Skip to content

Extracorporeal Life Support (ECLS)

Definition

  • ECLS is a form of cardiopulmonary bypass providing temporary life support for critically ill patients with acute respiratory and/or cardiac failure.
  • It facilitates gas exchange by removing carbon dioxide and oxygenating blood, ensuring circulatory support.
  • First reported in 1976 for neonatal use, it has become a standard therapeutic option for cardiopulmonary failure refractory to maximal medical therapy.
  • Widely used in extracorporeal cardiopulmonary resuscitation (eCPR), though its role in neonatal and pediatric resuscitation remains controversial.

Indications

  • Neonatal ECMO is primarily indicated for:
    • Meconium aspiration (most common with >90% survival rate).
    • Respiratory distress syndrome (RDS).
    • Persistent pulmonary hypertension of the newborn (PPHN).
    • Sepsis.
    • Congenital diaphragmatic hernia (CDH).
  • ECMO is generally recommended when 80% mortality is predicted due to cardiopulmonary function deterioration.
  • Guidelines for ECMO initiation:
    • Alveolar-arterial oxygen gradient (AaDo2):
      • Greater than 610 for 8-12 hours or 620 for 6 hours, with extensive barotrauma and severe hypotension.
    • Oxygen index:
      • Calculated as (FiO2 × mean airway pressure × 100) / PaO2. An oxygen index >40 correlates with 80% mortality.
  • Contraindications:
    • Severe prematurity due to a high risk of intracranial bleeding.
    • Weight <2 kg or presence of intracranial hemorrhage (Grade II intraventricular hemorrhage).
    • Non-reversible pulmonary conditions such as congenital alveolar dysplasia.
    • Cyanotic congenital heart disease, major genetic defects, and intractable coagulopathy are also exclusion criteria.

Physiology of ECLS

  • Cannulation:
    • For venoarterial ECLS, the right internal jugular vein and common carotid artery are used for cannulation due to their size and collateral circulation.
    • For venovenous ECLS, a double-lumen single cannula is placed via the right internal jugular vein, avoiding carotid arterial cannulation.
  • ECLS Circuit Components:
    • Silicone rubber bladder.
    • Roller pump.
    • Membrane oxygenator.
    • Heat exchanger.
    • Tubing and connectors.
  • Mechanism:
    • Desaturated mixed venous blood from the right atrium drains into the venous cannula and moves to the bladder.
    • Blood is then pumped to the membrane oxygenator, where carbon dioxide is removed and oxygen is added.
    • The oxygenated blood passes through the heat exchanger and returns to the patient via the arterial cannula.
  • Anticoagulation: Necessary to prevent clotting in the ECLS circuit but increases the risk of bleeding complications.
  • Indicators of Lung Recovery:
    • Increased PaO2, improved lung compliance, and clearing of the chest radiograph.
    • Patients are trialed off bypass by clamping the cannulas to assess tolerance before removing from ECLS.
  • Alternative Techniques:
    • In older pediatric and adult patients, venous cannulas can be placed in both the internal jugular and femoral veins to achieve venovenous ECMO circulation.

Complications

  • Bleeding: Most common complication, occurring at catheter or surgical sites, including intracranial hemorrhage.
    • Gestational age is the most significant predictor of intracranial hemorrhage, especially in premature infants (<34 weeks).
  • Other Complications:
    • Seizures and neurologic impairment.
    • Renal failure, often requiring hemofiltration or hemodialysis.
    • Hypertension.
    • Infections.
    • Mechanical malfunctions of the oxygenator, pump, heat exchanger, or cannulas.

This summary covers the key concepts of extracorporeal life support (ECLS), focusing on its indications, physiology, and complications, ensuring comprehensive understanding for clinical application.