Transcript Atelactasis - Lung Therapeutics

Atelactasis
By Don Wynn
Atelectasis
• Greek = incomplete stretching
• Definition: diminished gas
within the lung associated with
reduced lung volume and
radiologic signs
Signs of Atelactasis
• Direct
• Indirect
Direct Signs
• Displacement of fissures
• Increased opacification of the
airless lobe.
• Crowding of pulmonary vessels
Indirect Signs
• Displacement of hilar structures
(Katan’s triangle sign)
• Cardiomediastinal shift toward the side
of collapse
• Narrowing of ipsilateral intercostal
spaces
• Elevation of the ipsilateral
diaphragmatic leaflet (Juxtaphrenic
peak sign)
Indirect Signs
• Compensatory hyperexpansion and
hyperlucency of the remaining
aerated parts of the lung
• Obscuring of structures adjacent to
the collapsed lung, such as the
diaphragm, heart, or pulmonary
vessels.
Types of Atelactasis
• Obstructive
• Nonobstructive
Types of Atelactasis
• Obstructive
• Blockage of an airway.
• Air retained distal to the occlusion
is then resorbed from
nonventilated alveoli. Over time,
the affected regions become
totally airless.
Obstructive Atelectasis
• Causes:
• 1). Bronchogenic carcinoma (always a
consideration in patients with histories of
persistent atelectasis, recurrent atelectasis, or
recurrent pneumonia with failure of complete
clearing after treatment)
• 2). Bronchial carcinoid (above considerations
also apply here)
• 3). Metastases to the bronchi: most commonly
renal cell carcinoma, breast carcinoma,
melanoma, adenocarcinoma of the colon,
sarcomas
Obstructive Atelectasis
• Causes:
• 4). Lymphoma (usually late stage and
accompanied by hilar and mediastinal
lymphadenopathy) or other causes of bulky
adenopathy
• 5). Tuberculosis
• 6). Left atrial enlargement from mitral stenosis
(left lower-lobe atelectasis)
• 7). Foreign body obstruction
• 8). Mainstem bronchus intubation
Types of Atelactasis
• Nonobstructive
• Causes:
• Loss of contact between the parietal
and visceral pleura,
• Parenchymal compression,
• Loss of surfactant,
• Replacement of lung tissue by
scarring or infiltrative disease.
Types of Atelactasis
• Mechanisms of Atelactasis
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Relaxation
Compressive
Adhesive
Cicatrization
Replacement
Rounded
Types of Atelactasis
• Relaxation
• Contact between the parietal and
visceral pleurae is eliminated.
• 1). Pleural effusion
2). Pneumothorax
3). Hydrothorax, hemothorax
4). Diaphragmatic hernia
5). Pleural masses (including
metastases and mesothelioma)
Types of Atelactasis
• Compressive
• Chest wall, pleural, intraparenchymal
masses, or loculated collections of
pleural fluid lead to a diminution in lung
volume below the usual resting volume.
• It has much in common with relaxation
atelectasis, but is distinguished by local,
rather than generalized, collapse.
Types of Atelactasis
• Compressive
• Causes:
• peripheral tumor compressing
adjacent normal lung,
• extensive air trapping (as seen in
bullous emphysema, lobar
emphysema, interstitial emphysema,
or bronchial foreign body obstruction)
Types of Atelactasis
• Adhesive
• Induced by surfactant dysfunction.
• Decreased production or
inactivation of surfactant leads to
alveolar instability and collapse.
• Respiratory distress syndrome of
premature infants, ARDS, acute
radiation pneumonitis, PE and lung
contusion.
Types of Atelactasis
• Adhesive
• In the appropriate clinical setting,
PULMONARY EMBOLISM MUST
ALWAYS BE CONSIDERED in the
patient with SUBSEGMENTAL
atelectasis AND PLEURAL
EFFUSION. Induced by surfactant
dysfunction.
Types of Atelactasis
• Cicatrization
• Diminution of volume as a sequel of
severe parenchymal scarring.
• Etiologies include:
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granulomatous disease,
late sequelae of TB,
necrotizing pneumonia,
radiation
pneumoconioses
Collagen vascular diseases (e.g.,
scleroderma, rheumatoid lung)
Types of Atelactasis
• Replacement
• Occurs when the alveoli of an
entire lobe are filled by tumor,
such as bronchioloalveolar cell
carcinoma, with ensuing loss of
volume.
Types of Atelactasis
• Rounded
• Also called folded lung or
Blesofsky syndrome
• A distinct form of atelectasis
associated with pleural disease,
particularly following asbestos
exposure
MRI
• Can distinguish between
obstructive and nonobstructive
atelectasis.
• Obstructive atelectasis displays
high signal intensity on T2weighted images due to protonrich mucus accumulation.
MRI
• Nonobstructive atelectasis
shows low signal intensity on
T1 and T2 images
• The use of MRI in diagnosing
atelectasis is still experimental,
and more experience needs to
be accrued
RUL Collapse
• Elevation of the right hilum and
the minor fissure
• Convex upward
• Collapse lobe tends to shift
cephalad and medially
Right Upper Lobe
Atelactasis
• This configuration of the minor
fissure is called the S-sign of Golden
and indicates a probable neoplastic
etiology for the obstructive
atelectasis.
• A juxtaphrenic peak indicates loss
of volume in the upper lobe and can
be a helpful sign of upper lobe
atelectasis.
RUL Atelactasis
• Medial collapse of the right upper
lobe can occasionally mimic a right
paratracheal mass
• Lateral collapse lead to a peripheral
mass-like opacity that mimics a
loculated pleural effusion.
• Right middle and lower lobes
hyperexpand superiorly and medially
rather than laterally.
RML Atelactasis
• Greater tendency to collapse
because of:
1) decreased collateral
ventilation
2) a long thin curved bronchus
3) Possible compression by a
collar of enlarged lymph nodes
at bronchus origin
RML Atelactasis
• Chronic RML Atelactasis
• RML syndrome
• Frequently nonobstructive
• Accompanied by scarring and
bronchiectasis
• Often found in elderly women
RML Atelactasis
• Total collapse has little impact
on appearance of surrounding
structures
• Absent contour of right heart
border
• A small triangular opacity
pointing laterally
RML Atelactasis
• On CT scan, the atelectatic
right middle lobe presents as a
triangular opacity with its apex
pointing laterally and with its
medial contour apposed against
the right heart border.
• This has been called the "tilted
ice cream cone" appearance
RLL Atelactasis
• Tethered to the mediastinum by the
hilar structures and the inferior
pulmonary ligament.
• Visibility of major fissure – early sign
of RLL collapse on frontal X-ray
• Forms a triangular opacity that
obscures the lower lobe pulmonary
artery.
RLL Atelactasis
• Eventually, the collapsed lobe
forms a right paraspinal mass
that projects behind the right
atrium.
• Superior mediastinal structures
shift to the right and form a
superior paratracheal triangular
opacity.
RLL Atelactasis
• In lateral view, posterior third of
right hemidiaphragm is
obscured.
• In frontal view, dome of right
hemidiaphragm is often not
obscured
RLL Atelactasis
• On CT scan, RLL atelactasis can
mimic a paraspinal mass.
• If present, air bronchograms
may reveal the true nature of
such a space occupying lesion.
RML and RLL Collapse
• Combined RML and RLL
collapse can mimic an elevated
right hemidiaphragm or a
subpulmonic effusion.
• Obscuring of the right hilum and
the straight contour of the
minor fissure interface help
establish the correct diagnosis.
LUL Atelactasis
• The left upper lobe is larger than the right
upper lobe.
• Because it lacks a minor fissure in most
cases, the pattern of collapse is different
from that seen with right upper lobe
collapse .
• A completely atelectatic left upper lobe
tends to retract more anteriorly than
superiorly.
• On the frontal view, it produces a faint,
hazy opacity in the left upper hemithorax,
which can be mistaken for pleural
thickening
LUL Atelactasis
• The left cardiac contour is
frequently obscured by the lingula
• The main pulmonary trunk and the
upper contour of the left central
pulmonary artery are obliterated,
• The left hilar structures are
retracted cephalad
• The left lower lobe basilar
segmental arteries are elevated and
clearly visible in retrocardiac
location.
LUL Atelactasis
• The hyperexpanded left lower
lobe occupies most of the left
hemithorax, with the superior
segment occupying the apex,
thus mimicking an aerated
upper lobe.
LUL Atelactasis
• Luftsichel, is an indirect sign of
left upper lobe atelectasis
• Crescent of aerated lung
• This represent an incomplete
major fissure pulled forward by the
atelectatic upper lobe, interposed
between the atelectasis and the
aortic arch
Note the increased opacification of the left upper
lung field with elevation of the left
hemidiaphragm. In addition, there is lucency
adjacent to the aorta. This is the Luftsichel sign,
representing an overexpanded right lower lobe.
LUL Atelactasis
• On the lateral view, the major fissure
is markedly displaced anteriorly
• The atelectatic left upper lobe forms
a narrow crescent adjacent to the
anterior chest wall.
• The hyperexpanded anterior
segment of the right upper lobe can
herniate across the midline into the
retrosternal clear space, sharply
outlining the anterior contour of the
ascending aorta.
LUL Collapse
• CT-scan reveals the anterior
orientation of the collapsed
lobe and displays the aerated
lung tissue of the right upper
lobe interposed between the
aortic arch and the collapsed
left upper lobe.
LLL Atelactasis
• Collapse of the left lower lobe is frequently
seen after cardiac surgery.
• Cold cardioplegia with damage to the left
phrenic nerve
• Compression of the lobe by an enlarged
heart
• Postoperative contusion
• Mucus accumulation due to a slightly more
vertical orientation of the left mainstem
bronchus.
LLL Atelactasis
• Increased retrocardiac opacity with
obscuring of the left lower lobe
vessels and the left hemidiaphragm
• Caudad displacement of the left
hilum
• Levorotation of the cardiac
silhouette with flattening of the
cardiac waist (the flat waist sign)
LLL Atelactasis
• The left major fissure can
parallel the left cardiac border,
and the completely atelectatic
lobe can mimic a left paraspinal
mass.
• Mediastinal shift can lead to
partial obliteration of the aortic
arch (the top of the knob sign)
RML and RLL
Atelactasis
• The most common combined
atelectasis.
• Explaination: a simple
obstructing lesion, located
within the bronchus
intermedius, can affect the
aeration of both lobes
simultaneously.
RML and RLL Collapse
• Common lesions:
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mucous plugs,
lung cancer,
foreign bodies,
hamartomas
carcinoid tumors
RML and RLL Collapse
• Rare lesions:
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Endobronchial tuberculosis,
Histoplasmosis,
Broncholithiasis
Inflammatory pseudotumors.
Entire Lung Atelactasis
• Total collapse of a lung leads to
complete opacification of an entire
hemithorax with ipsilateral
cardiomediastinal shift.
• The latter finding distinguishes
atelectasis from a massive pleural
effusion, a setting in which the
mediastinum shifts to the
contralateral side.
Entire Lung Atelactasis
• In the lateral projection, the
cardiac silhouette, one
hemidiaphragm, and one hilum
are obscured.
• CT scan demonstrates to best
advantage the shift of
cardiomediastinal structures.