One-Lung Ventilation Techniques

Indications for OLV - Going Solo Lung

• Absolute (Mandatory for patient safety):
  • Isolate bleeding/infection: Massive hemoptysis, copious purulent secretions (e.g., lung abscess).
  • Control ventilation: Large bronchopleural fistula, major airway disruption/trauma, giant unilateral bulla/cyst.
  • Unilateral whole lung lavage (e.g., pulmonary alveolar proteinosis).
• Relative (Improves surgical conditions/gas exchange):
  • Surgical exposure: Thoracic aortic aneurysm, pneumonectomy, lobectomy, esophagectomy, thoracoscopy (VATS).
  • Severe unilateral parenchymal disease with refractory hypoxemia.

  ⭐ In cases of massive hemoptysis, OLV is crucial to protect the contralateral lung from blood aspiration. oka

OLV Techniques - Tubes & Tricks

• Double Lumen Tubes (DLTs): Preferred for most OLV.

  • Types: Left-sided (common), Right-sided (⚠️ RUL obstruction risk).
  • Sizing: Female: 35F, 37F; Male: 39F, 41F.
  • Advantages: Rapid lung collapse, suction access, allows CPAP/PEEP to operative lung.
  • Disadvantages: Tracheal injury, difficult placement in distorted airway.
  • Confirmation: Auscultation, Fiberoptic Bronchoscopy (FOB) - Gold Standard. 📌 FOB visualizes carina & cuff.

• Bronchial Blockers (BBs): Used with single-lumen ETT.

  • Types: Univent, Arndt (wire-guided), Cohen (flexitip), EZ-Blocker (Y-shaped, bifurcated).
  • Advantages: Useful in difficult airway, pediatric use, post-op ventilation with SLT.
  • Disadvantages: Slower lung collapse, dislodgement risk, occlusion of lumen by secretions.
  • Confirmation: FOB essential for placement and adjustment.

⭐ Right-sided DLTs have a Murphy eye on the bronchial lumen to ventilate the Right Upper Lobe (RUL), but precise placement is crucial to avoid RUL collapse.

OLV Physiology - One-Lung Drama

• Core Problem: Non-dependent lung (NDL) perfused, unventilated → large shunt. Dependent lung (DL) ventilated.
• V/Q Mismatch: Severe. NDL = pure shunt.
• Shunt ($Q_s/Q_t$): ↑↑, initially 20-30%. NDL gets ~40-50% cardiac output.
• Gravity (Lateral Decubitus):
  • DL: ↑ perfusion, ↑ ventilation.
  • NDL: ↓ perfusion, no ventilation.
• Hypoxic Pulmonary Vasoconstriction (HPV):
  • Key reflex: constricts NDL vessels, diverts blood to DL.
  • Reduces shunt by ~50%.
  • Inhibitors: Volatiles >1.5 MAC, vasodilators, severe hypocapnia.
• Challenges: Hypoxemia (PaO2 < 60 mmHg), DL hyperinflation/barotrauma.

⭐ HPV is the primary intrinsic mechanism protecting against hypoxemia during OLV.

Managing OLV Hypoxia - Airway SOS

Algorithm for managing acute hypoxemia ($SpO_2$ < 90%) during OLV:

• 📌 Airway SOS Steps:
  • Scope: Verify DLT/blocker position (FOB).
  • Oxygenate: FiO2 1.0, PEEP (5-10 cmH2O) to dependent lung, Recruitment maneuvers.
  • Strategies (Non-Dep. Lung): CPAP (2-5 cmH2O), Intermittent inflation. If fails, Stop OLV.

⭐ The most common cause of hypoxemia during OLV is malposition of the DLT or bronchial blocker, readily identified by FOB.

High‑Yield Points - ⚡ Biggest Takeaways

• Key absolute OLV indications: Massive hemorrhage, bronchopleural fistula, unilateral lung lavage.
• Left-sided Double-Lumen Tubes (DLTs) are generally preferred for lung isolation.
• Fiberoptic bronchoscopy (FOB) is gold standard to confirm correct DLT position.
• Hypoxemia from intrapulmonary shunt (V/Q mismatch) is the main physiological challenge in OLV.
• Managing OLV hypoxemia: ↑FiO2 to 1.0, PEEP to dependent lung, CPAP to non-dependent lung.
• Bronchial blockers are key alternatives to DLTs, vital for difficult airways or selective lobar blockade.