Fluid Stop Points! More POCUS goodness from Korbin Haycock. #FOAMed, #FOAMcc

I am really enjoying this exchange, and I think it is in the true spirit of #FOAMed to foster these discussions, as we have the opportunity to combine and fine tune our understanding of a topic from several really bright people’s view and experience. 

Korbin:

Jon-Emile, excellent points and insight. I should clarify a couple of my comments. To be specific, by “renal vein flow” I am referring to intra-renal venous flow. Apologies for my imprecision! Thanks for pointing that out.

Yes, a lot of these renal and portal Doppler patterns are surrogates of CVP. But I don’t think any of us would use CVP in isolation these days to make any decision what-so-ever on whether fluids were indicated in our patient.

Also, to clarify, I am not using intra-renal venous flow or renal resistive index as measures of non-fluid responsiveness. Rather, I use these measures as a stop point for attempting to solve the patient’s hemodynamic dysfunction with crystalloid regardless of whether or not my straight leg test tells me the patient is still fluid responsive.

And that is a key re-iteration to me. It is important to set these stop points and not only look at whether the cardiac output can be maximized. This has been tried. And failed. Let’s remember that sepsis is not inherently a disease of low flow. It isn’t cardiogenic or hypovolemic shock at the core.

My rationale for the strategy of using intra-renal Doppler, E/e’, and Lung US (now, I can include portal vein pulsatility) as a stop point for IVF administration is that I think the patient is best served to avoid iatrogenic edema of the upstream organs, primarily the lungs and the kidneys. These are the two organs (maybe you could put the endothelium in this category as well–glycocalyx being a whole other can of worms!) most easily damaged by the chase for optimizing every bit of fluid responsiveness. We have good evidence that getting wet lungs and swollen, congested kidneys is a bad thing, and we have these tools to hopefully warn us when we are pushing things too far.

Absolutely. And the whole glycocalyx is something to keep in mind, even if only to me mindful to disrupt it as little as possible.

Of course renal resistive index, intra-renal venous flow, portal vein pulsativity, and whatever else you like will have limitations and confounders. As long as you understand what can cause abnormalities with these tools, you can make an educated guess as to what’s going on. If our creatinine is off and our RRI is high, but intra-renal venous flow and portal vein flow is normal, perhaps the RRI is caused by something other than renal congestion, like ATN. If the portal vein is pulsatile, but the Doppler patterns of the hepatic vein, kidney and the heart look ok, maybe something else is wrong with the liver. But, if all our modalities are in agreement and pointing to congestion, we should perhaps believe that it’s congestion and stop the fluids. 

That is an awesome approach to integrating RRI. I’ve been toying with it for the last couple of days, and much thanks to Korbin, I think that the limitations of RRI can be overcome by using the rest of our clinical and POCUS data.

It isn’t a hard technique, though in some patients getting a good signal can be tricky.

I think that the kidney, being an encapsulated organ, and the fact that much of our crystalloid ends up as interstitial edema, the kidney will develop sub-optimal flow patterns before CVP would cause congestion. The same is true regarding the lung, except that it’s just related to increased pulmonary permeability due to inflammation. Regardless, the idea is to save organs, and the earlier you can detect the problem, the sonner you can stop battering the more delicate organs with fluid.

As I think we have all mentioned, you really have to look at the whole picture, and put it together to tell the story of what is wrong, so we can logically and thoughtfully treat our patients.

I really appreciate this discussion. Thanks!

 

 

Thanks to Andre, Jon and Korbin for making this very educative for all!

Cheers

 

Philippe

Portal Vein POCUS: A Reader’s Case and a Follow-Up to the Denault Discussion

So I’ve been meaning to post a follow up and discussion about portal vein POCUS and how I am integrating it so far, and a few days ago I got a really interesting comment from Dr. Korbin Haycock, and I think it’s got some awesome elements to discuss.

Before we get into it, I would invite anyone reading this to go listen to the original Denault Track here, without which this discussion would be missing some elements.

What we are looking at here is the physiological assessment of venous congestion, and how doppler interrogation of the portal vein may help us. So here is Korbin’s case, and I will interject (in bold) where I think a point can be made, or at least my thoughts on it.

“Awesome post. Awesome website. I had never heard about portal vein pulsatility until reading your blog. I have previously been looking at the renal resistive index and renal vein Doppler pattern in my hypotensive/shock patients (along with doing a bedside ECHO and POCUS pulmonary exam) to guide when to stop fluid resuscitiation.

Very impressive. I have only ever heard of a handful of resuscitationists looking at this (including Andre, and consequently myself) so I’m gonna have to have a chat with this fellow soon! For those who have not tried or are not familiar, some basic info can be found here. I’ll have to review this, but I think one issue with RI is that there is an associated ddx, so that without knowledge of baseline, I would not be certain how to use it. Renal vein doppler seems very interesting to me, as that venous path is the one of the cardiorenal syndrome (forget about all that “low flow” nonsense in CHF – not in shock – patients), and there is clearly bad prognosis associated with abnormal (discontinuous) flow patterns. Here is a really good study (Iida et al)  and its editorial (Tang).

Iida Doppler_CHF Heart Failure JACCHF 2016

Tang Editorial JACCHF 2016

I had a case last night that I think illustrates that fluid administration can be the wrong thing to do in some septic shock patients. Plus, I got to try something new and look at the portal vein for pulsatility.

My case was a gentleman in his late 60’s with a history of HTN, atrial fibrillation and HFrEF who presented with three days for a productive cough and fever. POC lactate was 2.7. His HR was 130-140’s, in atrial fibrillation, febrile, MAP was 50, and he looked a bit shocky and was diaphoretic. The resident had started antibiotics and a fluid bolus of LR, of which not much had gone in (maybe 200cc) when I came to start a night shift and evaluated the patient. I asked that the fluids be stopped until we could have a look at him.

His IVC was about 1.5-2 cm with >50% collapsibility.

So I’m gonna hit the pause button right there for a couple of comments. That’s not a hypovolemic IVC. The RAP may be raised by some of the  It may very well be volume responsive, but I think the first thing to go for is correcting that tachycardia. The antibiotics are definitely the right call, but the fluids should, in my opinion, be held until assessment for volume tolerance is done.

His LV looked to have some mildly decreased EF and was going very fast. RV looked normal. His average SV was 45, CO was 6.1, E/e’ ratio indicated a slightly elevated left atrial pressure. His estimated/calculated SVR by the ECHO numbers was about 550. Lungs were dry anteriorly, without B-lines, but PLAPS view was c/w bilateral lower lobe PNA. Renal vein Doppler was biphasic and the resistive index was very high. I looked at his portal vein and it was pulsatile.

Excellent. So there is pulmonary pathology, which makes fluid tolerance already of concern. The CO is certainly adequate and SVR is low, suggesting a vasodilatory shock etiology. 

In the past, based on the IVC and the way the RV looked, I would have done a straight leg raise or given a given some crystalloid to see if his SV and BP improved, and if it did, give some IVF. Instead, I told the staff to given no more fluids and I gave him 20 mg of diltiazem.

His heart rate decreased from 130-140’s to 90. His averaged SV increased to 65 (probably due to increased LV filling time and better diastolic perfusion time), CO was 5.9, estimated SVR was 570. The renal and portal vein Doppler were unchanged. The MAP didn’t bulge and stayed low at 50-55. At this point I ordered furosemide and but him on a norepinephrine infusion to increase the SVR, first at 5 mcg/min, then 7 mcg/min.

Totally awesome to see. It isn’t unusual for me to diurese patients in vasopressor-dependant shock, as more and more data is emerging on how venous congestion has deleterious effects on the gut and may even contribute to the SIRS-type state. And once a patient is in a euvolemic to hypervolemic state, the only fluid they get from me is the one containing norepinephrine. Maintenance fluid is not for critically ill patients IMO.

The NE gtt increased his MAP to 75 mmHg. His SV was 80, CO 7.1 (I was a little surprised it didn’t go down a bit), estimated SVR was 700. I had his labs back at this point and his creatinine was 1.8 and the last creatinine we had was 1.1 a few months ago. His renal vein pattern was still biphasic and his renal resistive index was also still quite high at 0.89, which would probably predict a significant kidney injury in 2-3 days.

Even though his MAP and hemodynamics looked great, I was worried about the renal resistive index. I ordered a little more furosemide and started him on a little bit of a vasopressin infusion. After things settled down, MAP was 75-80, his average SV was 80, CO 7.3, estimated SVR was about 800, and his renal resistive index (RRI) was 0.75. He looked much better too. The second lactate was 1.3.

Very interesting to see the drop in RRI.  Great case to show how you don’t need to chase lactate with fluids. That is an antiquated knee-jerk reflex hinging on the concept that hyperlactatemia is primarily due to tissue hypoperfusion, which we have learned is not the main cause. 

This morning his creatinine had improved to 1.3 and he is doing well.

South of your border, CMS considers me a bad doctor for not giving 30 cc/kg crystalloid as a knee jerk reaction and instead giving a diuretic and early vasopressors as we did in this patient. Just looking at his IVC would indicate that IVF would be a reasonable strategy. If I had done a SLR or fluid challenge and found him fluid responsive, in the past, I would be temped to chase every bit of fluid response with pushing more fluids, but the renal and portal vein Doppler made me stop fluids in this patient this time. I think this example illustrates the importance of looking at each of your patients on a case by case basis and looking at the whole picture (heart, lungs, kidneys, now portal system too for me!), rather than following protocols.

Kudos. 

 

So then, Andre decides to chime in as well:

Very interesting but be careful about the interpretation of portal pulsatility because it can be falsely positive particularly in hyperdynamic young patient, which was may be not the case. We published an algorithm in order to identify the true portal pulsatility associated with right heart failure and fluid overload and a normal portal vein with pulsatility:

Tremblay Portal pulsatility Flolan Mil AACR 2017

(Tremblay 2017 A&A care report) A & A Case Reports. 9(8):219–223, OCT 2017 DOI: 10.1213/XAA.0000000000000572 , PMID: 28604468)

The latter will be associated with normal RV even hyperdynamic, normal hepatic venous and renal flow, normal IVC. We still need to explore the significance of portal hypertension outside the area of cardiac surgery where we are finalizing our studies.

Always tell my residents and fellow, treat the patient and not the number or the image. That being said, the patient got better so cannot argue with success.

So I think this is a really important point, that it can become dangerous in POCUS to look for a simple, single-factor “recipe” with which to manage the patient, when in fact you can have many factors which, integrated, can give you a much better understanding about your patient’s pathophysiology.

My take on portal vein POCUS so far is that it is a marker of critical venous congestion, beyond simply a plethoric IVC. I think it is wise to stop fluids before the plethoric IVC, but a plethoric IVC with a pulsatile PV should bring fluids to a screeching halt and some decongestive therapy started. The data for this?  Andre is cooking it up, but in the meantime, there is plenty of evidence that congestion is plenty bad, and NO evidence that maximizing CO works at all, so I am very comfortable in witholding fluids and diuresing these patients. 

For fun, here is a little figure from Tang et al about the doppler patterns discussed.

Love to hear everyone’s thoughts!

 

cheers

 

Philippe

Tom Woodcock: The Revised Starling Principle and The Glycocalyx! #FOAMed, #FOAMcc

Screen Shot 2016-08-05 at 11.57.11 PM

So today, I had the chance of having a private tutorial with Dr. Thomas Woodcock (@thomaswoodcock) about the glycocalyx and the revised Starling principles.  For anyone interested in fluid resuscitation, this is an area you have to delve into. The basic principles we all learned (which are still being taught) are basically the physiological equivalent of the stick man we all started drawing as toddlers: overly simplified and far from an accurate representation of reality.

Now my first disclaimer is that I have been a colloid supporter for many years. My physiological logic for that had been to minimize the crystalloid spillover into inflamed/septic areas, particularly the lungs and abdomen, when those are the septic sources. However, I was likely misled by my education and lack of knowledge about the endothelium.

So I stumbled upon the whole glycocalyx thing a couple years ago, and this prompted me to try more enteral fluids – the only way fluids normally ever enter the vasculature – but little else. Aware that it’s there, but unsure what to do about it.

Now a year and a half ago, Andre Denault, my closest thing to a mentor, casually dropped the line to me about albumin not working. “Don’t use it. It doesn’t act the way we think it does.”  But it was a brief chat, and I didn’t get to pick his brain about it.  Just a few weeks ago, I discuss with Jon Emile (Kenny), and he’s coming to the same conclusion.  Damn. I’m finding it a bit harder to hang on to my albumin use, which is beginning to look a bit dogmatic and religious.

Here is Jon-Emile’s take on it – a must-read.

Here is Tom Woodcock’s site and article – another must-read.

And here is my discussion (in two parts) with Tom (to skip the silence, skip forward to about 30 seconds into each – sorry my editing skills are limited!)

 

Bottom line?

Probably stick to isotonic crystalloids, and some hypertonics.

 

Love to hear some thoughts!

Cheers

 

Philippe

 

 

Physician, know thy fluids! #FOAMed, #FOAMcc, #FOAMer

So I posted a quick poll on http://www.therounds.com, a really upcoming physician site, with the intent of getting an idea of what people use as fluids and what they know about them.

 

The first question was “What is your fluid of choice for resuscitation?”

Screen Shot 2015-03-24 at 10.58.56 AM

…no big surprise, 61% choose NS.  Despite the evidence of increased renal dysfunction (JAMA 2012 – I posted about this here: https://thinkingcriticalcare.com/2013/11/18/enough-with-the-normal-saline-foamed-foamcc/)

Well, at least this is chosen with good knowledge of its pharmacological properties, right?

Screen Shot 2015-03-24 at 10.59.12 AM

Hmmm… 57% peg it as physiological or basic.  Only 9% get it right. The pH is 5.6 or so.

So here we have favorite medication used by a lot of people, who use a lot of it, usually in quite ill patients, often acidotic, and who are not aware that the pH is in fact also quite acidotic.

I think it just is an important example on how we need to treat fluids as medications, and not think of them as benign interventions, and by doing so, we’d feel much more obliged to look at what we are giving in terms of composition and quantity, rather than the debonair attitude we have mostly grown up with.

 

cheers!

 

Philippe

 

 

Musings with Jon-Emile & Philippe – Fluid Resuscitation: Physiology and Philosophy! #FOAMed, #FOAMcc, #FOAMer

So here, Jon-Emile and I explore a topic I’ve posted about before (http://wp.me/p1avUV-bd) so I can see if a master physiologist agrees with my rationale (…not just my rationale but supported by a ton of literature many choose to overlook!).

Please visit http://www.heart-lung.org for Jon’s awesome physiology tutorials!

Love to hear listeners’ thoughts!

cheers

 

Philippe

Enteral Fluid Resuscitation? The WHO to the rescue in the ED/ICU? (ORT part 1) #FOAMed, #FOAMcc, #FOAMer

So something has been trotting around my head for a few months, and it actually stems from a small and not-so-proud moment I experienced during a conversation with my wife, while she was still a resident.

She was telling me some of the stories of the day, and how one of her supervisors who had a mixed outpatient and ED practice, always pushed them to use PO fluids, get rid of IVs and get the patients home.  I kind of scoffed, in a sadly typical acute care physician mode, saying how you had to be a bit more aggressive and give them IV fluids to revert their dehydration a bit faster.

Then I caught myself. Hmmm. What exactly am I saying this (con brio) on the basis of. Knowledge, or belief?    I tried to find knowledge but came up woefully short. It seems I’m doing this out of habit, what I’ve seen/learned/believed in the two decades since someone handed me an MD degree. Damn.

So, I do believe in evolution. We have evolved platelets to stop bleeding, fibroblasts and osteoblasts that can fix bones, white cells that go mop up the messes, and all kinds of other good stuff.  One thing we do NOT have is small openings in vascular structures that allow unprocessed, man-made fluids directly into the bloodstream. We make these. We insert tubing into normally sterile environment and infuse a vast number of medications directly into this fragile matrix of cells and organic colloid – with the best of intentions.

In our physiology, however, the ONLY way fluid ever enters the vascular spaces is by diffusion from the outside of the endothelial cell into the lumen, molecule by molecule and ion by ion.

So let me seemingly diverge for a bit…

Screen Shot 2015-02-09 at 12.05.58 PM

Prior to the 1970’s, restricting oral intake was a “cornerstone” therapy of diarrheal illness, due to the pervasive belief that the GI tract needed time to heal and recover before resuming normal function. This was felt to be crucial. Hence, only IV therapy was used (in developed countries), and in the underdeveloped world, the death toll was appalling – especially among children.   In the 40’s, Dr. Darrow of Yale started actually studying the GI tract fluid and electrolyte issue, and advocating oral rehydration with mixed fluids. He was able to bring infant mortality radically down in his practice, but it would take over twenty years before a groups started to formally look at this in the 60’s.  Finally, in the late 70’s, the WHO pushed this out into the field, and the childhood worldwide mortality from acute diarrheal illness dropped by over 70%, from over 5 million deaths a year to a bit over 1 million – at that time.

Oral Rehydration Therapy (ORT) is now felt to be one of the most significant advances in modern medicine. Compared to that impact, all the critical care and cardiology trials are about as significant as a drop in a bucket. We’re not talking about composite end points and subgroup odds ratios of 0.85…

For a great review on this check out The History of Oral Rehydration Therapy by Joshua Nalibow Ruxin (google it).  A great story of science and humanity, good and bad.

So, back to 2015 ED/ICU’s.

Screen Shot 2015-02-09 at 12.06.26 PM

The question now becomes the following: why – in the presence of a functional gut – do I choose to entirely rely on non-physiological IV fluid resuscitation?

I can already hear the roars and the outrage and the cries of heresy.  And heresy is certainly what this is (Heresy is any provocative belief or theory that is strongly at variance with established beliefs or customs – Wikipedia). But that doesn’t make it wrong.

So I would ask everyone – particularly the naysayers, to examine their knowledge and see if they actually have any at all that supports the strong conviction that IV fluids are the way to go in ALL cases (my N=1  principle precludes going for the one-size-fits-all therapeutic approach).

Now everyone agrees that, once patients are better, they should be on feeds with little maintenance fluids. I don’t think many will debate that. So that should be the basis to wonder whether, in the presence of a functional gut, a variable proportion of fluid resuscitation in acute illness should be enteral…

I’ll let everyone digest that.

Comments more than welcome.

More to come in Part 2.

 

 

cheers!

Philippe

Limited EGDT in Zambia Study: Salt Water Drowning Syndrome… #FOAMed, #FOAMcc

So in this month’s issue of Critical Care Medicine, an interesting article was published, where investigators took a (necessarily) simplified version of EGDT to Zambia and applied it to septic patients. It turned out they had to stop it early due to an excessive number of cases of respiratory failure in the treatment group.  The difference was – you guessed it – they got “aggressive” volume resuscitation – up to 4l in the first 6 hours – guided by JVP assessment, and blood and dopamine if needed.

Simplified_Severe_Sepsis_Protocol___A_Randomized.1

The amounts received by 6, 24 and 72h were 2.9, 3.9 and 5.6 l for the treatment group vs 1.6, 3.0 and 4.3 l.

Now lets keep in mind that the patients, for the most part, did not have access to critical care, so the limited resources for ventilatory support made stopping the trial a bit early the only reasonable thing to do. Mortality in the treatment group was 64% and control 60%. High numbers, but this is explained in part by the prevalence of HIV (80%) and TB (37% of the HIV positive patients), so this data can’t necessarily be extrapolated to all populations, but to me, this is physiological support for the concept that aggressive fluid resuscitation – as I have stated in prior posts/podcasts – is most dangerous in those patients where the septic source – presumably “leaky” is ill-equipped to handle extra-physiological fluid.  In these patients, as Myburgh states in a sepsis talk, “noradrenaline is the fluid of choice,” and although perhaps a bit tongue in cheek, this certainly speaks to my beliefs of resuscitating to euvolemia rather than to the lack of volume responsiveness (http://intensivecarenetwork.com/myburgh-john-beta-blockers-and-sepsis/).

Additionally, these patients were not hypotensive, and lactate was not available – local limitations of medical system. Hence the definition of severe sepsis triggering aggressive fluid resuscitation was based  on SIRS type criteria, rather than some form of volume assessment.

 

Bottom line?

Be cautious in aggressive fluid administration in pulmonary sepsis. What, I really dislike when people say “be careful” or “be cautious,” because let’s face it, that doesn’t really mean anything, does it?  It doesn’t tell you what to actually do… We are frontline clinicians, so I’ll say to limit fluid resuscitation in pulmonary sepsis.  2 litres up front?  Probably ok so long as I have a varying, mid-size IVC (maybe 10-15mm – arbitrary and chronic pulmonary disease and hypertension have to be factored in) and a decent heart, but I don’t want to get to the point of no longer being fluid-responsive. Rather, go to pressors a bit earlier, perhaps, and no need for ongoing “maintenance” fluids at 100-150 cc’s an hour – remember that 80% of this wonderful therapy ends up where we don’t want it to.

 

cheers!

 

Philippe

PS for awesome talks by amazing speakers, don’t forget to register for CCUS 2015!!! For more info: http://wp.me/p1avUV-aU and register at http://www.ccusinstitute.org