1) Arterial Limb Ischemia

Causes

  • Large femoral arterial return cannula (low insertion/SFA entry).

  • Dissection, vasospasm, PVD, vasopressors, distal thrombo-embolism.

  • Can appear on insertion or after decannulation.

Diagnosis & Monitoring

  1. Exam: color, mottling, coolness, cap refill, pulses/Doppler.

  2. NIRS: tissue sat <50–60% or >20% limb difference.

  3. Ultrasound/angiography; labs: lactate/CK.

  4. SVS staging: I (viable) → IIa (marginal) → IIb (immediately threatened) → III (non-salvageable).

Prevention & Treatment

  • Distal perfusion cannula (DPC) into SFA; confirm flow (e.g., popliteal).

  • Insert at cannulation; can be salvage later.

  • Heparin, minimize vasopressors, rewarm limb; vascular consult.

  • If needed: contralateral cannulation, smaller cannula, fasciotomy, amputation.

2) Differential Hypoxia (“North–South/Blue Head”)

Required Triad

  • Peripheral VA-ECMO, recovering LV, impaired lungs.

Recognition

  • Right arm A-line/SpO₂ low while leg sats normal.

  • NIRS: brain low, legs high.

  • Mixing point in aorta depends on ECMO flow vs LV output.

Management

  1. Increase ECMO flow.

  2. Optimize ventilation (↑PEEP/FiO₂, consider NO).

  3. If persistent: switch to VV (if heart recovered) or VAV (add IJ venous return + Hoffman clamp to balance flows), or central VA.

3) Left Ventricular (LV) Distension

Why it Happens

  • VA-ECMO ↑ afterload → ↑ LVEDP & O₂ demand (opposite of Impella/IABP).

Five Monitors

  1. Arterial pulse pressure flattening.

  2. CVP ↑ / ScvO₂ ↓.

  3. CXR: pulmonary edema.

  4. Echo: larger LV/LA, smoke, closed AV.

  5. PA catheter: PCWP ↑.

Unloading Strategy

  • Non-invasive: ↓ECMO flow, diuresis, inotropes/vasodilators, ↑PEEP.

    • Impella, IABP, atrial septostomy/transseptal LA cannula,

    • Surgical LV vent (apical/mitral) or PA vent, central ECLS.

      Invasive (drain LV/LA/PA):

  • Practice trend: close observation and intervene when signs appear.

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