Notes from the Community: Cardiac Ultrasound

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Amal M. -

Rob, nice discussion. I'm curious to know how far into the cardiac arrest would Mike and Matt stop to do U/S. Also, in the studies mentioned, how far into the code did the researchers stop to do U/S? It's possible that the duration of the code at the point of U/S performance is even more predictive than the U/S finding itself. For example, maybe the survivor they mentioned who had an U/S finding of asystole was still very early in the code and therefore still had a decent chance of survival (and did).

Another concern is that interruptions in compressions are harmful as you mentioned: chance of survival drops 50% for every 10 second interruption in compressions in a pulseless patient. Early interruptions are probably the worst of all, whereas interruptions after 30-60 minutes of pulselessness probably don't matter. I'd suggest that in the hypothetical patient you presented who was only 10 minutes post-arrest, interruption for U/S should definitely not be done at all (unless there's a high concern for tamponade or PE). Just keep pushing on the chest at that point.

Matthew D. -

Great points and questions. Here are some thoughts from us (Mike and Matt) on this.

The papers we mentioned do not specifically state the time (from onset) which the cardiac ultrasound was performed, simply that it was performed during the code.

When we use echo during a code it's for two reasons:
1) Determine if there is a treatable cause such as effusion or evidence of PE in early codes.
2) As an "excuse" to stop the code (No cardiac function = stop) in later codes when it is seemingly futile.

We do this by taking a very brief look during pulse/rhythm checks while another provider or nurse check the rhythm/pulse. If we don't get the view in a reasonable time, we stop trying and back to compressions we go because you're obviously right about interruptions. And by "reasonable time" I mean the EXACT time it takes for rhythm/pulse check so no extra interruption is caused.

In an early code the real reason for the ultrasound is to find a treatable cause. You suggest that U/S should not be done early (in the hypothetical 10 min patient) unless there's a high concern for tamponade or PE. To us a trigger for high concern for tamponade or PE is cardiac arrest itself. So we would really want a reason not to suspect those in cardiac arrest in order not to look for them (such as overdose or other obvious cause). With practice the views for checking for this can be obtained in the time it takes to check a pulse. And if not, then you can try a different window during the next pulse check. We wouldn't do multiple views and prolong interruptions searching for these things. Just as minimizing compressions is important, dx and treating those two things is also important and time sensitive.

This issue of holding compressions to get cardiac ultrasound views is a very reasonable concern and a big reason some US directors (Mostly Mike Blaivas) are using transesophageal echo which allows the probe to remain in place and significantly minimizes the time to get an adequate view. An added benefit is that you can use TEE to judge the quality of compression.

It's important to remember that ETCO2 is also a highly specific marker for futility in arrest and may help suggest when ROSC occurs. In my opinion both should be used in conjunction in making the right decisions about when to stop a code. We're planning on diving more into TEE at an upcoming conference we're having and ibook we're writing. It's coming in the future and we'll hopefully podcast about it more in the near future.

Brian A. -

Wow, great talk. We need these guys on EMRAP more often. This Matt guy is hilarious and gives a great review of the literature on cardiac standstill and prognosis in the setting of arrest.

Maxime V. -

On the 2nd point above note that if EtCo2 doesn't change : cardiac function doesn't either ... unless someone is bagging in a weird and/or different manner ...
No need then to repeat the US if EtCO2 is stable and reversible causes have been addressed by the first US scan.
For the time needed to perform US in cardiac arrest the FEER protocol published by Breitkrutz and colleagues in 2007 looked at that very issue. Experienced sonographers are able to get a sense of cardiac function or strain in less than 5 seconds (beginners 5-10 seconds)
Of course in such a short time period the ED sonographer must have clear questions and a structured approach when performing the exam.

Cameron -

Yes. The FEER exam has been mostly ignored. Later re-termed FEEL for a mostly English speaking audience. At least one exam protocol was a direct unreferenced copy. The point is that it is not that hard to throw the probe on during an arrest to gain some info.

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