All about PE today

This item appeared in Medscape here but is a must read for any physician who deals with acute PE presentations.

Evaluation of Patients With Suspected Acute Pulmonary Embolism: Best Practice Advice From the Clinical Guidelines Committee of the American College of Physicians

Raja AS, Greenberg JO, Qaseem A, Denberg TD, Fitterman N, Schuur JD; Clinical Guidelines Committee of the American College of Physicians
Ann Intern Med. 2015;163:701-711

The diagnosis of pulmonary embolism (PE) is definitely one of the great challenges in acute care medicine. I can't think of any condition that is so frequently worked up with negative results and yet is also so often underdiagnosed, with catastrophic results and resulting litigation. In addition, we in EM are often chastised for overordering D-dimer levels and CT pulmonary angiograms (CTPAs), yet we continue to practice in this way for lack of an acceptable standard method of working up patients. However, there may finally be some good news that will decrease workups, misdiagnoses, and litigation.

In November 2015, the American College of Physicians' Clinical Guidelines Committee published a set of recommendations for best practice with regard to working up PE. The document was evidence-based, straightforward, and clinically relevant. The document essentially serves as a guideline recommendation from a major national organization, which provides strong medicolegal protection when following the recommendations.

There were six pieces of "Best Practice Advice" from the Committee, which I have listed below.

• Best Practice Advice 1: Clinicians should initiate their evaluation of patients with possible PE by using validated clinical prediction rules (eg, Wells or revised Geneva scores) to estimate the pretest probability of PE as low, intermediate, or high risk.
• Best Practice Advice 2: Clinicians should not obtain D-dimer measurements or imaging studies in patients with a low pretest probability of PE and who meet all of the pulmonary embolism rule-out criteria (PERC). If the patient with low pretest probability is PERC-negative, PE is considered ruled out and the workup is completed. If the patient is PERC-positive, a D-dimer value may then be obtained.
• Best Practice Advice 3: A high-sensitivity D-dimer test (enzyme-linked immunosorbent assay) should be obtained as the initial diagnostic test in patients who (1) have a low pretest probability for PE but are PERC-positive, or (2) have an intermediate pretest probability of PE. If the D-dimer value is within normal limits, imaging is deferred and the workup for PE is completed. D-dimer testing should not be performed for patients with high pretest probability for PE (see Best Practice Advice 6, below).
• Best Practice Advice 4: Clinicians should use an age-adjusted D-dimer threshold (top normal level = age × 10 ng/mL rather than a generic 500 ng/mL cutoff) for patients older than 50 years to determine whether imaging is necessary.
• Best Practice Advice 5: Clinicians should not obtain imaging studies in patients with D-dimer levels below the cutoffs noted above.
• Best Practice Advice 6: Clinicians should obtain imaging with CTPA in (1) patients with high pretest probabilities for PE, or (2) patients with elevated D-dimer levels based on the evaluations noted above. Clinicians should reserve ventilation/perfusion scans for patients with contraindications to CTPA or when CTPA is not available.

The authors add a recommendation to obtain lower-extremity ultrasound before CTPA in patients who have lower-extremity symptoms or in pregnant patients during the first trimester.

This set of recommendations, when taken as a whole, is certain to reduce testing, especially imaging and radiation exposure for many patients. The guidelines are a quick read and are chock-full of useful clinical information; they are a must-read for anyone who has an interest in the topic or who desires some of the background information behind these Best Practice Advice statements.