Page 464 - WSAVA2018
P. 464

 25-28 September, 2018 | Singapore
How to perform AFAST technique?
Free fluid tends to accumulate in the most dependent areas of the abdomen. The examination can be completed without clipping and application of alcohol. Can be performed in right or left lateral recumbency.
To detect fluid in the abdomen, ultrasonographic views (transverse and longitudinal) are obtained at each of 4 sites; just caudal to the xiphoid process, on the midline over the urinary bladder, and at the left and right flank regions (Figure 1). The examiner may choose right lateral if volume status of the patient is to be evaluated ultrasonography or if the left retroperitoneal space is to be evaluated. Left lateral recumbency may be preferred if right retroperitoneal space is to be evaluated. The transducer is centered at one of four locations and
then moved at least 4 cm and fanned through at least 45 degrees in a cranial, caudal, left, and right direction. The examination can be accomplished using only the longitudinal view at each site, although adding the transverse view is helpful if results of the longitudinal view are equivocal.
The four sites are:
the presence of air in the pleural space.
Lisciandro et al, JVECC 2008 showed that TFAST
has 78% sensitivity and 93% specificity for detecting pneumothorax. In contrast to AFAST this technique need more experienced (non radiologist) emergency doctor. In that study there were considerable differences in sensitivity when performed by an experienced sonographer (95% sensitivity with >70 scans) compared with a unexpirienced sonographer (45% sensitivity with <15 scans). "Gliding sign" should be detected in order
to diagnose pneumothorax. Despite variation, the negative predicative value of the TFAST examination is high, which indicates that the presence of the glide sign essentially rules out pneumothorax. However, failure to detect a glide sign may result from conditions other than pneumothorax.
TFAST technique:
TFAST can be performed in left, right, or sternal recumbency, and involves five views:
1. Chest tube site [CTS] view- one on each side of the thorax in longitudinal plane perpendicular (horizontally) to the ribs in the dorsal third, between the 7-9 intercostal spaces. Used to confirm or rule out pneumothorax. The sonographer must keep the transducer immobile on the chest wall to maximize the chance of detecting the glide sign.
2. Pericardial chest site [PCS] view- one on each side of the chest in the longitudinal and transverse planes, with movement and fanning of the transducer, between the 5-6 intercostal spaces.
3. Diaphragmtaico- hepatic view of AFAST.
In the normal lung there will so called the alligator sign or Bat sign: The pleural- pulmonary interface (PP line) is the roughly horizontal white line running between the two ribs and is usually visible just distal to the ribs (with exception of subcutaneous emphysema).
Lung point: The severity of pneumothorax can be evaluated by moving the probe in a dorsal to ventral direction. The point at which the glide sign returns is known as the lung point in which the step sign will be presented. This is a very specific finding and confirms the presence of pneumothorax. In the case of massive pneumothorax a lung point will not be detected.
 1.
2. 3. 4.
Figure 1
Diaphragmatico- Hepatic: just caudal to the xiphoid. Can also evaluate the thoracic cavity (pleaural and pericardial cavities)
Cysto- Colic: midline site over the bladder Hepato- Renal: right flank site
Spleno- Renal: left flank site
     TFAST-Thoracic Focused Assessment with Sonography for Trauma
TFAST are designed to RI/RO the presence of air or fluid in the pleural space, and RI/RO the presence of fluid in the pericardial space. In the normal lung movement of the pleural line on each other create the normal Glide sign indicating a normal apposition of the lung against the thoracic wall: a dynamic finding. It may be intermittent with low respiratory rates or apnea. When the gliding is lacking and and there is step sign it may be indicative to
  462
43RD WORLD SMALL ANIMAL VETERINARY ASSOCIATION CONGRESS AND 9TH FASAVA CONGRESS








































































   462   463   464   465   466