IMG_7951IMG_7949

Given that we cannot always predict the response to an inotrope – depending on the amount of recruitable myocardium, it is reassuring to see an improving trend. This enabled us to decrease the vasopressor dose significantly.

Note that, so far, and unless some good evidence comes out, I don’t use a goal value, and so far, I have not identified a value that is predictive of prognosis. However, downward trends usually bode very poorly. For instance, I had a severe chronic cardiomyopathy patient whose cerebral saturation was 15%!!!  But more surprisingly, she was awake, alert and hemodynamically stable. Adaptation.

Part 2 and the stuff on cardiac arrest coming soon!

Please, anyone using NIRS in shock, share your experience!

 

cheers

 

Philippe

Volume responsiveness and volume tolerance: a conceptual diagram. #FOAMed, #FOAMcc, #FOAMus

So I know I’ve belaboured the point about the difference between volume responsiveness (i.e. will there be significant increase in cardiac output with volume infusion) and volume tolerance (is the volume I am considering giving going to have nefarious consequences), because in my opinion, the focus has been – rightly so to some degree – to look for an accurate way of discerning responsive patients from non. Of course this is absolutely necessary, as one does not want to give volume if it will not have any benefit, but the too-common corollary to that is to automatically give volume to those who are responsive.  Here is an earlier post about this:

https://thinkingcriticalcare.com/2014/10/06/fluid-responsiveness-getting-the-right-answer-to-the-wrong-question-foamed-foamcc-foamus/

So in discussing with a bright young colleague yesterday, Dr. St-Arnaud (@phil_star_sail), I realized that there may be a common conception that physiologically, the relationship between the two may be the following:

Screen Shot 2016-02-21 at 9.03.01 AM

This would mean that it is safe to give volume until a patient is no longer volume responsive, and even perhaps a bit more. Alternately, the two may be closer:

Screen Shot 2016-02-21 at 9.02.27 AM

This would mean that once can go just till the point where the patient is no longer volume responsive.

Either one of these scenarios would be awesome. That would mean that by using any of the flow or volume variation techniques, arterial or venous, we could pretty much remain safe.

However…

While the above may hold true for healthy subjects, I would contend that in sick people (which is who I tend to deal with, especially when resuscitating shock), that the more likely physiological relationship is the following:

Screen Shot 2016-02-21 at 9.03.28 AM

Hmmm… That would mean that assessing for volume responsiveness would only tell you that there would be an increase in cardiac output, but absolutely nothing about whether it would be safe to do so.

This concept is not a new one by any stretch of the imagination. It’s inferred in the diagnosis of “non-cardiogenic pulmonary oedema.” So what causes this shift? Here:

Screen Shot 2016-02-21 at 9.25.50 AM

So, how do we figure out where the point is? Sorry to say there is no answer that I know of. My friend Daniel Lichtenstein uses the FALLS Protocol (identifying the appearance of B lines during resuscitation) which is the least we should do, but I suspect that at that point, we have already overshot the mark. My adopted mentor Dr. Andre Denault (@Ad12andre, in addition to IVC, has identified portal vein characteristics including pulsatility (lots of stuff in press) to show that the viscera are at risk, but as of yet there is no simple answer. CVP value? Please. CVP tracing morphology? Maybe.

No simple answer. No one-size-fits-all velue to look for. Clinical integration.

In my opinion, one should not, in sick patients, seek to volume resuscitate until the point of no-volume-responsiveness. The old adage of “you have to swell to get well” likely kills a few additional patients along the way, just as much as under-resuscitation. I plead guilty for over-resuscitating patients for years before realizing that being on the flat part of Frank-Starling is 100% a pathological state.

Love to hear your ideas and comments!

 

Jon-Emile Kenny says:

I like your graphics, it makes the concepts tangible. I think we should try to integrate ‘volume status’ into this framework as well. A physiological purist might say that as soon as you are ‘hypervolemic’, you are volume intolerant, because hypervolemia is an abnormal state which should always be avoided. A functionalist might say that you become volume intolerant as soon as you have physiological embarrassment of any organ system – but how is this determined? My gut is that by the time there are B-lines in the lung, you’ve gone too far. By the time there is abnormality of splanchnic venous return, you’ve already gone too far. I am more of a purist, so in my perfect ICU, I would perform q4-6 hour radio-labeled albumin studies to determine the patient’s true plasma volume. In health, the normal blood volume is about 80 mL/kg [thus, once you’ve given a 70kg man 5 L of NS, you’ve almost certainly replenished his vascular volume]. The moment that the blood volume becomes > 95% the norm, I would call the patient volume intolerant and stop volume expansion and focus on venous tone with pressors, cardiac function with inotropes, etc. To me, this makes the most sense in the pure Guytonian world; if you keep flogging a patient with litre after litre of fluid and the patient’s BP remains low, you are missing something – volume is not the answer – regardless of what an ultrasound shows you:
1. trouble shoot the venous return curve [i.e. too little blood volume, too little venous tone, too high resistance to venous return]
2. trouble shoot the cardiac function [i.e. poor rate, rhythm, contractility, valve function, biventricular afterload]
If you need some objective measure of blood volume before you can call volume status optimized before moving onto the next problem to fix – that’s a radio-labeled albumin.
Maybe I’m crazy.cheers

Jon

Thanks for commenting Jon!

I totally agree, if we knew each patient’s normal blood volume, that would be a starting point.  And of course, that would prevent the over resuscitation of a very dilated and compliant venous system (small IVC on ultrasound). Let us know if you figure out a practical way to do that!

It’s too bad that extravascular lung water doesn’t seem to have panned out – not sure why exactly.

 

 

Philippe