why this blog?

Likelihood Ratio (LR) in Emergency Medicine

10/31/2012

Can we fight against Pulmonary Embolism using the LR’s arrows?


Clinical Scenario

A 80 y/o woman presented to the ED for dyspnoea.
She underwent a knee replacement 2 weeks ago, RR is 24, O2 saturation is 88%. HR is 90, the knee is edematous.
You are going to hunt a pulmonary embolism (PE)
While you phone the radiologist for a thorax CT scan you have an idea:




Can a compression ultrasonography (CUS) helps to avoid a CT?











Conclusion 

Using Wells Score in this setting the PE pretest probability is intermediate (around 30%). 
Effectively the post test probability after a positive CUS is very high. Diagnosing a deep vein thrombosys (DVT) in patients with suspected PE doesn’t require other tests: the treatment of DVT with or without associated PE is the same.  
On the other hand after a negative CUS you need to keep hunting…


Bibliography 

Emergency Medicine Australasia (2005) 17, 322–329
Likelihood ratios increase diagnostic certainty in 
pulmonary embolism 
K Chu and A FT Brown



Journal of Internal Medicine 250: 262-264
Utility of ultrasound imaging of the lower extremities in the diagnostic approach in patients with suspected pulmonary embolism
PS Wells et al
to be continued...


Ciro Paolillo

3 comments:

  1. Hi Ciro. thank you for this new clinical scenario. I think the big issue in pulmonary embolism is a rule-out test when d-dimer is positive (it happens all the time). the SPES study (Accuracy of Multi-organ Ultrasound -Venous, Cardiac and Thoracic- for the Diagnosis of Pulmonary Embolism) is actually recruiting patients. I hope that a complete negative ultrasound algorhytm (negative CUS, normal heart and no pleural or subpleural lesions)could have a sufficient negative LR to exclude PE in moderate risk patients...Mauro

    ReplyDelete
  2. Hey I just came through your blog. Its really nice way to define. You share some good information about Pulmonary Embolism.
    Pulmonary embolism is a blockage in an artery in the lung. It is usually due to a blood clot that has traveled to the lung from another part of the body, usually the leg.
    Blood Clot Symptoms

    ReplyDelete