Point-of-Care Ultrasound Techniques for the Small Animal Practitioner. Группа авторов
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FASTVet.com, Spicewood, TX.Figure 7.4. AFAST‐applied AFS and the small‐volume versus large‐volume bleeder principle. Cartoon of a dog in right lateral recumbency and the “small‐volume versus large‐volume” bleeder/effusion principle. In (A) and (B) the AFS is 1 and 2, respectively. Anemia is not expected in AFS 1 and 2 (modified AFS system <3) bleeding patients. In (C) and (D) the AFS is 3 and 4 (modified AFS system ≥3), respectively. These bleeding dogs will predictably be or become anemic from the intraabdominal volume of blood. The same principle holds true for cats. The AFS is validated only in lateral recumbency. CC, cysto‐colic view; DH, diaphragmatico‐hepatic view; HRU, hepato‐renal umbilical view; SR, spleno‐renal view.Source: Reproduced with permission of Dr Gregory Lisciandro, Hill Country Veterinary Specialists and FASTVet.com, Spicewood, TX. Illustration by Hannah M. Cole, Adkins, TX.Figure 7.5. AFAST‐applied AFS system and the small volume versus large volume principle. Cartoon of a dog in left lateral recumbency and the “small‐volume versus large‐volume” bleeder/effusion principle. In (A) and (B) the AFS is 1 and 2, respectively. Anemia is not expected in AFS 1 and 2 (modified AFS system <3) bleeding patients. In (C) and (D) the AFS is 3 and 4 (modified AFS system ≥3), respectively. These bleeding dogs will predictably be or become anemic from the intraabdominal volume of blood. The same principle holds true for cats. The AFS is validated only in lateral recumbency. CC, cysto‐colic view; DH, diaphragmatico‐hepatic view; HRU, hepato‐renal umbilical view; SR, spleno‐renal view.Source: Reproduced with permission of Dr Gregory Lisciandro, Hill Country Veterinary Specialists and FASTVet.com, Spicewood, TX. Illustration by Hannah M. Cole, Adkins, TX.Hemodilution has occurred from fluid therapy, which is much less common than a couple of decades ago because of more recently taught titrated fluid therapy.Lab error.
Large‐Volume Bleeders: AFS 3 and 4 (AFS ≥3)
AFS 3 and 4 (AFS ≥3) are “large‐volume bleeders” that are or will reliably become anemic from their intraabdominal bleed because, simply put, there is enough intraabdominal blood to cause anemia (see Figures 7.4 and 7.5).
Generally expect a 20–25% decrease from baseline packed cell volume (PCV) for all dogs and cats.
In the author's experience, ~1 in 4–5 dogs (unknown in cats) will become severely anemic (dogs PCV <25%; cats PCV <20%), requiring a blood transfusion(s).
Surgical intervention varies with patient subsets (Table 7.2).
A hemoabdomen decision‐making algorithm for correlating the AFS to the anticipated degree of anemia and decision making in different patient subsets is provided in Table 7.3.
Importance of the Serial Exam
Serial AFAST with an assigned AFS is key for monitoring changes, and for better detecting the “small‐volume bleeder” that is becoming a “large‐volume bleeder” often before overt patient decompensation, referred to by some as the “crump factor” (Bilello et al. 2011) (see Figure 7.9). Veterinarians using the AFAST and AFS approach have advantages over human medicine, in which hemorrhage scoring systems are not routinely implemented despite the fact that occult or unrecognized ongoing hemorrhage is the top cause of death next to traumatic brain injury in hospitalized human trauma patients within their first 48 hours of care (Bilello et al. 2011; Sobrino and Shafi 2013). Moreover, the most important intervention that prevented the “crump factor” in people with prehospital hypotension was the “liberal use of FAST” examinations over physical examination, vital signs, and base deficit (Bilello et al. 2011).
In addition, serial exams are important because they allow for the evaluation of the urinary bladder in two major ways: the integrity of the urinary bladder (expected rounded contour versus suspect rupture) and estimation or urinary bladder volume and urine output (Lisciandro and Fosgate 2017) (see Figures 7.9 and 7.15). Soft tissue and luminal conditions (masses, sediment, calculi, thrombus) can also be recognized. Patients change and a minimum of one postresuscitation serial exam should be standard of care, four hours post admission in stable patients and sooner in unstable or questionable patients (Lisciandro et al. 2009; Boysen and Lisciandro 2013).
Table 7.2. Summary of patient management guidelines for hemoabdomen and positive abdominal fluid scoring (AFS) for different patient subsets.
Source: Reproduced with permission of Dr Gregory Lisciandro, Hill Country Veterinary Specialists and FASTVet.com, Spicewood, TX.
| Type of trauma | Major injury/pathology, small‐volume bleeder(AFS 1, 2; modified AFS system <3) | Major injury/pathology, large‐volume bleeder(AFS 3, 4; modified AFS system ≥3) |
|---|---|---|
| Blunt trauma | ||
| Think Medical First Use AFS to help with decision‐making regarding transfusions and surgical intervention. Blood rapidly defibrinates thus is seen even acutely as anechoic (black) triangulations | If stays AFS 1, 2 (AFS <3) no blood transfusion necessary if only bleeding intraabdominallyDo NOT expect anemiaExpect PCV to be >30% in dogs and >24% in cats if only bleeding intraabdominallyIf stays AFS 1, 2 (AFS <3) and becomes anemic <30% in dogs and <24% in cats, rule out another site of bleeding (retroperitoneal, pleural cavity, fracture site, externally) so do Global FAST and a good physical examUncommon but possible for other nonhemorrhagic effusions (uroabdomen, bilioabdomen, other) | If an AFS 3, 4 (AFS ≥3) or becomes AFS ≥3 then expect anemia <30% in dogs and <24% in catsUse titrated fluid therapy strategies as 1/3 shock dose and repeat as fluid challenges are neededIf patient becomes severely anemic <25% in dogs and <20% in cats then generally treat medically first by blood transfusion(s)Note most intraabdominal bleeding in this subset will stop with 1 or 2 rounds of blood transfusion +/‐ replacement of clotting factorsUncommonly need exploratory surgeryUncommon but possible for other nonhemorrhagic effusions (uroabdomen, bilioabdomen, other) |
| Penetrating trauma | ||
| Think Surgical for Any Positive AFS Blood often acutely clots from ripping, tearing, crushing of tissue and thus is often missed during AFAST because clotted blood looks like adjacent soft tissue In time, blood clots will defibrinate and become free fluid, detected as anechoic (black) triangulations In time, ruptured, injured viscus organs will also leak or effuse, thus serial AFAST exams are key in cases in which medical vs surgical management is unclear Serial AFAST exams are key – at four, eight, 12 and 24 hours, two, three and five days You will miss a developing septic abdomen, pyothorax, by not using this strategy | Generally best to assume in penetrating trauma that all cases are surgical with ANY positiveCombine AFAST (or Global FAST) with other clinical findings and surgical indications (hernia, pneumoperitoneum, septic abdomen, refractory pain, etc.)Sample fluid when safely accessible and characterize the effusion with fluid analysis and cytologySerial exams are key – at four, eight, 12 and 24 hours, two, three and five daysYou will miss a developing septic abdomen, pyothorax, by not using this strategyCT is the gold standard imaging test |
Generally |