fluid resuscitation

December 10, 2014

Cool stuff coming in 2015!

I gotta give a shout out to the #FOAMed world.  The last year and a half has been really stimulating, learning from and exchanging with an amazing cohort of peers, all striving towards self-improvement and saving a few extra lives. I’m also really thankful for all those who take a few minutes of their busy days to read or listen to some of the stuff I spew out, and truly appreciate comments and discussion.

Undeniably #FOAMed has made me a better doc, both from the standpoint of learning and inspiration, which is really the fuel behind continuing education. I’ve been involved in organizing events, and in fact, doing so, and the interaction with both the faculty and the participants has been, in and of itself, of immense worth in terms of motivation and a feeling of kinship to a like-minded group, which I think is very important to practicing physicians.

As a consequence of some of these #FOAMed introductions, some good things are in the planning stages for 2015.

Winter: check out BEEM january 26-28 out in Vancouver BC – I can’t make that but really wish I could.

Spring: Two really interesting events in collaboration with l’ASMIQ (Association des Specialistes en Medicine Interne du Quebec – Quebec internists), one being a half day on Shock & Resus (may 30th), and a full day on Lung Ultrasound (may 29th) featuring the grandfather of it all, guru Dr. Daniel Lichtenstein, the one who invented it (well…discovered it, technically). Both take place in Montreal. (Technically this is for ASMIQ members but if anyone is interested, let me know and I’ll see what I can do!)

Of course, CCUS 2015 takes place may 1-3 in Montreal. Can’t miss that. Register at http://www.ccusinstitute.org.

Summer? I’m not running anything, but definitely going to SMACC Chicago. Just go. ‘Nuff said. http://www.smacc.net.au.

Fall: Ken Milne (@TheSGEM) and I will be planning a really cool day combining a critical appraisal workshop and a review of acute care highlights, taking place in Montreal in the fall. Ken will teach us how to learn while being skeptical, and participants should leave with an important skill as well as a headful of practical knowledge. We don’t have a title for this yet but I’ll be sure to let you know! In the meantime be sure to check out Ken’s awesome stuff at http://www.thesgem.com. He keeps it real.

SGEM Ken

 

I’ve also been asked to organize an Ultrasound Simulation Workshop (we are doing an EchoSchockSim in CCUS 2015), which may also happen towards the end of the year.

 

conferences 2015

Ok, so that was just a bit of an update on what’s up in the next year. Hope to meet some of you at these events, do come and say hi!

cheers

 

Philippe

November 29, 2014

Venous Hypertension: The Under-Appreciated Enemy Part 2: Discussion with Jon-Emile

So I posted about this a few weeks ago, and the discussion it brought up with Jon-Emile (www.heart-lung.org) turned out to be way better than the original post, and I just wanted to make sure everyone interested got to see it, so here we go (part 1 is here, for those who didn’t come across it: http://wp.me/p1avUV-bJ):

Jon-Emile

 

Jon-Emile: This is a great topic for review Philippe!

I have come across this problem, certainly on more than one occasion. I was first introduced to the idea of renal venous pressure and renal hemodynamics as a house-officer at Bellevue Hospital in New York. Dr. Jerome Lowenstein published work on this phenomenon as it pertained to ‘Minimal Change Syndrome.” He used to ‘wedge’ the renal vein and measure renal interstitial pressure in these patients and measured the response to diuresis. It was very enlightening and made me feel more comfortable given more diuretics in such patients. [Am J Med. 1981 Feb;70(2):227-33. Renal failure in minimal change nephrotic syndrome].

I am also glad that you bring up the cranial vault in this discussion, because I have often wondered if the encapsulated kidneys behave in a similar way. That is, as renal interstitial volume increases from edema, if there is some point on their compliance curve [like the cranium] where there is a very marked increase in renal interstitial pressure? I have found a few articles which loosely address this idea, but would be interested if anyone else knew of some. In such a situation, there would be a ‘vascular waterfall’ effect within the kidneys whereby the interstitial pressure supersedes the renal venous pressure [like West Zone II in the lungs]; then, renal blood flow would be driven by a gradient between MAP and renal interstitial pressure [not renal venous pressure]. I know of one paper that addresses this physiology in dogs, and finds the vascular ‘choke point’ to be in the renal venous system and not Bowman’s space.

What’s even more interesting, is that when renal interstitial pressure is elevated is that the kidney behaves in a sodium avid state [i.e. urine electrolytes will appear ‘pre-renal’] and this physiology has been known for at least a century!

Lancet. 1988 May 7;1(8593):1033-5. Raised venous pressure: a direct cause of renal sodium retention in oedema?

There is no good explanation as to why this occurs, but one I read is that the high renal interstitial pressure tends to collapse the afferent arteriole and the decrease in afferent arteriole trans-mural pressure which facilitates renin secretion [just like low blood pressure would]; but that would require a fairly high renal interstitial pressure unless the MAP was concomitantly low.

Again, what I must caution [and I’ve been personally wrong about this] is the reflex to give diuretics when seeing a ‘plump IVC’. When I was treating a woman with mild collagen-vascular-related pulmonary arterial hypertension, community-acquired pneumonia with a parapneumonic effusion and new acute renal failure, I assessed her IVC with ultrasound. It was plump an unvarying. I lobbied the nephrologist to try diruesis based on the aforementioned reasoning, but was very wrong. Her kidneys took a hit with lasix. What got her kidneys better was rehydration. In the end, what happened was her mild PAH raised her venous pressure and the hypoxemic vaso-constrction from her new pnuemonia only made that worse. Her right heart pressures, venous pressure and probably renal venous pressure were undoubtedly high. But I didn’t take into consideration her whole picture. She had a bad infection, had large insensible losses and had not been eating and drinking. She was hypovolemic, no doubt, despite her high right heart pressures. Fortunately, her pneumonia resolved and fluids brought her kidneys back to baseline.

Thanks again for another thought-provoking topic

 

Me: Great points as usual Jon, and your last one brings up a bit of a concern I have always had. To play devil’s advocate, one could argue that it may have been resolution of the pneumonia and its metabolic sequelae and possibly other treatment that resulted in improvement of her renal failure, rather than the fluid, no? Did her hypoxia resolution decrease PAP back to normal – with IVC dynamics restoring – and relief of renal congestion, and improvement “despite” fluid?

To me, fluid administration must – at least transiently – increase CO to have any effect on the perfusion side. To do so, my understanding is that it has to go from right to left. Because of the pericardium and interdependence, if RAP exceeds LVEDP, we will start to impair LV preload, which sets up the vicious cycle of a shrinking LV and growing RV. If we can’s increase our RT heart output, obviously our LV CO headed to the kidneys can’t increase either. Hence the assumption would have to be that somehow this additional fluid can – by increasing RV preload (without increasing RV size and further impinging LV?) – help overcome elevated PAP and increase right to left flow. To me, hard to believe without a pericardiectomy (on a short time frame, naturally). Hence I struggle with understanding how a really plump IVC with little variation (if significant pleural pressure variation is occurring) can really still need fluid.

I’d really, really like to get your comments on this. I’ve had a number of conversations about this with people – some of them pretty bright – but none satisfying. Am hoping you can point out my flawed thinking.

 

Jon-Emile: Philippe, you ask very good questions. Your first point is quite valid. I think we have a bias of assigning meaning to a particular intervention because we think that particular intervention will work. For the patient I treated, we administered multiple drugs [oxygen, antibiotics, bronchodilators, we may have even given a dose of steroids] and yet I assign meaning to the fluids given. I think in all patients with complex hemodynamics that there are multiple co-varying interventions that all [hopefully] push the patient in the right direction – making it quite hard to grant significance to one in particular. Yet in the patient I treated, the timing with respect to creatinine change and urine output made it very hard to argue in favor of diuresis. We were checking her creatinine fairly regularly as she was in step-down and we were concerned about the trajectory of her illness. With lasix, her creatinine jumped abruptly on the following chemistry while with fluids, creatinine dropped and her urine output really picked up.

Which brings me to Ulrich’s point. It is well-taken and I hope to have a pulmccm post on this shortly. While the CVP does not have any correlation with volume status or volume responsiveness as you point out, the physiology of the CVP can help explain confusing echocardiographic findings.

All a plump, unvarying IVC with spontaneous inspiration means [if you believe the Guyton, or Magder approach] is that the IVC transmural pressure is remaining on the flat portion of its compliance curve during inspiration.

Click to access cc11824.pdf

In other words, the IVC is at such high volume [on the flat portion] that lowering its transmural pressure [lowering the CVP, raising the intra-abdominal pressure or both] does not cause it to shrink in volume.

The question then becomes why is the IVC in this state? And a great analysis to this question is to consider the determinants of great vein volume [which really is a question of great vein/right atrial pressure or the CVP – which is related to volume by compliance].

There are two primary processes which will raise great vein volume and these flow from the Guyton Diagram 1. excessive venous return 2. poor cardiac function or a combination thereof [its really just inflow versus outflow]. Volume status plays one part of venous return, so certainly, if someone is hugely fluid overloaded, their venous return will be enhanced and this will favour a high great vein volume and high great vein pressure, BUT this will be mediated by cardiac function because if the heart can eject the large venous return it is receiving, then the great vein pressure and volume won’t change or may be low. Conversely, if cardiac function is poor, a patient could have a low venous return [e.g. be hypovolemic or euvolemic] and still have a high great vein volume and pressure – simply, because the heart can’t expel from the thorax what little venous return it receives. Importantly, poor cardiac function can mean almost anything [valve dysfunction, tachycardia with arrhythmia, high afterload, poor contractility, etc.].

To me, the above is the true value of thinking about Guyton and the CVP, so when I approach a patient, I try to think about what their venous return curve looks like [by a clinical exam] and I use a TTE to actually see what their heart function looks like [and to me this is the true power of ICU TTE]. The above also explains why CVP simply cannot be a marker of volume status.

In the patient I was treating, her history and physical really suggested poor venous return [she was clearly with a pneumonia, hadn’t been eating and was euvolemic to dry on examination] yet her great vein volume was high on TTE which meant that her cardiac function was most likely poor [on the Guyton Diagram her low venous return curve would be intersecting a very low, flattened cardiac function curve such that shifts with intra-thoracic pressure would not change right heart pressure at all].

But why was her heart function poor? Why could her right heart not eject what little inflow it was receiving? It was probably a combination of things. The pneumonia probably increased right heart afterload which caused some TR, she was tachycardic so wasn’t getting optimal filling time, she was septic with perhaps some underlying cardiomyopathy, perhaps her diastolic blood pressure was lower than normal [she was an elderly lady with likely stiff arteries] and she wasn’t perfusing her right coronary artery well and was suffering from relative ishcemia] it’s certainly is a lot of hand-waving, but all taken together perhaps plausible.

The antibiotics improved her lung function as did the bronchodilators which lowered pulmonary vascular resistance which improved right heart forward flow, maybe the inhaled beta-agonists increased her contractility, maybe the oxygen also lowered her pulmonary vascular resistance, maybe the steroids sensitized her to catechols and this raised her blood pressure and coronary perfusion pressure which improved her right heart function, but also maybe the fluids? Empirically, and in retrospect, venodilating her with lasix probably really lowered her venous return and this crashed what little cardiac reserve she had. It was improving her venous return with fluids that helped.

Sorry if this post is getting too long …

In terms of ventricular interdependence [an excellent, under-appreciated point in the ICU] I think that you have to be very careful extrapolating whether or not this effect is present from an IVC examination. In a classic paper [that caused much consternation at the time] Pinsky found that right atrial pressure was completely uncoupled from right ventricular end-diastolic volume [why the CVP is a poor indicator of volume responsiveness]. Her is a recent review of that paper by Pinsky himself.

http://www.ncbi.nlm.nih.gov/pubmed/24760121

The take home is that while right atrial volume and pressure [and by corollary great vein volume and pressure] can be high, this may not translate to a right ventricle near its elastic limit. Pinsky offers no good explanation as to why this is, but postulates that it may have to do with the complex RV geometry and how this changes during diastole. So until there is a widely accepted means of assessing RV filling with TTE [like an Ea ratio] which could pick up a restricted filling pattern, this is really hard to call on echo. As you are aware, you could look for a flattened septum or D sign during diastole, but I’m not sure how well that sign predicts a patient’s response to a fluid challenge – it certainly screams caution.

This Pinsky paper also highlights a potential disconnect between the physiology proximal to the tricuspid valve and the physiology below it which is also part of my general reluctance to use IVC volume change as a marker of fluid responsiveness, just as I have total reluctance to use CVP [or its change with respiration] as a marker of fluid responsiveness.

Unfortunately, a lot of the time it comes down to ‘guess and check’ – give fluids or give lasix and see what happens. This is why I firmly believe that determining volume status and volume responsiveness are the hands-down hardest party of ICU medicine.

If you’re still reading, I hope this helps.

One more point. I don’t think I gave a full explanation to one of your questions. Please bear with me as this is exceptionally hard to explain with words [indeed why I made heart-lung.org].

The venous return and cardiac function curves are essentially inverse of each other [that is lowering right atrial pressure increases venous inflow but decreases cardiac outflow] so they approximate the letter X [venous return is the \ and cardiac function is the / & the point at which the two lines intersect make up the CVP and defines cardiac output].

If you consider the patient I described, If we assume her venous return is low [because she is venodilated from sepsis and hypovolemic from low PO] then the venous return curve [\] is shifted leftwards. If we assume her cardiac function is poor the cardiac function curve slope [/] is shifted down and to the right.

When she takes a breath in, the lowering of intrathoracic pressure pulls the cardiac function curve leftwards [lowers its pressure relative to venous return] while the increase in in abdominal pressure with diaphragm decent tends to temporarily increase venous return by decreasing abdominal venous capacitance. This effect shifts the venous return curve in a rightward manner.

If the patient’s venous return curve initially intersects the ascending portion of the cardiac function curve [i.e. she is truly volume responsive] BUT, the intersection is very near the plateau of the cardiac function curve [i.e. the portion of the cardiac function curve that will render the patient non-volume responsive and also favour unvarying respiratory change in right atrial pressure/volume with inspiration], THEN with inspiration it is possible to see the intersection of the two curves on the flat portion of the cardiac function curve [as the cardiac function curve is pulled leftwards and the venous return curve is pushed rightwards], even though she does have some cardiac preload reserve. This would be an example of impaired specificity of IVC volume change with spontaneous inspiratory effort as a predictor of volume unresponsiveness [i.e. a false positive for a plump IVC predicting the lack of fluid responsiveness].

I address this physiology in chapter 6 parts C and D and chapter 8 part F.

 

Me: Very, very interesting. I think this discussion, as many, show how medicine is not a “hard science” but remains a “pseudo-science”, inherent to the fact that we are blending physics, chemistry, biology and cannot really apply simple principles of flow and pressures when dealing with elastic, muscular systems lined with microscopic coating whose compliance and resistance change from moment to moment and thru effect of neural and hormonal influence. There are simply too many unmeasurable variables to come up with single guidelines and rules.

I think, as you say, that there remains a need for some degree of trial and error, that we are hopefully narrowing with the appropriate application of technology and proper data integration.

I’ll percolate all this and see how I can tweak my mental model!

Thanks a lot Jon-Emile!

Philippe

 

 

please visit Jon-Emile at http://www.heart-lung.org

Heart-Lung

 

 

cheers!

…and don’t forget to register for CCUS 2015 at http://www.ccusinstitute.org!!!

Philippe

November 23, 2014

A Bedside Ultrasound Case & Poll: All Infiltrates are not created Equal: A Follow Up! #FOAMed #FOAMcc #FOAMus

Ok so so far, the votes show the following:

CHF 52%

PE 26%

Pneumonia 21%

So, as most of you had figured out, the fever and white count turned out to be fairly insignificant.  I started diuretics on him and stopped IV fluids (in truth, he spent a few hours still receiving IV NS at 100cc/hr as it sadly slipped by me – I know… NS to add insult to injury).  I also stopped antibiotics to the alarm of some, but keep in mind we have a lot of c.difficile in our institution, and I did not believe the had CHF AND a significant pneumonia (that would go against Occam’s razor…). He was not septic, and another discrepancy that led me away from the diagnosis of pneumonia is that a patient with significant bilateral infiltrates due to pneumonia is sick: toxic, dyspneic, fulfills Scott’s LLS score of 1 (Looks Like Shit – range 0 to 1).

Within a few hours and perhaps a negative balance of a liter or so, he feels much better. Here is his IVC at that point:

36 hours later, his CXR is clear and he is off O2.

Angiogram turns out normal – as anticipated – EKG only ever had some vague non-specific ST abnormalities. He likely had a viral cardiomyopathy – some ancillary tests still pending (HIV, etc), but is to be discharged soon.

For those who voted pneumonia, certainly initially it could not be ruled out, only the clinical evolution made it highly unlikely as a significant player.

For those who felt this represented pulmonary embolism, remember that the primary hemodynamic mechanism will be right heart failure, hence the RV would most likely be as large, and potentially larger depending on the severity of the embolism. Again, this cannot be ruled out by bedside ultrasound, it can only be ruled out as a main cause of respiratory failure. Also note that the chest xray is generally normal, or may show the peripheral wedge shaped infarct (Hampton’s hump). Bilateral infiltrates would not be the rule. But it’s always a good thing to keep it in mind!

Bottom Line?

I think this case illustrates well the limitations of physical examination, and although more commonly, pneumonias (especially in the elderly) get digressed because they “had crackles,” sometimes, patients we might not expect may have CHF.

From the moment one notes a large, plethoric IVC, one should anticipate downstream pathology of some kind (overzealous iatrogenic fluid overload being the exception), whether tamponade, pulmonary embolism, LV failure, pulmonary hypertension, but something.

Hence, in this case, bedside ultrasound proved invaluable. After all, he was recieving less-than-optimal therapy for CHF: fluids and antibiotics… This may be a case that would have proceeded to “ARDS”, and although I don’t doubt that at some point along the line, an echo would have been done, the delay may have had consequences. In our center, no one gets into the ICU without at the very least a cardiopulmonary bedside ultrasound. It is done routinely, not only for specific indications – the real indication is having a patient in front of you.

Please don’t forget, if this is up your alley, don’t miss CCUS 2015: Way Beyond EGDT and ACLS!!!  #CCUS2015

cheers!

Philippe

 

Jon Emile says:

Great case, great windows and images. I agree with your management totally. I do recall once, however, having a patient admitted for heart failure following a bedside TTE performed by a great resident, unfortunately [and in retrospect] the patient likely had a septic cardiomyopathy. The patient felt great with diuresis, but then his BP crashed as the sepsis took hold.

Recall the classic paper by Parrillo NEJM 1993 who looked at the left ventricle during the acute phase of septic shock and found LVEDV to LVESV values of 225 ml to 150 mL. The EF was in the low 30s. During the recovery phase, LVEDV to LVESV was 150 to 75 mL and EF of 50%. He noted that dilation of the left ventricle seemed to confer a mortality benefit, & that this may be a compensatory response to maintain stroke volume. This may be more striking in young patients as yours. When I first read your case a mycoplasma peri-myocarditis came to mind [I treated a case of this as a resident in the Manhattan VA]. The classic finding in this disease being bullous myringitis.

Thanks for the awesome echo videos!

 

Great point Jon!  Septic cardiomyopathy – which is very common – is definitely something to keep in mind. Indeed the LV dilation noted by Parillo would be a sensical adaptation to limited contractility. I remember seeing a particularly impressive case in a young woman with significant dilation and an EF in the 15-20% range, with incredibly rapid recovery to the 40’s and 50’s  by a day later. I’ve yet to see septic cardiomyopathy happen, however, in a patient who isn’t that sick, i.e. no pressors, no acidosis, etc…

Great point about mycoplasma, which was brought up by our ID consultant at first, but who also agreed he wasn’t that sick and agreed to stop once noting the CXR had cleared with diuresis.

 

Thanks for reading!

November 13, 2014

Bedside Ultrasound Case Debate Part 1: A Poll ! #FOAMed, #FOAMcc, #FOAMus

So I’m walking to the ED to reassess a COPD’er that was on BiPAP, and one of the ED docs sees me in passing and says – “I might have a case for you, she’s on her 3rd litre and still a bit hypotensive…I’ll let you know.”  So I re-route and decide to take a look right away, because I’m never fond of shock NYD.

So here is this woman in her 50’s, BP is 93/67, RR 22 and moderately dyspneic. She has been increasingly so for a few days without infectious symptoms. The X-ray is clear and her labs unremarkable aside from a lactate at 3.3 mmol/l.  She is moderately overweight but quite active. Non=smoker without any cardiorespiratory known illness and on no medications.

Here is what we see on ultrasound-enchanced physical examination:

So, what do you see?

In the first clip, we see a large, dilated IVC with little variation – despite the dyspnea, making it a more significant finding – according to the Effort-Variation Index (http://wp.me/p1avUV-9k).   This automatically implies there will be some pathology (unless iatrogenically very volume loaded) to be found downstream.

In the second clip, you have a hyperdynamic and underfilled LV and a dilated, poorly contractile RV.  In the absence of cardiopulmonary disease and in an active patient, this is highly suggestive of an acute process, namely pulmonary embolism.

On further questioning she had done a new yoga stretching class as a possible endothelial-damaging process.

So what did I do? Get a STAT angioscan:

 

What would you do next?

 

I’ll tell you what I did tomorrow, and hopefully have some good bloody arguments!

 

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 www.ccusinstitute.org!

 

cheers

 

Philippe

 

November 4, 2014

ECMO for Cardiac Arrest: a big CHEER! #FOAMed, #FOAMcc

So a couple of years ago after hearing Scott’s interview of Joe Bellezzo and Zack Shinar (http://emcrit.org/podcasts/ecmo/) I figured this was the future, and promptly got a hold of these guys and got them to present at CCUS 2013 (link to Zack’s lecture below), where their lectures were mind-blowing and instantly made any resuscitationist green with envy, me included.

So just last month, two articles came out in Resuscitation which are highly pertinent and add a lot of legitimacy to the concept of ECMO for CA, one being the CHEER study by Bernard et al (CHEER Study) and the other, a very interesting canadian retrospective observational study by Bednarczyk et al (ecmo arrest canadian).

 

CHEER!!!

First, the CHEER study. Very well done, designed to combine ECMO, mechanical CPR and hypothermia, N=26, so not massive, but given the magnitude of the treatment effect, IMHO highly significant. Very good criteria (18-65, VF) so basically working with patients having a reasonable prognosis (aside from the cardiac arrest…), and their starting point was after 30 minutes of unsuccessful ACLS.

Now, for experienced clinicians out there, it is fairly obvious that at around 30 minutes, we start to get a little discouraged. Maybe not ready to throw in the towel, but we know things are looking dim. And most of those who do get a late ROSC don’t tend to do very well on the long term…

So it takes the CHEER team about 56 minutes to ECMO runtime.  Now, by 56 minutes of no-ROSC, most arrests would have been called. I think that is a key point to underline – the study essentially begins here, at a point where prognosis is no longer that 8-26% “quoted” survival, but pretty close to 0%.

So what happens? 54% of these patients survive to hospital discharge with good neurological recovery. Lets put this in perspective again. They bring back half the people we probably would have given up on…and discharge them home!!!  That’s crazy impressive.

This pretty much correlates with the experience of Zack and Joe (www.edecmo.com), who recently told me the story of a 20 year old diabetic with a K of 9.0 and an arrest of over 45 minutes. Discharge home a week or so later. Completely fine. Back on facebook and skyping with Zack & Joe.

That’s a humbling thing, because in my ED, my ICU, my hands, she’s a goner. 

 

The Canadian Perspective

Ok, so the Bernardczyk article is also really interesting, because it shows that this can be accomplished in a community hospital, and not necessarily only a tertiary care center, and their numbers (albeit retrospectively) are in the same ballpark.

And here is an awesome point of view from their discussion which I completely agree with and ascribe to:

“This (…) challenges our understanding of cardiac arrest as a terminal manifestation of a dis-ease process with treatment options fraught with futility. Rather, for selected patients, cardiac arrest may be better considered anexacerbating symptom of underlying disease with a therapeutic window to effectively restore perfusing circulation while providing definitive therapy.”

 

Thoughts…

So one concern is with bringing back severely neurologically disabled patients. I think the CHEER, the canadian and the japanese data all pretty much refute this. ECMO, particularly paired with hypothermia (probably TTM style now), seems to have remarkable neuroprotective effects, despite prolonged low-flow states. I think we all rarely see patients with 40-50 minute range arrests showing CPC scores of 1…

So why might this occur?  Does the sudden flow reverse some of the vasoconstriction caused by the epinephrine?  I know from discussing with Joe that if they are thinking that the patient is going to ECMO, they will avoid epinephrine. Recent years have clearly shown that the improved ROSC of epinephrine comes at a cost of greater neurological damage, hence equivocal final result of intact neurological survival.

 

Bottom line?

If you’re a resuscitationist, get on board.  Its expensive, but no more than a bunch of other (sometimes dubious or dogmatic) things we do – and the data is there. I’ve been working on my (community) hospital and will not quit until we have it.

What do you need? A cooperating ER chief / ICU chief, and either a cath lab and a vascular surgeon in your institution or in a collaborating neighbourhood one.

…and some cojones.

 

Absolutely love to hear your thoughts, particularly from anyone with ECMO experience!

…this, of course, and more, at CCUS 2015!   http://ccusinstitute.org/Symposium7.html

 

cheers! (pun intended)

Philippe

 

…and here is Zack at CCUS 2013:

http://www.ccusinstitute.org/Video.asp?sVideo=Resuscitation%20Zach

 

October 8, 2014

Bedside ultrasound for Hospitalists: A Must! #Hospitalist, #FOAMed, #FOAMus

Hi, so here is a quick little overview on why anyone taking care of hospitalized patients unequivocally need to use bedside ultrasound in a daily, integrated fashion, even if they don’t realize it yet.

It isn’t just for the flashy spot diagnoses in the ICU or the ER, but really for daily rounds, assessing common cardiac, respiratory, renal, gastrointestinal and even neurological syndromes.

Love to hear from any hospitalists or medical consultants out there about their use of bedside ultrasound!

Cheers

Philippe

September 20, 2014

Fluids and Vasopressors in Sepsis, Wechter et al, CCM Journal: Anything Useful? #FOAMed, #FOAMcc

A couple of articles on fluid resuscitation worth mentioning. Not necessarily for their quality, but because they will be quoted and used, and critical appraisal of the content and conclusion is, without a doubt, necessary to us soldiers in the trenches.

The first one, Interaction between fluids and vasoactive agents on mortality in septic shock: a multi-center, observational study, from the october issue of the CCM Journal (2014) by Wechter et al, for the Cooperative Antimicrobial Therapy of Septic Shock Database Research Group, is a large scale effort do shed some light on one of the finer points of resuscitation, which is when to initiate vasopressors in relation to fluids in the face of ongoing shock/hypotension.

So they reviewed 2,849 patients in septic shock between 1989 and 2007, trying to note the patterns of fluid and vasopressor therapy which were associated with the best survival.  They found that survival was best when combining an early fluid loading, with pressors started somewhere in the 1-6 hour range.  I do invite you to read it for yourself, it is quite a complex analysis with a lot of permutations.

So…is it a good study?  Insofar as a retrospective study on a highly heterogeneous bunch of patients, I think so. But can I take the conclusion and generalize it to the patient I have in front of me with septic shock? I don’t think so. In all fairness, in the full text conclusion the authors concede that this study, rather than a clinical game-changer, is more of a hypothesis generator and should prompt further study. That, I think, is the fair conclusion.

In the abstract, however, the conclusion is that aggressive fluid therapy should be done, withholding vasopressors until after the first hour.  This is somewhat of a concern to me, since it isn’t uncommon for some to just read that part…

So why is this not generalizable?  First of all, I think that the very concept of generalizing is flawed.  We do not treat a hundred or a thousand patients at a time, and should not be seeking a therapeutic approach that works best for most, but for the one patient we are treating. Unfortunately, this is the inherent weakness of any large RCT and even more so in meta-analyses, unless the right subgroups have been drawn up in the study design.

Let me explain.

Patient A shows up with his septic peritonitis from his perforated cholecystitis. He’s a tough guy, been sick for days, obviously poor intake and finally crawls in. If you were to examine him properly, you’d have a hard time finding his tiny IVC, his heart would be hyperdynamic, his lungs would have clear A profiles, except maybe for a few B lines at the right base. You’d give him your version of EGDT, and he’d do pretty well. A lot better than if you loaded him with vasopressors early and worsened his perfusion. Score one for the guideline therapy.

Patient B shows up with his septic pneumonia, also a tough guy, but happens to be a diabetic with a past MI. He comes is pretty quick cuz he’s short of breath.  If you examine him properly, he has a big IVC, small pleural effusions, right basal consolidation and B lines in good quantity. He gets “EGDT” with an aggressive volume load and progressively goes into respiratory failure, which is ascribed to his severe pneumonia/ARDS, but more likely represents volume overload, as he was perhaps a little volume responsive, but not volume tolerant. An example of Paul Marik’s “salt water drowning.” (http://wp.me/p1avUV-aD) Additionally he goes into acute renal failure, ascribed to severe sepsis, but certainly not helped by the venous congestion (http://wp.me/p1avUV-2J). If he doesn’t make it, the thought process will likely be that he was just so sick, but that he got “gold standard” care. Or did he?

It may very well be that the studied group may include more Patient A types, and less B types, whose worse outcome will be hidden by the “saves” of the As. If you have a therapy that saves 15/100 but kills 5/100 you still come out 10/100 ahead… Great for those 15, not so much for the 5 outliers.

We, however, as physicians, need to apply the N=1 principle as we do not treat a hundred or a thousand patients at a time. I would not hesitate to be much more conservative in fluid resuscitating a B-type patient, regardless of the evidence.

Unfortunately, until trials include a huge number of important variables (an accurate measure of volume status, cardiac function, capillary leak, extravascular lung water, etc), it will be impossible to extrapolate results  to an individual patient.  These trials will, I suppose, eventually be done, but will be huge undertakings, and I do look forward to those results.

So, bottom line?

It’s as good a study of this type as could be done, but the inherent limitations make it of little clinical use, unless your current practice is really extreme on fluids or pressors. What it will hopefully be, however, is an onus to do the highly complex and integrative trials that need to be done to determine the right way to treat each patient we face.

 

thanks!

 

Philippe

 

COMMENTS:

Lawrence Lynn says:

Excellent post. This thoughtful quote should be read and understood by every sepsis trialists!!

“We do not treat a hundred or a thousand patients at a time, and should not be seeking a therapeutic approach that works best for most, but for the one patient we are treating.”

This single quote exposes the delay in progress caused by the ubiquitous oversimplification which defines present sepsis clinical trials. Bacteria (and viruses) generate “extended phenotypes” which are manifested in the host. These phenotypes combine with the phenotypic host response to produce the range of “dynamic relational hybrid phenotypes of bacterial and viral infection”. These hybrid phenotypes are also affected by the innoculum and/or the site of infection (vis-à-vis, your example of peritonitis).

Certainly Wechter et al and the Cooperative Antimicrobial Therapy of Septic Shock Database Research Group should be commended for beginning the process of moving toward the study of the dynamic relational patterns of complex rapidly evolving disease and treatment.

We are excited to see the beginning of the move of trialists toward the study of dynamic state of disease and treatment. However, before they can help us with meaningful results, trialists will need to study and define the range of “the dynamic relational phenotypes of severe infection” and then study the treatment actual phenotypes. This will not be easy as these organisms have had hundreds of thousands of years of evolution writing the complex genotypes which code for the extended of human infection. Sepsis trailists need to be encouraged by clinicians to rise to the task.

The clinicians must actively teach the trialists, (as you have in your post) that we expect trails which help to identity the therapeutic approach that works best in response to the dynamic hybrid phenotype “we are treating”.

The two linked articles below explain the present oversimplified state of the science of sepsis trails and why we clinicians must teach the trailists not to oversimplify and assure that they move quickly toward the study of the actual dynamic phenotypes of severe infection.

http://www.ncbi.nlm.nih.gov/pubmed/24834126

http://www.ncbi.nlm.nih.gov/pubmed/24383420

This is a paradigm shift so we, as clincians, must act to teach trailists this move is necessary. Otherwise we will continue to be left with hypotheses, which, while nice, are not useful at the bedside.

Lawrence Lynn

 

 

August 20, 2014

Revisiting our beliefs about Fluid Resuscitation: An N=1 Podcast. #FOAMed, #FOAMcc

So if you keep abreast of the fluid literature, you’ll note that more and more logical voices are bringing up very, very valid points against the powerful cultural backdrop of aggressive fluid resuscitation in various pathologies. Paul Marik’s recent publication, a great SMACC 2013 lecture by John Myburgh, not to mention several studies and analyses (VISEP, SOAP) illustrating consequences of overzealous fluid resuscitation. On the other side of the fence, you have the guidelines of various associations proclaiming loudly that fluids are “critically important” that there is a need to be “aggressive” and “generous.”  However, scratch a little beneath the surface and find…very little besides opinion and history. Zip. Nothing.

So my aim isn’t to make anyone stop giving fluids, but instead to treat fluids as any other therapy. Carefully given and assessed rather than in hyped-up frenzy.

I invite every physician reading or listening to, for a few minutes, put pre-concieved notions aside and approach the problem from a neutral and educated point of view, and come to your own conclusion, as unbiased as possible.

So here is my little podcast.

 

cheers

 

Philippe

 

ps just as I was uploading, checked my twitter and noted a great addition to the body of analysis by Josh Farkas, check it out:

http://www.pulmcrit.org/2014/08/the-myth-of-large-volume-resuscitation.html?m=1

July 6, 2014

Bedside Ultrasound in Cardiac Arrest: A Quick Overview, ISURA 2014. #FOAMed, #FOAMcc, #FOAMus

Here’s a quick lecture I gave at Vincent Chan’s ISURA 2014 in Toronto.  It was a great event attracting anasthetists from all over the world, and it was an honor to work with Massimiliano Meineiri, Alberto Goffi, Adriaan Van Rensburg, Colin Royse and many more.

Unfortunately it was my first time using Prezi, which is pretty cool but doesnèt allow you to loop your videos, which really, really sucks!  So unfortunately the clips are very short…

Love to hear any comments!

Philippe

June 16, 2014

Another plea. Please stop embarassing us. #FOAMed, #FOAMcc.

Despite physiological rationale, common sense, and a JAMA article now almost 2 years old, I still sadly see most of my internal medicine colleagues still routinely reaching for (ab)normal saline.

Its embarrassing.

I genuinely feel bad recommending other fluids in consultations, or in the room of a crashing patient asking the nurse to stop the bolus of NS and change it at least to RL, because it is such a ‘basic’ intervention. Prior to the JAMA article, I mostly gave people the benefit of the doubt. Resuscitation isn’t everyone’s field of interest, nor is physiology, so I didn’t feel that necessarily everyone HAD to know this and ascribe to it. I do understand the 10 year time of knowledge translation, but that’s why #FOAMed exists, to try to cut that down.

So please, unless your goal is specifically chloride repletion, take a deep breath and release your grasp on habit and tradition, and embrace physiology (at least to some degree) and stop using NS as a volume expander whether in bolus or in infusion. RL or plasmalyte – although not physiological, at least not as biochemically disturbing as is 0.9% NaCl.

Having said that, let’s keep in mind that human fluid is colloid, whether it includes a cellular suspension (blood, lymph) or not (interstitial fluid), made of a varying mix of proteins, electrolytes, hormones and everything else we know – and some we don’t – floating around. There is no compartment that contains a crystalloid solution.

I’m quite aware that no meta-analysis has shown that colloids are superior, but it likely is just a matter of the right colloid. Resuscitating with crystalloids is kinda like throwing a bucketful of water at an empty bucket across the room. 70-80% spill, if you’re lucky. And the cleanup may be more costly than a few sweeps of the mop. This is evidence based (SOAP, VASST, etc..).

So a plea to all, spread the word. Its a simple switch. Boycott hyperchloremic acidosis at least.

For more details, here’s a link to my earlier post on NS: http://wp.me/p1avUV-5x

cheers

 

Philippe