Page 153 - Basic Monitoring in Canine and Feline Emergency Patients

human literature. Once this bullseye effect is appre- The abdominal fluid score (AFS) has been devel-
ciated, the operator may cannulate the vessel or oped to predict the severity of anemia in the trau-
VetBooks.ir collect the blood sample. matic hemoabdomen by differentiating between a
For longitudinal orientation venipuncture, the
small and large bleeding event. The same AFS sys-
operator should start by identifying and focusing
rhage serial monitoring. The AFS allows for
on the image of the vessel in transverse orientation. tem has also been applied in postoperative hemor-
Then, the US probe is rotated 90° so that the vessel semi-quantification of the degree of hemorrhage for
appears as an anechoic to hypoechoic tract across comparison at different time points and may allow
the screen with the probe indicator/notch facing veterinarians to predict the future need for blood
rostrally. The needle or introducer catheter should products. This scoring system has been validated in
be held within the dominant hand and placed cases of trauma in dogs but is not predictive for
through the skin 1–2 cm rostral to the US probe anemia and transfusion requirements in cats.
and perpendicular to the indicator/notice on the An AFS of 1–2 is associated with small amounts
transducer. The angle that the needle or introducer of bleeding, and an AFS of 3–4 is associated with
catheter should be inserted into the skin is depend- larger bleeding events. In dogs, higher AFS scores in
ent upon the depth of the vessel and distance of trauma cases are associated with development of
insertion rostral to the US probe. anemia, a higher need for blood transfusions, and,
Once the needle or introducer catheter is inserted rarely, a requirement for surgical intervention. In
into the skin, the US probe is moved slightly ros- trauma patients, the AFS can also help a practi-
trally to visualize the hyperechoic needle as it tioner to determine sources of blood loss. For
inserts into the vessel through the dorsal vessel wall example, if a patient without a pre-existing anemia
(Fig. 7.9B). The vessel wall may bow inward or roll that has a static traumatic AFS of only 1–2 devel-
away from the US view. If this occurs, the operator ops anemia in the hospital, a clinician should look
should slightly withdraw the needle or introducer for other sources of ongoing hemorrhage including,
catheter and optimize the image of the vessel before but not limited to, the pericardial space, pleural
trying again. When the vessel has been successfully space, pulmonary parenchyma, and fracture sites.
penetrated, the bowing of the vessel should resolve Clinically, the AFS has been also utilized for scor-
and a flash of blood into the catheter or needle ing the accumulation of other non-traumatic abdom-
should be seen. inal effusions. If the effusion amount is increasing, it
5. If the operator is using the UST for vascular indicates a need for further diagnostic or therapeutic
access to achieve a central venous catheter, once vas- interventions. These effusions include non-traumatic
cular penetration has been confirmed, the modified bleeding (ruptured masses, coagulopathies, and post
Seldinger technique (guidewire-based technique) can interventional hemorrhage), urine, septic effusion,
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be performed for either approach. The US can be used and non-septic effusion. The AFAST can be more
to identify if a guidewire is feeding into the vessel sensitive in detecting hemorrhage than serial packed
appropriately during that step of the Seldinger tech- cell volume/total solids (PCV/TS), physical examina-
nique. See Further Reading section for a more detailed tion findings, and radiographs since there is a great
description of the modified Seldinger technique. ability to compensate for blood loss. Humans with
ongoing blood loss have been noted to compensate
with normal vital parameters until nearly 30% total
7.3 Indications for Ultrasound blood loss has occurred.
Evaluation
AFAST /Abdominal Fluid Score
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TFAST /VetBLUE
Since its first description in veterinary medicine in
2004 and validation in 2009, AFAST has multiple Use of TFAST in veterinary medicine was first
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applications (Table 7.3). It has been shown to be documented in 2008 for detection of pneumotho-
superior to physical examination alone and more rax (Lisciandro, 2008) in trauma patients. This
sensitive than abdominal radiographs for small study found that US by an experienced operator
amounts of effusion (up to 24% of patients with had a sensitivity of 95% for detecting pneumotho-
normal abdominal radiographs have been shown rax. Since then, the TFAST has been utilized to
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to have fluid present on AFAST examination). evaluate the intrathoracic organs and thoracic
Applications of Serial Focal Ultrasound Techniques in the Hospitalized Small Animal Patient 145