December 16, 2019

Background: The clinical diagnosis of pulmonary embolism (PE) can be challenging given its variable presentation, thus 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 rates (less than 10%). This combination results in the overdiagnosis of subsegmental PEs, unnecessary exposure to radiation and false positive results.

Though the D-dimer test has long been maligned for its low specificity the real issues around it rest in indiscriminate use and threshold value. In recent years, age-adjustment of the D-dimer and the YEARS algorithm have attempted to adjust the threshold in order to “rule-out” more patients without advanced imaging. The YEARS creates a two-tiered D-dimer threshold by first asking three questions:

  1. Are there clinical signs of DVT?
  2. Does the patient have hemoptysis? and
  3. Is PE the most likely diagnosis.

If the answer to all 3 questions is no, the D-dimer threshold is set at 1000 ng/mL FEU (500 ng/mL DDU) and if the answer is “yes” to any of the 3 questions, the D-dimer threshold is set at 500 ng/mL FEU (250 ng/mL DDU). More recently, the YEARS algorithm has been assessed in pregnancy.

Age-adjustment of the D-dimer assay simply multiplies 10 X the patients age (if using FEU and 5 X age if using DDU) and uses this number as the threshold for the test. This adjustment is applied to patients > 50 years of age. Age-adjustment of the D-dimer was endorsed by an ACEP clinical policy in 2018.

The PEGeD study is another attempt to show the safety of using an adjusted D-dimer threshold.

February 11, 2019

Background: Syncope, defined as a transient loss of consciousness with a complete recovery, is a common ED presentation. There are numerous causes of syncope ranging from the relatively benign (eg vasovagal syncope) to the potentially life-threatening (eg dysrhythmia, ectopic pregnancy, aortic dissection). Among the life-threatening diagnoses is pulmonary embolism (PE). PE is a common cause of sudden, unexpected, non-traumatic death and, syncope in the setting of PE portends poor 30-day outcomes (Roncon 2018). What is not well known is how often ED presentations of syncope are the result of PE. A study in 2016 demonstrated a 17.3% rate of PE in first time syncope presenting to the ED but, had numerous significant biases and limitations (Prandoni 2016). Ultimately, this study is unlikely to reflect the reality of ED syncope cases and lacks external validity. Incorporating the PESIT trial data into clinical assessment would lead to a profound increase in PE evaluation without adding significant benefit. Additional clinical data demonstrating the true prevalence of PE in syncope patients is needed to confirm these suspicions.

September 20, 2018

Background: Venous thromboembolism (VTE) occurs frequently in patient with cancer. Treatment in this group entails a number of challenges including a higher rate of thrombosis recurrence and a higher risk of bleeding. Standard therapy in 2018 for both symptomatic and asymptomatic VTE is with low-molecular-weight heparin (LMWH) based on this study. Prior to 2003, patients were treated with warfarin after bridging with either unfractionated or LMWH. This approach requires frequent monitoring due to unpredictable anticoagulation levels associated with drug interactions, malnutrition and vomiting. Due to these issues, treatment with LMWH alone may be both more efficacious as well as preferred by patients.

August 30, 2018

Background: Venous thromboembolism (VTE) occurs frequently in patient with cancer. Treatment in this group entails a number of challenges including a higher rate of thrombosis recurrence and a higher risk of bleeding. Standard therapy at this time for both symptomatic and asymptomatic VTE is with low-molecular-weight heparin (LMWH) based on results from the CLOT trial (Lee 2003). In non-cancer patients, new oral anticoagulants (NOACs) like  rivaroxaban have been shown to be effective in treatment without increasing bleeding events. The NOACs also add ease of use for the patient. Though these agents are frequently used in the treatment of cancer-associated VTE, there is a dearth of evidence supporting this practice.

November 6, 2017

Background: Previously, I had given a talk on the use of thrombolytics in submassive PE in 2016. This year, I had the privilege of speaking at ACOEP 2017 again with an update on the critical pulmonary embolism patient. This post will serve as a reference for that talk. There are many ways to classify pulmonary embolism, but the best clinical definition would depend on the hemodynamic consequences.  For example, massive pulmonary embolism can be defined as systemic hypotension (SBP < 90 mmHg or a drop in SBP of at least 40mmHg for at least 15 min) or shock (tissue hypoperfusion, hypoxia, altered mental status, oliguria, or cool clammy extremities.)  There is a second subset of patients that also warrant discussion; submassive pulmonary embolism.  These patients are defined as lack of systemic hypotension (<90mmHg), but have right ventricular dysfunction/hypokinesis. RV dysfunction tells us that there is severe pulmonary artery obstruction and impending hemodynamic failure.
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