Practical aFAST & tFAST Flashcards
AFS
abdominal fluid score 1-4
The abdominal fluid score (AFS) helps rapidly categorize the patient as a small volume (AFS 1 and 2, or <3) versus large volume bleeder (AFS 3 and 4, or ≥ 3).
AFS 1 and 2 (< 3) do not have enough blood intra-abdominal to directly result in anemia.
An increase in AFS over time suggests ongoing bleed.
Application of AFAST in blunt trauma
The basic four-view protocol provides the foundation for the AFAST examination
(Fig. 7). The technique has been validated in right and left lateral recumbency in
dogs.
Dorsal recumbency is not typically recommended because thoracic injury is common after blunt trauma and pulmonary function may
deteriorate when patients with significant thoracic injury are placed in dorsal recumbency.
Also, the AFS system has not been validated in dorsal recumbency.
The median time to perform AFAST in dogs is reported to be 3 to 6 minutes using the
four standard views, consisting of
the (1) subxiphoid view to evaluate the hepatodiaphragmatic interface, gallbladder region, pericardial sac, and pleural spaces;
(2) a left flank view to assess the splenorenal (SR) interface and areas between the spleen and body wall;
(3) a midline bladder view to assess the apex of the bladder (cystocolic view); and
(4) the right flank view to assess the hepatorenal (HR) interface and areas between intestinal loops, right kidney, and the body wall.
The examination is typically evaluated in a clockwise rotation, moving from
the subxiphoid, to the non–gravity-dependent flank, to bladder, to gravity-dependent flank.
At each site, the ultrasound probe can be moved a few inches in several directions and fanned through an angle of 45 degrees until target organs are identified.
The subxiphoid or DH site is a good initial starting point because it allows the gallbladder to be identified. The gallbladder can be visualized by tilting
the probe to
the right of midline, and adjusting the gain until the fluid-filled gallbladder
appears anechoic.
Serial AFAST examinations should be performed every
4 hours, or more frequently if clinical findings (eg, deterioration in hemodynamic status) dictate otherwise.
The TFAST3 examination consists of
five points or areas to scan: the stationary horizontally probe-positioned CTS view; the two bilateral dynamically spotlighted PCS
views; and the DH view (part of both AFAST3 and TFAST3)
How to perform TFAST
Fur does not need to be shaved for the TFAST3; rather, the fur can be parted for probe-to-skin contact with the use of alcohol and acoustic coupling gel.
For positioning, either right or left lateral recumbency may be used in nonrespiratory patients with all but the opposing CTS (chest tube site).
The pulmonary-pleural interface (PP-line) is not to be confused by the distally positioned equidistant reverberation artifacts A-lines (air reverberation artifact) that parallel and extend from the PP-line.
B-lines
TFAST sites (3)
chest tube site / CTS
pericardial site / PCS
hepatodiaphragmatic / HD
A-lines are
air artefact, reverberation
sideways
B lines are
air artefact like bubbles, reverberation, from edema
longways
ULR =
ultrasound rockets aka another word for B lines
The step sign is defined as
an inconsistency from the normal expected linear continuity along the PP-line.
The observance of the step sign should arouse clinical suspicion for thoracic wall injury, such as intercostal tears, rib fractures, flail chest, subcostal hematoma, hemothorax, and so forth.
In non-trauma subsets of patients, the step sign may represent types of pleural effusion, lung consolidation, or lung masses (Fig. 12).
The step sign may be misinterpreted (eg, as a false-positive) if the probe is placed toofar caudally on the thoracic wall where the lung, diaphragm, and thoracic wall dynamically come into close proximity
