Question Of The Day #15

Which of the following is the best course of action to further evaluate for a diagnosis of pulmonary embolism?

Explanation

Pulmonary embolism (PE) is a potentially lethal diagnosis evaluated by a combination of a thorough history, physical exam, and the use of risk stratification scoring tools. The Wells criteria and the PE rule-out criteria (PERC) are two well-accepted risk stratification tools for PE. These criteria are each listed below (Wieters et al., 2020).

Wells’ Criteria for Pulmonary Embolism

Criteria	Point Value
Clinical signs and symptoms of DVT	+3
PE is #1 diagnosis, or equally likely	+3
Heart rate > 100	+1.5
Immobilization at least 3 days, or Surgery in the Previous 4 weeks	+1.5
Previous, objectively diagnosed PE or DVT	+1.5
Hemoptysis	+1
Malignancy w/ Treatment within 6 mo, or palliative	+1

Interpretation
Score >4 = High probability
Score 2–4 = Moderate probability
Score <2 = Low probability

Pulmonary Embolism Rule Out Criteria

All Variables Must Be Present for <2% Chance of PE
Pulse oximetry >94% (room air)
HR <100
No prior PE or DVT
No recent surgery or trauma within prior 4 wk
No hemoptysis
No estrogen use
No unilateral leg swelling

The patient in this clinical vignette would have a Wells score of 1.5 (low risk) due to her persistent tachycardia of unknown etiology. The PERC rule can not be applied to this patient as she is over 50-years-old and has tachycardia. If the patient was low risk on Wells score and meet all the PERC rule criteria, she would have a less than 2% likelihood of her symptoms being due to a PE. It is important to note that only patients with a low-risk Wells score (low pretest probability for PE) can be subjected to the PERC rule. A low-risk Wells score (<2) is investigated with a D-Dimer test (Choice B), while moderate to high-risk Wells scores are investigated with a CT Pulmonary Angiogram (CTPA) (Choice C). A V/Q Scan (Choice A) is not a first-line test for the diagnosis of PE as it is less sensitive than a CTPA scan. Unlike a CTPA scan, a V/Q scan may be nondiagnostic in the setting of lung consolidation, effusions, or other airspace diseases. V/Q scans are second-line tests to CTPA when there are contraindications to a CTPA (i.e., renal failure). Lorazepam (Choice D) is a benzodiazepine that may be helpful in reducing tachycardia, which is secondary to anxiety. However, this therapy does not help further discern if the patient may have a PE. Correct Answer: B

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Which of the following is the best course of action to further evaluate for a diagnosis of pulmonary embolism?
— iem-student (@iem_student) October 2, 2020

References

Wieters J, McDonough J, Catral J. Chest Pain. In: Stone C, Humphries RL. eds. CURRENT Diagnosis & Treatment: Emergency Medicine, 8e. McGraw-Hill; Accessed August 17, 2020. https://accessmedicine.mhmedical.com/content.aspx?bookid=2172&sectionid=165059275

Nickson, C. (2019). Pulmonary Embolism. Life in the Fastlane. Accessed on August 17, 2020. https://litfl.com/pulmonary-embolism/

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