Lecture Notes: Differences Between VV and VA ECMO

Introduction

• Presenter: Eddie Watson from ICU Advantage
• Topic: Differences between VV (Venovenous) and VA (Venoarterial) ECMO
• ECMO: Extracorporeal Membrane Oxygenation used for severe respiratory/cardiac failure

ECMO Overview

• VV ECMO: Respiratory support
  • Drains blood from a vein, oxygenates it, removes CO2
  • Returns blood to right atrium via a vein
  • Supports gas exchange for failing lungs
  • Requires preserved cardiac function
• VA ECMO: Cardiac support
  • Drains blood from a vein, oxygenates it
  • Returns blood to an artery (towards aorta)
  • Provides organ perfusion and decompresses heart

VV ECMO Details

Cannulation Configurations

• Two Separate Cannulas
  • Drainage: Femoral vein to inferior vena cava/right atrium
  • Return: Right internal jugular to superior vena cava/right atrium
  • Placement under fluoroscopy
• Dual Lumen Cannula
  • Single insertion in right IJ vein
  • Includes both drainage and return lumens
  • Requires fluoroscopy and echo for placement

Recirculation

• Oxygenated blood may be pulled back into ECMO circuit
• Decreases level of support
• Causes: Cannula configuration, flow rates, pressures
• Preferred cannulation: Drain from IVC, return to SVC/RA
• Monitoring: Preoxygenator and arterial oxygen saturation

Pathophysiology

• Oxygenation: Mix of ECMO and native blood flow
• Hemodynamics: VV ECMO doesn't influence hemodynamics directly
• Anticoagulation: Reduced or eliminated to lower bleeding risk

VA ECMO Details

Cannulation Configurations

• Two Separate Cannulas
  • Venous: Femoral vein, tip in right atrium
  • Arterial: Femoral artery, tip in common iliac artery
  • Risk of limb ischemia, requires reperfusion cannula
• Central Cannulation
  • Requires open chest, cannulas in RA and ascending aorta
  • Common post-cardiotomy

Pathophysiology

• Oxygenation: No risk of recirculation, Mixing cloud phenomenon - needs to be on the right radial due to it being the first to receive oxygenated blood from the aorta.
  • Requires monitoring of native and ECMO blood flow
• Hemodynamics: Influenced by ECMO flow, preload, and afterload
• Left Ventricular Distension: Risk if low LV output or aortic regurgitation
• Anticoagulation: Must maintain therapeutic levels to prevent stroke risk

Conclusion

• VV and VA ECMO are similar yet distinctly different
• Understanding differences is crucial for patient care

Additional Information

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