Evidence Behind VV ECMO
Historical Evolution
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1970s–1990s: Early use, poor outcomes, limited support
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2009 CESAR Trial: Demonstrated ECMO benefit in specialized centers
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2018 EOLIA Trial: Confirmed ECMO improves survival in severe ARDS despite crossover limitations
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COVID-19 era: Registry data validated ECMO outcomes in high-volume centers
Landmark Studies
CESAR Trial
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Randomized trial (UK, 2001–2006), 180 patients
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Outcome: ECMO in a specialized center reduced death/severe disability
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Key insight: Referral to high-volume ECMO centers improves outcomes
Australian H1N1 Study
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Observational, high survival (71%) in severe viral ARDS
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Showed ECMO is feasible, safe, and life-saving in a pandemic
EOLIA Trial
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Randomized controlled trial, 249 patients
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Strict criteria: Severe hypoxia/hypercapnia despite optimal ventilation
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Results: Trend toward mortality benefit (34% vs. 46%)
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Significant crossover (28%): Confirmed rescue ECMO saves lives
Post-EOLIA Practice
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ECMO recognized in international ARDS management guidelines
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Recommended for severe ARDS in specialized centers
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ECMO strategy now focuses on early initiation, careful patient selection, and lung-protective ventilation
Technological Advances
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Shift from roller to centrifugal pumps
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Reduced hemolysis, improved safety, smaller portable machines
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Improved outcomes due to better devices, circuits, and anticoagulation protocols
Risk Prediction and Decision-Making
RESP Score
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12-variable tool to stratify survival likelihood in VV ECMO
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Class I (>90% survival) to Class V (<20%)
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Variables include age, days on ventilation, PaCO₂, driving pressure, CNS dysfunction, etc.
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Online calculator available to support decision-making
Patient Selection Criteria
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Favorable predictors: <7 days MV, viral ARDS, prone use, neuromuscular blockade
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Poor prognosis: >14 days MV, fibrosis, comorbidities, age >65, multi-organ failure
When to Say No
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Absolute contraindications: irreversible lung damage, advanced age/frailty, uncontrolled sepsis
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Referral pathways essential: Central ECMO coordination improves timely access
Changing Paradigms in Ventilation on VV ECMO
Mechanical Power Concept
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Unifying model to quantify lung stress
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Power = 0.098 × RR × VT × (Ppeak – ½ × ΔP)
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High mechanical power >17 J/min linked to VILI
Ventilator-Induced Lung Injury (VILI) Mechanisms
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Volutrauma: excessive VT
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Barotrauma: high plateau pressure
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Atelectrauma: inadequate PEEP
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Ergotrauma: high mechanical power
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Biotrauma: inflammatory response from ventilation
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Corotrauma: excessive respiratory drive
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Energotrauma: high driving pressure
Ultraprotective Ventilation Strategy
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Tidal volume ≤4 ml/kg, plateau ≤25, driving pressure <14, PEEP 10–24
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Mechanical power <8 J/min is ideal
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Respiratory rate 4–30/min, FiO₂ 30–50%
Supported by CESAR and EOLIA Trials
Weaning Strategies and Recovery Pathways
Types of VV ECMO Recovery
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Rapid Recovery (<7 days): Quick improvement, early decannulation
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Slow Recovery (7–21 days): Gradual lung healing, often tracheostomy
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Fibroproliferative (>21 days): Consider lung transplant
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Non-Recovering: Multiorgan failure, consider withdrawal
Monitoring Markers of Recovery
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↓ ECMO sweep/flow
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↓ ventilator settings (FiO₂, PEEP)
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↑ compliance, ↓ plateau pressure
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Stable ABG, ↓ IL-6, improved imaging (CXR, CT, LUS)
Awake ECMO vs Conventional Weaning
Conventional Pathway
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Wean ECMO, then extubate
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More controlled, lung-protective, familiar
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Sedation risks: delirium, diaphragmatic dysfunction
Awake ECMO Pathway
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Extubate first, wean ECMO later
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Less sedation, early mobilisation, diaphragm preserved
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Risks: P-SILI, accidental decannulation, resource intensive
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Ideal patient: Cooperative, intact airway, low RR drive, hemodynamically stable
Challenges
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Balance between lung protection and diaphragm preservation
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Monitor for P-SILI (↑RR, ↑VT, signs of distress)
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Use diaphragm ultrasound, pressure monitoring, stepwise weaning
Final Concepts
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ECMO doesn’t kill patients; it buys time for recovery
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Time-limited trial of ECMO helps avoid futile interventions
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ECMO should be initiated early in reversible severe ARDS
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Multidisciplinary collaboration is key (intensivist, nurse, perfusionist, physiotherapist)
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No one-size-fits-all strategy; continuous reassessment essential
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Future research needed in ECMO timing, ventilator strategies, and weaning protocols