Lung Ultrasound

LUS Basics - Echoes & Airwaves

• Echoes (Tissue Appearance):
  • Anechoic (Black): Simple fluid (e.g., pleural effusion).
  • Hypoechoic (Grey): Consolidated lung, complex fluid.
  • Hyperechoic (White): Pleura, bone, air artifacts (A/B-lines).
• Key Structures & Artifacts:
  • Pleural Line: Bright, hyperechoic line; visceral-parietal pleural interface.
  • Lung Sliding: Shimmering/gliding movement at the pleural line. Absence suggests pneumothorax (or adhesions, mainstem intubation, apnea).
  • A-lines: Horizontal, repetitive, hyperechoic artifacts arising from pleural line; indicate normal aerated lung.
  • B-lines: Vertical, hyperechoic, laser-like artifacts from pleural line to screen edge; erase A-lines, move with lung sliding. Indicate interstitial syndrome (e.g., edema, inflammation, fibrosis).
    • Pathological: ≥3 B-lines in one intercostal space.

⭐ Diffuse, bilateral B-lines (often called "lung rockets") are a key sign of cardiogenic pulmonary edema.

Normal Lungscape - Sliding & Shining

• Pleural Line ("Shining"): Bright, hyperechoic, smooth, horizontal line.
  • Represents visceral-parietal pleural interface.
  • "Bat Sign": Key landmark; two ribs (wings) sandwiching pleural line (body).
• Lung Sliding: Dynamic "to-and-fro" shimmering or twinkling at the pleural line.
  • Synchronous with respiration.
  • Indicates visceral pleura sliding against parietal pleura.
• A-lines: Horizontal, hyperechoic reverberation artifacts below pleural line.
  • Equidistant, parallel to pleural line.
  • Signify air; normal in aerated lung with sliding.
• M-mode: "Seashore Sign" confirms normal sliding.
  • Chest wall: Static lines ("waves").
  • Lung: Granular pattern ("sandy beach") below pleural line.

⭐ The presence of lung sliding effectively rules out pneumothorax at the specific intercostal space being examined with high negative predictive value.

Pathology Patterns - Spotting Trouble

• Pneumothorax (PTX):
  • Key signs: Absent lung sliding, absent B-lines, exclusive A-lines.
  • M-mode: "Stratosphere"/"Barcode" sign (vs. "Seashore").

  ⭐ The Lung Point sign (sliding/non-sliding interface) is pathognomonic, 100% specific for pneumothorax.

• Pleural Effusion:
  • Anechoic/hypoechoic space between pleurae.
  • Signs: "Quad sign", "Sinusoid sign" (inspiratory lung movement).
  • "Jellyfish sign": Atelectatic lung floating.
• Pulmonary Edema (Interstitial Syndrome):
  • Multiple (≥3), bilateral, diffuse B-lines ("lung rockets").
  • Erase A-lines, move with sliding.
  • Thickened, irregular pleural line.
• Consolidation:
  • Subpleural, tissue-like pattern ("hepatization").
  • "Shred"/"Fractal sign" (irregular border).
  • Dynamic air bronchograms (pneumonia-specific).
• Atelectasis:
  • Similar to consolidation; loss of aeration.
  • Static/absent air bronchograms.
  • Volume loss signs (e.g., raised hemidiaphragm).

PeriOp POCUS Plays - Guiding Care

• Preoperative Assessment:
  • Identify occult pathology: pleural effusions, B-lines (interstitial syndrome), consolidations.
  • Risk stratify for Postoperative Pulmonary Complications (PPCs); informs anesthetic plan.
• Intraoperative Guidance:
  • Fluid management: Titrate fluids by monitoring B-lines (target <3 per zone) to prevent overload.
  • Diagnose acute respiratory distress:
    • Pneumothorax: Absent lung sliding, "lung point" sign (pathognomonic).
    • Atelectasis: "Lung pulse" with absent sliding, tissue-like pattern.
    • Pulmonary edema: Diffuse, bilateral B-lines (≥3 per zone).
    • Endobronchial intubation: Unilateral absent sliding.
  • Confirm ETT placement: Bilateral lung sliding, diaphragmatic movement.
• Postoperative Care:
  • Early detection & monitoring of PPCs: atelectasis, pneumonia, effusions.
  • Guide ventilator weaning: Assess lung aeration (LUS score), predict extubation success.
  • 📌 BLUE protocol for acute dyspnea.

⭐ Lung ultrasound (LUS) rapidly diagnoses causes of perioperative respiratory failure, often outperforming CXR and guiding immediate intervention.

High‑Yield Points - ⚡ Biggest Takeaways

• A-lines: Horizontal artifacts; normal lung or pneumothorax if no lung sliding.
• B-lines (≥3 per zone): Vertical artifacts; indicate pulmonary edema or interstitial syndromes.
• Lung sliding absence: Key sign of pneumothorax ("stratosphere sign" on M-mode).
• Lung point: Highly specific for pneumothorax; transition from sliding to no sliding.
• Pleural effusion: Anechoic fluid in dependent areas; "sinusoid sign" may be present.
• Consolidation: Tissue-like pattern ("hepatization") with characteristic air bronchograms.
• BLUE protocol: Systematically diagnoses causes of acute respiratory failure using LUS (Lung Ultrasound).