Evidence Behind VV ECMO

Historical Evolution

  • 1970s–1990s: Early use, poor outcomes, limited support

  • 2009 CESAR Trial: Demonstrated ECMO benefit in specialized centers

  • 2018 EOLIA Trial: Confirmed ECMO improves survival in severe ARDS despite crossover limitations

  • COVID-19 era: Registry data validated ECMO outcomes in high-volume centers

Landmark Studies

CESAR Trial

  • Randomized trial (UK, 2001–2006), 180 patients

  • Outcome: ECMO in a specialized center reduced death/severe disability

  • Key insight: Referral to high-volume ECMO centers improves outcomes

Australian H1N1 Study

  • Observational, high survival (71%) in severe viral ARDS

  • Showed ECMO is feasible, safe, and life-saving in a pandemic

EOLIA Trial

  • Randomized controlled trial, 249 patients

  • Strict criteria: Severe hypoxia/hypercapnia despite optimal ventilation

  • Results: Trend toward mortality benefit (34% vs. 46%)

  • Significant crossover (28%): Confirmed rescue ECMO saves lives

Post-EOLIA Practice

  • ECMO recognized in international ARDS management guidelines

  • Recommended for severe ARDS in specialized centers

  • ECMO strategy now focuses on early initiation, careful patient selection, and lung-protective ventilation

 Technological Advances

  • Shift from roller to centrifugal pumps

  • Reduced hemolysis, improved safety, smaller portable machines

  • Improved outcomes due to better devices, circuits, and anticoagulation protocols

Risk Prediction and Decision-Making

RESP Score

  • 12-variable tool to stratify survival likelihood in VV ECMO

  • Class I (>90% survival) to Class V (<20%)

  • Variables include age, days on ventilation, PaCO₂, driving pressure, CNS dysfunction, etc.

  • Online calculator available to support decision-making

Patient Selection Criteria

  • Favorable predictors: <7 days MV, viral ARDS, prone use, neuromuscular blockade

  • Poor prognosis: >14 days MV, fibrosis, comorbidities, age >65, multi-organ failure

When to Say No

  • Absolute contraindications: irreversible lung damage, advanced age/frailty, uncontrolled sepsis

  • Referral pathways essential: Central ECMO coordination improves timely access

Changing Paradigms in Ventilation on VV ECMO

Mechanical Power Concept

  • Unifying model to quantify lung stress

  • Power = 0.098 × RR × VT × (Ppeak – ½ × ΔP)

  • High mechanical power >17 J/min linked to VILI

Ventilator-Induced Lung Injury (VILI) Mechanisms

  • Volutrauma: excessive VT

  • Barotrauma: high plateau pressure

  • Atelectrauma: inadequate PEEP

  • Ergotrauma: high mechanical power

  • Biotrauma: inflammatory response from ventilation

  • Corotrauma: excessive respiratory drive

  • Energotrauma: high driving pressure

Ultraprotective Ventilation Strategy

  • Tidal volume ≤4 ml/kg, plateau ≤25, driving pressure <14, PEEP 10–24

  • Mechanical power <8 J/min is ideal

  • Respiratory rate 4–30/min, FiO₂ 30–50%

Supported by CESAR and EOLIA Trials

Weaning Strategies and Recovery Pathways

Types of VV ECMO Recovery

  • Rapid Recovery (<7 days): Quick improvement, early decannulation

  • Slow Recovery (7–21 days): Gradual lung healing, often tracheostomy

  • Fibroproliferative (>21 days): Consider lung transplant

  • Non-Recovering: Multiorgan failure, consider withdrawal

Monitoring Markers of Recovery

  • ↓ ECMO sweep/flow

  • ↓ ventilator settings (FiO₂, PEEP)

  • ↑ compliance, ↓ plateau pressure

  • Stable ABG, ↓ IL-6, improved imaging (CXR, CT, LUS)

 Awake ECMO vs Conventional Weaning

Conventional Pathway

 

  • Wean ECMO, then extubate

  • More controlled, lung-protective, familiar

  • Sedation risks: delirium, diaphragmatic dysfunction

Awake ECMO Pathway

  • Extubate first, wean ECMO later

  • Less sedation, early mobilisation, diaphragm preserved

  • Risks: P-SILI, accidental decannulation, resource intensive

  • Ideal patient: Cooperative, intact airway, low RR drive, hemodynamically stable

Challenges

  • Balance between lung protection and diaphragm preservation

  • Monitor for P-SILI (↑RR, ↑VT, signs of distress)

  • Use diaphragm ultrasound, pressure monitoring, stepwise weaning

Final Concepts

  • ECMO doesn’t kill patients; it buys time for recovery

  • Time-limited trial of ECMO helps avoid futile interventions

  • ECMO should be initiated early in reversible severe ARDS

  • Multidisciplinary collaboration is key (intensivist, nurse, perfusionist, physiotherapist)

  • No one-size-fits-all strategy; continuous reassessment essential

  • Future research needed in ECMO timing, ventilator strategies, and weaning protocols

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