Page 146 - Basic Monitoring in Canine and Feline Emergency Patients

patient’s ventrum or toward to the AFAST opera- The CTS is performed via the following steps.
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tor’s left-hand side.
VetBooks.ir 2. Direct the US probe toward the table into the 1. The transducer is placed on the chest wall at the
highest point of the thorax in right lateral recum-
gravity-dependent area of the scan. Look for fluid
accumulation in this region. In some cases, the US
at the level of approximately the eight to ninth inter-
probe can be used to gently direct the loops of bency (approximately the dorsal third of the thorax,
bowel out of the field of view. costal spaces in normal chested dogs and cats and
3. If trauma to the right kidney is suspected, roll seventh to eighth intercostal space in barrel chested
the patient slightly dorsal (dorsolateral positioning) or brachycephalic breeds). This point is usually
to allow the probe to be placed under the patient in aligned with and dorsal to the xiphoid process. The
order to visualize the right kidney and retroperito- indicator notch of the transducer should be facing
neal space. Larger patients may need to be placed cranially (toward the patient’s head). Theoretically,
in left lateral recumbency to image the right kidney. when there is a pneumothorax, this region will
This view can also be obtained with the patient in accumulate air since this is the highest point (least
sternal recumbency in hemodynamically compro- gravity-dependent) portion of the chest. The opera-
mised patients. This view is not obtained in a typi- tor should ensure that the diaphragm and liver are
cal AFAST . out of the field of view, as the presence of these
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structures in the CTS view may interfere with imag-
ing and create a false positive step sign. In brachy-
Abdominal fluid scoring system cephalic patients or those with an intra-abdominal
The abdominal fluid score (AFS) has been utilized mass that is pushing the diaphragm forward, it may
clinically to survey for development or resolution be necessary to move up one intercostal space.
of a hemoabdomen, ongoing hemorrhage, and 2. Next, the operator should attempt to isolate the
worsening volumes of free fluid. The scoring sys- ‘bat/gator sign.’ This sign consists of the two rib
tem consists of a numeric grading system (0–4). heads that appear as hypoechoic shadowing artifact
For each quadrant surveyed during an AFAST and the interposed intercostal space (Fig. 7.6A).
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examination containing fluid, a score of 1 is Once the gator sign is isolated, the observer
added to the AFS. It is recommended to record must look for the presence of the ‘glide sign.’ The
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results on a standardized template to allow conti- glide sign (also called lung slide in human TFAST )
nuity of communication of findings between vet- is created by movement of the pulmonary–pleural
erinarians and serial screenings. A template also line cranially and caudally along the thoracic wall
promotes completion of a full examination. See as the patient inspires and expires. The PPL
Further Reading section for examples of such appears as a bright hyperechoic line. If the glide
templates. sign is present, then a pneumothorax at that chest
level is unlikely. Shallow and rapid breathing may
make observing the glide sign more difficult and
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The TFAST examination could possibly result in a false diagnosis of a
The examination is performed starting on the left- pneumothorax.
hand side and continuing to the right-hand side There should be visible air reverberation artifact
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(Fig. 7.3). The TFAST views consist of the left and within the lung creating parallel A-lines (Fig. 7.6A).
right pericardial site (PCS) views, right and left These A-lines do not typically move. The US trans-
chest tube sites (CTS), and the DH view. These ducer may need to be moved horizontally and
views are outlined in Fig. 7.3. pivoted dorsally or ventrally to achieve an oblique
image to more accurately obtain the glide sign.
3. Assess for B-lines. Ultrasound B-lines are also
Chest tube site view
referred to as US lung rockets. They are created when
The CTS view has been used predominately to fluid is immediately next to air within the peripheral
diagnose the presence or absence of a pneumo- lung parenchyma, specifically the outer 1-3mm. The
thorax, but can also be used clinically to assess for B-lines appear as hyperechoic streaks that run paral-
US B-line artifacts (previously known as lung lel to the rib space; they may oscillate back and forth
rockets/comet tails/ring-down) and the step, shred, with respiration and will obliterate the perpendicu-
and node signs (Fig. 7.6). lar A-lines (Fig. 7.6B). It is normal to have 1-2 B-lines

138 D.M. Hundley