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

penetrating trauma, postinterventional (percutaneous biopsy, laparoscopy, and postlaparotomy, i.e., ovariohysterectomy, splenectomy, adrenalectomy, liver lobectomy, nephrectomy, gastrointestinal surgery, bladder surgery, etc.) by applying its abdominal fluid scoring system.

       Can be used serially (repeating AFAST) for surveillance of all patients atrisk for bleeding, peritonitis, and other nonhemorrhagic effusive conditions.Table 7.1. Questions answered during AFAST.Source: Reproduced with permission of Dr Gregory Lisciandro, Hill Country Veterinary Specialists and FASTVet.com, Spicewood, TX.Is there any free fluid in the abdominal (peritoneal) cavity?Yes or noHow much free fluid is in the abdominal cavity using the AFAST‐applied fluid scoring system?0 (negative), 1, 2, 3, and 4 (maximum score)Is there any pericardial effusion?Subjective amount?Yes or noTrivial (<0.5 cm), mild (>0.5 and <1.0 cm), moderate (>1.0 and <2 cm), severe (>2 cm) on DH view (Candotti and Arntfield 2015)Is there any pleural effusion?Subjective amount?Yes or noTrivial, mild, moderate, severeWhat does the pulmonary‐diaphragmatic surface look like?Are there any lung lesions along the diaphragm?Unremarkable or abnormalB‐lines, shred sign, tissue sign, nodule sign (Lisciandro 2014c; Lisciandro and Fosgate 2017)What does the gallbladder look like?Unremarkable, halo sign, abnormalities in its lumen or wallWhat do the target organs look like at each AFAST view?Unremarkable or abnormalWhat do the caudal vena cava and its associated hepatic veins look like?Unremarkable (bounce) or abnormal (FAT, flat) (see Tables 7.6 and 36.3 and Figures 36.7, 36.10–36.12) and presence of “tree trunk sign” (see Figure 36.8)What is estimated bladder volume?What is estimated urine output?Length (cm) × width (cm) × height (cm) × 0.625 = estimation in milliliters (mL)Difference in serial volume measurements/time (Lisciandro and Fosgate 2017)Could I be misinterpreting an artifact or pitfall as pathology?Know pitfalls and artifacts (see Chapter 6)

       Can serially track bleeding patients as worsening (ongoing) hemorrhage (increasing AFS), static hemorrhage (no change in AFS), and resolution (decreasing AFS).

       Can serially track peritonitis (and other nonhemorrhagic effusions) as worsening (increasing AFS), static (no change in AFS), and resolution (decreasing AFS).

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

       Can detect pleural and pericardial effusions by routinely imaging cranial to the diaphragm at the AFAST DH view.

       Can screen for anaphylaxis in dogs through the detection of sonographic striation of the gallbladder wall, referred to as the “halo effect,” “double rim effect” or “gallbladder halo sign” at the AFAST DH view; however, the finding is not pathognomonic and cardiac conditions should always be ruled out in the acute triage setting and other more chronic causes.

       Can assess volume status and right‐sided cardiac function by evaluating caudal vena caval size and characterization coupled with hepatic venous distension and gallbladder wall edema at the AFAST DH view.

       Can screen for obvious target organ injury or pathology, serving as a soft tissue screening test.

       Can assess urinary bladder integrity (rupture or intact) at the AFAST cysto‐colic (CC) view in trauma and urinary obstructed cases.

       Can noninvasively estimate urinary bladder volume and thus urine output through bladder measurements at the AFAST CC view.

       What AFAST Clinical Integration Cannot Do

       Cannot ultrasonographically characterize fluid, so sample acquisition via centesis and fluid analysis and cytology is required when free fluid is safely accessible.

       Lacks sensitivity for injury in penetrating trauma because blood acutely clots, but is likely highly specific for intraabdominal and retroperitoneal injury similar to human studies; serial examinations are imperative in questionable patients.

       Potentially misses peritonitis and small‐volume bleeds in dehydrated or hypotensive patients. AFAST examinations should be applied minimally once after resuscitation and rehydration has taken place and as many times as necessary until you are assured that the patient is not surgical

       Cannot replace a detailed complete abdominal ultrasound.

       Cannot replace proper training.

       Indications

      In reality, AFAST and the Global FAST approach are everyday imaging modalities for nearly every patient as an extension of the physical examination. However, to better grasp this concept with baby steps to get to “an extension of the physical examination” mentality, we have bulleted the following.

       All blunt and penetrating trauma cases as standard of care for screening for indirect evidence of intraabdominal injury.

       All collapsed (both recovered and unrecovered) cases with unexplained hypotension, tachycardia, or mentation changes.

       All anemic cases.

       All “ain’t doing right” (ADR) cases.

       All postinterventional, postsurgical cases, at risk for bleeding, infections, vascular complications.

       All peritonitis suspects, including acute abdomen, for expedient diagnosis through the detection of free fluid (and sampling, fluid analysis testing as deemed appropriate).

       Add‐on for all POCUS exams (abdomen, thorax, eye, brain) to make sure that forms of peritonitis and pleuritis, presence of bleeding, cardiac and pulmonary complications are not being missed that could have easily been detected with the Global FAST* approach.

      *The Global FAST approach includes the combination of AFAST and its fluid scoring system and its target organ approach, the TFAST and Vet BLUE combined as part of the physical examination (see Chapters 36 and 37).

       Objectives

       Perform the five acoustic windows of AFAST and accurately assign and abdominal fluid score.

       Apply the “small‐volume bleeder versus large‐volume bleeder” principle to hemorrhaging subsets of small animal patients to better direct definitive therapy and decision making, including the need for blood transfusion and exploratory surgery and medical versus surgical management.

       Recognize sonographic striation of the gallbladder wall referred to as the “halo effect,” “double rim effect” or “halo sign.”

       Know additional rule‐outs (cardiac causes) for the collapsed or acutely weak dog with sonographic striation of the gallbladder wall.

       Know additional rule‐outs for sonographic striation of the gallbladder wall in dogs and cats without acute collapse and weakness.

       Recognize retroperitoneal free fluid and distinguish it from intraabdominal fluid.

       Recognize pleural and pericardial effusion via the DH view by looking cranial to the diaphragm.

       Know how to assess volume status through characterization of the caudal vena cava and its associated hepatic veins.

       Know common artifacts and pitfalls at each respective AFAST view (see Chapter 6).

       Final Note

      The POCUS abdominal, thoracic, ocular, neurological,