🫁 Chapter 58: Extracorporeal Membrane Oxygenation (ECMO)

VA-ECMO · VV-ECMO · Oxygenation Index · Bridge to Recovery · Anticoagulation · E-CPR · Circuit Management

🫁 ECMO: Mechanical Cardiorespiratory Support for Refractory Failure

📊 Indications (OI >40 is indication)
OI = (MAP × FiO₂)/PaO₂ × 100. OI >20 → consider ECMO; OI >40 → ECMO indicated. Cardiac: myocarditis, post-cardiotomy, cardiomyopathy, septic shock with cardiac failure. Respiratory: ARDS, PPHN, CDH, meconium aspiration.
🩸 VA-ECMO vs VV-ECMO
• VA-ECMO: cardiac + respiratory support (cannulation: artery + vein). Use for cardiac failure, E-CPR.
• VV-ECMO: respiratory support only (cannulation: vein only). Requires native cardiac function.
📋 Circuit Basics
Centrifugal pump (preferred, less haemolysis) + membrane oxygenator (PMP) + heat exchanger. Blood flow: neonate 100-150 mL/kg/min, child 80-100 mL/kg/min. Sweep gas determines CO₂ removal.
💊 Anticoagulation
Heparin 100 units/kg at cannulation. Target ACT 180-220 (VA-ECMO) or 160-180 (VV-ECMO). Monitor platelets (>80,000) and fibrinogen. ATIII deficiency → FFP transfusion.
⚠️ Complications
Bleeding (most common), circuit thrombosis, haemolysis (pink urine → free Hb), infection, neurological (stroke/intracranial bleed), air embolism, limb ischaemia.
🔄 Weaning & Decannulation
Gradually decrease flow while assessing native function. For VA-ECMO: watch for return of pulsatility. Clamp circuit for trial off (2-4 hours). Surgical decannulation ± vessel repair.
📌 Oxygenation Index (OI) = (Mean Airway Pressure × FiO₂)/PaO₂ × 100. OI >40 indicates ECMO. E-CPR (ECMO-assisted CPR) for witnessed arrest with ≤2 rounds of epinephrine.

🩺 Step-by-Step: ECMO Management

1
Identify indication & contraindications
OI >40 or refractory cardiac failure. Contraindications: irreversible brain injury, lethal chromosomal anomaly, severe IVH (grade III/IV), futility.
2
Select mode (VA vs VV)
VA-ECMO for cardiac failure or E-CPR. VV-ECMO for isolated respiratory failure with normal cardiac function.
3
Cannulation
Peripheral (IJ + carotid/femoral) or central (sternotomy). Neonate: right IJ + carotid. Ensure tip position by ECHO/CXR.
4
Initiate ECMO & set flows
Target blood flow: neonate 100-150 mL/kg/min, child 80-100 mL/kg/min. Maintain ScvO₂ (pre-membrane) >70%.
5
Anticoagulation & monitoring
Heparin bolus 100 U/kg at cannulation. Target ACT 180-220 (VA) or 160-180 (VV). Monitor ACT q1h, then q2-4h. Platelets >80,000, fibrinogen >150 mg/dL.
6
Ventilator management (rest settings)
Rate 10-12/min, FiO₂ 30%, PEEP 5-10, tidal volume 1-4 mL/kg. Prevents VILI and allows lung recovery.
7
Daily checks & troubleshooting
Check circuit for clots (flashlight). Monitor pre/post-membrane O₂ saturation (gradient >10% suggests oxygenator failure). Pink urine = haemolysis → check plasma-free Hb.
8
Weaning & decannulation
Gradually decrease flow (0.5-1 mL/kg/min steps). Trial off by clamping circuit for 2-4 hours. If stable → decannulate surgically.