fluid resuscitation

June 2, 2014

Bedside Ultrasound Clip Quiz: Abdominal pain and fever! #FOAMed, #FOAMcc, #FOAMus

Saw this poor fellow recently who presented to the ED with fever and abdominal pain. 73 years young. He came to my attention because of borderline BP (95 systolic) and a lactate of 4.5 mmol.

Here is a transverse scan at his lower right costal margin:

 

What do you think?

Turns out he had been having pain for about two weeks, and it had intensified about two days ago. His wife dragged him in.

What would you do?

 

 

 

 

 

 

 

 

 

 

 

This is septated fluid collection around the liver.  With the fever and history, sounds pretty suspicious for a septic source. After carefully scanning in all angles and watching for a while to make sure this wasn’t a strangely placed loop of bowel, a 22g needle aspiration showed cloudy bilious fluid and a trip to the OR a couple of hours later revealed a perforated duodenal ulcer.

He made it ok.

 

cheers

 

Philippe

May 29, 2014

(some) CCUS 2014 Lectures available!!! #FOAMed, #FOAMcc, #FOAMus

Slowly but surely getting everything up, all free in the spirit of #FOAMed:

Massimiliano Meineiri on The Patient with Chest Pain

Vicki Noble (@nobleultrasound) on Ultrasound and SBO

Mike Stone (@bedsidesono) and Catherine Nix (@Nixlimerick) on Ultrasound, Broken Bones and Blocks

Haney Mallemat (@criticalcarenow) on Ultrasound and the Patient with Abdominal Pain

JF Lanctot and Max Valois (@EGLS_JFandMax) on Ultrasound in Shock

Andre Denault on Multimodality Assessment of Hemodynamics

 

find these at: http://ccusinstitute.org/e-Store.asp?method=evideos

…more to come!

 

 

 

April 1, 2014

The IVC Assessment by bedside ultrasound: Let’s apply some common sense! #FOAMed, #FOAMcc

So I have a huge issue the IVC and its ultrasound assessment. For the most part, neither the yay-sayers or the nay-sayers are applying much sound physical principles, as far as I’m concerned.

To assess a patient’s volume status, it may be practical to begin with the sub-xiphoid view of the IVC, since the decision to give fluids or not – especially in emergency situations – can then be taken within the first few seconds of examining the patient. The physiological rationale behind assessing the IVC as a marker for volume responsiveness is simple and solid. As the venous compartment fills, the size of the IVC will gradually increase until it reaches a maximal size of about 20-25mm or even 30mm, depending on physical size and chronicity.

Concomitantly, the phasic respiratory variation will decrease as the venous pressure increases and the effect of varying intrathoracic pressure is no longer felt. At this point, the flat part of the Starling curve of the right ventricle is approaching, and there is little response to volume, and little physiological rationale to support giving more.

Currently, many use a variation of about 20% or more to suggest a volume responsive state in ventilated patients or an inspiratory collapse “sniff test” of 50% or more in spontaneously breathing patients.

There remains controversy around using IVC assessment for volume responsiveness, and with good reason! There are a few important reasons why:

a. technique – First of all, there is the manner in which IVC measurement has been taught: the M-mode measurement of the antero-posterior (AP) diameter during breathing (usually of ventilated patients) about 3 cm below the diaphragm. Although highly practical and reproducible, it has many shortcomings. If we look at the physiology, what changes with cycles of respiration is the volume of blood entering the chest/right atrium. Hence the key variable we are trying to assess is the transient variation in IVC size – which is a volume, not a linear dimension (I’m getting painful flashbacks of using pressure  to determine volume!)Hence the use of a single linear measure on one point along the length of the IVC to assess this is inherently flawed. For instance, the figure to the left shows how, if this IVC were to be measured in its AP diameter, the variability may not be that great. In the short axis, however, one can clearly see the significant change in surface area, and hence volume between phases of mechanical ventilation. Also, the IVC is rarely perfectly circular, but often ovoid, and occasionally with the greatest diameter in an anteroposterior axis, making that single AP measurement even less relevant.

b. intrathoracic pressure – Secondly, the variation in intrathoracic or intrapleural pressure (Pip) must be measured, as, for instance, a young and fit patient can generate large changes, which would result in more significant IVC variation, as compared to a frail elderly patient, even if they are on the same point of their Starling curve, invalidating the IVC measurement. All “sniffs” are not created equal.

c. intra-abdominal pressure – Finally, the intra-abdominal pressure (IAP) must also be assessed, since an elevated pressure would decrease the size of the IVC and make that measure no less accurate, but less relevant in terms of representing venous filling.

So what should we do?

Instead, a more global assessment of the IVC volume, measuring short axis area measurements and variation at several points along the IVC would give a much more accurate estimate of IVC volume variation. This is currently being studied by our group.

“Eyeballing the IVC” Attempting to link evidence and physiology, some bedside sonographers’ approach is to take a global look at the IVC in both long and short axis during respiration, while clinically assessing the respiratory effort and the abdominal pressure. This approach is analogous to the “eyeballing” of LV function – versus more formal measurements such as Simpson’s disk method, etc – which has been proven just as accurate with sufficient clinical experience.

The figure below shows an IVC that is about 10-12mm along most of its intrahepatic segment on expiration, and collapses almost completely on inspiration. If this belongs to a patient breathing with little effort and with a soft abdomen to palpation, it is physiologically quite clear that this patient would be fluid responsive. It also shows how impressive the collapse is in the short axis.

IVC insp dual

For instance, let’s say Patient A is in respiratory distress and using accessory muscles and presents to the ER with a respiratory rate of 35 and a systolic BP of 80. His IVC measures approximately 21 mm in diameter at several points along its axis, and has a brief collapse to about 10 mm with strong inspiratory efforts. His abdomen is soft during inspiration but firm during a prolonged expiratory phase.

Patient B is brought to the ER somnolent with a respiratory rate of 10 and a systolic BP of 80. His IVC measures 15 mm with minimal respiratory variation. His respirations are shallow and his abdomen soft. These two patients show how the IVC assessment needs to be taken in clinical context.

Patient A has some 50% inspiratory collapse of a large IVC in the context of large variations in Pip, whereas Patient B has little variation of a mid-sized IVC in the context of very small variations in Pip. In all likelihood, Patient A is not very volume responsive, while Patient B probably is.

Volume Responsiveness vs. Volume Tolerance – it is critically important to distinguish the difference between these two concepts as they are often misused interchangeably: Volume responsiveness refers to an increase in cardiac output (CO) to a fluid challenge. This is a purely hemodynamic concept. Volume Tolerance refers to whether or not a patient can tolerate volume without clinically significant side effects. This is a complex clinical assessment that should include: -the patient’s plasma oncotic pressure (serum albumin) and level of capillary leak, if present, -the patient’s pathology – is there risk of capillary leak in critical tissues such as lung, brain, abdomen? -the type of fluid being considered (isotonic crystalloid vs hypertonics or colloids/blood products). It is important to distinguish that not all patients who are volume responsive are necessarily volume tolerant.

Volume assessment summary – this issue remains a difficult one, even with the use of bedside ultrasound, because the optimal point for any one patient to be on his or her Starling curve at any one time in different clinical conditions remains elusive. Despite considerable study and several proposed management algorithms, there is no means by which to determine exactly how much of any given fluid is enough, without being too much.

In my opinion… – no direct evidence – keeping an IVC below 20mm and probably below 15mm with significant respiratory variation, if hemodynamics allow, is probably ideal. However, bedside ultrasound allows to clearly identify the cases where fluid is clearly needed and those where fluid is unlikely to benefit. Both of these scenarios are easily and routinely missed by traditional examination. Additionally, when the IVC assessment is done in conjunction with lung ultrasound, it becomes possible to detect early development of pulmonary edema and halt aggressive fluid resuscitation (FALLS Protocol, Daniel Lichtenstein).

 

Technical Pearl: the part of the IVC we generally assess being the intrahepatic segment, it is possible to find it almost by scanning through any part of the liver, which happens to provide a great acoustic window. This may be particularly useful when the epigastric area is difficult to access (incision/bandage, drains, in the OR, etc…) or when there is bowel gas in the epigastrium. The figures below show the same IVC, first in a “traditional” epigastric view, then in a view approximately along the plane of the red arrow on the CT scan.

2 views IVC std:liver

CT liver IVC views

 

Bottom line?

When assessing volume status, it is absolutely essential to keep the clinical question in mind. It is a great minority of patients who are volume responsive who actually need volume. Normal, healthy humans are very much fluid responsive and fluid tolerant but certainly not in need of any. Much of the current studies and literature focus on assessing volume responsiveness in the setting of shock, which, although arguably the most important, is not the only type of information that can be obtained from the IVC. For instance, as will be discussed in the chapter on congestive heart failure, knowing that your patient is very “full” should prompt further diuresis. If you are dealing with managing severe anasarca, knowing that a patient’s intravascular volume is low may prompt the use of albumin or hypertonics prior to further diuresis to help resorb some of the interstitial fluid. Another critical question to which there is currently no answer is just how much fluid to give to patients in shock. There are many opinions but no certainty. It is common practice to fill a patient in shock until they are no longer fluid responsive, in an effort to avoid or minimize the use or dose of vasopressor medications. There is no study to date that compares a “moderate fluid/early vasopressors” vs “aggressive fluid/avoid-vasopressors-if-possible” approach.

Hopefully this will be answered soon. In light of the clear evidence linking positive fluid balance and mortality, it would seem wise to fill to a “moderate fullness” where some respiratory variation remains, rather than to the point of no longer being fluid responsive. After all, physiologically, the only time humans are really full (>20mm IVC with little or no variation) is in pathological states of congestive heart failure or obstructive shock. So again, when assessing an IVC, keep in mind what your clinical question is and interpret the sonographic data accordingly.

 

cheers!

 

Comments:

Marco says:

Thanks Philippe, very interesting post.
Using your great categorization, I think that the worst scenario is represented by a patient who is volume responsive but poorly volume tolerant. In that case, it is important to have clear in mind which is our target: cerebral perfusion, oxygenation and lung extravascular fluid, ventilatory weaning, renal function, avoiding vasopressors or mechanical ventilation, etc…
Very often, maintaining a brain dead heart beating donor, every organ would require a different volemic status, and if all of them are suitable for transplantation you have to compromise.
Just a last thought: as well as “all sniffs are not created equal”, also tidal volumes are very variable. Assessing respiratory variations during protective (low TV) ventilation requires a thoughtful interpretation of the results.

 

Absolutely. Interpretation of the findings in each individual case is key. 

Philippe

March 19, 2014

NEJM: The Septic Shock Issue…groundbreaking or same old same old? #FOAMed, #FOAMcc

Ok, so it was pretty cool to see an NEJM issue basically dedicated to septic shock management, I must admit. But let’s dig a little deeper, shall we?

So here is where they are: http://www.nejm.org, and fully available for now.

I won’t go through all the details and numbers, after all they are in the papers, so let’s just analyze them from two principles:

a. the N=1 principle – how was therapy individualized?

and

b. was there any integrated monitoring of the therapeutic goals?

…and we’ll conclude by looking at the potential practice-changing potential of each of these studies.

So first of all,

High vs Low BP Target in Septic Shock, by Asfar et al.

So basically a negative study except for two findings, the increased incidence of afib in the high target group and the decreased need for renal replacement therapy among chronic hypertensives in the high target group.

so N=1 is not really revealed:

“Refractoriness to fluid resuscitation was defined as a lack of response to the administration of 30 ml of normal saline per kilogram of body weight or of colloids or was determined according to a clinician’s assessment of inadequate hemodynamic results on the basis of values obtained during right-heart catheterization, pulse-pressure measurement, stroke-volume measurement, or echocardiography (although study investigators did not record the values for these variables).”

So lets just hope that the variability evens itself out between the groups, since we don’t really know. The numbers don’t really tell the tale, because the average fluids received (10 liters over 5 days) could mean one patient got 15 and one got 5 – although let’s trust they followed the French Fluid Resus protocol…

So the atrial fibrillation makes total sense – more B agonism should result in that, and the decreased renal failure also does.

As the authors note, the actual BP averages were higher than planned. For those of us practicing critical care, we know most nurses titrating prefer having a little bit of extra BP – even when I prescribe MAP 65, I usually see the 70 or so unless I make a point to tell them. Understandable. They also note the underpowered-ness of their own study, but I think it is still worth looking at their results.

So…bottom line?  I think it’s a great study for a couple of reasons.

The first is to remind us to pay a little more N=1 attention to the chronic hypertensives, and that it is probably worth aiming for slightly higher MAPs.

The second, debunking the myth of “levophed, leave’em dead” (which I heard throughout residency at McGill), and the concept of doing everything (ie juicing patient into a michelin man) in order to avoid the “dreaded and dangerous” vasopressors. So really I think an alternative way to conclude this study is that it isn’t harmful to have higher doses of vasopressors. I think this is actually a really good study on which to base assessment of more aggressive vasopressor support vs fluid resuscitation, in the right patients.

It would have been interesting to have echo data on those who developed a fib – were they patients who had normal to hyperdynamic LVs who in truth did not need B agonism at all and would have been fine with phenylephrine?  Perhaps…

Cool. I like it.

Next:

Albumin Replacement in Patients with Severe Sepsis or Septic Shock, by Caironi et al. The ALBIOS study (a Gattinoni crew)

So basically showed no difference, so pretty much a solid italian remake of the SAFE study in a sense, confirming that albumin is indeed safe overall, and may be better in those with shock.  As the authors note, mortality was low, organ failure was low, so study power a little low as well. Note the mean lactates in the 2’s at baseline. The albumin levels of the crytalloid only gorup were also not that low, low to mid 20’s, whereas I often see 15-20 range in my patients, especially if I inherit them after a few days, as I do use albumin myself a fair bit. They also used a target albumin level, not albumin as a resuscitation fluid purely.

In my mind the benefit of albumin would be greatest in those with significant capillary leak, particularly those with intra-abdominal and pulmonary pathology. It would have been nice to see a subgroup analysis where extravascular lung water was looked at (especially coming from a Gattinoni crew!).

Another interesting thing would have been to know the infusion time of the albumin, since animal data tells us that a 3hr infusion decreases extravasation and improves vascular filling vs shorter infusion times. I routinely insist on 3hr infusion per unit, which sometimes results in 9-12hr infusions, almost albumin drips!

Bottom line?

I like it. Reinforces that albumin is safe, so makes me even more comfortable in using it in the patients where my N=1 analysis tells me to be wary of third-spacing. Also the fact that they used 20% – in Canada we have 100cc bottles of 25% for the most part – is nice, since the SAFE data used 4%.

Next!

A Randomized Trial of Protocol-Based Care for Early Septic Shock – The ProCESS Trial.

So right off that bat my allergy to protocols flares up, so I’ll try to remain impartial. It just goes against the N=1 principle. The absolutely awesome thing about protocols is that it primes the team/system to react – so clearly protocols are better than no-protocol-at-all, but strict adherence would clearly not fit everyone, so that some built-in flexibility should be present.

This being said, the ProCESS study is really interesting, for a number of reasons. They have three groups, and compare basically (1) Rivers’ EGDT to (2) their own protocol (see the S2 appendix online) which gives a little more flexibility and (3) “usual care”.  Net result is that all are pretty equal, no change in mortality. As the authors note, their mortality was low, so again may not have been able to detect a difference.

So, what does this mean. To me it’s a little worrisome because I doubt that the “usual care” represents the true usual care found in EDs/ICUs all over the world, so I am concerned that many docs will use this as a reason to justify not changing their practice, similarly to many I’ve heard say they don’t need to cool anymore after the TTM trial. Human nature for some I guess.

Bottom line? You don’t have to follow EGDT if you’re conscientious and reassessing your patient frequently and have done all the other good things (abx, source control, etc). I think that’s really important because giving blood (see my post about S1P) to those with hb > 70 and giving dobutamine to patients with potentially normal or hyper dynamic LVs never made physiological sense to me, and the problem with a multi intervention study such as EGDT is that you can’t tease out the good from the bad or the neutral. Again, studies such as EGDT are pivotal in changing practice and raising awareness, so this is not a knock against a necessary study, just to highlight the point that each study is a step along the way of refining our resuscitation, and the important thing is to move on. In fact, the reason that this is a negative study is probably due to the improvement in “usual care” that EGDT brought along.

Conclusion: No new ground broken, but these studies do make me feel more confident and validated in continuing to not do certain things (strict EGDT) and  doing others (albumin and earlier use of vasopressors).

Kudos to all investigators.

 

let me know what you think!

 

P

 

March 7, 2014

Bedside Ultrasound and PEA: CPR or no CPR…? #FOAMed, #FOAMcc

The usefulness of bedside ultrasound in cardiac arrest is clear, giving the clinician instant information on the hemodynamic process resulting in arrest. My arrest sequence is generally done as follows:

Step 1: IVC assessment

Step 2: Subxiphoid cardiac views

Step 3: Lung views if pneumothorax suspected.

Step 4: remaining views if possible (eg abdominal views to find source of bleeding, etc…)

The important part (as per current recommendations) is to have minimal interference on chest compressions. The IVC view, albeit jumpy, can generally be obtained during CPR.  The subxiphoid view should be “prepared” during CPR, meaning that the sonographer warns the team member doing CPR not to stop compressions until he is told to do so (unless the team are already used to ultrasound in cardiac arrest), the probe positioned optimally, then instruction given to stop for five seconds while a look +/- loop is acquired. This should be enough to look for pericardial effusion, RV/LV ratio and LV contractility. In fact, experienced sonographers can usually get this while CPR is going on in many cases. Then CPR should be restarted. Hence for now, minimal interruptions in CPR (until the concept of “stutter CPR” really emerges!!!).

Here are a couple of views with active CPR:

In this case there is  a clear RV overload with a dynamic but underfilled LV.

From the information obtained in those 5 seconds, one should be able to consider the need for volume (hypovolemia), thrombolytics  (pulmonary embolism suspected) or drainage of fluid (tamponade) or air (pneumothorax). The possibility of an acute myocardial infarction must be considered as it is one of the most common causes but is difficult to confirm by ultrasound.

Pulseless Electrical Activity

This may be the most exciting area in which ultrasound will change management.  In the absence of ultrasound, all PEA is more or less alike: there is organized electrical activity, but no pulse. Physiologically however, the range of diagnoses is very wide, with on one end, a perfectly good heart that is empty (hypovolemic shock in extremis), and on the other, cardiac standstill despite electrical activity. An astute physician does not need a randomized clinical trial to know that the management and prognoses of those two extremes are very different. Without bedside ultrasound, however, these would appear identical: “PEA.”

 The heart rate cannot be relied on since it will largely depend on the phase (both would begin as tachycardic, then eventually bradycardic until asystole occurs).

Notwithstanding guidelines,  the information obtained should be considered strongly. If we start by looking at the first end of the spectrum, there would be no physiological rationale for performing chest compressions or an empty and hyperdynamic ventricle: rapid infusers and vasopressors (to recruit venous unstressed volume) should be used instead. At the other end, the heart in standstill definitely needs compressions. Of course, there is then the whole range of varying RV and LV pathologies, tamponade, etc, all of which need to be dealt with individually. It is really a huge grey zone…

CPR or no CPR?

A very important question is whether CPR should or should not be performed in certain cases of PEA.  Certainly ACLS protocol dictates so. However, ACLS has not yet truly integrated bedside ultrasound into management, only suggests in a very loose way – understandably since the protocols must be applied by all, and still only few use it regularly.

I have to credit Dr. Sue, an ER doc from Atlanta, who asked me the question about CPR in extreme hypotension, and I had to rewind in my mind the cases in which I had used physiological information to overrule the ACLS protocol in one direction or another and try to formulate an answer.

It is an excellent question and made me realize that there is no clear answer for two reasons:

One: PEA is not a diagnosis but a clinical syndrome. It relies on manual pulse check (unless the arrest occurs in a patient with an arterial line), hence the line between severe hypotension and true PEA is difficult to determine. Technically and physiologically speaking, if the LV contraction is sufficient to open the aortic valve, there is a “pulse.” Now how far along the arterial circuit this pulse travels is not known…unless it is monitored.

Two: The key question then becomes the following: at what level of endogenous blood pressure is the perfusion better than with “good” CPR?  We do not yet have that answer. The coronary perfusion pressure (diastolic pressure – wedge pressure) data often quotes a minimal range of 15-25 mmhg, which – if we arbitrarily choose a high-ish wedge – would suggest we need a diastolic pressure in the 40’s (also note that that data is imperfect). Hence the arterial line. Perhaps there could be a role for tissue saturation/near-infrared spectroscopy or other microvascular flow indices in the future…

Now what about the huge spectrum of cases in between?  Let us exclude the cases with immediately reversible causes such as tamponade and pneumothorax, where the initial management is clear, and instead focus on differing levels of RV and LV dysfunction resulting in the absence of a palpable pulse.

Predominant RV failure – although PE should be strongly suspected and thrombolysis considered, the question remains about management if you see a hyperdynamic but underfilled LV.  CPR would appear reasonable in an effort to try to get some RV to LA flow. Endotracheal milrinone, sometimes used in cardiac anasthesia, can be an option as it provides inotropy and pulmonary vasodilation.

Predominant LV or biventricular failure – if cardiac activity is present, it seems imperative to start an infusion of vasopressors, and traditionally, do CPR until there is a measurable blood pressure. I have used CPR with progressing bradycardic rhythms for a few seconds to circulate the epinephrine, with at least short-term success.

Here is a typical LV “PEA” from the subxiphoid view:

Ideally, an arterial line would be very useful in these patients, and may help to decide on an individual basis when CPR should be used. Remember that CPR on a beating heart will likely worsen cardiac output as asynchronicity and increased mean intrathoracic pressure will impair filling.

Additionally, the arterial line also allows us to notice small trends during resuscitation, such as seeing that a few seconds of CPR may help circulate a bolus of vasopressor and enable it to take effect – progressive BP increase, or that the BP may be trending downwards despite vasopressor infusion – CPR may be useful until enough vasopressor/inotropes have infused.

Bottom Line:

1. if possible, put in an arterial line

2. bedside ultrasound is mandatory if you don’t want to miss anything reversible

3. if you don’t have a palpable pulse and your diastolic pressure (arterial line) is less than 40, consider some CPR until vasopressors/inotropes have had effect.

4. if you are lucky enough to have ECMO (shout out to Joe and Zack at http://www.edecmo.org)  or other mechanical support, it would be the time to consider!

I think this is actually a really interesting area to develop, and I’d really, really like to hear what other sonographer-resuscitationists are doing, or what anyone else might think!

 

Philippe

 

Joe Bellezzo – yes, THE Joe, says:

Phil, I agree with all your points here. Great post! As you know, Shinar, Weingart and I recently published a rant on PEA (over at http://www.edecmo.org/13) and Weingart threw out two possible new monikers: PRE-M (Pulseless Rythm with Echocardiographic – Motion) and PRE-S (Pulseless Rythm with Echocardiographic – Standstill). I don’t disagree with any of those concepts but I think its simpler than that.

PRE-S (standstill) = asystole and you start compressions.
PRE-M (organized cardiac activity) = profound shock. In this setting I like the recent Littmann paper that gives a simplified approach (http://edecmo.org/wp-content/uploads/2014/08/A-Simplified-and-Structured-Teaching-Tool-for-the-Evaluation-and-Management-of-Pulseless-Electrical-Activity.pdf).

As you pointed out above, the real big question is at what point do you start compressions when you have cardiac motion? Your points above are spot on. The problem with compressions on a beating heart is that you don’t know what your end-point is. You lose the ability to do minute-minute diagnostics and doing any procedures with ongoing compressions is tough. And it seems to be a knee-jerk reaction for the RN or pharmacist to have an amp of epi ready to blast away at this point. NO!

I wait. I do stuff first. Step 1 is ECHO. If PRE-M (aka profound shock): EKG and arterial line NOW. Step 2: Stop, think and decide what you think is your top probable etiology of this profound shock and fix that. Step 3: reassess = repeat echo, EKG, and see what your art line pressures are doing. I try to do all that before I start compressions.

Example: “PEA” hits your door. Echo shows a wall motion abnormality and hypokinesis. EKG suggests ischemia but is not obvious STEMI. art line goes in simultaneously. I think this is MI. This heart does NOT NEED epi 1 mg! This is cardiogenic shock and I need to fix some stuff before I start pushing on the chest and blasting superhuman doses of epi! I usually start with a push dose epi (10-20 mics or so) while a pressor drip is prepped. Calcium bolus is given. I likely start dobutamine here (or milrenone if beta blocked). If that fixes your problem, then the pt goes to the cath lab. If it doesn’t, I cannulate and put the pt on VA-ECMO.

And what if I were wrong? what if this were a big PE? massive beta blocker OD? the protocol above is works in those cases too.

An aside, since you already placed a femoral venous line….and you popped in the Art line immediately, you have nice conduits to upsize to ECMO cannulas.

Great post Phil!

 

Thanks for sharing your approach!  As you know and clearly show, a sensical physiological approach is absolutely needed in a day and age when we can (bedside ultrasound) see what’s really going on, and we can (ECMO) give these patients a fighting chance!  See you at BMBTL in a couple of weeks!

Philippe

 

PS Joe (and Zack and Scott) will be talking about all this and more at CCUS 2015! http://www.ccusinstitute.org to register soon!

February 18, 2014

Central line insertion: US-spotted “Blind” technique video. #FOAMed, #FOAMcc

So a few months ago I posted about central line insertion and my concerns about the current standardization of care of ultrasound guidance:

http://thinkingcriticalcare.com/2013/10/21/ultrasound-guided-central-venous-catheter-insertion-standard-of-care-or-preventing-procedural-skills-foamed-foamcc

I promised a video so finally got around to remembering to do it.  This one actually happens to be a dialysis catheter so a bit bigger, but otherwise the technique is the same. In this case I am using my standard ultrasound-spotted procedure with “blind” insertion.

So here, I spot the vein, confirm it is just lateral to the carotid, and that it collapses nicely, without thrombosis:

Now, I insert the line. A few important points to note that are not seen in the frame:

Line Insertion video:

a. my introducer needle/syringe and loaded guide wire (pulled pack and “loaded”)  are ready  and within my vision, and also nearby are the dilator and catheter.

b. note that the off hand (right hand in this line) protects the carotid and stays in place until there is venous flashback, then secures the needle position.

 

Note that in this particular case, I didn’t quite make a large enough incision so the dilator insertion was a little difficult – unnecessary delay, and also unfortunately lost the last few seconds as my iPhone memory was full. 

Next, I confirm position in the internal jugular vein, and verify for lung sliding to rule out and anterior/apical pneumothorax.

In me experience, the key mistake I see inexperienced operators (and sadly, some experienced ones also) make is not to have a proper setup, such that once they do find the vein with the introducer needle, their subsequent steps are not immediately ready, and in the process, the relationship between needle tip and vein is lost, resulting in an inability to thread the guidewire (often blamed on mysterious anatomical abnormalities). It is key to find the vein with the freezing/searcher needle, fix the depth/angle relationship in your mind, withdraw and reach for the introducer needle/syringe using peripheral vision so as not to break the visual fix, and reproduce this while introducing it.

This is what I try to install in students/residents rounding with me, and in fact this approach is useful for any procedure.  Not having to turn your head, reach and fiddle with things that are not ready prevents mistakes.

If you haven’t read my previous post on central line insertion, I’m not advocating agains the use of ultrasound guidance, but for the maintenance of the ability to insert blind lines if necessary.

cheers!

Philippe

January 29, 2014

CCUS 2014: Taking your Ultrasound Game to another level! Montreal may 9-11, 2014!

Registration is open!

For the 7th edition of our Annual Symposium, we’ve assembled a great cast of characters to bring your bedside ultrasound game to a whole new level! Whether you’re a novice or have some experience in bedside ultrasound, we’re sure you’ll find our program very interesting, as the perspective we have chosen to take is patient-based, with each lecture explaining how ultrasound findings are integrated into clinical decision-making.

First of all, it’s in Montreal, May 10th and 11th, 2014. If you’re from out of town, its an awesome city to visit, and if you’re a Montrealer, well, it’s an awesome conference at home!

Indeed, this isn’t “just” a “how-to” course – although that is what we’ll be covering in the workshops which will follow each lecture – but a “how to integrate ultrasound into your daily practice” course, so no matter what your level is, you’ll find something suited for you. The workshops will be divided into novice and experienced and with a low participant to faculty ratio, will ensure a great experience.

So what are we going to be talking about?

In the CC/ED/hospital scene:

–       the patient with chest pain, by Max Meineiri

–       the patient with CHF, by Mike Stone

–       the patient with renal failure, by Sara Sebbag

–       the patient with a swollenleg, by Michael Woo

–       what’s my patient’s volume status? By Ashraf Fayad

–       the patient with a decreased level of consciousness, by Robert Chen

–       the patient in shock, by JF Lanctot and Max Valois

–       the patient with abdominal pain, by Haney Mallemat

–       the patient with a bowel obstruction

–       the patient with broken bones: finding and freezing, by Catherine Nix

–       the patient with dyspnea, by Alberto Goffi and Edgar Hockmann (KEYNOTE)

–       the hemodynamically unstable patient: multi-modality assessment, by Andre Denault (KEYNOTE)

In the office scene:

–       the patient with a neck mass, by Sarah Sebbag

–       the patient with arthritis, by Alessandra Bruns

Here is the program:

CCUS 2014 Master Programme

Who made this up?  Our scientific committee is made up of Michael Woo, Catherine Nix, Edgar Hockmann, Alberto Goffi and Andre Denault, who is also the co-chair – with myself – of this year’s symposium.

For those of you part of the twitterverse and #FOAMed movement, you’ll get a chance to meet @criticalcarenow (Haney), @bedsidesono (Mike), @nobleultrasound (Vicki), @EGLS_JFandMax (JF and Max) and @ThinkingCC (yours truly)…and Matt (pulmccm.org) will be there to chronicle the event and bring the highlights to the #FOAMed world.

So who should come?  Anyone taking care of sick patients.  If you’re an ED doc, ICU doc, hospitalist, anaesthetist, surgeon, student or resident, this stuff is gold. Even if most of your practice is office-based, precise assessment of dyspnea, volume status and cardiac function is highly practical.

Additionally, there are several very interesting pre-congress courses taking place on May 9th, particularly the Echo-Guided Life Support course (JF Lanctot and Max Valois), a Bedside Ultrasound Course for Nurses, an Acute Care Procedures Course and a Symposium for Ultrasound Educators on how to set up training programs. All in all, a lot of great stuff.

For more details and registration, please go to www.ccusinstitute.org.  And yes, of course there are CME credits by the University of Montreal.

As I said a few months ago – well, tweeted, to be exact – if you’re an acute care MD and NOT using bedside point-of-care ultrasound, you’re stuck in the 20th century… rude, but true.

Hope to see you there!

Philippe Rola

President, CCUS Institute

January 22, 2014

Blood transfusion and serum S1P levels in Sepsis: a leaky proposition? (Protecting the Glycocalyx Part1) #FOAMed, #FOAMcc

So in my ongoing quest to reframe my resuscitation step-by-step, I’ve been following up on a number of leads regarding the glycocalyx, as previously stated, and John’s reference to this article in a previous comment I feel is highly relevant. So this is it:

Synergistic Effect of Anemia and Red Blood Cells Transfusion on Inflammation and Lung Injury,  Anping Dong, Manjula Sunkara, Manikandan Panchatcharam, Abdel Salous, Samy Selim, Andrew J.Morris, and Susan S. Smyth

Advances in Hematology, Volume 2012, Article ID 924042, 8 pages

http://www.hindawi.com/journals/ah/2012/924042/

S1P (sphingosine-1-phosphate) is a regulator of endothelial permeability and immune function.  Uh-oh, why had I not heard of it? Hmmm…I don’t think it was in Guyton’s or in Harrison’s…and there hasn’t been an RCT about it… Ok, that about explains it.

So here are some factoids about S1P:

–       serum levels correlate with HCT as RBCs serve as an S1P reservoir.

–       anemic patients’ S1P levels are NOT fully replenished by transfusion, especially the older the transfused blood is.

–       In fact, older RBCs may actually remove plasma S1P.

The study:

They basically took mice, and in the first group, bled them (by 20ml/kg) and looked at inflammatory markers, lung permeability and also S1P levels. That’s basically the control group, and they noted that hemorrhage significantly increased inflammatory markers (interesting in and of itself) . They then transfused these mice using wither fresh, S1P-loaded RBCs, or 14-day old RBCs, and, lo and behold, the fresh blood resulted in less inflammation, increased S1P, but most importantly, markedly decreased lung permeability. So clearly, S1P attenuates transfusion associated lung permeability.

In the next group, they injected the mice with LPS following hemorrhage, and found a synergistic effect of blood loss and LPS on inflammation and lung permeability, as could be imagined. Following the LPS, they were transfused with one of four strategies: fresh blood, old blood, fresh blood + S1P or old blood + S1P.  Well, lung permeability still increased in all groups, but least in the fresh blood + S1P, and the old blood + S1P a close second.

Note, interestingly enough, that saline alone (the “control”) also increased lung permeability, highlighting yet again that NS (and probably any crystalloid) is not innocuous…

So here we’re looking at the finer effects of transfusion, and why, against “common-sense” correcting a patient’s hemoglobin level does not seem to help in all situations.  We have understood the aging issue and loss of deformability, but it is time to take a finer look.  We are familiar – at least in concept – with transfusion-associated lung injury or TRALI, but the mechanism remains unclear.

Summary and Take-Home message:

S1P infusions in sepsis?  Maybe someday…

Yes, this is an animal study, and the results cannot be extrapolated directly to humans, but it is food for thought, as John had mentioned.  Certainly at least this should tell us to keep and ear/eye out for human work with S1P, but personally, it will make me even more comfortable in not transfusing my septic patients with hb’s in the low 70’s and maybe even high 60’s (try repeating the cbc, more often than not comes back a couple points higher and you can avoid transfusion), and for those who are a little more aggressive with transfusion, maybe this should make them think twice…

I’ll add what I can dig up on human S1P studies soon.

cheers!

Philippe

January 15, 2014

Bedside Ultrasound Clip Quiz #7: Discussion #FOAMed, #FOAMcc

So here is the clip again.  This is a transverse epigastric view with the IVC in short axis and the hepatic veins (bunny ears) draining into it.  We can see bright hyperechoic material moving up and down, which are air bubbles.  Note that this is air in the hepatic veins and NOT the portal veins, which can be “relatively” common due to ischemic bowel and a few unusual causes.

Air in the systemic hepatic circulation is quite unusual.  Obviously, air anywhere in the circulation implies a breach of vascular integrity somewhere – in the case of portal venous air, the breach is in the bowel microvasculature as the bowel breaks down. In the case of air in the hepatic veins, we are looking at air coming from (a) the lower body vasculature, so in the absence of trauma the most likely cause is iatrogenic from a femoral line, or (b) the upper body vasculature if associated with tricuspid regurgitation (iatrogenic or lung vascular injury coupled with positive pressure ventilation).

Here is an article discussing hepatic vein air.

533.full

Their clinical point is important to note – you have to investigate to get an idea of the amount of air and the possible source.

So this patient was transferred to my ICU from a smaller centre for more aggressive care. He was in profound septic shock felt to be pulmonary in aetiology, on levo/vaso/epi and dobutamine, ventilated on 100% with PEEP 16. My basic CUSE (critical ultrasound examination) done on essentially every critical care patient revealed this rapidly and, concerned that air embolism had occurred (femoral line was in situ at arrival), I scanned him.

Here is the CT:

photo-8 copy

 

photo-7 copy

You can see a small sliver of air in the IVC, and none was noted in the liver or in the heart (which was what I wanted to r/o). Now of course ultrasound is much more sensitive than CT for identifying small air bubbles (a CT image is a composite of several slices so a small bubble is lost) but when he returned form CT and I scanned him again, the hepatic veins no longer had air, but the IVC was full of air below the liver (as in the CT), so I think moving the patient had relocated the air.

More to come on the clinical story and investigations of this particular case, which is still ongoing.

thanks for looking!

 

Philippe

January 10, 2014

Transfusion and the Glycocalyx: John strikes again! #FOAMed, #FOAMcc

A great surprise this morning:  a comment from John. Yup, THE John. So taking a page out of Scott’s book, I thought it would be worth sharing with everyone as its own post, as opposed to just a comment. I think this is must-read material for everyone.

So without any further adue:

“I thought I might add some quirky ideas to your discussion.

We are now getting familiar with the concept of endothelial cells covered by a surface glycocalyx layer, that forms part of the barrier and mechano-sensing functions of the blood-tissue interface. We have discussed in some detail, the role of the glycocalyx in preserving endothelial integrity. I am gonna try and add a bit more spice into the whole transfusion drama.

In recent times, we have started talking a lot about a bioactive phospholipid called sphingosine-1-phosphate (S1P), as a crucial element in preserving vascular barrier integrity by ‘protecting’ the Glycolcalyx. (Most geeky papers on TRALI and other transfusion related complications do mention it).

Because albumin is one of the primary carriers of sphingosine-1-phosphate (S1P), it is possible that S1P, acting via S1P1 receptors, plays the primary role in stabilizing the endothelial glycocalyx. Infact, antagonism of S1P1 receptors have been shown to cause widespread shedding of the glycocalyx, as evidenced by increased serum concentrations of Heparan sulphate and Chondroitin sulphate. (This might probably be one of the mechanisms how albumin is glycocalyx friendly).

RBC transfusions are a double edged sword…..especially in situations of acute anemia as in post hemorrhagic situations ( major GI bleed or trauma.)….I totally agree with you in that the two are conceptually very similar.

Erythrocytes have been identified as an important buffer for sphingosine-1-phosphate . In mice, depletion of plasma S1P by genetic inactivation of S1P synthesizing enzymes (sphingosine kinases 1 and 2) elicits profound pulmonary vascular leak, which can be reversed by restoring circulating S1P via RBC transfusion.

In humans, hematocrit (Hct) predicts plasma S1P levels. There also seems to be a dynamic equlibrium between SIP levels of the plasma, and the circulating RBCs. It has been demonstrated that in anemic individuals, plasma S1P levels are not uniformly restored by RBC transfusion. Rather, the age of the RBC unit at the time of transfusion tended to negatively correlate with the ability of RBC transfusion to replenish plasma S1P. During storage, the S1P content of human RBC markedly declines, likely due to enzymatic degradation. Because erythrocytes serve as a buffer for circulating S1P, aged RBC with low S1P content may be incapable of restoring plasma S1P levels and may actually remove S1P from plasma, which in turn could contribute to increased endothelial permeability, capillary leak, and infiltration of inflammatory cells.

I hope this partly answers your question as to how the glycocalyx may be impacted by inappropriate and irresponsible transfusion triggers. I agree that these are all very novel ideas and as such, exist in the realm of experimental clinical physiology, but my gut tells me that the delicate Glycocalyx may hold the clue to a lot of answers to questions that have plagued us for a long long time!

Cheers,
John from India…”

So first of all, thank you very, very much for reading and taking the time to comment and enlighten us.

As John says, this is still in the realm of experimental physiology, but I think there are a lot of situations we are faced with, perhaps grey zone areas where we debate two potential therapeutic avenues, where we can use some of this data. We might debate giving that extra bit of fluid, or debate crystalloid vs albumin, or blood or no blood with an Hb of exactly 70, and I think we have to start weighing in some of this physiological data, even if it isn’t “evidence-based-by-RTC” to help guide these decisions.

The more I look into it the more it seems that our interventions – particularly fluid resuscitation, needs to be reassessed from the ground up both in nature, quantity and rate of infusion while measuring glycocalyx damage – e.g. biomarkers such as S1P, heparan or chondroitin sulfate, etc…

I’ve previously posted and podcasted about my general strategy for fluid resuscitation, and I am definitely in the process of revising it, still unsure what is best. I’d love to hear how John resuscitates his patients…

thanks!

Philippe

Other Comments:

Mystery John has an uncanny ability to describe complex physiology in the simplest way possible. I am very interested in digging more into his predictions of the possibility of aged erythrocytes removing S1P from circulating plasma.

Dr. John, if you’re out there, could you point us all to some of these studies you’ve mentioned? Any good S1P review papers you’d recommend to those, like me, who are S1P novices?

Thanks for your input! It was a pleasure.

Warm regards,

Derek

Thank you Derek, for the kind comments…. I think the concept of S1P is still in the process of evolving and assuming a definitive shape, so a good review might be hard to stumble across.

A good research article which cites some excellent references might be —

Synergistic Effect of Anemia and Red Blood Cells Transfusion on Inflammation and Lung Injury
— Anping Dong et al. (It is open access at http://dx.doi.org/10.1155/2012/924042).

Hope this helps……

John.

Here is the article:

924042

P