Pulmonary Embolus: Evaluating the Five Ps of PE

Years ago, my physician father said to me; “If something does not make sense, if you struggle to determine the pathology, consider pulmonary embolus (PE).” More recently, an ER physician colleague offered me the following advice: “If you think about PE, test for it.”

  Revised Geneva Score

Objectifies risk of PE, like Wells’ score.

  Two-level Wells score

DVT likely 2 points or more...

  YEARS Algorithm

Helps rule out pulmonary embolism; also validated in pregnant patients.

  Wells Score

Some advocate using the Wells’ score over clinician gestalt to predict who is low-risk and then applying the PERC rule to stop workup for PE. As with all clinical decision aids, the physician must first have a suspicion of the diagnosis before attempting to apply the Wells criteria. The original intent of this tool was to determine who was low risk enough to rule out testing with a d-dimer.

  PERC Rule

In the setting of a low-risk patient who is not PERC negative, the physician should consider a d-dimer for further evaluation. If the d-dimer is negative, and clinical gestalt determines a pre-test probability is <15% then, the patient does not require further testing for PE. If the d-dimer is positive, further testing such as a CT-angiography or V/Q scan should be pursued.

  PERC – Still (Mostly) Useless

…except, perhaps, in a risk-management sense – but, only if we keep beating it down into its narrowest application due to its terrible specificity.

 Pulmonary Embolism Decision Rules - Beyond the Basics

So let’s talk about how we can determine who is high risk and who is low risk. First off, why do we care? First off, PE is a very much-feared missed diagnosis, which carries an 8% 30-day mortality** after diagnosis (this was much lower than I expected, to put this into context, hemorrhagic strokes carry a 25-40% mortality depending on your source and hip fractures carry a 4-10% mortality rate depending on your source).

 Testing For Pulmonary Embolism is More Harmful Than Helpful

This is not unique to pulmonary embolism – this is partly the same issue we encounter with overtesting our low-risk chest pain patients, particularly with CTA.

Failings of Modern Medicine

A brilliant piece that eloquently states many of the ideas espoused on this blog, focusing on pulmonary embolism as the poster child for over-testing, over-diagnosis, and lack of sound evidence underlying treatment.

Nothing Excludes Pulmonary Embolism?

It’s hard to find a diagnostic pathway with greater variation than that of pulmonary embolism. On one hand, you have the YEARS protocol, in which D-dimer is the definitive gatekeeper without carve-outs or exclusions. On the other hand, you have an article like this – saying even CT pulmonary angiograms are inadequate to rule-out PE.

PERCs of the Wells Score

In order to avoid missing a PE while mitigating the risks associated with overtesting, some clinical decision tools have been created to aid in the diagnostic process. We will focus on two of these commonly used decision tools: the PERC rule and the WELLS score for PE.

Using PERC & Sending Home Pulmonary Emboli For Fun and Profit

Frankly, given the shifting gestalt relating to the work-up of PE, the best cut-off is probably not PERC, but simply stopping the work-up of most patients not intermediate- or high-risk.

Challenges, Controversies, and Hot Topics in Pulmonary Embolism Imaging

Pulmonary embolism (PE) is a relatively common vascular disease. PE and deep vein thrombosis (DVT) comprise two clinical presentations of the same pathologic process: venous thromboembolism (VTE). The reported prevalence of PE is 0.4%, and according to data collected between 1979 and 1999, the incidence is 600,000 cases annually in the United States. Acute PE is the third most common acute cardiovascular disease, after myocardial infarction and stroke. Untreated PE is fatal in up to 30% of patients, but its mortality rate is 2% to 10% with timely diagnosis and treatment.

CTPA – Is This Test Just a Little Too Good?

I never thought I would be writing about a test that was too good. But it is clear that CT pulmonary angiograms (CTPAs) fit the bill. But first some background.

Diagnosis of Pulmonary Embolism with d-Dimer Adjusted to Clinical Probability

Using a d-dimer cut off adjusted for clinical probability appears to be a safe strategy to reduce the use of diagnostic imaging in low-risk patients with PE.

Episode 21: Pulmonary Embolism

What are the most important under-recognized risk factors for pulmonary embolism, and how does the absence of risk factors change the pre-test probability of PE?

Imaging of acute pulmonary embolism: an update

Imaging plays an important role in the evaluation and management of acute pulmonary embolism (PE). Computed tomography (CT) pulmonary angiography (CTPA) is the current standard of care and provides accurate diagnosis with rapid turnaround time. CT also provides information on other potential causes of acute chest pain.

New Guidelines For Evaluation Of Pulmonary Emboli Released By American College Of Physicians

For patients with a low pre-test probability of developing PE (<15 % pre-test probability), healthcare providers should use the PERC rule (Pulmonary Embolism Rule-Out Criteria). The test is comprised of 8 criteria to evaluate risk profile (age >50, HR >100, oxygen saturation < 95%, prior history of venous thromboembolism, trauma or surgery within the last 4 weeks, unilateral leg swelling, use of any pill containing estrogen, or coughing up blood).

Pulmonary Embolism and Atrial Fibrillation: Two Sides of the Same Coin? A Systematic Review

Pulmonary embolism (PE) is a common, potentially fatal thrombotic disease. Atrial fibrillation (AF), the most common arrhythmia, may also lead to thromboembolic complications. Although initially appearing as distinct entities, PE and AF may coexist.

Pulmonary Embolism Challenges in Diagnosis Part 1

If we were to design a perfect emergency medicine brain buster, it would have all the qualities of pulmonary embolism. It would affect the young and the old. It would be precipitated by seemingly anything: medications, smoking, and even video gaming. It would be dynamic, anything from asymptomatic to killing in minutes. It would have a huge variability in presenting signs and symptoms depending on a whole host of patient factors. It would have multiple decision rules, imaging modalities, and treatment options. It’s as if pulmonary embolism was invented just to challenge the minds of ED docs!

Pulmonary embolism, ambulatory care and the goddess of the hunt

Why are we talking about this? Well, PE lends itself very well to the topic of ambulatory care. It is a potentially serious condition with significant morbidity and mortality, and it often presents insidiously. So we think about it. And we look hard for it. And this is good. But our increasing vigilance in tandem with better scanners, keener radiologists and patient awareness has resulted in a dilute pretest probability of around 5%. So we need to think carefully about how we balance resource use and time.

The role of pretest probability calculation in determining subsequent investigations for pulmonary embolism

It is very commonly seen in many situations in which frontline clinicians (both junior and senior) faced with the prospect of pulmonary embolism (PE) as amongst the list of possible differential diagnoses in a clinical presentation would order a D-dimer testing or diagnostic imaging without much consideration, and then calculate the pretest clinical probability (usually Well’s criteria in my region) in retrospect when asked to justify their action later.

The YEARS Study – Simplified Diagnostic Approach to PE

The clinical diagnosis of pulmonary embolism (PE) can be challenging given its variable presentation, requiring dependence on objective testing. Decision instruments such as PERC and the Wells’ score help stratify patients to low or high probability, enabling focused use of CT pulmonary angiography (CTPA) for diagnosis. However, despite these algorithms, there is evidence of increasing use of CTPA along with diminishing diagnostic rate (less than 10%). This combination results in the overdiagnosis of subsegmental PEs, unnecessary exposure to radiation, false positive results and the potential for contrast-induced nephropathy.

YEARS, But Wells

At the very least, please considering using PEGeD or YEARS as the basis for your imaging algorithm – and add age-adjusted D-dimer on top for even better reductions in unnecessary imaging.