What is the role of VV (Veno-Venous) ECMO (Extracorporeal Membrane Oxygenation) in managing severe inhalation poisoning with respiratory failure?

Role of VV-ECMO in Managing Severe Inhalation Poisoning with Respiratory Failure

Veno-venous extracorporeal membrane oxygenation (VV-ECMO) should be considered as a rescue therapy for patients with severe inhalation poisoning who develop refractory respiratory failure unresponsive to conventional ventilation strategies. 1

Indications for VV-ECMO in Inhalation Poisoning

• VV-ECMO should be considered when conventional ventilation strategies fail to maintain acceptable gas exchange in patients with inhalation poisoning, particularly when there is persistent hypoxemia (PaO2 < 55 mmHg) despite optimal mechanical ventilation 2

• VV-ECMO is indicated after failure of less invasive rescue therapies such as inhaled nitric oxide/prostacyclin, prone positioning, neuromuscular blockade, and corticosteroids 2

• Early initiation of VV-ECMO should be considered in the emergency department for patients with inhalation poisoning presenting with refractory hypoxemic respiratory failure 3

• VV-ECMO provides respiratory support as a "bridge to recovery" in poisoned patients, as the clinical impact of many intoxications is often temporary 1

Patient Selection Criteria

• Patients with severe ARDS from inhalation poisoning with Murray scores > 3.0 and refractory to conventional ventilation may benefit from VV-ECMO 4

• VV-ECMO should be initiated within 7 days of respiratory failure onset for optimal outcomes 2

• Absolute contraindications include uncontrolled coagulopathy and severe intracranial bleeding that precludes anticoagulation therapy 1

• Relative contraindications include advanced age, severe irreversible brain injury, untreatable metastatic cancer, severe organ dysfunction (SOFA score > 15), and high-pressure positive pressure ventilation for more than 7 days 1

Benefits of VV-ECMO in Inhalation Poisoning

• VV-ECMO facilitates lung-protective ventilation, decreasing further ventilator-induced lung injury and allowing lung recovery from the toxic effects of inhaled substances 5

• VV-ECMO enables reduction of harmful ventilator settings that would otherwise be required to maintain oxygenation, including:

  • Lower tidal volumes to avoid volutrauma
  • Lower airway pressures to avoid barotrauma
  • Decreased FiO2 to reduce oxygen toxicity 5

• VV-ECMO can provide full respiratory bypass in patients with severe respiratory failure as a bridge to recovery 6

Implementation Considerations

• VV-ECMO should be performed at centers with sufficient experience, volume, and expertise to ensure it is used safely 2

• Hospitals without ECMO capability should establish institutional guidelines to identify ECMO-eligible patients and relationships with ECMO-capable institutions for timely transfer 2

• A multidisciplinary team including intensivists, pulmonologists, and respiratory therapists should be involved in decision-making 7

• Continuous monitoring of arterial blood pressure, respiratory parameters, regular arterial blood gas analysis, daily echocardiography, and meticulous tracking of fluid balance are essential 7

Potential Complications

• Bleeding is the most common complication of ECMO, occurring in 10-36% of patients, with intracranial hemorrhage seen in up to 6% of patients 1

• Other complications include cannulation site bleeding, infection, sepsis, circuit component malfunction, and right ventricular dysfunction 5

• Close monitoring for complications and prompt intervention are critical for successful ECMO support 5

Evidence from Case Reports

• Case reports have demonstrated successful use of VV-ECMO in patients with severe inhalation injuries:
  • Early VV-ECMO initiation in the emergency department for sodium dichloroisocyanurate (NaDCC) inhalation with refractory respiratory failure 3
  • VV-ECMO as rescue therapy for severe respiratory failure resulting from burns and smoke inhalation injury 4

Institutional Requirements

• ECMO centers caring for more than 20-25 cases per year have significantly better outcomes than centers with lower volumes 2

• The learning curve to establish competence requires at least 20 cases for optimal results 2

• A culture of safety should be emphasized, with properly functioning teams including nurses, perfusionists, respiratory therapists, and other specialists 5

Current Evidence Limitations

• There are no randomized trials of ECMO specifically in poisoned patients with refractory shock or ARDS caused by intoxication 1

• Additional evidence is necessary to make definitive recommendations for or against the use of ECMO in all cases of severe ARDS, including those from inhalation poisoning 2

• The American Thoracic Society recommends ongoing research measuring clinical outcomes among patients with severe ARDS who undergo ECMO 2

While evidence is still evolving, VV-ECMO represents an important rescue therapy for patients with severe inhalation poisoning causing respiratory failure when conventional therapies fail. Early consideration and transfer to an experienced ECMO center may be life-saving in these challenging cases.