Is the eFAST Slowly Fading?
When the point of care ultrasound in trauma was first introduced to North America, Canada and Australia in the 1990’s it had already been used for just under 2 decades in Europe in a less structured approach. After being labelled as the FAST and sealed into the writ of trauma care, this new modality quickly came under scrutiny. Initial investigators quote sensitivities and specificities in the high 80’s and 90’s (1) yet many of these early studies were conducted in healthy young men and relied on progression to laparotomy, rather than CT findings, as a gold standard(2). This clearly biased method of reporting was put to bed after comparison with CT; also in part due to CT’s increased ability to detect solid organ and intra-capsular injuries which don’t cause free-fluid. Advanced imaging therefore diminished the reverence for the FAST, dropping it to an accuracy that sat in the high 60’s to 70’s(3).
Since then, the addition of the “e” to the eFAST for cardiac views in the early 2000’s, and later lung views(3), has seen the exam waver in favourability from fad to sad and back again. It almost feels as though the chances of someone hating this poor exam are about as good as a chest X-ray’s inability to detect a pneumothorax (Supine CXR missed up to 76% of pneumothoracies in Ball et al’s 2009 study (4)). Which isn’t having a jibe at the expense of the humble chest radiograph; plain chest films simply aren’t a test that’s particularly well cut-out for detecting pneumothorax.
Which brings us back to the eFAST.
The way we use ultrasound in our trauma care today is radically different from the way it was used twenty to thirty odd years ago. We no longer routinely do diagnostic peritoneal lavages, CT scans are easily accessible and fast, and our contemporary conservative approach to trauma is an alien notion to the aggressive and invasive style of 1990’s Post-MASH era ATLS.
All too often, the eFAST is abused as a diagnostic exam; misused for all the wrong reasons. It was designed for use in the unstable, “sick” adult trauma population, in an environment where access to CT scan was limited, if not completely unfeasible, and where trauma surgeons were often the most experienced resuscitationists in the room. Today’s clinical landscape is different. Highly specialised critical care providers are using increasingly evidence based guidelines to optimise trauma care. Teams are multidisciplinary. And most of all, the truly sick trauma patient is usually either expedited straight to the CT scanner, to theatres for surgical intervention, or to interventional radiology. It is the often moderately unwell trauma patient in whom we now perform an eFAST, many of whom do not have the acuity to have progressed to the odd 500mls of intra-abdominal free blood to yield a “positive” exam finding. (5)
In response to this acknowledgement; that it takes time to develop the volume of blood necessary to detect a positive eFAST; serial examinations arose. (1)
A test which was originally designed to detect gross and large volume intraabdominal blood loss now became used as a conservative ‘watch and wait’ screening tool, almost as if we all acknowledged that it could not be used to rule-out bleeding, but decided to use it as such, irrespectively.
And so we find ourselves in 2018.
With the prevalence of CT imaging and a clinical disconnect between a positive FAST and a need for operative intervention; one must ask “Is there still a role for the eFAST?”
I would argue that there is.
One wouldn’t perform a focussed bedside echo and conclude that; simply because one could not detect a subtle valvular abnormality today, that one should see the patient again in a week when they present with profound systolic failure detectable on focussed exam. Similarly, the eFAST should not be used to replace comprehensive imaging in the “stable” trauma patient.
The eFAST should be respected for its intended purpose; that is, a highly targeted screening tool for life-threatening pathology in the acutely unwell trauma patient or the profoundly unwell ectopic pregnancy. It should remain a powerful ally in detecting “quick kills”; to rule out massive tension haemopneumothorax in the context of the hypotensive and dyspnoeic polytrauma patient, to rule out cardiac tamponade in the blunt chest wall injury, to aid the in decision making process to trigger a massive transfusion protocol and move to definitive care for massive intraabdominal bleeding.
This is what the eFAST was intended for.
It was not designed to be used as a bargaining chip between admitting teams over a “stable” single organ injury patient.
It was intended, and performs to the heights of its test characteristics, when used in the severely unwell with gross pathology; as do almost all POCUS exams. As a quick, ‘fast’ (if you will) tool to detect pathology that will imminently harm our patient, and to focus our efforts on that threat.
Aidan @ AIU
- Nunes LW, Simmons S, Hallowell MJ, Kinback R, Trooskin S, Kozar R. Diagnostic performance of trauma US in identifying abdominal or pelvic free fluid and serious abdominal or pelvic injury. Academic Radiology [Internet]. 2001 Feb;8(2):128–36. Available from: http://linkinghub.elsevier.com/retrieve/pii/S1076633201900571
- Pearl WS, Todd KH. Ultrasonography for the initial evaluation of blunt abdominal trauma: a review of prospective trials (Structured abstract). 1996;(March):353–61. Available from: http://onlinelibrary.wiley.com/o/cochrane/cldare/articles/DARE-11996000599/frame.html
- Richards JR, McGahan JP. Focused Assessment with Sonography in Trauma (FAST) in 2017: What Radiologists Can Learn. Radiology [Internet]. 2017;283(1):30–48. Available from: http://pubs.rsna.org/doi/10.1148/radiol.2017160107
- Ball CG, Ranson K, Dente CJ, Feliciano D V., Laupland KB, Dyer D, et al. Clinical predictors of occult pneumothoraces in severely injured blunt polytrauma patients: A prospective observational study. Injury [Internet]. 2009 Jan;40(1):44–7. Available from: http://linkinghub.elsevier.com/retrieve/pii/S0020138308003604
- Branney SW, Wolfe RE, Moore EE, Albert NP, Heinig M, Mestek M, et al. Quantitative Sensitivity of Ultrasound in Detecting Free Intraperitoneal Fluid. The Journal of Trauma: Injury, Infection, and Critical Care [Internet]. 1995 Aug;39(2):375–80. Available from: https://insights.ovid.com/crossref?an=00005373-199508000-00032