(AFS 3 and 4). Moreover, the study answered what was implied in the original FAST study, that the historical use of radiographic abdominal serosal detail was an unreliable test for the presence or absence of free peritoneal fluid and its volume (Boysen et al. 2004; Lisciandro et al. 2009). In fact, 24% of dogs with normal abdominal radiographic serosal detail were AFAST positive, and 32% with decreased abdominal radiographic serosal detail were in fact AFAST negative (Lisciandro et al. 2009). Thus, in summary, not only was abdominal radiographic serosal detail unreliable for the presence and absence of free fluid, but abdominal serosal detail also could not reliably estimate the volume of free fluid present (see Figure 7.9).
The repeating of at least one more AFAST and assigning an AFS allowed the attending clinician to not only screen for the presence of free fluid that may have been missed or absent on the first AFAST examinations, but also to reassign an AFS and evaluate the urinary bladder (Lisciandro et al. 2009; Lisciandro 2011, 2012; Boysen and Lisciandro 2013). AFAST and the use of the patient’s AFS were shown to be invaluable for the detection of developing hemoabdomen (initially negative [AFS 0] turned AFAST positive [AFS 1‐4]), the detection of ongoing hemorrhage (increasing fluid score), and evidence‐based resolution of hemoabdomen (decreasing fluid score) (see Figure 7.9). Interestingly, the American College of Emergency Physicians has advocated the use of a serial four‐hour postadmission FAST examination for all at‐risk human patients since 2001 yet at the time of writing this chapter, the number one cause of death in hospitalized human trauma patients surviving traumatic brain injury during their first 48 hours of care remains ongoing, unrecognized bleeding (Bilello et al. 2011; Sobrino and Shafi 2013).
Figure 6.1. AFAST on a dog in right and left lateral recumbency. In (A) AFAST is shown on a dog in right lateral recumbency and in (B) left lateral recumbency. Sites are named by their target organs. The AFAST order is always the same. In right lateral, (1) DH view, (2) SR view, (3) CC view, (4) HRU view. In left lateral recumbency, (1) DH view, (2) HR view, (3) CC view, (4) SRU view. These AFAST views are part of the abdominal fluid scoring (AFS) system and the order ends at the most gravity‐dependent view where abdominocentesis is likely to be performed in higher‐scoring patients. Note that the 5th AFAST bonus view is not shown in these images. The AFAST views are nearly identical sonographically no matter the positioning (lateral recumbency versus standing‐sternal). AFAST target organs are imaged in the same standardized manner regarding probe maneuvering with the “fan, rock (cranially) and return to your starting point” approach.
Source: Reproduced with permission of Dr Gregory Lisciandro, Hill Country Veterinary Specialists and FASTVet.com, Spicewood, TX.
Table 6.1. Changes in methodology from FAST to AFAST.
Source: Reproduced with permission of Dr Gregory Lisciandro, Hill Country Veterinary Specialists, FASTVet.com, Spicewood, TX.
| Parameters | FAST (Boysen 2004) | AFAST (Lisciandro et al. 2009) |
|---|---|---|
| Shaving patient | Shaving | No shaving |
| Primary probe orientation | Longitudinal and transverse | Only longitudinal |
| Primary probe maneuver | Sliding, rotating and sweeping | Fanning and rocking |
| Main probe direction | Toward spine | Gravity‐dependent pouches |
| Laterala | Left | Right |
| Fluid scoring | No | Yes |
| Naming acoustic views | External locations | Target organs |
| Timing of examination (median time presentation to ultrasound examination) | Post resuscitation (median 1 hour) | Presentation and serially post resuscitation (median <5 minutes) |
a Lateral recumbency was a brilliant proposition, being markedly safer than dorsal recumbency (see Figure 6.5).
More recently, a human study showed that in people with prehospital hypotension, the only intervention that prevented the “crump factor,” the phenomenon of a patient decompensating unexpectedly, was the liberal use of FAST examinations (Bilello et al. 2011). The upshot is veterinarians have a better tool, the AFAST and its applied fluid scoring system, to determine within minutes of presentation or during hospitalized care when patients are becoming unstable, to not only “see” if the patient is positive or negative for free fluid, but also the degree of bleeding (or effusion) by easily calculating the patient's AFS (0–4 scale). AFAST and AFS are the missing link to traditional trauma, triage and tracking algorithms, and by adding the target organ approach, a huge amount of clinical information is easily gained within minutes, when minutes count.
The comparison of the original FAST to the subsequent AFAST study is fascinating and some important differences are noted (see Table 6.1) (Boysen et al. 2004; Lisciandro et al. 2009). Remarkably, degree of trauma was very similar, including numbers of pelvic fractures and pneumothoraces (Table 6.2), suggesting that the overall degree of trauma between studies was comparable and thus inferences may be loosely drawn (Boysen et al. 2004; Lisciandro et al. 2009).
One involves the case management and decision making for blood transfusion(s), and that knowing if the dog at triage was AFS positive affected fluid therapy administration strategies. In other words, intravenous fluid resuscitation was likely titrated more closely to low normal endpoints, such as mean arterial pressure, thus mitigating exacerbation of hemorrhage by lessening the probability of “popping the clot” and diluting clotting factors through overresuscitation in bleeding dogs (Lisciandro et al. 2009). The differences in median time from trauma to FAST/AFAST, median time presentation to FAST/AFAST (240 versus <5 minutes), and numbers of transfusions FAST/AFAST (9 versus 3) support this conclusion. AFAST was performed as part of the physical exam versus FAST, which was a second line test after initial assessment, intravenous fluid resuscitation, and blind abdominocentesis possibly to the dog's detriment by the much higher positive rate (45% versus 27%).
The original FAST study lacked a fluid scoring system, and as simple as the AFAST system is, with a range of 0–4 (AFS 0 negative all AFAST views to a maximum of four being positive for fluid at all four AFAST views), AFS provides an effective tool for decision making (see Table 7.3). This decision making, ranging from intravenous fluid resuscitation strategies to administration of blood transfusion products to the need for exploratory surgery, importantly carries the potential to improve outcome and decrease complications, as shown in people (see Chapter 7) (Blackbourne et al. 2004; Ollerton et al. 2006; Bilello et al. 2011).
