Page 2219 - Cote clinical veterinary advisor dogs and cats 4th

FAST Ultrasound Examinations 1103

• Lung ultrasound identifies interstitial/alveolar • False-negative results ○ Decrease in AFS indicates resolving
pathology. ○ Patients initially negative on emergency ○ AFS has been validated only in lateral
hemorrhage.
VetBooks.ir Indications time. Re-evaluate in 2-4 hours (sooner if positions.
ultrasound scans may become positive over
• Aid in obtaining fluid samples for cytologic
examination via ultrasound-guided aspiration
patient status changes).
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• Any trauma patient ○ Glide sign may be intermittent with low TFAST
respiratory rates and absent during apnea.
• The probe is placed on five sites. Fanning
• Critically ill or unstable patients Procedure the probe is not necessary for the chest tube
• Respiratory distress site (CTS). The five locations are:
• Change in patient status AFAST ® ○ DH: with the probe directed cranially to
• Free fluid often appears as hypoechoic/ observe the pericardium and pleural spaces
Contraindications anechoic (black) triangles. (adjust depth to view heart)
None. Does not require sedation, shaving, • Left or right lateral recumbency preferred ○ CTS: left and right CTS at the level of
or anesthesia; can be performed patient-side (but can be done standing) the seventh to ninth intercostal spaces on
during stabilization without compromising • The ultrasound probe is placed on four the dorsolateral thoracic wall (closer to
patient stability because of special positioning, regions of the abdomen in a consistent, vertebrae) Procedures and Techniques
transport, or restraint. systematic approach. At each site, the probe is ○ PCS (pericardial site): left and right PCS
fanned through an angle of 45° in long- and over the heart at the level of the fifth and
Equipment, Anesthesia short-axis views and moved 1 inch (2.5 cm) sixth intercostal spaces on the ventrolateral
• B-mode ultrasound with a 5- or 7.5-MHz in cranial, caudal, left, and right directions. thoracic wall (closer to the sternum)
curvilinear probe (former for larger dogs) Fanning increases likelihood that abdominal • Patients are placed in left or right lateral
○ Linear array probes may help identify glide fluid is detected and that target organs are recumbency for the DH and nondependent
sign properly identified. The four locations are: thoracic site views (CTS and PCS views;
• Alcohol and/or ultrasound gel ○ Diaphragmatic-hepatic (DH): at the see below) and then rolled into sternal
subxiphoid, allows visualization of the recumbency for the contralateral thoracic
Anticipated Time diaphragm, liver lobes, and gallbladder site views. Patients in respiratory distress
3-6 minutes for each of AFAST, TFAST, and ○ Splenorenal (SR): allows visualization of should be placed in sternal recumbency or
lung ultrasound. Requires minimal training. the spleen and left kidney scanned in standing position to obtain the
○ Cystocolic (CC): allows visualization of four thoracic site views.
Preparation: Important the bladder • The DH site can detect pericardial (p. 773)
Checkpoints ○ Hepatorenal (HR): allows visualization of and pleural effusion (p. 791).
Do not need to clip hair the liver and right kidney • The CTSs are used for detecting pneumo-
• Fluid aspiration confirms fluid type (e.g., thorax (p. 797), pleural effusion, and B-lines.
Possible Complications and transudate, exudate, bile, blood, urine, chyle, ○ The probe is placed between two ribs. The
Common Errors to Avoid septic, inflammatory) (pp. 79 and 1343). characteristic image obtained is called the
• A negative scan does not exclude pathology. • Abdominal fluid score (AFS) is specific to bat sign.
• Retroperitoneal and focal injury may be trauma patients. ○ Bat sign: two adjacent ribs (hyperechoic
missed on AFAST scans. ○ AFS 1: positive fluid in one site; AFS 2: arched structures with distal black
• FAST scans do not identify the fluid type positive in any two sites; AFS 3: positive shadowing) with the horizontal pleural
or its origin. in any three sites; AFS 4: positive in all line extending between and slightly distal
• False-positive results four sites to the two ribs. This line represents the
○ Vascular structures, intestinal wall, and ○ AFS aids in documenting fluid progression interface between visceral pleura and
gallbladder can be confused for free fluid. or resolution. parietal pleura.
Two views (long and short axes) decrease ○ Short-term increase in AFS suggests ○ The glide sign and/or B-lines can be
false-positive results. ongoing intraabdominal hemorrhage; identified between the two ribs at the
○ Glide sign is difficult to identify in panting further patient evaluation is warranted. level of the pleural line.
or severely tachypneic patients.

CTS
HR

CC PCS

SR
DH
DH
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FAST ULTRASOUND EXAMINATIONS TFAST : patient is in left lateral
recumbency. The probe is placed on five sites: 1) diaphragmatic-hepatic (DH) at
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FAST ULTRASOUND EXAMINATIONS AFAST : patient is in left lateral the subxiphoid, with the probe directed cranially to observe the pericardium and
recumbency. The probe is placed on four regions of the abdomen: 1) diaphragmatic- pleural spaces; 2) left and right chest tube site (CTS) at the level of the seventh
hepatic (DH): at the subxiphoid; 2) splenorenal (SR) at left sublumbar region; 3) to ninth intercostal spaces on the dorsolateral thoracic wall (closer to vertebrae);
cystocolic (CC), on midline over the bladder; and 4) hepatorenal (HR) at right 3) left and right pericardial sites (PCS) over the heart at the level of the fifth to
sublumbar region. sixth intercostal spaces on the ventrolateral thoracic wall (closer to the sternum).
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