PE or not PE, that is the question… - The Original Kings of County

Written by Randi Ozaki

…and probably one of the more annoying clinical questions that we’re faced with in the ED. PERC (pulmonary embolism rule-out criteria), D-dimer and Well’s criteria have been discussed ad nauseam, but the question I pose to you, is how does ultrasound fit in to our algorithm and can it help aid us in our diagnosis and/or management in patients suspected of having a PE?

CT PA is the diagnostic modality of choice in patients suspected of having a PE, however there are many instances where CT may not be possible or even feasible. The fact that patients require a good IV placed in the antecubital fossa is often a rate-limiting step and in a busy ED, it may be some time before a line is successfully placed. Patients with renal insufficiency are unable to receive contrast and in pregnant patients, the risk of radiation exposure to the fetus often precludes the possibility of a CT scan. Additionally, radiation exposure to young reproductive age patients in general is something optimally avoided. Furthermore, patients with massive PE may be too unstable to leave the ED to obtain a CT scan.

Rock. Me. Hard Place.

There is a solution: ultrasound, of course!

While direct visualization of a thrombus in the right atrium or pulmonary artery is possible, it is a rare finding. There are, however, indirect findings on ultrasound which may heighten or confirm your suspicion of PE.

Echocardiography and evaluation of right ventricular strain or dysfunction may heighten one’s suspicion of a clinically significant PE. Patients with unexplained hypotension or shock, secondary to PE will show signs of RV dysfunction. The absence of such findings on echo, should lead the provider to seek an alternative explanation for the patient’s instability. Unfortunately, in patients without shock or hypotension and who have a normal echo, the diagnosis of pulmonary embolism cannot be ruled out.

What do you see in the ultrasound below?

Answer:

What is McConnell’s sign?

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Answer:

What are other indirect indicators of a possible PE?

Answer:

Summary:

1. Aside from direct visualization of a thrombus, there is no direct way of diagnosing PE on ultrasound.

2. A negative echo and negative DVT does not exclude the diagnosis of PE.

3. The ability to find a DVT on exam or signs of RV strain in patients suspected of PE will allow for faster initiation of appropriate therapies.

4. Look for other causes of hypotension in patients without signs of RV strain on bedside echo

References:

Borloz et al. “Emergency department focused bedside echocardiography in massive pulmonary embolism.” The Journal of Emergency Medicine. 41(6): 658-660, 2011.

Squizzato et al. “ “Point-of-care ultrasound in the diagnosis of pulmonary embolism.” Crticial Ultrasound Journal. 7:7, 2015.

The views expressed on this blog are the author's own and do not reflect the views of their employer. Please read our full disclaimer here. Any references to clinical cases refer to patients treated at a virtual hospital, Janus General Hospital.