Point-of-Care Ultrasound Techniques for the Small Animal Practitioner. Группа авторов

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

       looking cranial to the diaphragm into the thorax at the DH view for pleural and pericardial effusion and lung conditions

       examining the gallbladder wall for signs of intramural edema

       characterizing the caudal vena cava and its associated hepatic venous system

       observing the urinary bladder for its expected rounded contour and measuring it (when applicable) for bladder volume estimation and urine output

       calculating the AFS to better make sense of the volume of blood in hemorrhaging small animals

       serving as monitoring tool for any and all effusive conditions

       taking advantage of its target organ approach.

      In other words, an AFAST not only provides a highly sensitive and specific means to detect intraabdominal and retroperitoneal effusions, but also serves as an abdominal soft tissue screening test for obvious target organ pathology. Patient information is acquired rapidly during AFAST (<3–4 minutes) with low patient impact (minimal restraint, no shaving) and point of care (Lisciandro et al. 2009; Lisciandro 2012, 2016a; Boysen and Lisciandro 2013; McMurray et al. 2016).

Abbreviations and terminology are listed in Table 6.4.

      POCUS abdominal, thoracic, ocular, neurological, and musculoskeletal examinations are more extensively described in their respective chapters; however, the POCUS approach should always include minimally an AFAST, with its target organ approach, and AFS, and, much better, the Global FAST approach, as an extension of your physical exam for best practice. Global FAST has been advocated by the author as an extension of the physical examination for virtually any small animal patient since 2005 (Lisciandro 2011, 2012, 2014a–c, 2016a,b; Lisciandro et al. 2019), with a similar approach more recently advocated in human medicine (Lichtenstein 2010; Narasimhan et al. 2016).

       What AFAST Can Do

       Can detect free fluid in small amounts superior to physical examination and abdominal radiography and comparable to the gold standard of computed tomography (CT).

       Can detect clinically significant pleural and pericardial effusions in most cases by imaging past or cranial to the diaphragm at the AFAST DH view.

       Can detect retroperitoneal effusion when imaging at the AFAST spleno‐renal (SR) and hepato‐renal (HR) views and the HR5th and SR5th bonus views.

       Can anticipate degree of anemia in different patient subsets by using its easily applied abdominal fluid scoring system.

       Can be used to screen for canine anaphylaxis through the detection of sonographic striation of the gallbladder wall as the “double rim effect” or “halo effect” or “halo sign” at the AFAST DH view, referred to as the “anaphylactic gallbladder,” coupled with the finding of a flat caudal vena cava (CVC) (see Figure 36.9).

       Can be used to screen for right‐sided congestive heart failure through the detection of sonographic striation of the gallbladder wall as the “double rim effect” or “halo effect” or “halo sign” at the AFAST DH view, referred to as the “cardiac gallbladder,” coupled with the finding of a FAT CVC (see Figure 36.7).

       Can be used to assess volume status and right‐sided cardiac function by evaluating CVC size and for the presence of hepatic venous distension, the “tree trunk sign,” at the AFAST DH view (see Figure 36.8).

       Can screen for concurrent target organ injury or pathology for basic soft tissue conditions of the liver, gallbladder, kidneys, urinary bladder, spleen, and gastrointestinal tract.

       Can assess urinary bladder integrity at the AFAST cysto‐colic (CC) view especially when there are concerns regarding rupture in trauma cases.

       Can noninvasively estimate urinary bladder volume and thus urine output at the AFAST CC view using the