Notes From the Community – Accelerated Diagnostic Pathway: PE

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Nurses Edition Commentary

Mizuho Spangler, DO, Lisa Chavez, RN, and Kathy Garvin, RN

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Michael W. -

Listened to this months talk with Cameron Berg -- good stuff. Can he provide specific data regarding usage, etc. The >50% reduction in CT is great but I need something a bit more concrete.

Regarding his cardiac ADP - his pathway is much more aggressive than Dr Mattu's. For example Dr Mattu's has shared decision making HEART 0-3 but observation HEART 4-6 while Dr Berg gave examples of discharging higher risk (older, history of CAD/nonSTEMI) patients. These would be folks with HEART scores 4-6.

Any chance there could be...
1) a head to head discussion Berg vs Mattu regarding their ADP especially on moderate risk chest pain patients
2) an evidence based breakdown of risk to discharge a patient for outpatient stress testing. For example HEART 0-3 carries 1.7% MACE 6 weeks -- but what is risk within 72 hours? 1 week? Same for HEART 4-6 -- MACE 20% at 6 weeks but what is risk at 72 hrs, 1 week?

Thank you!

Michael W.

Kyle E. -

A few questions:

1) I had been under the impression that PERC rule could be applied to any patient and, if negative, can be used to rule out a PE?

2) The Well's criteria originally was low risk: 0-2 points. This lecture states they use 0-4 points. It also indicated that a D-dimer was applicable in only low risk and not moderate risk, which this lecture seems to dismiss and allow you to use it in moderate risk. Has this been validated in some way?


which Well's criteria do yo use? Well's PE or Well's DVT? Or does it matter?

cameron b. -

Hey All,

Great questions. I'll take them sequentially.

1) I'm happy to provide more granular information about our CTPA reduction. What do you want to know?
2) I stand by my proposed chest pain ruleout pathway. In subsequent analysis, we haven't really found any important differences in outcome regardless of clinical risk scores. History, physical, ECG and troponin...this is the recipe for success. I'd be honored to talk more with Dr. Mattu.
3) PERC cannot be applied to every patient. It's intended to be used in low risk populations. There are definite PERC "misses," though the decision instrument was not designed to be perfect. Rather, it was intended to define a post-test cohort of risk <2% (an evidence-based threshold selected by Kline on the basis of harm from testing and overdiagnosis).
4) Since Wells' initial work, many technologies have changed, D-Dimer in particular has become far more sensitive. I realize that I've defined different cut-points, but this is well-supported by many other authors.
5) We use Wells' PE

Cameron Berg

Joshua B. -

Dr Berg

Great talk! I was wondering if you would be willing to share the protocol with me/us. This is something I would be looking to bring to my hospital.


james s. -

RE Diagnosis is PE (May 2015) -

It's reasonable to perform bilateral leg ultrasounds in hemodynamically stable patients suspected of having PE. If a DVT is found, it is not necessary to expose the patient to risks of chest CT IV contrast and radiation. Except for the rare patient who would benefit from thrombolytic or thrombectomy, the treatment for DVT and PE is the same.

Michael D., D.O. -

What percentage of the patients had a PE when the physician deviated from the protocol?

cameron b. -

Joshua - I'd be happy to give you our exact documents. Send me an email (

James - I agree.

Mike - Very low...under 2% when I last looked.


Andrea W., M.D. -

Excellent discussion. I looked at the references for the adjusted d-dimer thresholds for pregnant patients, and I'm just wondering how you arrived at those particular values for the cutoff levels for each trimester? It seems that all the studies (the ones cited as well as others I found) are using very different cutoffs and different assays, so I'm just curious to understand where these specific values come from. Thank you!

Seth Alkire, MD -

I am designing an ADP for a small community hospital and would also be interested to learn which studies used which assays. It looks like the Wake Forest study used a typical 'non-highly sensitive assay,' but is there sufficient data to support an ADP for low-risk patients using a typical cardiac panel assay? If so, would it require a serial troponin at 4-6 hours like in the WF study?

James M., MD -

If you have a moderate risk of PE by the Wells score and then go to PERC, does that mean that everyone 55 or older gets a CTA since the PERC is positive for all those above 55.

cameron b. -

Andrea - the values I recommended are the most conservative consensus position in the literature for a modern FEU-based assay (baseline cutoff of 500). Many of my citations actually use DDU-based units, leading to the confusion. Ultimately, I can expound at much greater length, but I think my cited values are valid.

James - No. The PERC is ONLY used on low risk patients by Wells. Moderate risk goes straight to Dimer. Only High risk passes dimer.

Make sense?

Cameron Berg

James M., MD -

I'm sorry I got the criteria wrong but the question is still the same. Does everyone over 55 get a CTA since that gives them a positive PERC if when the Wells score is low risk. Sorry about the repeat.

Kyle S. -

1. In the interview, you state you use "slightly different breakpoints" for low (0-4) vs moderate risk (5-6). I note this difference when review Wells’ Criteria for Pulmonary Embolism on MD Calc, my frequent resource for CDI. How did you arrive at this modification?

2. Have you made this a formal policy or protocol at your institution? If so, would you be willing to share it? Just curious to what extent you formalized this CDI/ADP for your group (aside from informal distribution of research, discussions, and yes, $ incentivization to adhere.


cameron b. -

James - positive PERC (for low-risk Wells') is followed by D-Dimer. It's a sequential pathway, and D-Dimer precedes CTA for every cohort except high risk.

Kyle - there are a wealth of different references for Wells' risk stratification. It'd be nice if there was a universal consensus, but this simply is not the case. We've found these tiers to work well.

Regarding the policy. This is a formal local protocol. We analyze adherence by provider, and the protocol extends to hospitalists, critical care doctors, and all acute care providers (UC, ED, etc.).

Thanks again,

george h. -

Dr. Berg,

Excellent talk and topic. I'd like to standardize our hospitals approach to PE and have had discussions with Critical Care and Hospitalists. I believe further detail would help. Could you also share your documents with me for to move this algorithm along at my hospital? Thanks.

cameron b. -

Send me an email, George, and I'll get you everything you need:


Robert A. A., M.D. -

Great talk.

But it seems like an extra step, that might not be necessary, to do a Wells score on everyone you "suspect".

(If a pt is PERC neg, than it is virtually impossible for them to be moderate risk per Wells. Please give me an example of a pt who would fit this picture if I am missing something.)

So why not just start with a PERC for everyone you "suspect", then if they are PERC neg you are done .... but if they are PERC positive then apply Wells and so on.

Daniel T., MD -

PERC only applies if your pre-test probability is low (<15%) using either gestalt, Wells or Geneva scores. If your pre-test probability is moderate or high (no matter the method), PERC should not be applied. For this reason, if you use a Wells score, this must be done first. If the patient is low pre-test prob, then you can attempt to apply PERC.

Stephen T. -

Have you had a problem with frequently having to roll the d-dimer dice with this pathway? Basically, anyone over the age of 50 (failed PERC) who you are trying to r/o PE with this pathway gets a d-dimer at the very least. That's a large chunk of patients.

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