Section 2: The ABCDE Systematic Approach

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A – Airway and Mediastinum

This step evaluates the central thoracic structures:

Key Checks:

• Tracheal Position: Is it midline or deviated?

  • Pushed: May suggest pleural effusion or tension pneumothorax.

  • Pulled: Seen with atelectasis (lung collapse) or fibrosis.

• Carina Visibility: Confirm it’s visible. Hints: an NG tube should pass below this point if in the stomach. An endotracheal tube should be positioned 4 (+/- 2 cm) above the carina.

• Mediastinal Contours:

  • Look for widening (e.g., aortic dissection, lymphadenopathy).

  • Assess for the silhouette sign: loss of normal borders indicating adjacent pathology.

B – Breathing (Lungs & Pleura)

Now assess the lungs and pleural spaces:

Inspect for:

• Increased opacities:

  • Consolidation (e.g., pneumonia)

  • Masses or nodules

• Decreased markings:

  • Pneumothorax (absence of lung markings)

  • Emphysema (hyperinflated lungs with flattened diaphragms)

• Pleural changes:

  • Effusions (look for meniscus sign or blunting of costophrenic angles)

  • Thickening or calcifications

⚠️ Symmetry is key: Always compare both lung fields side by side.

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C – Circulation (Heart & Great Vessels)

Analyze the cardiovascular structures:

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Key Points:

• Cardiothoracic Ratio: Heart should occupy <50% of thoracic width on PA view. If larger, consider heart failure.

• Silhouette Sign:

  • Loss of right heart border = right middle lobe pathology

  • Loss of left heart border = lingular pathology

• Aortic Contour:

  • Inspect the aortic knob and aortopulmonary window for contour abnormalities.

⚠️ Be cautious with AP views. They can artificially enlarge the heart, leading to false positives for cardiomegaly.

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D – Diaphragm

Review the lower thoracic region:

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Normal & Abnormal Findings:

• The right hemidiaphragm is typically higher than the left due to liver pushing up on it.

• Look for:

  • Free air beneath diaphragm = sign of perforation

  • Blunting of costophrenic angles = pleural effusion

  • Gastric bubble under the left hemidiaphragm (normal)

⚠️ Missing angles or diaphragm contours may indicate an incomplete or rotated image.

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E – Everything Else

Lastly, assess non-pulmonary structures.

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Key Areas to Review:

• Bones:

  • Check ribs, clavicles, spine for fractures, lytic lesions, or deformities.

• Lines and Tubes:

  • Confirm proper placement of ETT, NG tubes, pacemakers, etc.

• Soft Tissues:

  • Look for subcutaneous emphysema, swelling, masses, or surgical changes (e.g., mastectomy).

⚠️  Don't limit your review to just the lungs. Critical findings may lie elsewhere.