Jon-Emile (@heart_lung) chimes in on the whole portal vein POCUS! #FOAMcc, #FOAMed

When it comes to physiology, there`s no doubt that Jon is the man, so I was really curious about his take on all this, which, no surprise, is definitely worth sharing, just in case everyone doesn`t go read the comments.

 

Jon:

Wow; there is a lot to unpack here.

My first comment is that intra-renal venous flow [*not renal vein flow], hepatic vein flow, portal vein flow, etc, etc, etc [as well as IVC size and respiratory variation] are all ultrasonographic transductions of the central venous pressure …so I’ll give my boxed disclaimer that volume status and volume responsiveness cannot definitively and reliably obtained from this marker because the CVP is too complicated to make these physiological leaps.

Indeed. It is important to realize that, as Jon states below, that the angle for looking at the PV in this case is to assess congestion, rather than responsiveness or the ever-so-nebulous ‘status.’

Wait for it … volume tolerance and the CVP, is a bit more nuanced, i think.  with a high CVP, you really have to ask yourself – **why** is the CVP elevated and go from there.  if the CVP is elevated because of tamponade, its very different management from a high CVP from a massive PE or air-trapping versus a high CVP from volume overload.

Absolutely. Diuresing a pre- or full-fledged tamponade, PE or air-trapping could have disastrous consequences, i.e. PEA arrest!

There seems to be some confusion about *the renal vein* versus *intra-renal vein*.  the lida trial is clear that it is intra-renal vein flow.  i am not terribly familiar with *the renal vein flow, however, my hunch is that renal vein flow should always be biphasic [just as the jugular venous flow, SVC flow, IVC flow and hepatic vein flow are always biphasic] – that is a normal pattern close to the right atrium.  normally the systolic inflow velocity is greater than the diastolic inflow velocity and there is fairly good data correlating reversal of systolic to diastolic venous flow ration to right atrial pressure [in the IVC and SVC].

Definitely the intra-renal vein should be the target here – not always easy in some patients, because the renal vein itself, especially the right (no crossover) really has an IVC pattern and won`t necessarily reflect the effect of intra-renal hypertension.

The pulsatility that evolves in the intra-renal vein as the CVP rises is beyond me, but the authors postulate that it has to do with the compliance of the vein at higher CVP and intra-renal interstitial pressure which makes some sense.  But it is important to note that the compliance curves of an intra-renal vein and *the* renal vein are probably quite different.

Secondly, the pulsatility of the PV is a neat idea because of its relative ease of assessment.  However, the pulsatility, presumably, is due to the PV encroaching the limits of its compliance curve – the PV, like the CVP – has an inflow and outflow pressure.  It is highly likely that a pulsatile PV in a post-operative cardiac patient relates to an angry RV – but is this always true?  What about the cirrhotic?  What about differential partitioning of fluid into the splanchnic bed versus the lower body?  What about differential expression of adreno-receptors between splanchnic arteries [beta and alpha] and splanchnic veins [mostly alpha].  My point is that there could be *other* inflow and outflow differentials that are affecting PV volume, compliance and therefore pulsatility that are not yet recognized.  A cirrhotic on bomb dose phenylephrine/vasopressin may have their splanchnic venous volume recruited with blood expelled towards the liver, an engorged PV that is pulsatile – but is that RV failure?  Is that a patient who needs to be decongested?  I don’t know.

Thirdly, there are complex cardiac contributions to venous flow phase and vein pulsatility such as arrythmia – atrial compliance, etc.  As the comment above notes – how might afib contribute to SVC or IVC venous inflow?  It’s hard to know, but my hunch would be that afib itself would tend to reverse the normal S wave: D wave supremacy … that is, decrease the normal systolic inflow velocity relative to the diastolic inflow velocity.  if the atrium is not emptied fully then its pressure with rise.  if atrial pressure rises, when the atrium is pulled downward during ventricular systole, the S wave will be diminished.  additionally, the more chronically dilated and poorly compliant the right atrium, the greater its pressure will be with the loss of atrial kick.

Fantastic points. Again, looking at POCUS metrics CANNOT BE DONE IN ISOLATION, from the rest of the POCUS and clinical data.

Lastly, the venous inflow pattern analysis approach to CVP estimation – i think – is better than IVC size and collapse because of how IVC size and collapse can also be affected by IAP, ITP/PEEP, etc.  Because ITP affects systolic and diastolic inflow patterns similarly, that confound should be lessened.  Nevertheless, as Dr. Denault mentions in the cases above – you have to treat the patient!  This means integrating what the data is telling you in the patient in front of you.  If in a certain clinical context the test results do not make sense, it’s probably a false positive or false negative test.

I dug up this gem from 30+ years ago. Excellent paper [https://www.ncbi.nlm.nih.gov/pubmed/3907280 – “Ultrasonic assessment of abdominal venous return. I. Effect of cardiac action and respiration on mean velocity pattern, cross-sectional area and flow in the inferior vena cava and portal vein”].

Ok that’s on my short reading list for the next 48h!

They show the venous inflow waveform for the IVC [presumably very similar to *the renal vein]; Afib *does* cause the S wave to become attenuated – so it would change the normal biphasic form to more of a monophasic form. In theory, giving a calcium channel blocker and slowing the patient down should improve this somewhat. They even have a brief discussion on portal vein pulsatility.

This venous inflow stuff is very interesting and potentially very applicable. @iceman tweeted out wave velocity patterns in the MCA during high ICP – indeed – an increase in ICP renders the flow more pulsatile and then there is loss of diastolic flow. Probably similar physiology for an intra-renal vein as intra-renal capsular pressure rises. A good sign that the kidney is under pressure!

Thank you Jon for some really excellent physiological points and the reminder that, in POCUS just as in clinical medicine, we cannot rely on one assessment, and that measure must be considered in the context of the factors affecting it. Otherwise, we are not truly tailoring our therapy to the patient, but only pretending to.

The Resuscitation Tracks 1: Portal Vein POCUS with Dr. Andre Denault. #FOAMed, #FOAMcc, #FOAMus

So this is one of the key discussions I wanted to have in my process of synthesizing my resuscitation algorithm. Dr. Denault is the one guy I’d call a mentor, and I think one of the rare and true clinician-scholar, who is just as comfortable being the anaesthetist/intensivist at the bedside of the crashing patient as he is being the keynote speaker in major conferences, or writing the textbooks that lead the field in acute care/perioperative TEE and critical care POCUS.

So to put some perspective to this discussion, back in 2014 I organized a resuscitation afternoon for internists with Andre and another awesome guy you probably all know, Haney Mallemat (@criticalcarenow). In a quick 15 minute discussion between talks, he shared with me the most recent of his discoveries, portal vein POCUS as a marker of right-sided failure/volume overload in his post-op cardiac patients, and how aggressively managing these resulted in much improved post-operative courses in terms of weaning, vasopressors and even delirium.

Interesting stuff.

So here you are:

So I’ll let you all ponder that and I would really like to hear comments and ideas. Sometime in the next few weeks I’ll be finalizing my resus algorithm – which will not be a recipe approach, as you might suspect if you have been following this blog, and will rely heavily on POCUS and the clinical exam.

cheers and thanks for reading and listening!

Philippe

 

Emergency Pericardiocentesis post-arrest (Part 1). #FOAMed, #FOAMus, #FOAMer

So a few nights ago I got pulled out of slumber to rush to the ER for an elderly patient who had arrested in hospital shortly after having been brought in for chest pain. The sharp ER doc had diagnosed a tamponade on a presumed aortic dissection, managed to get a needle in, aspirated some fluid and managed to get ROSC.

So when I got there we had a patient post-ROSC in rapid atrial fibrillation with a thready but palpable pulse. POCUS showed a large pericardial effusion with minimal LV filling. So here is what we did:

With the catheter in, we were able to drain. Note a couple of POCUS teaching points, always make sure to (1) visualize your guidewire in the right space, and (2) second, when using a dilator, you can note the disappearance of the proximal part of the guidewire as it is covered by the dilator. This tells you you have adequately dilated into the target structure – pericardium in this case, because it is possible (personal experience) to advance a dilator fairly deep, but not go through a perhaps fibrotic pericardium, and then result in pigtail mis-placement just outside of the target.

In part 2 you can also see the aspiration of the effusion and improved LV filling. The patient’s BP instantly rose to 140’s systolic.

More case details and POCUS teaching points to come in part 2.

cheers,

ps – a sterile probe cover was unavailable immediately in the ER. By the time it showed up the pigtail was in. We didn’t feel we could wait. We doused it in alcohol.

Philippe

 

To POCUS or not to POCUS… No, that is NOT the question! #FOAMed, #FOAMus, #FOAMer

So a few weeks ago I got into some twitter debates after I – not uncharacteristically – stated that, in my opinion, practicing acute care today without using/learning POCUS  is unethical. Now I was hasty, and, in my wording did not exclude those docs who simply do not have access to the technology, and I apologize for that. For the rest, however, I totally stand by my words.

So there was a bunch of smart people who exhibited the monosynaptic reflex of asking for the evidence, the studies, or else brandishing some that showed that some aspect or other of POCUS is flawed, or some anecdote about misdiagnoses, bla, bla, bla…

Now this time, I’m going to start the discussion with the bottom line, in a sense, and leave the nitty gritty for later (which is actually the most important part, tho). But here it is:

Unless you think that the addition of ultrasonography cannot perform more accurate and rapid diagnoses than you can with your inspection/palpation/percussion/auscultation, you cannot rule against POCUS. 

Now if you actually believe that, the corollary would be to never ask for an echocardiogram, abdo-pelvic ultrasound, etc… Not too many takers. Thats what I thought.

What you can challenge, however, is the process of POCUS, meaning how do you get Dr. John Doe competent enough to make a call of pathology X (for the diagnostic aspect) and how do we clinically integrate and act on the POCUS findings, many of them being “new” from increased sensitivity, what do they mean, what does their evolution mean? Many good questions there.

That’s why I lament the entire debate around POCUS. These smart people should focus their neurons on helping us fine-tune POCUS instead.  POCUS is a huge, exploding field. I’m pretty POCUS-comfortable, but don’t ask me to start looking at bones and tendons and ligaments and a myriad of other applications. There’s not much in the body we can’t get some ultrasound into, so all those represent areas of additional information to be assessed.

The education process is also clearly in need. I’m on a panel of the Quebec College of Physicians whose mission is to put some parameters around POCUS. There’s no holding it back, it’s just about getting it going in the right direction.

It’s like anything else in medicine. We have no perfect tools, because we are working with a hypercomplex system with many variables.

And speed. Anyone interested can scan thru the POCUS cases on my blog, and what you see every time is the speed and accuracy that POCUS brings. Studies are hard, and complex. POCUS is not a single intervention, so measuring impact is difficult. Let’s say we have a septic patient with an obstructed kidney. POCUS will assess the hemodynamics, guide fluid resuscitation and inotrope use, but also find the probable source quickly, then perhaps make sure there is no gastric distension prior to intubation, confirm ETT and CVC placement, and more as the evolution goes. How do you make an RCT around that?  It is, however, a good idea to validate every aspect (which has essentially been done already, but certainly there is more to do).

Sadly, most of the naysayers, in my experience, are not echo-competent and likely don’t want to feel like med students all over again, learning a complex skill from scratch, and instead are crossing their fingers hoping that somehow, ultrasonography will be discredited… Yup, it’s not just a river in Egypt.

POCUS is a work in progress. It won’t go away. Hop on and give us a hand. Your patients will benefit.

 

cheers!

Philippe

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

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

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

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

Bottom Line:

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

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

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

Love to hear anyone’s thoughts!

 

Cheers

Philippe

Bedside Ultrasound Quiz Part 1: a 50 yr old man with dyspnea, acidosis, hepatitis and leg edema. #FOAMed, #FOAMer, #FOAMus

So last night, an interesting call from the ED about a 50 year old man who presented with a 3 week history of increasing dyspnea, leg edema, temp of 39,  a lactate of 3.9, an INR of 1.7, elevated LFTs and a WBC of 18, but a BP of 130/75.

Fortunately, I was dealing with a saavy ER doc with some POCUS capabilities, so he also told me he saw a pretty big IVC and he was a bit leery about giving fluids, though this looked like pretty severe sepsis with 3 or 4 affected organ systems…

So I asked him to hold fluids until I got there. Here is what POCUS found:

He revealed a past history of untreated hypertention, and a flu-like illness 3-4weeks ago.

What’s the diagnosis (-es) and management?

Answers & Clinical evolution in part 2 tomorrow!

 

cheers

 

Philippe

 

 

 

 

 

 

 

 

Bedside Ultrasound Clip Quiz! A 72 year old man with fever, weight loss and tachycardia. #FOAMed, #FOAMcc, #FOAMer

So a 72 year old man is brought to the ER after collapsing at home. His family had noted weight loss in the last months, and recently some fever and general weakness.  His HR is 108, T 38.8, BP 80/40, GCS 14 – somnolent – he is in lactic acidosis (4.5) and renal failure (cr 180 – baseline 120), with some vague abdominal pain, a clear chest and warm extremities.

POCUS shows a normal IVC, normal RV/LV, A profile lungs, no ascites, and this on the left flank:

 

What is the main diagnosis?

Scroll below for the answer:

 

 

 

 

 

 

 

 

 

So the clip shows fairly severe hydronephrosis, the “bear paw” with very dilated calyces.  The patient was suffering from obstructed pyelonephritis due to massive retroperitoneal adenopathy later found to be lymphoma.  A couple of hours later he got a nephrostomy tube to take care of the septic source (double J could not pass) and his sepsis resolved within a few days, and he headed off to chemo for the NHL.

The advantage of POCUS here is. once again, the speed of diagnosis. He went straight from CT to the readied urologists and source control happened within a couple of hours. His relatively benign abdomen may not have prompted a rapid CT otherwise.

See here for more POCUS!

cheers!

 

 

Philippe