Venous Congestion from different Clinical Standpoints. #FOAMed, #FOAMcc, #FOAMus

 

So last week sometime we had an interesting twitter exchange which made me realize it is important to explain how some of us are using venous POCUS in different clinical scenarios, which is key, because the development of monosynaptic clinical reflexes with POCUS findings is a rabbit hole we should try not to go down. Instead, POCUS should be about asking the right question and taking that answer as a piece of the pathophysiologic puzzle facing us, which may mean intervening sometimes, and sometimes not, for the same given finding, but with different surroundings.

Here is the twitter exchange.

Thanks to those involved in that discussion – it is how we grow!

And here are some thoughts:

For those not up to speed on venous congestion POCUS I put up the chapter that Korbin Haycock, Rory Spiegel and I worked on in this earlier post.

Here are Korbin’s thoughts on this:

I’m very glad Dr. Eduardo Argaiz pointed this case out, as it brings up considerations apropos both chronic venous congestive cases as well as management of acute illness, particularly in sepsis, where we would expect patients to most likely be fluid responsive, but fluid tolerance is largely overlooked with current management strategies by the majority of clinicians.

Phil’s above audio commentary points out the difference is these two broad categories very nicely. If you didn’t listen to it–you should.

With respect to chronic venous congestive conditions, the knowledge and application of Doppler assessment to therapy will hopefully be the next advance in management at large. Already, I think there is more than adequate research available to show the value of Doppler POCUS (D’POCUS, D/POCUS, or DPOCUS?) in managing these patients. It’s only a matter of clinicians willing to commit to learning and integrate this technology into their skill set.

With respect to resuscitation of the acutely ill patient, there is by far less data, and we are probably into the realm of N=1 here, in terms of how to manage these patients. But, I personally believe–and I understand this is my opinion–that current trends in resuscitation (especially sepsis resuscitation), largely ignores the effect of over volume resuscitation and the potential downstream damage inflicted on our patients.

This theoretical damage of over aggressive fluid resuscitation is multifactorial, including glycocalyx shedding issues/endothelial dysfunction, positive fluid balance and EVLW causing increased mortality (which there is ample evidence for, I think), venous congestion leading to perfusion injuries to encapsulated organs, such as the kidney (AKI) and brain (congestive encephalopathy), and end organ edema leading to the perpetuation of a malignant inflammatory syndrome (portal HTN and gut edema).

In the case called out by Dr. Argaiz, (which can be reviewed by the previous post on this website) my patient had an IVC that whilst not plethoric, was not an IVC that one would expect to find in a patient with a typical distributive shock pattern (i.e. increased cardiac output, decreased SVR, and decreased RAP). Firstly, the complicating factor of atrial fibrillation with RVR was central to the patient’s shock state, however this was quickly addressed with rate control. However, in addition, this particular patient did exhibit additional signs of venous congestion. The portal vein was pulsatile and the intrarenal Doppler pattern was interrupted/bi-phasic in nature. Granted, a pulsatile PV Doppler could be interpreted as related to the hyper dynamic nature of septic shock (as the esteemed Dr. Denault correctly cautioned in his comments on the original post), however a less than flat IVC and the intrarenal findings gave weight to a venous congestive hypothesis as a cause the PV findings as well as a possible cause for his AKI evident on his initial labs.

With this particular case, given my personal global POCUS/FOCUS assessment of his increased LAP (high E/e’), RV dysfunction, RAP, PV, and intrarenal Doppler venous pattern, AND that fact that the RRI was insanely high with an AKI, I elected to treat my hypothetical construct of his renosarca with furosamide and his RRI with vasopressin (as the NE infusion did increase his MAP, BUT NOT decrease his RRI–which the vasopressin infusion did decrease, or so I presume as no other therapeutic interventions were given with respect to the time frame the RRI decreased).

In the end his kidneys had recovered by the next morning, which I’m sure that any intensivist will admit is the opposite of the norm, as the kidneys usually get, at least transiently worse initially-being the delicate sissies/whimps that they are. Whether this was because of the diuretic or the vasopressin, or something else, is debatable for sure, but it sure didn’t get better by 30 cc/kg of crystalloid mandated by CMS, because he got not a drop more than what was needed to push the diltiazem, the lasix, the antibiotics, and the vasopressors.

So to summarize, in the case of chronic cardiogenic venous congestion, clinician realization and adoption of Doppler assessment of this entity will likely be the next leap in improvement in the management of these patients. In the case of acute resuscitation, venous congestion may be a bit more nuanced, and a more comprehensive evaluation is in order in a case by case fashion. However, I think recognition of the issues of over aggressive volume administration will probably be the next frontier in sepsis resuscitation.

 

Love to hear your thoughts!

Cheers

 

Philippe

POCUS & Venous Congestion: a #FOAMed Collaborative Chapter.

 

So given the importance of these topics, the number of questions and discussions we’ve had on the twitterverse, and most importantly in the spirit of #FOAMed, here is the chapter from the POCUS book which was co-authored by Rory Spiegel (@EMnerd), Korbin Haycock (@korbinhaycockmd) and myself.

Venous Congestion Chapter

We’re also in there introducing our VEXUS score, and if anyone wants to use/validate it clinically, please do!

Love to hear anyone’s thoughts!

 

PS we’ll all be at H&R2019 and running workshops on venous congestion:

https://www.google.ca/amp/s/thinkingcriticalcare.com/2018/11/04/hr2019-final-programme-register-now-montreal-may-22-24-2019-hr2019/amp/

The rest of the chapters are here on Amazon and the e-version here on iTunes!

 

cheers

 

Philippe

The Andromeda-SHOCK trial with Korbin Haycock and the Nuclear Bomb Approach to Sepsis. #FOAMed, #FOAMer, #FOAMcc

So managed to pin another really bright guy down today and get his thoughts. Of course we digress some, but I think in all the topics that are truly important to sepsis resuscitation.

 

 

So I think all the resuscitationists I have spoken to tend to hover around the same common points:

  1. lactate is a marker of severity of insult/injury/inflammation but NOT something to specifically treat with an automatic fluid “chaser.”
  2. getting a global assessment of the patient’s perfusion – including things such as CRT is important.
  3. a strategy that seeks to exterminate fluid responsiveness is non-sensical and pathological.

The nice thing for our southern neighbours is that this study may give you a solid excuse to shake off that lactate mandate.

And I think that Korbin’s ending remarks are important, and it is something I try to teach residents, that there is little value in rapidly normalizing hemodynamic values – which treats the medical team very well – if there is an aftermath that is not beneficial for the patient. Kathryn Maitland’s FEAST study is the real groundbreaker for that concept. So probably a coordinated and careful ground assault is better than dropping the nuke.

 For more discussion on this trial check out Rory Spiegel’s breakdown at https://emcrit.org/emnerd/em-nerd-the-case-of-the-deceitful-lantern/ and our discussion at https://thinkingcriticalcare.com/2019/02/19/the-andromeda-shock-study-a-physiological-breakdown-with-rory-spiegel-emnerd-foamed-foamcc-foamer/

cheers!

 

a couple points:

First, much thanks to Scott Weingart whose technical pointers are improving my audio quality! Still a ways to go but on the path!

Second, if you’re not registered for H&R2019, there’s only about 20 spots left. And only a handful for the much-anticipated Resuscitative TEE course. Don’t miss out. If you enjoy these discussions, there will be plenty of that, especially in the protected meet-the-faculty times.

And finally, though he doesn’t yet have a blog, you can now follow Korbin on twitter @khaycock2!

 

Philippe

 

Is POCUS the new PAC??? A Chat with Jon-Emile Kenny (@heart_lung) #FOAMed, #FOAMcc

So here is what Jon tweeted a couple weeks ago:

Yikes! Does that spell doom for POCUS???

So clearly we had to get to the bottom of this statement…So a google hangout was in order.

 

Part 1 my intro:

and Part 2 our discussion:

 

So the bottom line is that we agree that there is a risk that POCUS may partly head the way of the PAC, or at least be challenged in a similar fashion. Hopefully the wiser physicians will see the inherently flawed logic that would push the field in that direction. Alternately, we could all get our minds and efforts together and try to do a triangulation of data to really pinpoint hemodynamics.

Love to hear comments!

For more of Jon’s physiology awesomeness, visit http://www.heart-lung.org.

Cheers

 

Philippe

 

 

PS for cutting-edge and bleeding edge discussions, including Jon-Emile and a lot more, don’t miss H&R2019 this may in Montreal…

#POCUS IVC Pitfall Twitter Poll & Discussion. #FOAMed, #FOAMer, #FOAMcc

So I ran a couple of twitter polls sets the other day. Here is the first:

(if you want the twitter videos see here)

 

 

and part 2:

And to sum it up:

So I just wanted to illustrate something I keep bringing up, essentially that the entire IVC literature based on the AP diameter measurement is physiologically and mathematically flawed. I think the poll and images above clearly support this: given a short axis view, clinicians clearly have a different opinion (and possibly intervention!) than using only a long axis view.

My take, as I’ve said and will keep saying, is that there is a lot of info in IVC POCUS, and the one I am LEAST concerned with is volume responsiveness, which sadly seems to be everyone’s only focus nowadays when it comes to the IVC.

But here’s some food for thought, some of my clinical applications in 5 seconds of scanning:

initial shock patient: big fixed IVC -> no fluids, hurry and find the downstream problem and correct!

resp failure patient: small IVC -> it’s not a massive PE, keep looking for the cause don’t send for a STAT CT angio!

AKI patient: big IVC look at venous doppler and call for lasix, stop the fluids and albumin that were being mistakenly given!

AKI or shock patient & small IVC: sure , start with some fluids and reassess soon (that means hours not the next day)

 

etc..etc.. there’s more, and “fluid responsiveness” is only in extremes and fairly low on the list for me!

 

cheers

 

Philippe

 

ps if you like physiology, and a physiologico-clinical approach, don’t miss H&R2019!

Discussing “ARDS” (and of course fluid management and #POCUS) with @iceman_ex! #FOAMed, #FOAMcc

So sparked by some recent twitter discussions where we were talking about ARDS in a somewhat controversial fashion, I thought it may be worth expanding a bit on the topic.

Essentially my stand is that ARDS is largely an iatrogenic disease mediated by (1) overeager fluid resuscitation of various disease states that fundamentally do not require large amounts of fluids despite commonly held beliefs (sepsis, pancreatitis, etc…) and (2) the absence of frequently used “stop points” of fluid resuscitation with instead a misguided focus on detecting (and intervening upon) volume responsiveness.

In our ICU, true “ARDS” (eg not generated by salt water drowning) is a rarity. Maybe one or two a year, usually a massive primary pulmonary insult.

Anyhow, here, Segun and I discuss this:

 

Ognjen Gajic refers to this article in our discussion.

 

So it seems clear that there is much to discuss. We didn’t even really get into the juice of the stop points. Stay tuned!

 

oh yes… so if these controversial, cutting- and bleeding-edge topics, don’t neglect joining us at H&R2019. Segun and many others will be there!

https://thinkingcriticalcare.com/2018/11/04/hr2019-final-programme-register-now-montreal-may-22-24-2019-hr2019/

 

 

cheers!

 

 

The First Steps Towards Physiological Resuscitation: A Team Effort. #FOAMed, #FOAMcc

(original figure from this old post)

So Rory (@EMnerd) hit us last week with an interesting question that was brought up by David Gordon, a resus fellow working with him, and thought some of us may be willing to belabour his point. A lengthy and really fascinating exchange ensued, which I felt was worth sharing with the #FOAMed community:

 

Rory (Spiegel @EMnerd) find him on emcrit.org

Korbin Haycock (please leave comments to encourage him to get on Twitter)

Segun (Olusanya @iceman_ex) find him on LITFL.com and The Bottom Line

Me (@ThinkingCC) also thinkingcriticalcare.com

David Gordon

My editorial comments!

 

Rory: 

David brought up an interesting question today. Why not do a straight leg raise and use TAPSE to assess the likelihood the pt will be “volume responsive”?

My answer was the following:
“I don’t think the RV increases TAPSE in response to fluid and so the only way TAPSE would be able to assess fluid responsiveness would be if it decreased in response to a a SLR. My contention is this would be a late marker of fluid intolerance and others signs of venous congestion (portal/renal vein doppler) would be seen far earlier. “
In addition I brought up that “volume responsiveness” is a flawed surrogate and we should rather be focusing on volume tolerance.
And that is, in my opinion, the critical concept. 
Anyway David seemed less than satisfied with my answers so I figured I would open the discussion to you physiology nerds…
Korbin: 
That’s an interesting thought, you have brought up.  To clarify, are you asserting that an increase in TAPSE from a volume challenge or SLR could be a indicator of volume responsiveness?  If I missed your meaning, please correct me.
I think Rory is right in his assessment that TAPSE would likely be a more valuable indicator of fluid tolerance (or more importantly , intolerance), rather than fluid responsiveness.  TAPSE, however,  may be (I don’t know) a more sensitive indicator of fluid tolerance than things like IVC collapsibility index, etc.  This might make sense as a decreasing TAPSE (or TAPSV, too for that matter) in response to a fluid challenge might be an earlier indicator that the RV won’t do much with more fluids before it would manifest in things like a non-collapsing, plethoric IVC, decreasing S’/D’ wave ratio on HVD, portal vein pulsitivity, or pulsatile intrarenal venous Doppler.
One problem I’ve had for a long time with fluid responsiveness from the standpoint of the circulation up to the pulmonary valve (IVC collapsibility index being the most common example), is that it doesn’t measure what you really want to know, and that is LV fluid responsiveness.  There is a whole lot going on hemodynamically from when blood leaves the RV to where it finally contributes to LV preload.  I think if you want to know if the patient is fluid responsive, there are quite a few ways to assess this directly, rather than looking at the RV, IVC, etc.
I stopped chasing every bit of volume responsiveness a long time ago, however it does have its place in managing the sick patient, I think.  Usually, my first question is about volume tolerance/intolerance, before I start to think about volume responsiveness.
To investigate the fluid tolerance/intolerance status, I’ll look into a lot of things, usually using a lot of ECHO/US information.  My sonographic considerations are: LV contractility, diastolic function and ventricular compliance, LVEDP, valve pathology, SVR, B-lines (and if B-lines are present, put that into the context of what the LVEDP is because if the pressures are low, but the lungs are wet, pulmonary vascular permeability is high and I’ll think very hard before giving fluids), pulmonary artery pressures, PVR, interventricular septal shifts, RV contractility, IVC, HVD, portal vein, and renal Doppler.
(has anyone ever seen an ED doc do this anywhere??? Wow!!!)
Also, I’m lucky to have some other tools at my place like transpulmonary thermodilution catheters and pulse wave analysis devices to assess things as well.  Sometimes these things make serial assessments more convenient than dragging the US machine over multiple times, and can also give additional information, like EVLW, PVPI, etc.
(I think in the case of Korbin’s hospital, it may be important to bring downstairs care upstairs!)
Secondarily, if I think the patient is volume tolerant and then I have determined that they are volume responsive, and would benefit from volume administration, the next question I ask myself is what’s the best way to do this.
Clinical assessment combined with ECHO comes into play, as if the patient is genuinely volume depleted, volume repletion makes sense.  However, a lot of volume responsiveness is driven by syndromes of high CO and low SVR.  In these cases, I usually give very little volume and opt for a vasopressor to drive venous return instead.  This strategy tends to correct the CO/SVR derangement as well as take care of the volume responsiveness at the same time.  I feel much better if I know that my MAP is being generated by a balanced CO, SVR, and volume status rather than having a “normal” MAP.
I think that is a really, really important cognitive model. The common and traditional approach is to try to maximize CO with fluids and avoid the terrible vasopressors. In a disease where the primary derangement is vasodilatory, it doesn’t seem logical… However finding the right balance is difficult. And with the near-extinction of the PA catheter, we no longer have a low SVR value staring us in the face begging for some pressors.
Sorry to be so long winded, guys.  Hope I didn’t bore you with stuff I’m sure you already know.  These topics are really interesting to me though!  I’d be interested in all of your thoughts on the TAPSE question.
Segun:
I think the RV is more likely to dilate in response to Fluid than change TAPSE, as suggested by a paper or two on RVEDA changes as a predictor of Fluid responsiveness https://ccforum.biomedcentral.com/articles/10.1186/cc3503
(RV dilatation May result in a reduction in TAPSE too?) 
Potentially, yes. SV may not decrease but TAPSE may.
The end result should be a change in stroke volume, so one could argue that rather than TAPSE you could just measure RVOT VTI in response to a passive leg raise. (I don’t really see the difference between M mode and PW doppler, and RVOT VTI is simple enough to measure from a PSAX or RV outflow view)
TAPSE is an Uber-simplified method of looking at RV contractilty rather than volume (overloaded RVs can have excellent TAPSE, for instance). I think it would answer a very different question.
Me:
Interesting question indeed. I can’t agree more with Rory and Korbin. Korbin’s clinical run-through is, as far as I’m concerned, completely on point and, if i weren’t so lazy, and had all the hardware he is fortunate to have, would consider as gold a standard as possible, until  mitochondrial monitoring and trans-capillary flow monitor technology is made.
I think it requires a bit of a paradigm shift away from volume responsiveness, that has been all the rage in the last decade or since the end of the swan age, and instead towards focusing on tolerance. There is significant and building evidence that congestion is end-organ damaging, and evidence that chasing maximal CO is mortality-causing (80’s and 90’s literature supranormal o2 delivery and all that), hence on both fronts focusing on congestion makes more sense.
I think we have to follow the fluid path (venous congestion y/n, rv ok y/n, lungs ok y/n and finally lv ok y/n) and then do a global almost holistic ‘is fluid the best option’ reflection including brain, gut, kidneys, peripheral tissues, etc, with Korbin’s nice little twist on balance of CO, SVR for the BP/perfusion. I don’t think there’s any point of care monitoring tool to unequivocally ascertain the best level of each today.
Rory:
So here is my question, should we be asking “Is this pt likely to benefit from fluids?” rather than “Is this pt likely to augment their CO with fluids?” 
Stop for a moment and think of most of your septic patients (not all, yes, some have cardiomyopathy, some are profoundly hypovolemic), are they actually in a low CO state?  The near-obsession with CO is probably rooted in the common belief that the elevated lactate stems from hypoperfusion, a myth which has been debunked.

Lets say we use Korbin’s gold standard I think we still have to ask what is the benefits of giving this pt fluids? There are many patients I see who would meet all the criteria outlined by Korbin in whom I still don’t administer fluids because whatever increase in cardiac output I get will be transient at best. I am inclined to sit tight allow my antibiotics to take effect and let the pt correct their own vasoplegia. After an initial small aliquot of fluid in the ED I like to see obvious signs of hypovolemia before I give additional boluses. I do like the CLASSIC trials criteria:

(1) Lactate of at least 4 mmol/L
(2) MAP below 50 mmHg in spite of the infusion of norepinephrine
(3) Mottling beyond the edge of the kneecap (mottling score greater than 2)

(4) Oliguria 

All this from the perspective of a decongested venous system and a under-filled heart on US
Korbin:
To Rory’s point, I agree that just because there is a lack of fluid intolerance and the presence of fluid responsiveness, it doesn’t necessarily mean fluids are indicated.
If I have a clinical story that supports a likely lack of hydration plus I’m looking at a high SVR, low CO, and a low SV, I will usually give some fluids.  Mottling, especially if pressors are on board, to me is a clue that some sort of volume might be indicated.
That’s actually quite interesting.  The pathophysiology of mottling isn’t clear (click here for an interesting read), but definitely a space to earmark, when trying to find the optimal balance between vasopressors and CO augmentation.
As far as the lactate goes, as everyone here knows, there’s a whole lot of reasons to have a hyperlactatemia.  It’s drives me a little crazy when I see a lactate come back elevated and the first thing someone wants to do is give fluids, especially if they haven’t considered any of the stuff we’ve been talking about.
I think if you have a patient with a high lactate, the first thing to do is ask yourself why they have a high lactate, rather than trying to correct the number.
Rory:
Agreed, most of the time in a septic pt I view a rising lactate as a sign I don’t have source control rather than a signal to give additional fluids.
Philippe:
So in terms of fine tuning, here is one thing I like to do with tissue saturation – SctO2 (cerebral)  and peripheral:   if it drops with vasopressors I favor augmenting CO (fluids if not too congested, inotropes to consider) if it rises or stays flat with pressors i stay the course. This is definitely not evidence-based, but to me, if tissue saturation decreases while increasing vasopressor dose, it seems logical that the perfusion is dropping, and not a course worth pursuing. I like to think of it as an example of MBE (medicine-based evidence) in the patient in which it is occurring.
David:
It seems to me the feeling is that we shouldn’t be chasing any single indicator of fluid status/tolerance/response/optimization evaluation and the key is to ask the clinical questions and pair that with our sonographic assessment.   RV functional assessment may have a role in that discussion, but TAPSE may not be the best indicator as RVOT VTI may be a better answer to the initial question.
The study that Segun sent out seems to indicate that LVEDA may be a better predictor of SVI.  The septal interdependence plays a larger role than I initially thought and perhaps using M mode to look at changes in septal motion gives you more information about the ability of the heart as a whole to manage the fluids…
That’s an excellent point, because even if the RV can handle the fluid, if the LV cannot, it’s gonna end up in the lungs.
Philippe, what kind of time course do you allow for your lactate to change, other than just response to your initial resuscitation?
Lactate should improve over hours. As Rory says, if a day later it’s still hovering above 4, and you don’t have impaired hepatic clearance, you might be missing something…
Korbin:
That’s something that certainly something to consider, Rory.   I think a lactate that is suddenly rising is most likely driven by a catecholamine surge driven by something going the wrong way.  But not always.
The important thing is to stop and think about what’s going on.
Case in point:  Last week I had a patient that had cardiac arrest due to an asthma exacerbation.  I had put a TEE probe down during he resuscitation, and a little bit afterward based on what I was seeing on the TEE, I felt she needed a pressor.  I used epinephrine because the beta-2 agonism might help with bronchodilation.  Everything hemodynamically look pretty good, except the lactate came up.  The ICU resident saw the lactate and ordered a liter of LR.  I called them and explained that the epinephrine was likely the cause of the lactate and it probably wasn’t anything to worry about.
Rory:
Just the other day I was called to the floor to assess a pt because the treating team was concerned he was septic when his lactate came back at 6.5. I walked in the rm as they were hanging the 30cc/kg fluid bolus. A brief assessment revealed he was in florid CHF. Once I convinced them to stop giving fluids and instead use an aggressively dose of diuretics he did just fine and cleared his lactate without issue.

In my mind lactate in and of itself uninterruptible. In a pt who is otherwise improving and the lactate is not clearing as fast as I would like I tend to just stop checking it. The one I find troublesome is in the post resus pt who doesn’t look great, I don’t have an obvious source, their pressor requirements are slowly rising and the lactate is hovering in the 4-5 range. That’s the pt that tends to do poorly if you don’t identify and establish source control

Korbin:
Agree with that Rory.
If I have those patient with a persistent lactate elevation, and they look like they could be malnourished, I’ll give them some thiamine, too.
Segun:
My two cents- there’s data soon to be released that compared echocardiographic dimensions (RV/LVEDA, IVC etc) to mean systemic pressure- showing no correlation with ANY echocardiographic parameters.
It would seem that going purely by dimensions, you cannot predict volume state on echo… so at the moment we can detect hypERvolaemia with lung, portal vein, and renal vein POCUS (and to a degree IVC), and profound hypOvolaemia by looking at doppler patterns (although the patient is more likely to tell you).
The other side of things, which has been clearly elucidated by everyone in this thread, is the concept of “permissive responsiveness”. Ruthlessly thrashing every heart to its maximum myocardial stretch doesn’t necessarily seem to be the best idea, to my mind.
I agree with everyone’s thoughts. Beyond the initial LLS/Shocked AF stage, you need a very good reason to give a fluid bolus!
And don’t get me started on lactate…
Korbin
I would only comment that the magic of Doppler probably is far more valuable than cardiac dimensions when dealing with hemodynamics.  Dimensions give anatomic values that can be extrapolated to hemodynamics, but PW and CW Doppler interrogation infers pressure differentials, which can directly be applied to things like flow and resistance.  Tissue Doppler has the added informative value of cardiac compliance, so that a comprehensive picture can be painted in light of filling pressures and the relationship to preloading.
When I look at all this together, I really feel that in most cases, a quite accurate picture of what’s going on is within grasp.
To emphasize again, something like B-lines with a compliant, low LVEDP LV, tells me valuable information about pulmonary vascular permeability.  Tread carefully about fluids here.
David:

How does the RV respond to a fluid bolus?

To answer this question first we must understand the role of the right heart in the circulatory system. Often the right ventricle (RV) is compared to the left ventricle, in reality it serves an entirely different function. The left ventricle generates the necessary pressures required to maintain systemic perfusion. The right ventricle’s job is to enable venous return, which is generated by the gradient between the mean systemic filling pressure and the right atrial pressure (RAP). The role of the RV is to maximize that gradient by keeping the RAP as low possible. 

With this in mind let us examine the RV’s response to a fluid bolus. As the RV becomes filled, conformational changes occur within the RV that allow it to increase its stroke volume without increasing the distending pressure.Under normal circumstances, the RV end diastolic distending pressure does not increase in response to fluid loading. Therefore, if the RV is functioning appropriately, RAP does not accurately reflect RV preload. But in pathological states, when the RV is hypertrophied, diseased, or overdistended there is an inverse relationship between RVEDV and RV stroke volume. Any fluid, or increased RV pressure beyond this point results in an increase in RAP, decreasing venous return.1

1. Pinsky MR. The right ventricle: interaction with the pulmonary circulation. Critical care (London, England). 2016;20:266.

So that was the discussion. I certainly thought it was very interesting. Following this, we decided we’d band together and try to hammer out what we think should be the optimal management of shock, trying to tie in physiology, the scant evidence that is out there about resuscitation, and the pitfalls of venous congestion. Finding the sweet spot in the balance between vasopressors, inotropes and fluids is a very real challenge that all resuscitationists face regularly, and it is very unlikely that, given the complexity of such a protocol, looking at tolerance, responsiveness and perfusion, that an RCT would be done anytime soon.

We’ll be sure to share when we come to a consensus, but certainly the broad strokes can be seen here, and I’d love to hear anyone’s take on this!

And of course, we’ll definitely be discussing this further with smarter people at H&R2019 – think Jon-Emile Kenny (@heart_lung), Andre Denault and Sheldon Magder!

Cheers

Philippe