Extracorporeal Membrane Oxygenation in NICU
Introduction to Neonatal ECMO
Extracorporeal Membrane Oxygenation (ECMO) is a form of cardiopulmonary bypass used in neonates with severe but potentially reversible respiratory or cardiac failure. It provides prolonged cardiac and respiratory support by oxygenating blood outside the body and returning it to the circulation.
Key Points:
- ECMO is a life-saving intervention for select neonates with severe cardiorespiratory failure
- It's typically used when conventional therapies, including mechanical ventilation, have failed
- ECMO allows time for lung or heart recovery by providing gas exchange and circulatory support
- It's a complex procedure requiring specialized equipment and a highly trained team
- The use of ECMO in neonates began in the 1970s and has evolved significantly since then
ECMO represents a significant advance in neonatal intensive care, offering a chance of survival for infants with otherwise fatal conditions. However, it carries significant risks and is used only in carefully selected cases.
Indications for Neonatal ECMO
ECMO is considered in neonates with severe respiratory or cardiac failure that is potentially reversible but unresponsive to maximal conventional therapy.
Common Indications:
- Respiratory:
- Meconium Aspiration Syndrome (MAS)
- Persistent Pulmonary Hypertension of the Newborn (PPHN)
- Congenital Diaphragmatic Hernia (CDH)
- Severe pneumonia or sepsis
- Air leak syndromes
- Cardiac:
- Congenital heart defects
- Cardiomyopathy
- Myocarditis
- Post-cardiac surgery support
Selection Criteria:
- Gestational age ≥ 34 weeks (relative criterion)
- Birth weight ≥ 2 kg (relative criterion)
- Reversible condition with a high mortality risk (>80%) with conventional treatment
- Failure of maximal medical therapy, including:
- High-frequency oscillatory ventilation
- Inhaled nitric oxide
- Surfactant therapy (if indicated)
- Inotropic support
- Oxygenation Index (OI) > 40 consistently
- PaO2 < 40 mmHg for >3 hours
- No contraindications to ECMO
The decision to initiate ECMO is complex and should be made by a multidisciplinary team considering the individual patient's condition, potential for recovery, and risks versus benefits.
Types of ECMO in Neonates
There are two main types of ECMO used in neonates, each with specific indications and characteristics:
1. Veno-Arterial (VA) ECMO:
- Description: Provides both cardiac and respiratory support
- Circulation: Blood is drained from the right atrium and returned to the aorta
- Indications:
- Combined cardiac and respiratory failure
- Severe cardiac dysfunction
- Inability to maintain adequate cardiac output
- Advantages:
- Provides complete cardiopulmonary support
- Can be used in severe hemodynamic instability
- Disadvantages:
- Higher risk of neurological complications
- Requires carotid artery cannulation (potential for long-term complications)
2. Veno-Venous (VV) ECMO:
- Description: Provides respiratory support only
- Circulation: Blood is drained from and returned to the right atrium
- Indications:
- Isolated respiratory failure
- Adequate cardiac function
- Advantages:
- Preserves pulmonary blood flow
- Lower risk of neurological complications
- Preserves carotid artery
- Disadvantages:
- Cannot provide cardiac support
- May be insufficient in severe hypoxemia
The choice between VA and VV ECMO depends on the neonate's specific condition, particularly whether cardiac support is needed in addition to respiratory support. In some cases, conversion from one type to another may be necessary during the course of treatment.
ECMO Procedure in Neonates
The initiation of ECMO in neonates is a complex procedure requiring a skilled team and specialized equipment.
Pre-ECMO Preparation:
- Optimization of conventional therapies
- Detailed assessment of cardiac function (echocardiography)
- Neurological examination and head ultrasound
- Informed consent from parents/guardians
- Preparation of ECMO circuit and team
Cannulation Procedure:
- Anesthesia and Positioning:
- General anesthesia and appropriate positioning
- Strict aseptic technique
- Vessel Selection:
- VA ECMO: Right common carotid artery and internal jugular vein
- VV ECMO: Right internal jugular vein (double-lumen cannula)
- Surgical Technique:
- Neck incision and vessel exposure
- Vessel ligation (for VA ECMO)
- Cannula insertion under ultrasound guidance
- Securing cannulas and closure of surgical site
- Circuit Connection:
- Connection of cannulas to the ECMO circuit
- De-airing of the system
- Gradual initiation of extracorporeal flow
ECMO Circuit Components:
- Pump (roller or centrifugal)
- Oxygenator
- Heat exchanger
- Tubing
- Monitoring devices (flow sensors, pressure monitors, etc.)
The procedure requires meticulous attention to detail to minimize risks such as air embolism, bleeding, and infection. Continuous monitoring and adjustment of the ECMO parameters are essential throughout the treatment period.
Management of Neonates on ECMO
Managing a neonate on ECMO requires a multidisciplinary approach and constant vigilance. Key aspects of management include:
1. ECMO Circuit Management:
- Continuous monitoring of circuit function, including:
- Blood flow rates
- Oxygenator function
- Pressure gradients
- Circuit integrity
- Adjustment of ECMO settings based on patient needs
- Regular circuit checks and maintenance
2. Ventilation Management:
- "Rest" ventilator settings to minimize barotrauma
- Typically low rate, low pressure, and moderate PEEP
- Gradual weaning as native lung function improves
3. Hemodynamic Management:
- Continuous monitoring of blood pressure, heart rate, and perfusion
- Echocardiography to assess cardiac function
- Careful fluid and electrolyte management
- Use of inotropes as needed
4. Anticoagulation:
- Typically heparin infusion
- Regular monitoring of ACT, aPTT, and anti-Xa levels
- Balancing anticoagulation needs with bleeding risks
5. Fluid and Nutrition Management:
- Careful fluid balance to prevent overload or dehydration
- Parenteral nutrition initially, transitioning to enteral feeds when possible
- Close monitoring of electrolytes and metabolic parameters
6. Neurological Monitoring:
- Regular neurological examinations
- Cerebral near-infrared spectroscopy (NIRS) monitoring
- Head ultrasounds to detect intracranial hemorrhage
7. Infection Control:
- Strict aseptic technique for all procedures
- Prophylactic antibiotics as per protocol
- Regular surveillance cultures
8. Weaning and Decannulation:
- Gradual reduction in ECMO support as native organ function improves
- Trial periods off ECMO to assess readiness for decannulation
- Careful planning and execution of decannulation procedure
Management of a neonate on ECMO requires 24/7 specialized care and the ability to rapidly respond to any complications or changes in the patient's condition. Regular team discussions and care plan reviews are essential for optimal outcomes.
Complications of ECMO in Neonates
While ECMO can be life-saving, it is associated with significant potential complications. These include:
1. Mechanical Complications:
- Circuit clotting or air embolism
- Oxygenator failure
- Cannula problems (malposition, dislodgement)
- Pump malfunction
2. Hemorrhagic Complications:
- Intracranial hemorrhage (most serious)
- Surgical site bleeding
- Pulmonary hemorrhage
- Gastrointestinal bleeding
3. Neurological Complications:
- Seizures
- Ischemic brain injury
- Developmental delays
4. Cardiovascular Complications:
- Hypertension
- Myocardial stunning
- Arrhythmias
- Cardiac tamponade
5. Renal Complications:
- Acute kidney injury
- Fluid overload
- Electrolyte imbalances
6. Infectious Complications:
- Bloodstream infections
- Surgical site infections
- Ventilator-associated pneumonia
7. Hematological Complications:
- Thrombocytopenia
- Hemolysis
- Disseminated intravascular coagulation (DIC)
8. Long-term Complications:
- Chronic lung disease
- Neurodevelopmental impairment
- Hearing loss
- Feeding difficulties
The risk and severity of complications can vary depending on the neonate's underlying condition, duration of ECMO, and type of ECMO used. Close monitoring and prompt intervention are crucial to minimize and manage these complications effectively.
Outcomes and Prognosis of Neonatal ECMO
The outcomes of neonatal ECMO have improved significantly since its introduction, but they can vary widely depending on the underlying condition, timing of ECMO initiation, and presence of complications.
Survival Rates:
- Overall survival to discharge: Approximately 70-80%
- Condition-specific survival rates:
- Meconium Aspiration Syndrome: 90-95%
- Persistent Pulmonary Hypertension: 80-85%
- Congenital Diaphragmatic Hernia: 50-60%
- Sepsis: 70-75%
- Cardiac indications: 40-50%
Short-term Outcomes:
- Length of ECMO run: typically 5-7 days for respiratory indications, longer for cardiac
- Hospital length of stay: often prolonged, averaging 4-6 weeks post-ECMO
- Common issues during recovery:
- Respiratory: need for prolonged ventilation, oxygen dependency
- Feeding difficulties
- Medication needs (e.g., pulmonary vasodilators, diuretics)
Long-term Outcomes:
- Neurodevelopmental:
- 15-20% risk of significant neurodevelopmental impairment
- Higher rates of subtle cognitive and motor delays
- Increased risk of attention and behavioral issues
- Pulmonary:
- Increased risk of reactive airway disease
- Potential for chronic lung disease, especially in CDH survivors
- Hearing:
- 5-10% risk of sensorineural hearing loss
- Growth:
- Potential for growth delays, especially in infants with chronic conditions
Prognostic Factors:
- Pre-ECMO factors:
- Underlying diagnosis
- Gestational age and birth weight
- Severity of illness before ECMO initiation
- ECMO-related factors:
- Duration of ECMO support
- Complications during ECMO (especially neurological)
- Type of ECMO (VA vs. VV)
- Post-ECMO factors:
- Residual organ dysfunction
- Ongoing medical needs
- Quality of follow-up care and early intervention
Follow-up and Monitoring:
Given the potential for long-term complications, comprehensive follow-up is crucial:
- Regular neurodevelopmental assessments
- Hearing and vision screening
- Pulmonary function monitoring
- Growth and nutrition surveillance
- Psychosocial support for families
While ECMO has dramatically improved survival for many neonates with severe cardiorespiratory failure, it's important to recognize that it's not without risks. The decision to initiate ECMO should always involve a careful consideration of potential benefits and risks, with ongoing research aimed at further improving outcomes and minimizing complications.
Extracorporeal Membrane Oxygenation in NICU
- What does ECMO stand for in neonatal care?
Answer: Extracorporeal Membrane Oxygenation - Which of the following is NOT a primary indication for ECMO in neonates?
Answer: Uncomplicated meconium aspiration syndrome - What is the minimum gestational age typically required for ECMO eligibility in neonates?
Answer: 34 weeks - Which of the following is a contraindication for ECMO in neonates?
Answer: Grade IV intraventricular hemorrhage - What is the primary function of the oxygenator in an ECMO circuit?
Answer: To oxygenate blood and remove carbon dioxide - Which type of ECMO provides both cardiac and respiratory support?
Answer: Venoarterial (VA) ECMO - What is the typical duration of ECMO support for neonates with respiratory failure?
Answer: 5-7 days - Which of the following is NOT a common complication of ECMO in neonates?
Answer: Hypoglycemia - What is the primary advantage of venovenous (VV) ECMO over venoarterial (VA) ECMO?
Answer: Preservation of pulmonary blood flow - Which of the following is a key component of pre-ECMO management in neonates?
Answer: Optimization of conventional mechanical ventilation - What is the recommended activated clotting time (ACT) range for neonates on ECMO?
Answer: 180-220 seconds - Which of the following is NOT a typical cannulation site for neonatal ECMO?
Answer: Femoral vessels - What is the primary purpose of the heat exchanger in an ECMO circuit?
Answer: To maintain normal body temperature - Which of the following is a potential neurological complication of ECMO in neonates?
Answer: Intracranial hemorrhage - What is the term for inadequate systemic perfusion during VA ECMO due to competition between native cardiac output and ECMO flow?
Answer: North-South syndrome - Which of the following is NOT a typical weaning strategy for neonatal ECMO?
Answer: Abrupt discontinuation of support - What is the recommended initial ECMO flow rate for neonates?
Answer: 100-120 mL/kg/min - Which of the following is a contraindication for VV ECMO in neonates?
Answer: Severe cardiac dysfunction - What is the primary advantage of using a centrifugal pump in neonatal ECMO circuits?
Answer: Reduced risk of circuit thrombosis - Which of the following is NOT a typical monitoring parameter for neonates on ECMO?
Answer: Continuous EEG - What is the term for hemolysis caused by mechanical destruction of red blood cells in the ECMO circuit?
Answer: Circuit-induced hemolysis - Which of the following is a potential renal complication of ECMO in neonates?
Answer: Acute kidney injury - What is the recommended hematocrit range for neonates on ECMO?
Answer: 35-40% - Which of the following is NOT a typical indication for ECMO in neonatal cardiac patients?
Answer: Isolated atrial septal defect - What is the primary purpose of the bladder in an ECMO circuit?
Answer: To serve as a compliance chamber - Which of the following is a potential long-term complication of ECMO in neonates?
Answer: Neurodevelopmental delay - What is the recommended platelet count threshold for neonates on ECMO?
Answer: >100,000/μL - Which of the following is NOT a typical criterion for ECMO discontinuation in neonates?
Answer: Complete resolution of underlying disease - What is the term for air entrainment into the ECMO circuit?
Answer: Air embolism - Which of the following is a potential infectious complication of ECMO in neonates?
Answer: Catheter-related bloodstream infection
