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!

and for those interested, there will be a workshop on this at H&R 2018:

more to come on this soon…

cheers

 

Philippe

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

 

It’s almost here…SIG.ECG – the next generation of ECG monitors!

So our ECG pad is ready.

I’ll let the images speak for themselves.

I’ll let your imaginations tell you where it would be most useful.

But think, no leads getting in the way or falling off. Think of the time saved in echo labs and clinics.

What does it give you?

  • leads for a monitored bed (ED, ICU, CCU, stepdown, etc).
  • a continuous 9-lead ECG. Sure, “it’s not a 12 lead,” but it doesn’t stop you from ordering one. And from my understanding of ECGs (let’s check with Steve Smith maybe?), I think that if you are isoelectric (ST-wise) in 9 leads, the chances of missing a STEMI are…somewhere between slim and none.
  • no problem with a gown, extra adipose tissue or sweat – those help if anything.
  • yes, the patient can be on his or her side, no problem.
  • infection control? they’re gonna love it.
  • eco-conscious – just wipe and reuse!

Data?

Yes. For those who don’t realize that an electrical signal is an electrical signal and that the challenge is to obtain it, two studies are underway to compare it to the current gold standard traditional ECG.

Bottom line?

First deliveries anticipated mid-2018.

We’re looking at about $5K apiece. Final price TBA and will vary with bulk orders. Expected to last years – so actually cheaper than all the leads we throw away.

The first run will be limited.

When it’s officially available for pre-order, how many do you think you would want? 😉

cheers!

 

Philippe

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

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

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

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

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

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

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

 

Clinical Case: HPVG and PE!

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

As always, I start with the IVC:

Big & fixed.

Hepatic veins:

Biphasic flow.

Femoral veins:

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

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

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

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

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

 

Pathophysiological musings:

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

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

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

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

 

Clinical course:

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

 

Take Home Message:

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

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

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

Love to hear of your experience with this.

cheers!

 

Philippe

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

 

HPVG Review article 2009:

wjg-15-3585

 

Wicked Clinical Case: POCUS & Prone save the day! #FOAMed, #FOAMcc, #FOAMer

So I get a call from a colleague in the ED at about 2am, telling me about a 39 yr old woman post-arrest. So I start putting on my boots and warming up the car (it’s January in Montreal folks).  Apparently she had presented earlier in severe acidosis, the diagnosis is unclear, but she apparently got 2 units for an Hb of 49, then went into respiratory failure and got intubated. She arrested about 30 minutes later, cause unknown.

I tell the ICU to prepare a bed but I want to see her in the ED first. Twenty minutes later I put probe to patient and see a full IVC with spontaneous echo contrast. On that I tell the nurse to hold the fluids – there was a bag and tubing and a pump with 100ml/hr on it – and turn into a subxiphoid view to see a normal RV and a hypokinetic LV with some WMAs. She has marked consolidations  in both posterior lung fields and B lines laterally, with small effusions and dynamic air bronchograms (indicating patent airways). At this point she has a HR of about 120, but there is neither perceptible BP (by NIBP) nor saturation. She’s on levophed at 20mcg. She’s about an hour post arrest which was witnessed and brief (<10min to ROSC).

The theories about the arrest are possible hyperkalemia: she was intubated with succinylcholine before the K of 6.1 was back from the lab, and her pre-intubation pH was 7.0, and post-intubation she was only ventilated at 400 x 18, possibly precipitating a drop in pH and a rise in K. Her EKG had some nonspecific signs at this point, but also a poor anterior R wave.

So we head to the ICU, as instrumentation was needed. Cerebral saturation (SctO2) is 42% and ETCO2 is 20mmhg, which reassures me that the BP is probably in the measurable range (normal SctO2 is >60% and varies, but 47% is certainly viable)…  A jugular CVC with continuous ScVo2 and a femoral arterial line goes in:

screen-shot-2017-01-05-at-10-44-50-pm

So with a BP of 59/44 (ignore the 100/46, not sure whose arm that was on!) I start epinephrine, as the POCUS is similar, as I want some added beta-agonism. ScVO2 matches SctO2 in the 40’s. We get the BP up the the 90-1oo range, the ETCO2 goes to 30, the SctO2 and ScVo2 go up into the high 40’s, which is very reassuring, because with this I know that my epi drip is improving perfusion and NOT over-vasoconstricting. Without looking at a real-time tissue perfusion index of some sort or other, it is nearly impossible to know rapidly whether your therapy is helping or harming (will discuss tissue saturation & resuscitation monitoring in more detail in another post sometime soon).

screen-shot-2017-01-05-at-10-46-31-pm

So now the sat finally starts to record in the low 60’s. We have a PEEP of 5, so start bringing it up. We hit 16 before the BP starts to drop, and that only gets us to the mid 70’s sat%. She actually squeezes my hand to command.

screen-shot-2017-01-05-at-10-45-21-pm

At this point I take a few seconds to recap in my mind. I’d spoken to the husband briefly and she had had recurrent episodes of feeling unwell with headache, nausea and diaphoresis, and that had been out for dinner earlier and she felt fine until later in the evening when this came on and eventually brought her to hospital. There was also a notion of hypertension at an ER visit a couple of weeks ago. Her history was otherwise not significant. Nonsmoker.

Pheo? Maybe, but shock?  I repeat the EKG, and now, in I and AVL, there is perhaps a 1mm ST elevation. She’s 39 and essentially dying. Lactate comes back >15, pH 6.9.  I give her a few more amps of NaHCO3. You can see the BP respond to each amp. I decide we need to go to the cath lab and get the cardiologist on call to get on the horn with the interventional team at a nearby hospital with a cath lab and ECMO, which is what I think she needs. Hb comes back at 116, making that initial 49 that prompted 2 PRBCs probably a technical or lab error…very unfortunate. There are no visible signs of significant bleeding.

But back to the patient, because this isn’t really a transferrable case.

Recap: a 39yr old woman in cardiogenic shock AND in severe congestive heart failure exacerbated by fluids and packed red cells, with a PO2 in the 40’s and sat in the 70’s.

So I decide to prone her.

screen-shot-2017-01-05-at-10-47-44-pm

Along with draining tamponades, this had to be one of the most rapid and rewarding maneuvers I’ve done. There was a scry drop of sat to the 40’s for a few seconds (may have been a technical thing), but then within a few minutes: BP to the 130’s, SctO2 to 59% and sat 100%!

screen-shot-2017-01-05-at-10-46-46-pmscreen-shot-2017-01-05-at-10-47-31-pm

screen-shot-2017-01-06-at-12-08-05-am

 

We dropped the vasopressors, the FiO2, and all breathed a collective sigh of relief. Now for the novices out there, prone ventilation improves VQ mismatch by moving perfusion from diseased, posterior lung fields to now-dependant, relatively healthy, anterior lung fields.

So transfer at this point was in the works. I planned to leave her prone until the last minute. The miraculous effect started to slowly wane within about 30 minutes, with sat and BP creeping down. At the time of transfer, we were back up to 80% FiO2.

So why is this?  Simple enough, this being simple pulmonary edema – rather than consolidated pneumonia – it migrated to dependent areas  relatively quickly. This was confirmed by a quick POCUS check:screen-shot-2017-01-05-at-10-48-06-pmscreen-shot-2017-01-05-at-10-48-26-pm

So in the still shots, you see a pristine “A” profile (normal, no edema) from the patient’s back, and a severe consolidation or “C” profile with ultrasound bronchograms in the antero-lateral (now dependant) chest. Impressive. (for those wanting some POCUS pearls see other posts and here). This is the reverse of her initial POCUS exam.

So we flipped her back and transported her – lights & sirens – the the cath lab, where they were waiting with ECMO cannulae. As an aside, it was quite refreshing to speak to the ICU fellow who spoke POCUS as well as french and english – it’s not usually the case, but I’m glad to see the change. I do believe it to be a direct effect of the influence of my friend and mentor, Dr. Andre Denault, one of the POCUS deities.

So she turned out to have a normal cath and a large adrenal mass. She did well on ECMO, being weaned off it today, and is now alpha-blocked and waiting for surgery, neurologically intact for all intents and purposes. A big thanks to the interventionists and the ICU team at the Montreal Heart Institute. Puts a smile on my face.

 

Take Home Points:

  1. don’t resuscitate without POCUS. I wouldn’t want anyone guessing with my life on the line, would you?
  2. keep pheo in mind as a cause of “acute MI” and shock
  3. if you’re not using some form of realtime monitor of perfusion (continuous CO, SctO2, ETCO2, ScvO2) then all you’ve got is looking at the skin and mentation, so you are essentially flying blind. Lactate and urine output are not realtime in real life.
  4. get ECMO in the house, it’ll come in handy. I’m working on it.

 

Love to hear some comments!

cheers

 

Philippe

 

ps I’ll try to add more ultrasound clips from this case in the next few days.

N=1 Principle in ARDS and esophageal pressure directed mechanical ventilation. #FOAMed, #FOAMcc

So i recently came across a review on esophageal pressure-guided ventilation in ARDS, which is in fact a technology I’ve had in my shop since 2008, but rarely use.

The truth is that I haven’t seen much “ARDS” in the last years, and I believe quite strongly that this reflects simply our hospital’s increased awareness of the nocive effects of over-zealous fluid resuscitation. Although in the ICU we still admit patients who, in our opinion, have received a bit more fluid than they should have, we have become more aggressive with diuresis “despite” the presence of shock, and usually see “ARDS” resolve. This is a direct consequence of actually “looking” at our patients’ volume status using ultrasound (for more see, well…most other posts on this blog!).

However, what seems like genuine ARDS does come around once in a while, and we recently had severe respiratory failure develop in a morbidly obese patient, and all of a sudden, in the presence of an FiO2 of 100%, a PEEP of 14, intra-abdominal pressures between 20 and 25, and on Flo-Lan, it seemed it might be a good idea to tailor ventilation.

Current Practice:

The most common practice currently is the ARDSnet type low volume (5-7ml/kg) lung protective ventilation, using a PEEP/FiO2 scale and aiming for plateau pressures (Pplat) below 30. Generally speaking a good idea, but one has to understand that this is, once again, a one-size-fits-all (except for the per kg) approach, which isn’t ideal if you try to follow  the N=1 Principle.

Why is this?  Because, due to physical characteristics (obesity, chest wall stiffness, etc,) and pathology (increased abdominal pressure, etc), the airway pressure reflects the respiratory system pressure (Prs) rather than the transpulmonary pressure (Ptp), which is the variable most related to volutrauma (which has eclipsed barotrauma as the mechanism for most ventilator-induced lung injury (VILI).  Ptp essentially relates to overdistension, which is what results in pneumothoraces. In terms of parenchymal micro-injury, it seems to be most related to atelectrauma, in essence the opening and closing of alveoli, with the resultant shear forces disrupting surfactant and cell surface. This type of injury relates best to finding optimal PEEP to both recruit and prevent de recruitment – in effect minimizing the amount of lung tissue collapsing and reopening.

 

Esophageal pressure (Pes)-guided Practice:

So Pes is used as a measure of pleural pleural pressure, and:

Ptp = Paw – Pes

That equation is the central tenet to this, and basically, you have to reset your goals to:

a. Ptp (exp) around zero – optimal PEEP – (meaning no over distension and no de-recruitment)

b. Ptp (insp) below 25 – though this is not really individualized as a hard data point, but has been shown to be a reasonable cutoff for volutrauma.

 

How do you do this?

By slipping in a special oro/naso-gastric tube with a balloon connected to the ventilator, one is able to simultaneously measure airway pressure (as is standardly done) and esophageal pressure. This is what it looks like:

img_6207

Here we can see that this patient has a PEEP of 20 (top), a Pes of about the same, and thus a Ptp (bottom) near zero.

We’ll discuss this case hopefully tomorrow, but just to show the mechanics/technique of it.

 

Bottom Line:

So this involves tossing out the ARDSnet charts and trying to individualize and optimize Ptp (insp and exp) instead of plateau pressures and PEEP.  How may it be useful clinically? Well, you may be able to detect unsuspected states of de-recruitment/ateletasis due to excessive chest wall or abdominal pressure, and allow you to increase PEEP “safely.”

When should I use this?

I’m not sure what everyone else is doing, but we are in the process of setting up a protocol where esophageal balloons will be inserted for any patient whose ventilator settings are approaching or exceeding FiO2 70%/PEEP 15, indicative of sufficiently severe respiratory failure warranting this additional level of fine-tuning.

I tend to use it when ventilating two groups: those with (a) elevated intraabdominal pressure, and (b) the obese patients, as they often have elevated Pes (usually due to diaphragmatic displacement. Interestingly, the correlation between obesity and Pes is not very good, so one should not “blindly” feel they can crank up the PEEP to 25 and ignore plateau pressures, as some obese patients have normal Pes (likely due to compliant abdominal walls.

Would love to hear what others do.

 

Here are the relevant articles/references:

talmor-nejm-2008

ajrccm-2014-review

 

Cheers!

 

Philippe

 

POCUS Course: Quebec city 2017!

Here’s a chance to learn with one of the masters in the field, my friend Andre Denault, internist-anaesthetist-intensivist extraordinaire, and a true mentor to me.

Designed for acute care docs, this is an approach to respiratory failure, shock and renal failure. I recommend it to anyone in the field!

 

screen-shot-2016-12-15-at-8-01-04-pm

 

I’ll likely be an instructor there is I can free up my schedule, so see you there!

 

cheers

 

Philippe