Page 144 - Basic Monitoring in Canine and Feline Emergency Patients

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If possible, fluid found on AFAST , TFAST , or A halo sign surrounding the gall bladder (gall bladder
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VetBLUE should be sampled via US-guided centesis wall thickens and appears striated with alternating
VetBooks.ir to further characterize the type of effusion. The echogenicity – hypoechoic and then hyperechoic) is
fluid should be sampled because visualization of
sometimes noted. This occurs with pericardial effu-
fluid alone cannot accurately characterize the type
pancreatitis, right-sided heart failure, and canine
of fluid. If unable to safely sample scant amounts of sion, severe hypoalbuminemia, cholangiohepatitis,
effusion, a reassessment FAST should be performed anaphylaxis.
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after fluid resuscitation. Any samples obtained 2. The US probe is then fanned to the left and right
should ideally be saved for culture, biochemical to evaluate other liver lobes. Always keep the dia-
testing, and cytology. The details of abdominal and phragm in view to look for effusion between the
thoracic fluid analysis methods are beyond the liver lobes and diaphragm. Make attempts to avoid
scope of this chapter and the reader is referred to the stomach during this component of the examina-
the Further Reading section for more information. tion to help prevent edge shadowing artifact.
For ultrasound-guided jugular venous catheteri- 3. Move the US probe so the beam is directed cra-
zation/blood sampling, the patient is typically nially through the diaphragm into the thorax and
placed in lateral recumbency but dorsal recumbency increase the depth to extend the viewing window
in stable animals has also been described. As men- into the pericardial and pleural spaces to assess
tioned above, dorsal recumbency is not recom- for fluid. This should be attempted in all patients
mended in hemodynamically compromised patients. but can prove challenging, especially in large breed
If other vessels are being catheterized/sampled, patients, as the distance may exceed the maximum
whatever recumbency and style of restraint required imaging window of the US. Viewing the pericardial
for access to that vessel is acceptable. and pleural spaces through this acoustic vantage
point allows for less air artifact. In some veteri-
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The AFAST examination nary patients, imaging of the heart through this
view can be challenging because the heart may not
With the patient in right lateral recumbency, per- lie on the diaphragm like it does in people. When
form the examination in a clockwise order starting this occurs, there can be an air interface between
at the cranial aspect of the patient (Fig. 7.2). The the diaphragm and the heart which can obscure
AFAST views are the following: diaphragmatico- imaging.
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hepatic (DH), splenorenal (SR), cystocolic (CC),
and hepatorenal (HR). When suspicious of or differentiating between peri-
cardial and pleural effusion, the operator should
Diaphragmaticohepatic view utilize at least one more additional TFAST view,
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such as the pericardial sites (see TFAST section
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The DH view is used to survey for fluid around the below), to confirm the presence of pericardial or
liver and diaphragm as well as to evaluate the pleu- pleural effusion. If pericardial effusion is suspected,
ral and pericardial spaces. This is one of the places the operator should also use multiple TFAST
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where fluid often accumulates first. views to differentiate pericardial effusion from a
The DH view is obtained in the following way:
dilated heart chamber to avoid a potentially life-
1. Utilizing the curvilinear probe, place the probe threatening misinterpretation.
longitudinally (US indicator/notch pointed crani- Lisciandro et al. in 2012 showed that nearly
ally) at the base of the patient’s xiphoid process. 88% of pericardial effusions were detected by the
The depth should be adjusted to visualize the liver, DH view and used the term ‘race-track sign’ to
gall bladder, and diaphragm. The gall bladder can portray the presence of pericardial effusion. The
be assessed for contents and wall appearance, and race-track sign describes the smooth visible borders
the lobes of the liver and diaphragm can be evalu- created by the pericardial sac and border of the
ated for free fluid accumulation between them. Care myocardium that delineates the pericardial fluid
should be made to not mistake the gall bladder for within the pericardial sac. In contrast, pleural effu-
free fluid. The best way to do this is to move the US sion has more irregular borders.
probe (i.e. ‘fan’ it) to see all sides of the gall bladder The DH view into the thorax can allow for
and look for the biliary tree extending out of the evaluation of the presence or lack of the ‘glide sign’
gall bladder. (which will be discussed in more depth with the

136 D.M. Hundley