Ultrasound: Lungs

Pulmonary edema

• A lines and B lines
  • A lines:
    • Appear as horizontal lines
    • Indicate dry interlobular septa.
    • Predominance of A lines has 90% sensitivity, 67% specificity for pulmonary artery wedge pressure <= 13mm Hg
    • A line predominance suggests that intravenous fluids may be safely given without concern for pulmonary edema
  • B lines ("comets"):
    • White lines from the pleura to the bottom of the screen
    • Highly sensitive for pulmonary edema, but can be present at low wedge pressures

BLUE (Bedside Lung Ultrasound in Emergency) Protocol

• Predominant A lines + lung sliding = Asthma/COPD
• Multiple predominant B lines anteriorly with lung sliding = Pulmonary Edema
• Normal anterior profile + DVT = PE
• Anterior absent lung sliding + A lines + lung point = Pneumothorax (PTX)
• Anterior alveolar consolidations, anterior diffuse B lines with abolished lung sliding, anterior asymmetric interstitial patterns, posterior consolidations or effusions w/o anterior diffuse B lines = Pneumonia (PNA)
• Relevance of Lung Ultrasound in the Diagnosis of Acute Respiratory Failure - The BLUE Protocol
  • Must read for EM Physicians in using ultrasound for dx in acute respiratory failure

See Also

• Ultrasound (Main)