Q on Fat emboli and strokes

[fukdbyMIT]

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How do fat emboli from long bone fractures cause stroke/cerebral infarction? Wouldn't the embolus go through venous circulation first then go to the right side of the heart and then get stuck in pulmonary circulation? I don't see how fat emboli from long bone fractures can get to the brain, unless there was a VSD or ASD... but bone fractures don't predispose to them... Any thoughts?

 

[EPO]

How do fat emboli from long bone fractures cause stroke/cerebral infarction? Wouldn't the embolus go through venous circulation first then go to the right side of the heart and then get stuck in pulmonary circulation? I don't see how fat emboli from long bone fractures can get to the brain, unless there was a VSD or ASD... but bone fractures don't predispose to them... Any thoughts?

I believe fat emboli, being lipid-solubble, are able to get into the pulmonary circulation, and from there, the brain. The other types of emboli require a septal defect to "cross over" to the left side of the circulation. The only one out of FAT BAT (fat, air, thrombus, bacteria, amnionic fluid, tumor) I'm not sure about is air. Would an air embolus be able to cause a stroke? How's this for answering a question with another question. 😀

 

[sevoflurane]

I believe fat emboli, being lipid-solubble, are able to get into the pulmonary circulation, and from there, the brain. The other types of emboli require a septal defect to "cross over" to the left side of the circulation. The only one out of FAT BAT (fat, air, thrombus, bacteria, amnionic fluid, tumor) I'm not sure about is air. Would an air embolus be able to cause a stroke? How's this for answering a question with another question. 😀

Air embolus can cause a stroke post open heart surgery... in fact, if you are given a "snowstorm" pattern on echo, post open heart + neurologic dysfxn. = air embolus. As far as fat embolus... well, the only way I see that happening is through a PFO/ASD.... but the trick is to look for petechie and chest pain... not so sure about lipid soluability although it is a plausable thought... also a AVM could theoretically cause an emboli in the head as well.

 

[Ramoray]

ha that is funny, you dont think of some things, like how many times i have read and did questions on fat emboli and never stopped to think about how it gets there usually. I am thinking, isnt the presentation of a fat emboli following trauma usually like 24 to 48 jhours following the trauma you present with CNS disturbances? in that case it seems that it takes some time for the emboli to work its way through venous, pulmonary and back through arterial side. I am betting most dont get through but some manage to work thorugh the entire track and get to cns, which would eexplain why it takes so long to present compared to an PE which is immediate presentation for example. good question

 

[tigershark]

The mechanical theory of fat emboli suggests that small fat droplets are able to cross the pulmonary circulation...

the biochemical theory suggests that the fat emboli syndrome is due to toxicity from excessive free-fatty acids, not physical emboli per se.

There was a nice article in the nejm on this topic not too long ago.

 

[Idiopathic]

Couple of theories:

1) Actual fat droplets can pass through pulmonary capillaries, especially in the base of the lung.

2) Fat droplet deposits in vessel and causes a turbulent flow which predisposes to clotting.

The clinical presentation is likely way more important than the mechanism.

 

[fukdbyMIT]

interesting perspectives. thanks