Saddle Pulmonary Venous Embolism Presenting As Massive Pleural Effusion!

The differential diagnosis for pleural effusions is quite broad, but one of which must always include pulmonary venous embolism.  Pleural effusions are the accumulation of fluid in the pleural space.  What is the pleural space?  The pleural space is what separates your lungs from your chest wall.  It allows your lungs to expand and contract with every breath and not get stuck on your musculoskeletal organs.

Pleural effusions are most commonly  divided into two broad categories:  transudative or exudative.  In general terms, transudative pleural effusions are a volume issue and exudative pleural effusions are a disease specific issue.  In even more general terms, exudative=bad and transudative=good.  Volume issues such as heart failure and poor nutrition are  classic causes of transudative pleural effusions.  Cancer, pneumonia, auto immune disorders  and pulmonary venous embolism are classically associated with exudative effusions.

What are the criteria for determining if a pleural effusion is transudative or exudative?  The Light criteria describes pleural effusions as exudative if one or more of the following criteria are met
  1. a pleural fluid:serum protein ratio > 0.5
  2. a pleural fluid:serum lactic dehydrogenase (LDH) ratio>0.6
  3. a pleural fluid LDH>200
It came somewhat as a shock to me when this 52 year old male presented to the hospital in acute hypoxemic respiratory failure after telling his wife that he felt short of breath for the last three weeks.  Here is a picture of an xray similar to one he had on his presentation.  As you can see a large pleural effusion was consuming most of the right lung parenchyma (or left in the case of this stock xray photo).  Even stranger was the fact the man had a negative CT of his chest just one month prior, when he presented to the hospital with atypical chest symptoms.  To go from a normal CT scan of your lungs to a large effusion in just one month, and no other acute problems is a first for Happy.  It became quickly apparent that an elevated D-dimer and bloody pleural effusion was unlikely to represent a transudative process, such as heart failure.

Further pulmonary venous embolism evaluation and diagnosis (CT angiogram of the chest) confirmed the presence of massive saddle  pulmonary venous embolism.  What was the source of this man's thromboembolic disease?  Of course, his venous emboli came from his massive, asymptomatic and clinically unapparent deep venous thrombosis of his right leg.  From groin to ankle a large deep venous thrombosis consumed his leg.  Yet he had no symptoms.  He had no  swelling.  No pain.  No nothin'.

I forgot to mention that this man had a history of a pulmonary embolism five years prior, so pulmonary venous embolism was #1 on my list of the differential diagnosis, despite the terribly unusual presentation for pulmonary venous embolism this would represent.  I would consider this a long tail presentation of a common medical condition.    I've seen pleural effusions from pulmonary emboli before.  But I've seen never them like the one I did that day.

This case also shows how important the history and physical examination is in developing the differential diagnosis. And why you must always be on your guard for unusual presentations of common disease.  Something that the intensity of medical school and residency training turns just another provider into doctors.

Chest-Xray-Pleural Effusion-Pulmonary -Embolism

Facebook humor-->Someone found my blog by typing in "saddled pulmonary embolism"Giddy-up!

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