Ultrasound: Lungs

Technique

• Use vascular probe
  • Can use curvilinear or phase probe, but will need to decrease depth
• Place the probe vertically (marker toward head) over the 2nd intercostal space at the midclavicular line
• Adjust your view in order to see a rib on each side of the screen (designated by rib shadow)
• Look between the ribs for "lung sliding"
  • To document sliding on a single image, use M mode ("waves on a beach")
• Can continue to evaluate each intercostal space for sliding if needed

Pneumothorax

• No lung sliding seen (not specific for pneumothorax)
• May also identify "lung point": distinct point where you no longer see lung sliding (pathognomonic)
• Evaluate other intercostal spaces because pneumothorax may only be seen in least dependent area of thorax

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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 with out anterior diffuse B lines = Pneumonia

Further Reading

• Ultrasound (Main)

References

Authors

Ross Donaldson