Transcript Atelectasis

Atelectasis
Sam Wasmann
Atelectasis:
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Collapse or loss of lung volume
May involve entire lung, a lobe, a segment, or be
subsegmental
There are 5 mechanisms of atelectasis:
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1) (Post) obstructive
2-5) Non-obstructive – typically due to loss of contact
between parietal and visceral pleura.
This presentation will cover the 5 mechanisms of
atelectasis, as well as radiographic findings of
collapse in all 5 lung lobes.
Atelectasis Does Not Cause Fever
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In a 1995 study of 100 postoperative cardiac surgery
patients receiving daily portable chest x-rays, “no
association could be found between fever and amount of
atelectasis. This contradicts common textbook dogma but agrees
with previous human study and animal experiments.”
Engoren, Milo. “Lack of Association Between Atelectasis and Fever.” Chest. Volume
107(1) January 1995 pp 81-84
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A 1988 study of 270 patients after elective intraabdominal surgery found that “neither the presence nor the
absence of fever can assure clinicians of the presence or absence
of a postoperative pathologic pulmonary complication such as
atelectasis.” Roberts J, Barnes W, Pennock M, Browne GD. “Diagnostic
Accuracy of Fever as a Measure of Postoperative Pulmonary
Complications.” Heart Lung. 1988 Mar;17(2):166-70
CXR Findings in Atelectasis
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Direct:
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Displacement of fissures
Increased opacification of airless lobe
Crowded air bronchograms (non-obstructive only) or
vessels
Indirect:
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Displacement of hilar structures
Ipsilateral cardiomediastinal shift
Narrowing of ipsilateral intercostal spaces
Obscured structures adjacent to atelectasis
Elevation of ipsilateral diaphragmatic leaflet
Hyperexpansion/hyperlucency of remaining aerated
lung
Typical findings of
atelectasis in this
patient include:
1) Hazy opacity in left
upper lung (direct
sign)
2) Left tracheal shift
(indirect sign)
3) Loss of left cardiac
silhouette (indirect
sign)
Lobar Collapse
Right Lobar Anatomy
Approximate position of right upper, middle and lower
lobes on chest x-ray.
Right Lobar Anatomy
Lateral View
Left Lobar Anatomy
Approximate position of left upper and lower lobes
on chest x-ray.
Left Lobar Anatomy
Lateral View
Right Upper Lobe Atelectasis
Findings include:
 Elevation of right hilum and minor fissure
 Collapsed lobe shifts cephalad and medially
 If due to a central mass, the minor fissure
retracts cranially with a lateral upward convexity
and a medial caudal convexity (S-sign of
Golden). This suggests neoplastic etiology.
Right upper lobe
atelectasis: The
atelectatic RUL
forms a triangular
opacity (arrow).
The elevated minor
fissure is retracted
cranially (see image
below) and forms a
reverse S shape (Ssign of Golden) as it
curves around the
hilar mass (M).
Right Middle Lobe Atelectasis
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Right middle lobe is only 10% of total lung
volume.
Greater tendency to collapse than other lobes.
Radiographic findings can be subtle:
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Small triangular opacity pointing laterally
Obscured right heart border
Lateral view: obliquely oriented triangular opacity with
apex pointed toward hilum.
Right middle lobe
atelectasis: There
is a small
triangular opacity
pointing laterally,
right cardiac
border is partially
obscured, and
slightly lower
lung volume in
right compared to
left.
Lateral view:
The arrows point to
the major and minor
fissures which are
parallel to each
other. The
atelectatic middle
lobe is the opacity
between the
fissures. Notice that
it projects over the
cardiac silhouette.
Right Lower Lobe Atelectasis
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When atelectatic, right lower lobe retracts posteromedially
and inferiorly.
Major fissure is shifted downward and becomes visible
As RLL collapses, it forms a triangular opacity which
obscures the left lobe pulmonary artery, and eventually
forms a right paraspinal mass that projects behind the
right atrium.
On lateral view, posterior 1/3 of right diaphragm is
obscured by collapsed RLL. Diaphragm may not be
obscured on frontal view because hyperexpanded middle
lobe abuts it.
RLL Atelectasis:
Triangular opacity
in right lower
hemithorax. The
lateral border is the
major fissure (not
normally seen on
frontal view). Right
hilum is displaced
caudally and
partially obscured.
The hyperexpanded
RML outlines the
cardiac border and
right
hemidiaphragm.
Left Upper Lobe Atelectasis
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Faint, hazy opacity in left upper hemithorax
50% of patients have complete major fissure
Main pulmonary trunk and upper contour of left pulmonary
artery are obliterated
Left hilar structures and left lower lobe are retracted
caudally (look for superior segment vessels from the lower
lobe occupying the apex, mimicking an aerated upper
lobe)
50% have an incomplete major fissure
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Tongue of aerated lower lobe is pulled forward by atelectatic
lobe, between the atelectasis and the aortic arch, forming a
crescent-shaped lucency (Luftsichel sign)
Diaphragm typically elevated
Left upper lobe
atelectasis: Opacity
contiguous to the aortic
arch. The mediastinum
is shifted toward the left
hemithorax, which is
small in comparison to
the right. The main
pulmonary trunk and the
left pulmonary artery
are obliterated.
Left upper lobe
atelectasis in patient
with incomplete
major fissure: There
is an ill-defined
opacity in the left
half of the left upper
thorax. The trachea
is deviated left and
the left hilum is
retracted superiorly.
Vascular branches to
the left lower lobe
superior segment
form an array of
linear and tubular
opacities. The arrow
shows a vertical
lucency separating
the aortic arch from
the vertical margin
of the collapsed lobe
(Luftsichel).
Left Lower Lobe Atelectasis
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Common after cardiac surgery
Radiographic findings include:
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Increased retrocardiac opacity
Obscuring of the left lower lobe vessels and left
hemidiaphragm
Caudal displacement of left hilum
Levorotation of cardiac silhouette with flattening of
cardiac waist
Mediastinal shift can cause partial obliteration of aortic
arch
LLL Atelectasis:
Notice the wedge
shaped opacity
behind the cardiac
silhouette. The
border is formed by
the major fissure
(arrow). The left
hilum is partially
obscured and
displaced caudally.
The left upper lobe
is hyperexpanded
accounting for the
increased lucency in
the left hemithorax.
Complete Atelectasis of Entire Lung
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Total collapse of a lung
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Complete opacification of an entire hemithorax
Ipsilateral cardiomediastinal shift (in massive pleural
effusion, would shift to contralateral side).
Cardiac silhouette, one hemidiaphragm, and one hilum
are obscured in lateral projection.
Complete left lung
atelectasis: There is
mediastinal
displacement,
opacification, and
loss of volume in the
left hemithorax. The
cardiac silhouette
(which is shifted left)
is obscured, as are
the left hilum and left
hemidiaphragm.
Mechanisms of Atelectasis
Obstructive (Resorptive) Atelectasis
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Most common type
Results from blockage of airway
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mucous plugging, foreign body, neoplasm, or
inflammatory debris
Air distal to obstruction is resorbed from
nonventilated alveoli
Findings include loss of lung volume without
presence of air bronchograms
Post-obstructive
atelectasis of
RLL: The major
fissure is visible
as it has rotated
into view. There
are no air
bronchograms
seen within the
atelectatic region
of lung. The
patient is
intubated. The
obstruction is
likely due to
mucous plugging.
Non-obstructive Atelectasis
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4)
Passive
Compressive
Cicatrization
Adhesive
In these forms of atelectasis secretions are able
drain up the bronchial tree. Because there is no
obstruction, bronchoscopy is not therapeutic.
Passive (Relaxation) Atelectasis
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2nd most common form of atelectasis
Contact between parietal and visceral pleura is
lost due to pleural effusion or pneumothorax.
Leads to generalized collapse.
Passive atelectasis:
Notice the crowded
air bronchograms
(arrows) in the
setting of a left
pleural effusion. Air
bronchograms are
not present in postobstructive
atelectasis.
Compressive Atelectasis
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Due to external compression of lung
May be caused by loculated collection of pleural
fluid or by masses in chest wall, pleura, or
parenchyma.
Similar to relaxation atelectasis but collapse is
local rather than generalized.
Compressive
atelectasis: Chest
x-ray showing a
giant bulla
occupying more
than two thirds
of the right
hemithorax and
compressing the
underlying lung
upward and
toward the
mediastinum.
Crowded air
bronchograms
can be seen
(arrows).
Adhesive Atelectasis
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Caused by adherence of the alveolar wall
surfaces in the setting of surfactant deficiency
(e.g., hyaline membrane disease)
Surfactant has phospholipid dipalmitoyl
phosphatidylcholine, which prevents lung
collapse by reducing the surface tension of the
alveoli
Lack of surfactant or inactive surfactant cause
alveolar instability and collapse
Adhesive
atelectasis in infant
with hyaline
membrane disease:
CXR reveals
bilateral groundglass appearance of
the lungs
(atelectasis) and air
bronchograms
standing (red
arrow) out against
the collapsed
parenchyma.
Cicatrization Atelectasis
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Secondary to fibrosis (scarring) of lung
parenchyma with subseqent lack of expansion
Etiologies include granulomatous disease (often
occurs in sarcoid, fungal, and chronic TB),
necrotizing pneumonia, and radiation.
Cicatrization atelectasis:
Lung destruction in patient
with chronic pulmonary
tuberculosis.
References:
1) Sharma, Sat. “Atelectasis.” e-medicine, 2004.
http://www.emedicine.com/med/topic180.htm#section~pictures
2) Brad H. Thompson, M.D., William J. Lee, B.S., Jeffrey R. Galvin, M.D. and Jeffrey S. Wilson, M.D “Lobar
Anatomy” ElectricLungAnatomy
www.vh.org/adult/provider/radiology/LungAnatomy/LobarAnat/LobarAnat.html
3) Daffner, RH. Clinical Radiology – The Essentials. Williams and Wilkins, 1993, pp 80-85.
4) Engoren, Milo. “Lack of Association Between Atelectasis and Fever.” Chest. Volume 107(1) January
1995 pp 81-84
5) Roberts J, Barnes W, Pennock M, Browne GD. “Diagnostic Accuracy of Fever as a Measure of
Postoperative Pulmonary Complications.” Heart Lung. 1988 Mar;17(2):166-70
6) Stark, Paul. “Atelectasis: Types and Pathogenesis.” UpToDate, 2004.
7) Stark, Paul. “Radiologic Patterns of Lobar Atelectasis.” UpToDate, 2004.
8) Weed HG, Baddour LM. “Postoperative Fever.” UpToDate, 2004.
9) Federico Venuta and Tiziano de Giacomo. “Giant Bullous Emphysema.” CTSNET Experts' Techniques, General
Thoracic Experts' Techniques. http://www.ctsnet.org/doc/6761