Page 2220 - Cote clinical veterinary advisor dogs and cats 4th

1104 FAST Ultrasound Examinations

○ Glide sign: normal to-and-fro motion ○ B-lines: hyperechoic vertical streaks origi- • Vet BLUE involves four bilateral thoracic
of the pleural line as the parietal and nating from the pleural line. They swing sites:
VetBooks.ir during respiration; identified as horizontal sign and do not fade distally, extending 9th intercostal space or dorsal caudal lung
with the to-and-fro motion of the glide
visceral pleura slide past each other
○ Caudal dorsal: upper third of thorax at
through the far field (see Video). They
pendulous movement along the pleural
region
line (see Video). The presence of a glide
sign excludes pleural effusion and pneu- exclude pneumothorax at those focal probe ○ Perihilar: 6th intercostal space at middle
placement sites. Multiple B-lines suggest
third of thorax or perihilar region
mothorax at the probe placement site. alveolar-interstitial syndrome (AIS) such ○ Caudal-cardiac: lower third of thorax
The absence of a glide sign suggests the as pulmonary contusions, cardiogenic or near costochondral junction at 6th-8th
presence of pneumothorax. noncardiogenic pulmonary edema (p. intercostal space or middle lung region
836), pneumonia (pp. 793 and 795), or ○ Cranial-ventral: lower third of thorax
neoplasia. near costochondral junction at 3rd-5th
○ Lung point: location at which collapsed intercostal space or cranial lung region
lung secondary to pneumothorax re-contacts • Vet BLUE: the probe is placed at each site
the thoracic wall; increases the specificity and moved 1-2 rib spaces cranially/caudally
of detecting pneumothorax (see Video). to identify B lines:
The probe should be walked cranially and ○ In larger dogs, the probe can also be moved
Rib
Rib ventrally to identify the lung point. 1-2 cm dorsally/ventrally.
• The PCSs are used for detecting pleural and ○ If B lines are visualized, the probe is held
PL pericardial effusions. stationary, and the number of B-lines is
○ The probe is placed to visualize the heart, recorded.
pericardial sac, and pleural spaces. ○ ≤3 B lines at a single site can be normal.
• Ultrasound-guided, fine-needle aspiration ○ ≥3 B lines at a single site or that coalesce
can be safely performed for therapeutic and indicate AIS.
diagnostic purposes. ○ The more numerous the B-lines, the more
severe AIS at that location
LUNG ULTRASOUND
• Two protocols have been described: a dorsal- Postprocedure
ventral intercostal sliding protocol and Vet Emergency ultrasound scans that are initially
BLUE®. negative for fluid, air, or AIS may become posi-
• Intercostal sliding lung ultrasound: tive over time. Serial scans are recommended 2-4
○ Starting caudal dorsally at the 9th-10th hours after the initial scan (sooner if unstable)
intercostal space, the probe is placed and then as needed to decrease false-negatives.
perpendicular or parallel to the ribs and
then passed in a dorsal to ventral direction Alternatives and Their
within the intercostal spaces. Relative Merits
FAST ULTRASOUND EXAMINATIONS B-lines, ○ At the ventral margin of the lung/ • Radiographs are complementary tests that
glide sign, and bat sign. B-lines (white horizontal
arrows) are reverberation artifacts originating from diaphragm interface, the probe is moved should be considered in critically ill patients:
the pleural line (PL) extending to the edge of the far a rib cranially and passed in a ventral to use caution when restraining patients as
field image. NOTE: The PL of the image depicted in dorsal direction within the intercostal patients may decompensate. Small amounts
this figure can be seen in patients with or without space. The process is repeated, covering of air and/or effusion may be missed due to
a pneumothorax. the entire thorax bilaterally. lack of sensitivity.
• Emergency ultrasound scans do not replace
formal extensive ultrasound scans.
• Blind thoracocentesis (p. 1164) may be
used in dyspneic patients with suspected
pneumothorax and pleural effusion based

®
FAST ULTRASOUND EXAMINATIONS Vet BLUE : 1) caudal dorsal: upper
third of thorax at the 9th intercostal space or dorsal caudal lung region; 2) perihilar:
6th intercostal space at middle third of thorax or perihilar region; 3) caudal-cardiac:
lower third of thorax near costochondral junction at 6th-8th intercostal space or
middle lung region; 4) cranial-ventral: lower third of thorax near costochondral
junction at 3rd-5th intercostal space or cranial lung region. At the middle lung
site (3), if the heart obscures the field of view, the probe is moved caudally 1-2 rib FAST ULTRASOUND EXAMINATIONS Intercostal sliding lung ultrasound.
th
th
spaces until the heart is no longer visible and the lung can be evaluated. At the Starting caudal dorsally at the 9 -10 intercostal space, the probe is passed from
cranial lung site (4), the probe is moved cranially one rib space at a time until the a dorsal to ventral direction within the intercostal space. At the ventral margin of
heart is no longer visible and lungs can be evaluated. The patient’s forelimb can the lung/diaphragm interface the probe is moved a rib cranially and passed from
be pulled cranially to facilitate probe positioning. (Courtesy Dr. Jantina McMurray, a ventral to dorsal direction within the intercostal space. The process is repeated,
Calgary, Alberta.) covering the entire thorax bilaterally. (Courtesy Dr. Jantina McMurray, Calgary, Alberta.)
www.ExpertConsult.com