Point-of-Care Ultrasound Techniques for the Small Animal Practitioner. Группа авторов
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and an assigned abdominal fluid score, and even better the Global FAST approach. By only performing a POCUS examination targeted at a specific organ or system, you risk missing obvious significant conditions to the patient's detriment. Integration of POCUS information is now similarly being advocated in human medicine like the author's Global FAST approach (Lichtenstein 2010; Narasimhan et al. 2016; Ha and Yo 2016).
Calculating the Abdominal Fluid Score
The AFAST‐applied fluid scoring system is a simple and easy to remember 0–4 scoring system developed over a decade ago (Lisciandro et al. 2009). Originally, each AFAST view was scored as 0 being negative or 1 being positive; however, the abdominal fluid scoring system has been further modified, explained subsequently based on more recent studies (Romero et al. 2015; Lisciandro et al. 2019). With this system, an abdominal fluid score (AFS) of 1 was defined as positive at any single AFAST view, an AFS of 2 was positive at any two views, an AFS of 3 was positive at any three views, and the maximum AFS of 4 was positive at all four views (Figure 7.1). The impact of assigning an AFS is that in bleeding patients, an AFS of 1 and 2 is characterized as major injury/pathology, “small‐volume bleeder.” In contrast, an AFS 3 and 4 are characterized as major injury/pathology, “large‐volume bleeder” (Lisciandro et al. 2009; Lisciandro 2011, 2012). “Small‐volume” versus “large‐volume” effusions may also be semiquantitated regarding fluid loss (third spacing) into the abdominal cavity.
Figure 7.1. AFAST‐applied abdominal fluid scoring system. Calculating the abdominal fluid score (AFS) using the AFAST‐applied fluid scoring system shown on a cat placed in right lateral recumbency as a 0–4 system (the same system applies analogously to left lateral recumbency and to dogs). An AFS of 1 is a positive at any single view, an AFS 2 as any combination of two views, an AFS 3 as any combination of three views, and the maximum AFS of 4 when positive at all four views. Note the author has recently modified the AFS by assigning a score of ½ at views that have smaller pockets with maximum dimensions of ≤1 cm or >1 cm in dogs and ≤0.5 cm or >0.5 cm in cats based on more recent research (see Figure 7.2) (Romero et al. 2015; Lisciandro et al. 2019).
Source: Reproduced with permission of Dr Gregory Lisciandro, Hill Country Veterinary Specialists and FASTVet.com, Spicewood, TX. Illustration by Hannah M. Cole, Adkins, TX.
Modification of the Abdominal Fluid Scoring System – Using Maximum Dimensions
For several years the author has used a modified AFS system to better differentiate between small‐volume and large‐volume bleeder and effusions. The modified system now includes scores of 0, ½, and 1, which we refer to as the measurement approach (Lisciandro et al. 2015, 2019; Romero et al. 2015). The measurement approach categorizes positives as ½ or 1 dependent on the maximum dimension at each AFAST view (Figure 7.2). Based on recent research since the first edition, we suggest an “under–over” of 1 cm (10 mm) in dogs and “under–over” of 0.5 cm (5 mm) in cats (Lisciandro et al. 2015, 2019; Romero et al. 2015). Thus, in a dog, when a maximum dimension at an AFAST view is ≤1 cm, it is scored as a ½, and if >1 cm, it is scored as 1; and in a cat ≤0.5 cm is scored as a ½ and >0.5 cm is scored as a 1 (Figure 7.3; see also 7.8).
Figure 7.2. The “measurement” modification of the AFAST‐applied abdominal fluid scoring system. The figure shows the measurement abdominal fluid scoring (AFS) system. (A,B) Cartoons of a cat in right and left lateral recumbency and (C,D) cartoons of a dog in right and left lateral recumbency. The modification of the AFS better distinguishes between “small‐volume” and “large‐volume” bleeding (and other forms of nonhemorrhagic effusions) by assigning a score of ½ or 1 dependent on the maximum measured dimension at each AFAST view based on recently published studies (Lisciandro et al. 2015, 2019; Romero et al. 2015). The AFS is validated in either right or left lateral recumbency (Lisciandro et al. 2009). See also Figure 7.3.
Source: Reproduced with permission of Dr Gregory Lisciandro, Hill Country Veterinary Specialists and FASTVet.com, Spicewood, TX. Illustration by Hannah M. Cole, Adkins, TX.
The “small‐volume bleeder versus large‐volume bleeder” principle remains the same with a 0–4 system as published (Lisciandro et al. 2009); however, the addition of the ½ helps better semiquantitate and categorize the bleeding dog and cat (Lisciandro et al. 2019). The modified fluid scoring system may also be used with nonhemorrhagic effusions since any effusion potentially contributes to volume loss in your patient. Clinical judgment always should be considered along with the patient's entire clinical picture; however, this AFS modification provides an option to better categorize bleeding patients and those with other nonhemorrhagic effusions. For example, a dog may have small pockets at the DH, CC, and HRU views of <1 cm which would now be deemed a small‐volume bleeder (if a bleeding case) with a score of 1½ rather than a 3 (see Figure 7.8).
Applying the Abdominal Fluid Scoring System to the Hemoabdomen
The “abdominal” fluid scoring system was purposely named as such and not the “hemorrhage” scoring system to avoid the system being typecast for only hemorrhage. The name, however, seems to have prevented its routine use in bleeding cases despite its documented ability to semiquantitate volume, rapidly categorize the bleeding patient, and help with decision making regarding blood transfusion(s) and exploratory laparotomy. The AFS system furthermore serves to track patients for worsening hemorrhage (or effusions) by increasing AFS, static hemorrhage (or effusions) by no change in AFS, and resolving hemorrhage (or effusions) by decreasing AFS. Knowing the patient's AFS is incredibly helpful for clinicians performing AFAST to place the degree of hemorrhage into clinical context (Lisciandro et al. 2009). The AFS should be used as standard of care, calculated and recorded for all patients having AFAST.
Small‐Volume Bleeders: AFS 1 and 2 (AFS <3)
AFS 1 and 2 (AFS <3) are “small‐volume bleeders” that reliably will not become significantly anemic from their intraabdominal bleed because, simply put, there is not enough intraabdominal hemorrhage to cause anemia (Figures 7.4 and 7.5). Of course, they must remain an AFS of 1 or 2 (AFS <3) on serial AFAST examinations.
If an AFS 1 or 2 (AFS <3) dog or cat is or becomes anemic, then there are four major possibilities.The patient had preexisting anemia.The patient is bleeding somewhere else, emphasizing the importance of the Global FAST approach and a good physical examFigure 7.3. Modification of the AFAST‐applied AFS. The figure shows how size matters, using the AFAST CC view as an example. In (A) the small pocket, anechoic triangulation (circled) would be scored a ½ as a “soft” positive whereas in (B) the larger pocket would be scored a full 1 as a “strong” positive. This visual modification is used at all AFAST views and is an alternative to the measurement modification shown in Figure