Acute Respiratory Distress Syndrome (ARDS): Chest X-Ray Findings
Author: Iffat Naeem
Direct or indirect lung injury causing acute respiratory distress syndrome
(see Acute Respiratory Distress Syndrome slide for pathogenesis and clinical findings)
Activation of dysregulated inflammatory cascade
Absent pleural effusion
Normal heart size
Absent Kerly B lines
No perihilar infiltrate pattern
Bilateral infiltrate that can present in all regions of lung
Air bronchograms
Silhouette sign
Reviewers: Victória Silva, Mao Ding Tara Lohmann* *MD at the time of publication
Edema not due to a cardiogenic cause
Damage to alveolar epithelium
Necrosis of epithelial cells
Erosion of alveolar basement membrane
↑ Alveolar epithelium permeability
Damage to lung capillary endothelium
Release of inflammatory cytokines
Neutrophils migrate into alveoli
Fluid-filled alveoli show as white/grey opacities
Air-filled bronchi appear dark when surrounded by grey/white opacification of fluid-filled alveoli
Increased opacification from fluid-filled alveoli results in lack of differentiation of heart borders
Diffuse and
widespread damage to alveoli and interstitium that show as white/grey opacities
↑ Capillary endothelium permeability
Alveolar edema
Degradation of alveolar- capillary barrier
Proliferative phase
Alveolar epithelium attempts to recover
Chronic phase
Can either resolve or progress to fibrotic thickening and scaring of alveoli
↑ Leakage of fluid from capillaries into alveoli and lung interstitium
Pulmonary fibrosis (scarring)
‘White lung’ appearance
Image credit: Radiopaedia
Legend:
Pathophysiology
Mechanism
Sign/Symptom/Lab Finding
Complications
Published November 25, 2023 on www.thecalgaryguide.com

Acute Respiratory Distress Syndrome (ARDS): Chest X-Ray Findings Direct or indirect lung injury causing acute
Author: Iffat Naeem Reviewers: Victória Silva
respiratory distress syndrome*
Activation of dysregulated inflammatory cascade
Bilateral infiltrate that show as white/grey can present in
Damage to alveolar epithelium
Necrosis of epithelial cells
Erosion of alveolar basement membrane
↑ Alveolar epithelium permeability
Damage to lung capillary endothelium
Fluid-filled alveoli opacities
Air-filled bronchi appear dark when surrounded by grey/white opacification of fluid-filled alveoli
Increased opacification from fluid-filled alveoli results in lack of differentiation of heart borders
Diffuse and
all regions of lung
Release of inflammatory cytokines
Neutrophils migrate into alveoli
Alveolar edema
Air bronchograms
↑ Capillary endothelium permeability
Degradation of alveolar-capillary barrier
Proliferative phase
Alveolar epithelium attempts to recover
Chronic phase
Can either resolve or progress to fibrotic thickening and scaring of alveoli
↑ Leakage of fluid from capillaries into alveoli and lung interstitium
Silhouette Sign
widespread Pulmonary damage to alveoli
‘White lung’ appearance
fibrosis (scarring)
and interstitium that show as white/grey opacities
*See corresponding Calgary Guide slides for more details
Image credit: Radiopaedia
Legend:
Pathophysiology
Mechanism
Sign/Symptom/Lab Finding
Complications
Published X, 2023 on www.thecalgaryguide.com

Acute Respiratory Distress Syndrome (ARDS): Chest X-Ray Findings Direct or indirect lung injury causing acute respiratory
Author: Iffat Naeem Reviewers: Victória Silva
distress syndrome*
Activation of dysregulated inflammatory cascade
Bilateral infiltrate that show as white/grey can present in
Damage to alveolar epithelium
Necrosis of epithelial cells
Denudation of alveolar basement membrane
↑ epithelium permeability
Degradation of alveolar-capillary barrier
Alveolar epithelium
attempts to recover through (proliferative phase)
Damage to lung capillary endothelium
Fluid-filled alveoli opacities
Air-filled bronchi appear dark when surrounded by grey/white opacification of fluid-filled alveoli
Increased opacification from fluid-filled alveoli results in lack of differentiation of heart borders
Diffuse and
all regions of lung
Air bronchograms
Release of proinflamm atory cytokines
Neutrophil migration into airspace
Alveolar Edema
↑ capillary endothelium permeability
↑ leakage of fluid from vasculature into airspace and lung interstitium
Can either resolve or progress to fibrotic
Silhouette Sign
widespread Pulmonary damage to alveoli
‘White lung’ appearance
thickening and scaring of Fibrosis alveoli (chronic phase)
and interstitium that show as white/grey opacities
Image credit: Radiopaedia
*See corresponding Calgary Guide slides for more details
Legend:
Pathophysiology
Mechanism
Sign/Symptom/Lab Finding
Complications
Published X, 2023 on www.thecalgaryguide.com

Acute Respiratory Distress Syndrome (ARDS): Chest X-Ray Findings
Absent pleural effusion
Normal heart size
Absent Kerly B lines
No perihilar infiltrate pattern
Author: Iffat Naeem Reviewers: Victória Silva
Acute Lung Injury (see ‘ARDS: Pathogenesis and Clinical findings’ slide) causing impaired oxygenation
Lung injury not due to cardiogenic cause
(see ‘ARDS: Pathogenesis and Clinical findings’ slide)
Alveolar endothelium damage promotes inflammatory marker release
Exudative phase (1-6 days): neutrophils adhere to damaged endothelium and release pro- inflammatory mediators
Accumulation of intra-alveolar fluid that is rich in neutrophils, macrophages, and red blood cells
Proliferative phase (7-14 days): proliferation of alveolar epithelial
Fibroblasts deposit collagen tissue in alveolar walls and spaces
Can either resolve or progress to fibrotic thickening and scaring
Alveolar Edema
Fluid-filled alveoli show as white/grey opacities
Air-filled bronchi appear dark when surrounded by grey/white opacification of fluid-filled alveoli
Increased opacification from fluid-filled alveoli
Bilateral infiltrate present in all regions
Air bronchograms
results in lack of Silhouette Sign differentiation of
heart borders
Diffuse alveolar damage
‘White lung’ appearance
Image credit: Radiopaedia
*See corresponding Calgary Guide slides for more details
Legend:
(chronic phase) Pathophysiology
Mechanism
Sign/Symptom/Lab Finding
Complications
Published X, 2023 on www.thecalgaryguide.com

Lung injury not due to a cardiogenic cause
Absent pleural effusion
Normal heart size
Absent Kerly B lines
No perihilar infiltrate pattern
Acute Respiratory Distress Syndrome (ARDS): Chest X-Ray Findings