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:

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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).

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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.

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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.

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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%!

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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.

Transpulmonary Pressure (Ptp)-Guided Ventilation: A Case. #FOAMed, #FOAMcc

So in my last post I quickly reviewed the basics of Ptp-guided ventilation. So here is a case. We had a woman in her 60’s admitted with bilateral pneumonia, intubated and ventilated. She is morbidly obese and diabetic. Despite antibiotics and usual care, she was getting progressively worse, and was labelled “ARDS.”  POCUS showed she was not in terrible venous congestion, and she had been digressed to a relatively normal IVC. Slowly her ventilator settings crept up to a PEEP of 14 and FiO2 of 100%. As the plateau pressures were approaching 35, we were getting a little antsy, so decided to put in the esophageal balloon and get a better grip as to what was going on.

Here are her original readings:

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So here we can see that her Pes in expiration is around 23. With a PEEP at 15, that gives us a Pep (exp) of -8. That likely represents a fair bit of atelectasis/derecruitment. Here are some measurements:

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Her dynamic compliance is 21, and static 24. Not too great. Her PV loops are interesting, certainly not showing any over distension (the penguin beak look), and, as Jon Emile Kenny (@heart_lung) cleverly explains about the Pop tracing:

“On this patient, the stress index appears to be low, which is somewhat consistent with your Ptp tracing. there is a terminal fall in the Ptp [wave looks like an upside down U] which suggests terminal airway recruitment; that is, during the terminal portion of the breath, the Ptp is falling with equivalent volume delivered [again only works with square-wave/constant flow]. in other words, if [at the end of the breath] less Ptp is needed to accommodate equivalent flow/volume, there is terminal increase in compliance/decrease in elastance – or lung units are recruitedSo these numbers suggest that there is extrinsic compression of the lung, due to chest wall weight and abdominal pressure. This makes the airway pressure (Paw) not representative of alveolar stretch, and hence not a good guide of ventilation. The PEEP, despite being fairly high, is below the level needed to prevent atelectasis.”

Indeed Jon, that appears to be the case.

So we started to raise the PEEP, trying to get the Ptp (exp) closer to zero:

 

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So we can see that our Ptp (exp) is approaching zero, and the PV loops suggest there is still no over distension. In fact, the compliance, as Jon had predicted, improves slightly. The plateau pressures are up into the mid 40’s which, without a balloon, would be pretty concerning. But the Ptp (insp) is less worrisome, in the mid 20’s, about at the limit we’d like.

At this point, still seeing that increasing compliance, we continue raising the PEEP to 23, and actually see the plateau pressures start to drop, consistent with having recruited lung. Now the Ptp (insp) is 23, and the compliances have increased.

 

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We thus leave things as is, and by the next morning, we are down to 30% FiO2. Here are the before and after CXRs:

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So a fair bit of her “ARDS” was actually atelectasis related to obesity and increased intra-abdominal pressure, and that what seems like exceedingly high PEEP is actually just enough to prevent atelectasis.

 

Love to hear from others who use the technology, or just interested!

cheers

 

Philippe

 

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:

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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!

 

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

 

cheers

 

Philippe

Bedside ultrasound case: Fibroids, Syncope and Dyspnea. #FOAMed, #FOAMus, #FOAMcc

So today, a 33F presented following syncope. She was mildly tachypneic wiyh a HR of 135 and BP of 130/80. I’m inserting the clip of my bedside ultrasound evaluation, as this takes place essentially simultaneously with my history-taking:

So this clip runs thru a few views, starting with an IVC long axis, showing a relatively plethoric IVC with minimal variation. This is not normal. Tells me to expect something abnormal downstream, unless someone has flooded the patient with IV fluids. The next view is the parasternal long, then short axis, showing an increased RV to LV ratio, and a small, hypercontractile LV, with septal flattening consistent with RV pressure overload, the “D” sign.  The apical 4 chamber follows with little else to add (difficult to measure TAPSE well in that segment).

So this is sure looking like pulmonary embolism, and I’m already toying with a half dose TPA, MOPETT-style, until the reveals that the cause of her starting oral contraceptives two months ago was to control heavy menses associated with large uterine fibroids… So I figure I’ll buy myself some decision time anyhow by ordering the CT angio – unless in pre-arrest, I don’t thrombolyse without formal confirmation – but I did start IV heparin on the echo findings. Here is the CT:

So this indeed confirms submissive embolism, particularly to the left PA.

Next?  I work in a community hospital, and although I’m totally comfortable thrombolysing PE, in this case, I was concerned about bleeding related to the fibroids, and I haven’t yet figured out a way to embolize bleeding vessels at the bedside, so I felt that the safest thing was to transfer her to a tertiary care center with a solid interventional radiology program. So off she went. I’ll update if anything funky was done like a catheter suction and I can get some clips.

So in terms of POCUS, I think this illustrates how speedily a diagnosis can be made, and although in this case the pre-test probability and index of suspicion was pretty high, it isn’t always!

cheers!

 

Philippe

 

For more POCUS tips, see here!

POCUS in cardiac arrest: Great, but avoid Pitfalls! #FOAMed, #FOAMus

So just wanted to briefly review POCUS technique during arrest. What I like to do is to position my probe for a subxiphoid view while CPR is ongoing, and try to see what I can. It may look like this:

 

The best is to record a loop and review it immediately, in order to be able to focus properly on each important area and let CPR continue. For instance, in the clip above, there is a lot of information. There is a pericardial effusion, but clearly visible cardiac chambers make tamponade as the sole reason of the arrest unlikely (atrial pressures > pericardial pressure). The RV is not huge and crushing the LV, so massive PE – although not ruled out – probably isn’t the cause of arrest. 

Be wary, however, of making calls based on RV appearance or RV to LV ratios as representing PE in a nonbeating heart, as this is not necessarily representative of the state of the RV or RV/LV ratio immediately pre-arrest.

More Posts to come on the topic of peri-arrest POCUS…

Cheers,

For more POCUS tips, see here!

Philippe

CCUS Institute Mini-Fellowships: A Highlight and CME Update!

First of all, I just wanted to share some feedback I just received today, which to me exemplifies the impact that exposure can have. It’s now been about fifteen years since I independently picked up a probe (the cardiology department was decimated in my shop when I started there, and there was an unused full-sized echo machine that no one noticed or cared if I took), and maybe twelve years since the development of the first POCUS courses (shout out to my friend Dr. Yannick Beaulieu, intensivist-sonographer-inventer extraordinaire who started the first FOCUS course – now run by CAE), and although the FOAMed world is full of POCUS, the real world is still lagging behind.  But I think that’s about to change, and we should see the second generation of clinician-sonographers getting into the trenches soon. I’d call it a very slow explosion. But I have a feeling there is a lot brewing under the surface…

So, back to the feedback. A young internist, Dr. Alexandre Lafleur, joined me for a 2 or 3 day Mini-Fellowship in the ICU at Scarborough General Hospital a few years ago, and I remember he had quite a few “lightbulb” moments, where he clearly saw the immense clinical application of POCUS.  I just recently asked him for some feedback which he was kind enough to give me:

« I have had the chance to participate in a shadowing experience with Dr Rola at the Scarborough General Hospital ICU during two days in 2013. As a general internist and assistant program director, this experience really opened my eyes regarding the use of bedside ultrasound in general internal medicine and for IM residents. I think I would have benefited more of this experience if I had done more training previously, and I encourage future participants to do so. However, I came back from this experience with a very clear idea of the benefit of CUSE for my patients and for our residency training program. I really saw how ultrasound was used ‘in action’, in a much more realistic way than what is usually shown in CPD meetings. I also saw its limitations and the skills I needed to develop to generate good images (not something you can learn over the weekend!). Since then, I participated in formal trainings and licensing activities (more than 250 supervised US on acute care patients) and now practice bedside ultrasound autonomously. We now offer a bedside ultrasound training for our residents with the help of the emergency medicine department and an ultrasound-guided procedural simulation lab. Nothing in CPD has improved my practice and benefited the health of my patients as much as bedside ultrasound training. »

Alexandre Lafleur, MD, MSc (Ed.), FRCPC
Spécialiste en médecine interne
CHU de Québec – CHUL
alexandre.lafleur.1@ulaval.ca

Wow. So I can’t see a better scenario. From someone who had minimal ultrasound ability in 2013, to now an educator and policy decision-maker in the field. Absolutely fantastic. I am honoured to have triggered this domino effect. I am certain he has now countless tales of how POCUS saved the day.

 

CME now available!

So, great news, finally went thru the CME process and lo and behold, the Mini-Fellowships qualify for 25 Section 2 credits (regardless of the length) and 3 hours of Section 3 credits (per day of fellowship). For you americans:

Through an agreement between the Royal College of Physicians and Surgeons of Canada and the American Medical Association, physicians may convert Royal College MOC credits to AMA PRA Category 1 Credits™. 

See here for more info about the Mini-Fellowships.