Lung Ultrasound

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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.

Lung Ultrasound: A-lines, B-lines, Pleural Line

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. Lung Ultrasound: Bat Sign, Seashore Sign, and A-lines

⭐ 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

Lung Ultrasound: Normal vs. Heart Failure

  • 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).
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Practice Questions: Lung Ultrasound

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Which is NOT a feature of pleural effusion?

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Flashcards: Lung Ultrasound

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Laryngeal mask airway and other supraglottic airway devices are part of advanced airway management, which comes under _____ guidelines

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Laryngeal mask airway and other supraglottic airway devices are part of advanced airway management, which comes under _____ guidelines

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