Fat embolism syndrome
Typically when we start talking about anything related to fat embolisms our minds go immediately to trauma and long bone fractures as the cause, but this isn’t always the case. The constellation of signs and symptoms of respiratory insufficiency, neurologic dysfunction and petechial rash which are typically associated with fat embolism syndrome can also be caused by pancreatitis, sickle cell disease and liposuction; all of which show up regularly in the Emergency Department. With mortality rates as high as 20%, despite the fact that FES usually doesn’t present for at least 12 hours after the initial event, it should be something that we are aware of.
There are two competing theories as what causes FES. Some believe more in the mechanical-obstruction theory where the fat globules act similarly as other embolic events, showering throughout the end organs and wreaking havoc by those means. The new challenger to this theory is the biochemical theory where proponents support the notion that the fat is broken down into free fatty acids and the damage is caused by the endothelial damage and subsequent increased vascular permeability. No matter which theory you support, the clinical diagnosis is going to be equally as challenging. There are a few criteria/scores that have been developed in the past that are non-specific diagnostic tools to identify patients with FES, but they have not been compared head-to-head in their accuracy. In the Emergency Department we are limited with the tests that we can routinely order. Unfortunately, CXRs are going to be essentially useless in diagnosing FES, but MRI may hold more promise. The starfield pattern seen on MRI is not specific to FES, but has been seen routinely in patients who have disease processes associated with FES along with neurologic symptoms. Otherwise, in the ED this is going to essentially be a clinical diagnosis with a good history and a little bit of luck. There is some evidence that earlier fixation and specific orthopedic surgery techniques may decrease the rate of FES, but from an EM point-of-view it is essentially supportive care. Research seems to be lacking into the non-trauma causes of FES, so maybe there is somewhere for us to intervene in those patients…
Post by: Terrance McGovern DO, MPH (@drtmcg13)