Diagnostic ultrasound ( PDFDrive )

CHAPTER 50 The Pediatric Chest 1709
Sonographic Signs of Pleural Fluid
Sonographic Signs of Pleural Fluid
Fluid collection deep to the chest wall and/or above the
diaphragm
Posterior chest wall visualized behind the luid
Free luid moves with respiration
Septations move if luid is loculated
Color Doppler signal between visceral and parietal pleura
and/or at costophrenic angle
Diaphragm sign (luid outside or peripheral to diaphragm)
Displaced-crus sign
Bare-area sign
Free Fluid Movement With Respiration
Free luid changes position with changes in the patient’s position.
Fluid will move posterior to the liver and lungs when the patient
is in a supine position (Fig. 50.13). When the patient is upright,
the luid will move between the lung and the diaphragm. Free
luid is indicated by change in the shape of pleural luid with
inspiration and expiration and the presence of moving septations
within the pleural luid 7 (Video 50.1). hese septations are ibrin
strands.
Fluid Color Flow Doppler Signal
Color low Doppler ultrasound aids in distinguishing pleural
efusion from pleural thickening. 7 Color Doppler signal is
identiied during respiratory motion between the visceral and
parietal pleura in the presence of pleural efusion. Cell movement,
debris, and ibrin scatter sound waves, producing the color
low Doppler signal in the pleural luid collection (Fig. 50.14).
Organized pleural thickening will appear as a colorless pleural
lesion with no Doppler signal. he color low Doppler signal has
high sensitivity and speciicity in determining if a luid collection
can be aspirated. 8 he luid color low Doppler signal is particularly
useful in distinguishing if small, loculated collections can be
aspirated.
Diaphragm Sign
When the liver or spleen is used as an acoustic window and luid
is seen adjacent to these organs, the location of the luid is
determined in reference to the diaphragmatic position. If the
luid is below the diaphragm and more centrally located, it is
ascites. If the luid is above the diaphragm and more peripherally
located, it is in the pleural space (see Fig. 50.7).
Displaced-Crus Sign
here is luid in the pleural space if the luid is interposed between
the crus and the vertebral column, displacing the crus away from
the spine.
Bare-Area Sign
he posterior aspect of the right lobe of the liver is directly
attached to the posterior diaphragm without peritoneum. hus
ascitic luid in the subhepatic or subphrenic space cannot extend
behind the liver at the level of the bare area. Pleural luid
will extend behind the liver at the level of the bare area (see Fig.
50.13).
Sonography Versus Computed
Tomography Scan
Ultrasound, unlike CT, is a portable, bedside technique, making
it ideal for evaluating chest opaciication detected by conventional
radiographs in the critically ill infant or child, to distinguish
pulmonary from pleural disease (Fig. 50.15). Septations are better
visualized by ultrasound than CT (Fig. 50.16). CT is better at
identifying pulmonary parenchymal abnormalities, but this does
not improve the outcome in managing empyema. 9
Li
FIG. 50.13 Posterior Pleural Fluid Over Bare Area of Liver. Transverse
scan through liver with patient in supine position shows triangular
consolidated lung with air bronchograms (black arrow) behind the liver
(Li). Fluid (white arrow) is posterior to lung and is behind the bare area
of the liver, and therefore is in the pleural space.
Mass Versus Fluid
A limitation of chest sonography is that very homogeneous, solid,
hypoechoic lesions may appear luid illed. he criteria for luidilled
structures are (1) lack of internal echoes; (2) a sharp
posterior wall; and (3) increased through transmission of sound
deep to the collection of luid. he lack of echogenicity is a relative
phenomenon that is judged by the echogenicity of the surrounding
structures. he air-illed lung deep to a pleural collection will
have a strong echogenic interface regardless of the nature of the
pleural collection. Fluid in the pleural space produces acoustic
enhancement. he lack of referenced solid or cystic structures
in the chest makes detection of increased through transmission
diicult to judge within the chest. Observing a change in shape
of the pleural luid during respiration, the movement of echogenic
particles, and the luid color low Doppler signal is helpful in