1) Arterial Limb Ischemia
Causes
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Large femoral arterial return cannula (low insertion/SFA entry).
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Dissection, vasospasm, PVD, vasopressors, distal thrombo-embolism.
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Can appear on insertion or after decannulation.
Diagnosis & Monitoring
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Exam: color, mottling, coolness, cap refill, pulses/Doppler.
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NIRS: tissue sat <50–60% or >20% limb difference.
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Ultrasound/angiography; labs: lactate/CK.
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SVS staging: I (viable) → IIa (marginal) → IIb (immediately threatened) → III (non-salvageable).
Prevention & Treatment
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Distal perfusion cannula (DPC) into SFA; confirm flow (e.g., popliteal).
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Insert at cannulation; can be salvage later.
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Heparin, minimize vasopressors, rewarm limb; vascular consult.
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If needed: contralateral cannulation, smaller cannula, fasciotomy, amputation.
2) Differential Hypoxia (“North–South/Blue Head”)
Required Triad
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Peripheral VA-ECMO, recovering LV, impaired lungs.
Recognition
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Right arm A-line/SpO₂ low while leg sats normal.
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NIRS: brain low, legs high.
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Mixing point in aorta depends on ECMO flow vs LV output.
Management
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Increase ECMO flow.
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Optimize ventilation (↑PEEP/FiO₂, consider NO).
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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
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VA-ECMO ↑ afterload → ↑ LVEDP & O₂ demand (opposite of Impella/IABP).
Five Monitors
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Arterial pulse pressure flattening.
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CVP ↑ / ScvO₂ ↓.
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CXR: pulmonary edema.
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Echo: larger LV/LA, smoke, closed AV.
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PA catheter: PCWP ↑.
Unloading Strategy
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Non-invasive: ↓ECMO flow, diuresis, inotropes/vasodilators, ↑PEEP.
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Impella, IABP, atrial septostomy/transseptal LA cannula,
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Surgical LV vent (apical/mitral) or PA vent, central ECLS.
Invasive (drain LV/LA/PA):
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Practice trend: close observation and intervene when signs appear.