What is the management approach for neonates on Veno-Arterial (VA) Extracorporeal Membrane Oxygenation (ECMO) with elevated lactic acid levels and ischemic bowel?

Management of Neonates on VA ECMO with Elevated Lactate and Ischemic Bowel

Neonates on VA ECMO with elevated lactate and suspected ischemic bowel require immediate surgical consultation for exploratory laparotomy, as bowel necrosis represents a potentially reversible cause of refractory shock that must be addressed before ECMO can be effective. 1

Immediate Recognition and Assessment

Suspect Ischemic Bowel When:

• Lactate fails to clear despite adequate ECMO flows (>110 mL/kg/min should be avoided due to hemolysis risk, but flows should be optimized within safe parameters) 1
• Lactate clearance <3.8% at 3 hours, <51% at 9 hours, or <56% at 12 hours after ECMO initiation strongly predicts mortality and suggests ongoing tissue ischemia 2
• Abdominal distension, bloody stools, or feeding intolerance develop during ECMO support 1
• Persistent metabolic acidosis with rising lactate despite adequate cardiac output and oxygen delivery 2, 3

Critical Monitoring Parameters:

• Serial lactate measurements at 3,6,9, and 12 hours post-ECMO initiation to assess adequacy of resuscitation and identify occult ischemia 2
• Intra-abdominal pressure monitoring - pressures >12 mmHg indicate abdominal compartment syndrome requiring decompression 1
• Central venous oxygen saturation (ScvO2) >70% to confirm adequate systemic oxygen delivery 1
• Mean arterial pressure (MAP) >70 mmHg to maintain adequate perfusion pressure 1

Surgical Intervention Decision-Making

Indications for Immediate Exploratory Laparotomy:

• Necrotic tissue (bowel) represents a nidus of ongoing shock that must be removed for ECMO to be effective 1
• Pneumatosis intestinalis, portal venous gas, or free air on imaging mandate urgent surgical exploration 1
• Clinical peritonitis with abdominal wall erythema or crepitus requires immediate intervention 1

Timing Considerations:

• Do not delay surgery waiting for "stability" - the necrotic bowel IS the cause of instability 1
• ECMO provides the hemodynamic support necessary to tolerate surgery that would otherwise be impossible 1
• Survival with ECMO for neonatal sepsis is 80%, but only if reversible causes like bowel necrosis are addressed 1

Hemodynamic Optimization During ECMO

ECMO Flow Management:

• Maintain ECMO flows to achieve adequate oxygen delivery without exceeding 110 mL/kg/min to prevent hemolysis 1
• Monitor free hemoglobin and maintain <10 μg/dL by using adequate catheter, circuit, and oxygenator sizes 1
• Check cannula placement with chest radiograph and ultrasound to ensure optimal positioning 1

Vasoactive Support on VA ECMO:

• Inotrope requirements frequently diminish with VA ECMO but may still be necessary 1
• Continue dopamine/dobutamine or epinephrine as needed to maintain adequate perfusion pressure and cardiac output 1
• Normalize calcium concentration in the ECMO circuit (typically requires 300 mg CaCl2 per unit of packed red blood cells) 1

Blood Pressure Goals:

• Target MAP >70 mmHg to ensure adequate mesenteric perfusion 1
• Avoid hypotension as this exacerbates bowel ischemia even with adequate ECMO flows 1
• Monitor pulse pressure - values <20 mmHg in first 24 hours are associated with acute brain injury and likely reflect inadequate pulsatile flow to other organs including bowel 1

Metabolic Management

Lactate Clearance as a Prognostic Tool:

• Poor lactate clearance during ECMO is a significant marker for mortality and indicates inadequate resuscitation or ongoing tissue ischemia 2
• If lactate is not clearing appropriately, aggressively search for reversible causes including bowel necrosis, ongoing blood loss, or inadequate source control 1, 2

Correct Metabolic Derangements:

• Normalize calcium, glucose, and correct acidosis to optimize cellular function 1
• Avoid hypoglycemia which compounds ischemic injury 1

Renal Support Considerations

CRRT Integration with ECMO:

• In neonates with inadequate urine output and ≥10% fluid overload despite diuretics, CRRT should be performed on the ECMO circuit 1
• CRRT combined with ECMO increases blood volume, enables larger cannula use, and improves hemodynamic stability 1
• This is particularly important in neonates with ischemic bowel who may develop acute kidney injury from hypoperfusion 1

Critical Pitfalls to Avoid

Do Not Assume ECMO Alone Will Resolve the Problem:

• ECMO provides time and hemodynamic support, but does not treat the underlying pathology 1
• Necrotic bowel will continue to drive shock and lactate elevation regardless of ECMO flows 1

Do Not Delay Surgical Consultation:

• Every hour of delay with necrotic bowel in situ increases mortality 1
• The expected survival with ECMO for refractory shock is only 50%, and this drops further if reversible causes are not addressed 1

Monitor for Additional Complications:

• Pericardial effusion requiring pericardiocentesis 1
• Pneumothorax requiring thoracentesis 1
• Ongoing blood loss requiring transfusion and hemostasis 1
• Hypoadrenalism requiring hydrocortisone replacement 1

Anticoagulation Management:

• Balance anticoagulation needs for ECMO circuit with bleeding risk from bowel necrosis and potential surgery 4
• Coordinate closely with surgery regarding timing of intervention and anticoagulation adjustments 4

Prognosis and Expectations

• Overall survival for neonatal respiratory ECMO is 74%, but cardiac ECMO has lower survival rates 4, 5
• Neonates requiring ECMO for sepsis have 80% survival when reversible causes are addressed 1
• Failure to address necrotic bowel dramatically worsens prognosis regardless of ECMO support 1
• Elevated lactate and creatinine within 6 hours prior to cannulation are independent predictors of poor outcomes 3