FAST exam in Stable Pediatrics

Peds FAST byte


Effect of Abdominal Ultrasound on Clinical Care, Outcomes, and Resource Use Among Children With Blunt Torso Trauma: A Randomized Clinical Trial

JAMA June 2017) - Pubmed Link


Take Home Points

1. In this study, the FAST does not lead to a change in CT scans, missed intraabdominal injuries, ED length of stay, or hospital charge in hemodynamically stable pediatric patients.

2. The FAST is not sensitive enough to rule out intraabdominal injury in a hemodynamically stable pediatric trauma patients.

3. More research is needed to determine the appropriate way to incorporate the FAST exam into the evaluation of a stable pediatric trauma patient.


Related Material

EM Lit of Note Review

Editorial in JAMA

Here's another article from June 2017 on the same topic and similar conclusions - Calder et al FAST in Children Following Blunt Abdominal Trauma: a Multi-Institutional Analysis

Here's a similar study but in adult patients - Natarajan et al FAST Scan: is it worth doing in hemodynamically stable blunt trauma patients?


Background

The FAST scan is used to identify hemoperitoneum or hemopericardium in trauma patients. There is adult literature to support that use of FAST decreases abdominal CT use, hospital length of stay (LOS), complications, and hospital charges, however there is a paucity of evidence supporting its use in pediatric trauma patients. This study attempted to determine if the FAST exam during initial evaluation of injured children improves clinical care.


Questions

Does the FAST examination decrease abdominal CT use, ED LOS, and hospital charges without increasing the rate of misses intraabdominal injuries (IAI) when used in the initial ED evaluation of hemodynamically stable children with blunt torso trauma?


Population

Single site study at large urban level I pediatric trauma center

Inclusion and exclusion criteria designed to identify study population with approximately 5% risk of IAI


Inclusion

  • BTT (Blunt torso trauma) + concerning mechanism

            MVC > 60mph/96kph, ejection, rollover

            Auto vs ped/bike (speed >25mph)

            Fall >20 ft

            Crush to torso

            Physical assault involving abdomen

  • BTT + GCS <15

  • BTT + paralysis, multiple long bone fractures

  • BTT + H&P suggestive of intraabdomnal injury


Exclusion

  • Hypotension (age adjusted)

  • GCS < 9

  • Abdominal seat belt sign

  • Penetrating trauma

  • Trauma > 24 hours old

  • Transferred with prior imaging

  • Known disease process that leads to fluid in abdomen


Design

Randomized, non-blinded, clinical trial

Co-Primary Outcomes:

  1. Rate of abdominal CT use (including entire hospitalization)

  2. Missed intraabdominal injuries

  3. ED LOS

  4. Hospital charges

Non-pre-specified outcomes:

  1. Time to CT

  2. Hospital LOS

  3. Physician suspicion of IAI before and after FAST


Intervention

Stratified into 3 age categories (< 3 years, 3-9.99 years, >/= 10 years)

Randomized into blocks of 20 within these age cohorts - FAST arm received FAST exam with usual standard care, Standard trauma arm did not get FAST exam

Bedside FASTs performed by ED physicians providing care

Physicians made bedside interpretations, recorded on data collections forms and on scan at time of imaging

Classified into negative, positive, indeterminate. Later also reviewed by two experienced sonographers

Also recorded suspicion of IAI before and after FAST scan in the FAST group as <1%, 1-5%, 6-10%, 11-50%, > 50%

Physician performing FAST also documented if FAST scan results changed their decision to obtain CT scan (in either direction)

1 week telephone follow up

Missed IAI = diagnosis of such an injury after patient had left the ED


Who did the scans?

ED physicians certified to perform FAST by ACEP guidelines

35 EM physicians and 5 PEM docs


The Scan

Curvilinear probe

Curvilinear probe image

Standard FAST scan without extended views or paracolic gutters (this study on the LUQ view and this one on the most sensitive view of the FAST show how you might miss positives if you don't look at these locations


Learn how to to do the FAST exam


Results

n=925

  • 460 FAST

  • 465 Standard

  • Mean age 9.7 years old


Primary Outcomes

No difference in rate of abdominal CT scans, missed intrabdominal injury (IAI), ED Length of Stay (LOS), or projected hospital charges.

Peds Data Table


1 missed IAI in FAST group. In this case, the patient received a CT - initially read as negative and was discharged home, Later the CT was overread as grade 1 liver laceration, patient came back for further observation.


Secondary Outcomes

Agreement between ED physicians and US experts moderate (k=0.45)

Among the 19 in the FAST arm who had IAI and fluid on CT, both the ED physicians and experts did not do great with FAST (example: 10 negative and 12 negative for each group. However the article does not mention where the fluid is or how much on CT.

In the FAST group physician suspicion of IAI went down after the FAST in patients already felt to be low risk. Of the 173 considered to have very low risk of IAI (< 1%) after the FAST exam, none had IAI but... 49 (28%) still got CT scans

In patients thought to be higher risk (> 5%) for IAI, the FAST did not change suspicion (seems appropriate)

The only statistically significant finding between groups was a decreased hospital LOS 29.6 hrs vs 40.2 hrs in favor of the FAST arm


Limitations

FAST not designed for hemodynamically stable patients, generally it is a bedside test to help make decision to go to OR when patient is unstable

Not blinded (for obvious reasons)

Single site, heavy on adult physicians

Chose patients with low risk of IAI which will affect the predictive value of the FAST (low prevalence of injury)

Only 50 pts (5.4%) with injury, 40 with intraabdominal free fluid

Clinicians with perhaps pre-conceived notions about utility of FAST, which would lead to bias in the outcomes measured

Not measuring how good the FAST is, rather is measuring how good people think FAST is (everybody still got CT scans)

If not going to take child to OR, why CT? This study supports the use of serial abdominal exams, trending labs, repeat FAST scans, and shared decision making

Decision to perform CT is complex and likely involved conversation between ED and trauma surgery providers

These patients are pretty healthy/not sick

  • median GCS 15 (IQR 15-15)

  • Pediatric Trauma score was 10 (12 points is max and means not sick)

  • Only 13 patients in whom physicians had >50% suspicion for IAI, only 5.4% of injury (which was target)

  • On the other hand, 16.4% of these were placed in ICU

Low sensitivity of the FAST in this study (33% vs 66% in a metaanalysis of pediatric blunt trauma patients)

Why did it take 2.5 hours to get a CT? - reassessing? wasting time? Really long FAST exams?!


Some More Thoughts on the FAST in Pediatric Trauma

In general, there are two ways you can try to use the FAST exam

  1. Rule in intraabdominal injury

  2. Rule out intraabdominal injury

1 is not going to be very useful in children because many of these injuries will be managed non-surgically. Therefore, even with a positive FAST, it may not change your management. #2 is where the money is. Pediatricians of any variety love to avoid radiating their patients (you can only imaging how much pediatric ultrasound advocates love it!). Therefore, if we can develop an algorithm or decision instrument that uses the FAST exam to take pre-test low risk children to an even lower post-test probability of intervenable injury - then, you might be able to safely avoid CT in these patients. There are a few ways this might work:

  • FAST exam combined with labs and serial abdominal exams

  • Serial FAST exams

  • Contrast enhanced FAST exam (see our post on CEUS in adults)


Long story short - we need some more studies to see if FAST would add anything to any of these strategies.


Take Home Points

1. In this study, the FAST does not lead to a change in CT scans, missed intraabdominal injuries, ED length of stay, or hospital charge in hemodynamically stable pediatric patients.

2. The FAST is not sensitive enough to rule out intraabdominal injury in a hemodynamically stable pediatric trauma patients.

3. More research is needed to determine the appropriate way to incorporate the FAST exam into the evaluation of a stable pediatric trauma patient.


Our score

4 Probes


Cite this post as

Delia Gold, MD. FAST exam in Stable Pediatrics. Ultrasound G.E.L. Podcast Blog. Published on July 03, 2017. Accessed on October 22, 2019. Available at https://www.ultrasoundgel.org/23.
Published on 07/03/17 02:00 AM
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