Pulmonary Edema Pathophysiological Considerations Manifestations on Chest Radiography

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Pulmonary EdemaPathophysiological
Considerations Manifestations on Chest
Radiography

• Kathryn Glassberg MS4
• February 2006

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Pulmonary Edema Overview

• Pathophysiology Edema as an end result of a
  multitude of diverse insults (not just heart
  failure vs. ARDS!)
• Physiologic approach for radiologic evaluation of
  edema
• Hydrostatic edema
• Permeability edema /- diffuse alveolar damage
• Mixed permeability and hydrostatic edema

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Pulmonary Edema

• Edema occurs when physiologic resorption of fluid
  via lymphatics is overwhelmed
• Causes usually divided into hydrostatic and
  increased capillary permeability, but both
  mechanisms can occur in the same patient!
• Chest radiography, when combined with clinical
  data, helps distinguish pathologic cause in vast
  majority of cases

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Causes of Pulmonary Edema1
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Causes of Pulmonary Edema1
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Pathophysiology overview2

• Normally, excess hydrostatic transudate from
  pulmonary capillaries is filtered into
  peribronchovascular lymphatics and removed

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Pathophysiology overview2

• In hydrostatic edema, transudate accumulates in
  the interstitum initially, only entering alveoli
  in severe cases
• In permeability edema associated with diffuse
  alveolar damage (DAD), exudate fills the
  interstitum and the alveoli

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Hydrostatic Edema3

• The lungs can accommodate increases in fluid the
  lymphatic flow can increase 3-10x before edema
  develops
• Higher hydrostatic pressures force fluid through
  endothelial cell pores, but the tighter junctions
  of epithelial cells prevent fluid from entering
  alveoli until pulmonary capillary pressures reach
  40 mm Hg, causing stress failure

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Hydrostatic Edema radiologic manifestations3

• Earliest sign vascular indistinctness
• Bronchial wall thickening/peribronchial cuffing
• Septal lines Kerley A, B, C
• Thickened fissures
• Severe edema dependent ground glass opacities
  reflecting alveolar involvement
• Often associated with bilateral transudative
  pleural effusions

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Hydrostatic Edema radiologic manifestations3

• Cephalization or inversion not specific for
  edema
• Reflects chronic pulmonary venous changes in
  patients with left-sided heart failure
• Vascular pedicle width
• patients with volume overload often have widened
  vascular pedicles when compared to previous
  studies
• However, patients can certainly have hydrostatic
  edema despite a narrow pedicle, thus this sign
  can be misleading

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Vascular indistinctness
Normal
Edema
Images courtesy of Dr. Marc Gosselin
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Vascular Indistinctness
Normal
Edema
Images courtesy of Dr. Marc Gosselin
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Peribronchial cuffing

• Images shown are pre- and post-treatment for
  hydrostatic edema
• Arrowheads point to Kerley A lines

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Septal Lines3

• The presence of septal lines reflects fluid
  accumulation between the lung lobules
• Kerley lines
• A long, diagonal, central
• B short, horizontal, extend to lateral pleural
  surfaces
• C reticular pattern of 1 cm polygons
  representing septal lines viewed on end (Ive
  heard Dr. Kerley is the only one who has ever
  really seen these)

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Septal Lines

• Septal lines in a patient with cardiac failure

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Septal Lines

• Lateral view of same patient note fluid in
  both fissures

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Septal Lines

• All three Kerleys claim to be present can you
  find them?

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Septal Lines

• Even in you cant name the lines, you can see
  that this patient has severe hydrostatic edema in
  need of treatment!

A
B
C?
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Evolving hydrostatic edema4

• 33 year-old with AML admitted for renal
  failure and fluid overload

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Evolving hydrostatic edema4

• Arrows indicate peri-bronchial cuffing
• Note increasing size of azygous vein

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Evolving hydrostatic edema4

• Arrowheads indicate septal lines
• Note ground-glass, indicating alveolar edema

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Permeability Edema

• multiple insults can cause increased pulmonary
  vessel permeability resulting in leakage of fluid
  AND protein
• In its most severe form, the disease is a
  combination of vessel permeability and DAD,
  leading to the acute respiratory distress
  syndrome (ARDS)

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ARDS pathology3

• Acutely, exudative edema in the alveoli causes
  hyaline membrane formation
• Type II epithelial cells then proliferate and,
  usually, fibrosis occurs

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ARDS Radiologic manifestations3

• Patchy, diffuse ground glass opacities
• Pattern of opacification does not change with
  position change, as the exudates are trapped in
  alveoli
• Septal lines, peribronchial cuffing, and thick
  fissures are usually ABSENT
• In severe cases, air bronchograms can be seen
• Good rule of thumb presence of ET tube!

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ARDS Radiologic manifestations3

• Caution While a normal sized heart and narrow
  vascular pedicle are helpful signs, neither is
  specific for injury edema

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ARDS

• Patchy diffuse ground glass
• Air bronchograms
• ET tube

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Permeability Edema without DAD3

• Seen in IL-2 therapy for metastatic disease,
  hantavirus pulmonary syndrome
• Severe capillary permeability without alveolar
  involvement
• Radiographically, resembles hydrostatic edema
  (septal lines, peribronchial cuffing) because
  alveolar epithelium remains intact

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Mixed hydrostatic and permeability edema

• High-altitude pulmonary edema
• Neurogenic edema
• Reexpansion and post-obstructive

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High-altitude pulmonary edema (HAPE)3

• Hypoxia causes non-uniform pulmonary
  vasoconstriction, leaving other lung units
  over-perfused and predisposed to edema
• Higher pressures can result in some capillary
  damage and stress failure

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High-altitude pulmonary edema3

• Radiographs show patchy ground glass with a
  central distribution favoring peribronchial
  cuffing and vascular indistinctness over septal
  lines

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Neurogenic Edema3

• Pathophysiology similar to HAPE neural
  mechanisms result in non-uniform vasoconstriction
• High protein content of fluid indicates capillary
  leakage involved as well

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Neurogenic Edema3

• Classically, neurogenic edema has an upper lobe
  predominance however, it can present with any
  pattern
• Often clears rapidly, arguing for intact alveoli

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Neurogenic Edema4

• 54 year-old woman with intracranial hemorrhage
• Note upper lobe predominance

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Reexpansion and Postobstructive Edema3

• Both occur in setting of high negative pleural
  pressure
• Reexpansion usually seen as localized lung
  injury, with alveolar filling and exudative
  fluid, arguing for increased permeability as a
  cause
• Postobstructive pattern usually hydrostatic,
  secondary to increased central blood volume
  caused by the relief of obstruction

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Reexpansion Edema4
Right pneumothorax
One-hour post chest-tube placement
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Postobstructive Edema4

• Postextubation Laryngospasm note central
  distribution and peribronchial cuffing.

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Conclusions

• Hydrostatic Edema is characterized by
• Vascular indistinctness
• Peribronchial cuffing
• Septal lines/fissure thickening
• Permeability Edema with DAD (ARDS) is
  characterized by
• Diffuse, patchy ground glass opacities
• Air bronchograms
• Overlap is seen in pathophysiology, thus can be
  reflected in the radiograph

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Summary Table1
Hydrostatic Permeability with DAD
Heart size Often enlarged Usually not enlarged
Septal Lines Common Absent
Peribronchial cuffs Common Not common
Air bronchograms Not common Very common
Regional distribution Even or central Patchy or peripheral
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Hydrostatic and Permeability Edema
Images courtesy of Dr. Marc Gosselin
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The condition of the capillary endothelium and
that of the alveolar epithelium are the main
determinants3
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References

• 1Milne ENC and Massimo P. Reading the Chest
  Radiograph A Physiologic Approach. Mosby, 1993.
• 2Ware LB and Matthay MA. Acute pulmonary edema.
  The New England Journal of Medicine. 2005 353
  2788-96.
• 3Ketai LH and Godwin JD. A new view of pulmonary
  edema and acute respiratory distress syndrome.
  Journal of Thoracic Imaging. 1998 13 147-171.
• 4Gluecker T. Capasso P. Schnyder P. Gudinchet F.
  Schaller MD. Revelly JP. Chiolero R. Vock P.
  Wicky S. Clinical and radiologic features of
  pulmonary edema. Radiographics. 19(6)1507-31
  discussion 1532-3, 1999 Nov-Dec.

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References

• Images taken from
• myweb.lsbu.ac.uk/ dirt/museum/p6-71.html
• www.bcm.edu/.../cases/ pediatric/text/7a-desc.htm
  
• http//www.hcoa.org/hcoacme/chf-cme/chf00030.htm
• http//www-medlib.med.utah.edu/WebPath/LUNGHTML/LU
  NG131.html
• http//www-medlib.med.utah.edu/WebPath/LUNGHTML/LU
  NG133.html
• http//www.lumen.luc.edu/lumen/MedEd/MEDICINE/PULM
  ONAR/CXR/atlas/images/310a1.jpg
• www.high-altitude-medicine.com/ AMS-medical.html
• Sherman SC. Reexpansion pulmonary edema a case
  report and review of the current literature.
  Journal of Emergency Medicine. Jan 2003 24(1)
  23-7.
• Thanks to Dr. Marc Gosselin for images, insights