What is the best approach to manage hyperlacticemia in a neonate on Veno-Arterial (VA) Extracorporeal Membrane Oxygenation (ECMO)?

Management of Hyperlactatemia in Neonates on VA ECMO

In neonates on VA ECMO with elevated lactate, immediately assess for reversible causes—particularly ischemic bowel requiring urgent surgical exploration—while optimizing ECMO flows (without exceeding 110 mL/kg/min), maintaining MAP ≥70 mmHg, and targeting lactate clearance of at least 10% every 2 hours, as failure to clear lactate despite adequate ECMO support mandates aggressive investigation for surgical pathology. 1, 2

Immediate Recognition and Risk Stratification

Lactate Thresholds and Prognostic Significance

• Admission lactate <25 mmol/L predicts survival with 100% sensitivity and 71.4% specificity in neonates requiring ECMO 3
• Peak lactate levels differ significantly between survivors (13.7 ± 6.32 mmol/L) and non-survivors (38.4 ± 9.20 mmol/L) 3
• Lactate clearance at 3,9, and 12 hours after ECMO initiation significantly predicts mortality, with cut-off values of 3.8%, 51%, and 56% clearance respectively 2
• Persistent severe hyperlactatemia 12 hours after ECMO start indicates poor prognosis and demands immediate investigation for reversible causes 3

Critical Assessment for Ischemic Bowel

• Necrotic bowel represents a nidus of ongoing shock that must be surgically removed before ECMO can be effective—do not delay surgery waiting for "stability" as the necrotic tissue IS the cause of instability 1
• Assess for abdominal distension, bloody stools, feeding intolerance, or clinical peritonitis with abdominal wall erythema 1
• Pneumatosis intestinalis, portal venous gas, or free air on imaging mandate urgent surgical exploration 1
• Monitor intra-abdominal pressure—values >12 mmHg indicate abdominal compartment syndrome requiring decompression 1
• Every hour of delay with necrotic bowel in situ increases mortality—ECMO provides the hemodynamic support necessary to tolerate surgery that would otherwise be impossible 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
• Verify cannula placement with chest radiograph and ultrasound to ensure optimal positioning 1

Blood Pressure and Perfusion Targets

• Target MAP ≥70 mmHg to ensure adequate mesenteric and systemic perfusion—hypotension 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
• Verify central venous oxygen saturation (ScvO2) >70% to confirm adequate systemic oxygen delivery 1

Inotropic Support

• Continue dopamine/dobutamine or epinephrine as needed to maintain adequate perfusion pressure and cardiac output, though requirements frequently diminish with VA ECMO 1
• Be aware that epinephrine can cause elevated lactate through beta-2-adrenergic receptor stimulation independent of tissue perfusion 4

Metabolic Management

Lactate Clearance Monitoring

• Measure lactate every 2 hours during acute resuscitation, targeting clearance of at least 10% every 2 hours during the first 8 hours 4, 2
• Normalization of lactate within 24 hours is associated with 100% survival in critically ill neonates 4
• If lactate is not clearing appropriately despite adequate ECMO flows and hemodynamics, aggressively search for reversible causes including bowel necrosis, ongoing blood loss, or inadequate source control 1

Metabolic Optimization

• Normalize calcium concentration in the ECMO circuit (typically requires 300 mg CaCl₂ per unit of packed red blood cells) 1
• Normalize glucose and correct acidosis to optimize cellular function—avoid hypoglycemia which compounds ischemic injury 1
• Do NOT use sodium bicarbonate for pH ≥7.15 as it does not improve outcomes and may cause harm 4, 5

Renal Support Considerations

• In neonates with inadequate urine output and ≥10% fluid overload despite diuretics, perform CRRT on the ECMO circuit 6, 7
• CRRT combined with ECMO increases blood volume, enables larger cannula use, and improves hemodynamic stability—particularly important in neonates with ischemic bowel who may develop acute kidney injury from hypoperfusion 6, 1
• Use bicarbonate-based dialysate in patients with lactic acidosis rather than lactate-based solutions 7

Surgical Decision-Making Algorithm

When to Pursue Immediate Surgical Consultation

Obtain immediate surgical consultation for exploratory laparotomy if ANY of the following are present: 1

• Lactate fails to clear by at least 10% every 2 hours despite optimized ECMO flows (>100 mL/kg/min) and MAP ≥70 mmHg
• Abdominal distension, bloody stools, or feeding intolerance develop during ECMO support
• Pneumatosis intestinalis, portal venous gas, or free air on imaging
• Clinical peritonitis with abdominal wall erythema or crepitus
• Intra-abdominal pressure >12 mmHg

Prognostic Context

• 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—the expected survival with ECMO for refractory shock is only 50%, dropping further if reversible causes are not addressed 1

Critical Pitfalls to Avoid

• ECMO provides time and hemodynamic support but does not treat the underlying pathology—necrotic bowel will continue to drive shock and lactate elevation regardless of ECMO flows 1
• Do not assume adequate ECMO flows alone will resolve hyperlactatemia—persistent elevation mandates investigation for surgical pathology 1, 2
• Do not delay surgical exploration in hemodynamically unstable patients to perform additional laboratory testing 4
• Avoid exceeding ECMO flows of 110 mL/kg/min as this increases hemolysis risk without improving outcomes 1
• A single normal lactate value does not guarantee sustained recovery—continued monitoring prevents premature de-escalation of care 4

Special Considerations in Neonatal VA ECMO

• High lactate levels at ECMO cannulation appear to be associated with severe complications such as death and NEC 8
• Patients who developed NEC had higher lactate levels at the time of cannulation than at the time of NEC diagnosis, suggesting lactate is a risk factor for severe complications rather than a diagnostic marker 8
• Monitor for acquired von Willebrand syndrome (AVWS), which occurs in 79-100% of neonates on ECMO within hours of cannulation and may contribute to bleeding complications 6