6.2. Comparison of FAST and AFAST in dogs.
Source: Reproduced with permission of Dr Gregory Lisciandro, Hill Country Veterinary Specialists, FASTVet.com, Spicewood, TX.
| Parameters | FAST (Boysen et al. 2004) | AFAST (Lisciandro et al. 2009) |
|---|---|---|
| Primary presentations | 65% | 96% |
| FAST positive cases | 45% | 27% |
| Low‐scoring (AFS 1 and 2) small‐volume bleeders | NA | 13 |
| High‐scoring (AFS 3 and 4) large‐volume bleeders | NA | 14 |
| Cases of abdominocentesis prior to AFAST/FAST examination | 16 | 0 |
| Median time trauma to AFAST/FAST examination | 240 minutes | 60 minutes |
| Median time presentation to AFAST/FAST examination | 60 minutesFAST was a secondary evaluation post initial resuscitation | <5 minutesAFAST was a first‐line screening test |
| Median time for AFAST/FAST examination | 6 minutesShaved sites | 3 minutesNo shaving |
| Pelvic fractures | 20 | 22 |
| Pneumothorax | 21 | 22 |
| Appendicular fractures | 15 | 25 |
| Diaphragmatic hernia | NA | 2 |
| Number of blood transfusions | 9 | 3 |
Of note, dogs with pneumothorax (55%), pelvic fractures (40%), and high alanine transaminase (ALT) (>400 U/L) were also more likely to concurrently have or develop hemoabdomen detected by either their initial or serial AFAST examinations than dogs without these findings (Lisciandro et al. 2009; Lisciandro 2014c). The serial use of AFAST is helpful in determining the integrity of the urinary bladder, estimating urinary bladder volume and urine output during resuscitation (Lisciandro et al. 2009; Lisciandro 2011; Lisciandro and Fosgate 2017). Both FAST and AFAST studies documented that when the urinary bladder was imaged with an expected, smooth, rounded contour, it was unlikely to be ruptured, holding advantages over traditional means of palpation, characterization of urine post micturition, and plain radiography (Boysen et al. 2004; Lisciandro et al. 2009; Boysen and Lisciandro 2013).
More recently, a urinary bladder estimation formula for use during AFAST has been published and provides a noninvasive way to estimate urine output when serial calculations are made over time (Lisciandro and Fosgate 2017). AFAST additionally remains useful to survey for intrathoracic trauma, pleural and pericardial effusion, and lung conditions, through the acoustic window of the liver and gallbladder by imaging cranial to the diaphragm in every patient, dependent on patient size, coupled with depth limitations of the ultrasound machine (Boysen et al. 2004; Lisciandro et al. 2009; Lisciandro 2011, 2016a; McMurray et al. 2016).
Lastly, AFAST was never meant to be a “flash exam,” meaning that it was never meant to only answer a single binary question of whether free fluid was present or absent (Table 6.3). AFAST provides much more clinical information by:
Table 6.3. What clinical questions are answered using AFAST? Binary? Qualitative‐quantitive?.
Source: Reproduced with permission of Dr Gregory Lisciandro, Hill Country Veterinary Specialists and FASTVet.com, Spicewood, TX.
| Binary | Qualitative‐quantitive | aSensitivity (Se) aSpecificity (Sp) | |
|---|---|---|---|
| Does the patient have free fluid in the abdominal cavity? | √Yes or no | √Use AFAST‐applied fluid scoring system (1–4) | Se – HighSp – High |
| Does the patient have free fluid in the retroperitoneal space? | √Yes or no | √Trivial, mild, moderate, severe | Se – High to variableSp – High |
| Does the patient have any obvious AFAST target organ abnormalities? | √Yes or no | √ | Se – Variable, operator dependentSp – High |
| Does the patient have pleural effusion? | √Yes or no | √Trivial, mild, moderate, severe via its DH view | Se – HighSp – High |
| Does the patient have pericardial effusion? | √Yes or no | √Trivial (<0.5 cm), nild (>0.5 and <1.0 cm), moderate (>1.0 and <2 cm), severe (>2 cm) via its DH view (Candotti and Arntfield 2015) | Se – HighSp – High |
| Does the patient have lung pathology along the pulmonary–diaphragmatic interface? | √Yes or no | √Vet BLUE B‐line scoringVet BLUE 6 lung ultrasound signs (Lisciandro 2014b,c; Lisciandro and Fosgate 2017) | Se – Unknown, operator dependentSp – Likely high |
| What is the patient's volume status? | √Unremarkable or abnormal | √Characterizing the dynamic changes in height of caudal vena cava (bounce, fluid responsive; FAT, fluid intolerant; or flat, hypovolemic) (see Figures 36.7, 36.10–36.12); coupled with hepatic venous characterization (presence or absence of the “tree trunk sign” – see Figure 36.8); and absolute maximum CVC height measurements (see Table 36.3) | aHypervolemia Se – Likely high Sp – Likely high aHypovolemia Se – Likely variable Sp – Likely high aEuvolemia Se – Variable Sp ‐ Variable aIntegrating TFAST echo and Vet BLUE pulmonary information likely improves both Se and Sp |
| What is the patient's urine production? | √Length (cm) × width (cm) × height (cm) × 0.625 = volume estimation (mL) | Unknown |
a Clinical experience, limited veterinary studies, human studies.
having a fluid scoring system
