What is the role of Extracorporeal Membrane Oxygenation (ECMO) and Extracorporeal Carbon Dioxide Removal (ECCO2R) in the management of critically ill patients in the Intensive Care Unit (ICU)?

ECMO and ECCO2R in the ICU

Direct Recommendation

ECMO and ECCO2R should be reserved for highly selected critically ill patients at experienced, high-volume centers (>20-25 cases/year) after exhausting conventional therapies, with ECMO indicated for severe refractory hypoxemia in ARDS and ECCO2R considered only for persistent severe hypercapnic acidosis (pH <7.15) despite optimized lung-protective ventilation. 1, 2

---

ECMO: Indications and Patient Selection

When to Initiate VV-ECMO

• VV-ECMO should be considered for severe ARDS with very severe hypoxemia despite optimal conventional management, including lung-protective ventilation, higher PEEP, neuromuscular blockade, and prone positioning 2
• Initiate within 7 days of respiratory failure onset for optimal outcomes 2
• Select patients with reversible etiologies of respiratory failure and few risk factors for futility 2
• The American Thoracic Society provides only a conditional recommendation with low certainty of evidence due to limitations in the CESAR trial 2

Institutional Requirements for ECMO

• ECMO must be performed at high-volume centers caring for >20-25 cases per year, as these centers have significantly better outcomes 2
• A learning curve of at least 20 cases is required to establish competence 2
• Regional organization with mobile ECMO teams and transfer networks should be established 2
• Hospitals without ECMO capability must establish institutional guidelines to identify ECMO-eligible patients and relationships with ECMO-capable institutions for timely transfer 2

Monitoring During ECMO

• Continuous monitoring of arterial blood pressure and respiratory parameters is required 1
• Regular arterial blood gas analysis and daily echocardiography are essential 1
• Meticulous tracking of fluid balance must be maintained 1

---

ECCO2R: Indications and Limitations

When to Consider ECCO2R

ECCO2R might be considered in three specific scenarios if local expertise exists: 3

1. Despite optimized invasive mechanical ventilation using lung-protective strategies, severe hypercapnic acidosis (pH <7.15) persists 3
2. When lung-protective ventilation is needed but hypercapnia is contraindicated (e.g., patients with coexistent brain injury) 3
3. For invasive mechanical ventilation patients awaiting lung transplant 3

Critical Evidence Limitations

• ECCO2R in patients with acute exacerbation of COPD and inadequate response to NIV has NOT been shown to reduce intubation rates 3
• ECCO2R is associated with a 52% complication rate, which contributed to the need for intubation 3
• ECCO2R devices can reduce PaCO2 and minute volume, providing 30-50% of the body's CO2 clearance depending on blood flow and membrane efficiency 3, 4

Safety Requirements for ECCO2R

• ECCO2R is an experimental therapy and should ONLY be used by specialist intensive care teams trained in its use and where additional governance arrangements are in place or in the setting of a research trial 3, 4
• NICE guidance advises ECCO2R should only be used in patients with potentially reversible hypercapnic respiratory failure or those being considered for lung transplantation 3

---

Technical Considerations and Pitfalls

Gas Exchange Principles

• ECCO2R operates at lower blood flow rates (200-1,500 ml/min) compared to full ECMO, adequate for substantial CO2 removal but allowing only minimal blood oxygenation 4
• Sweep gas (typically oxygen or air) flows through the membrane oxygenator creating a concentration gradient that drives CO2 removal 4

Critical Safety Concern

• Avoid rapid decreases in PaCO2: drops >20 mmHg within 24 hours of cannulation have been associated with acute brain injury and poorer survival 4
• Target PaCO2 between 35-45 mmHg while avoiding rapid changes 4
• Sweep gas flow should be titrated based on arterial blood gas measurements to achieve desired pH and PaCO2 levels 4

---

Anticoagulation Management

Bleeding and Thrombotic Risk

• 42% of VV-ECMO patients experience thrombotic events (mostly ECMO circuit thrombosis) 3
• 37% experience bleeding events (including cannulation/surgical site bleeding and medical bleeding) 3
• 21% experience both complications while on ECMO 3
• Anticoagulation management during ECMO remains challenging and often empirical, with high variability in practice 3

---

Common Pitfalls to Avoid

1. Do not use ECCO2R at centers without specialized training and governance structures 3, 4
2. Do not initiate ECMO or ECCO2R before exhausting conventional therapies including lung-protective ventilation, prone positioning, and neuromuscular blockade 2
3. Do not allow rapid PaCO2 drops during ECCO2R (>20 mmHg in 24 hours) 4
4. Do not expect ECCO2R to reduce intubation rates in COPD exacerbations despite NIV failure 3
5. Do not perform ECMO at low-volume centers (<20-25 cases/year) due to significantly worse outcomes 2