What clinical, hemodynamic and laboratory parameters (e.g., mean arterial pressure (MAP), central venous pressure (CVP), circuit pressures, pump flow, sweep gas flow, arterial oxygen saturation (SaO₂), blood gases, complete blood count (CBC), coagulation profile, metabolic panel, renal and hepatic function, lactate, and hemolysis markers) should be monitored and how frequently in a patient on extracorporeal membrane oxygenation (ECMO)?

ECMO Management: Essential Monitoring Parameters

Core Monitoring Framework

You must implement standardized, continuous multimodal monitoring focusing on neurological surveillance, hemodynamic parameters, oxygenation targets, circuit function, and anticoagulation to detect complications early and reduce morbidity and mortality. 1

---

Hemodynamic Parameters

Blood Pressure Targets

• Maintain mean arterial pressure (MAP) >70 mmHg to ensure adequate cerebral and end-organ perfusion 2, 3, 1
• Monitor pulse pressure in the first 24 hours of VA ECMO, as values <20 mmHg are associated with acute brain injury and poor outcomes 4, 1
• For acute ischemic stroke patients, allow permissive hypertension (BP ≤220/120 mmHg) if cardiac function tolerates it 2
• For intracerebral hemorrhage, target systolic BP <140 mmHg 2

ECMO Flow and Circuit Pressures

• Target initial ECMO flow of 3-4 L/min immediately post-cannulation, gradually increasing as tolerated 4, 3, 1
• Maintain arteriovenous oxygen difference between 3-5 cc O₂/100mL blood as the most reliable parameter for setting flow goals 4, 3
• Visually inspect the ECMO circuit hourly for clots, dark discoloration, excessive negative pressures, or cannula vibration indicating mechanical hemolysis 2, 4
• Monitor for cannula suctioning and chatter, which indicate venous collapse and can cause both flow reduction and hemolysis 4

Central Venous Pressure

• Monitor central venous pressure (CVP) as part of hemodynamic assessment, though specific targets are not well-defined in ECMO patients 5
• Assess for hypovolemia carefully, as it can induce venous collapse and worsen hemolysis, but avoid volume overload which independently predicts poor outcomes 4

---

Laboratory Monitoring

Arterial Blood Gases - Frequency and Targets

• Perform serial ABG sampling in the first 24 hours of ECMO 2, 1
• Avoid arterial hypoxemia (PaO₂ <70 mmHg) for 24-48 hours in VA ECMO, especially in patients at high risk for reperfusion injury 2, 3, 1
• Avoid severe arterial hyperoxia (PaO₂ >300 mmHg) 3, 1
• Target arterial oxygen saturation of 92-97% by adjusting ECMO sweep gas oxygen percentage 3, 1
• Avoid rapid changes in carbon dioxide levels within the first 24 hours to prevent cerebrovascular complications 3, 1

Complete Blood Count

• Monitor hemoglobin daily, maintaining >10 mg/dL to optimize oxygen-carrying capacity 2, 4
• Maintain platelet count >100,000 per mm³ 2
• Check plasma-free hemoglobin immediately if hemolysis is suspected 4

Coagulation Profile - Daily Monitoring

• Check activated clotting time (ACT) hourly, targeting 180-220 seconds 2
• Perform daily anti-Factor Xa levels (target 0.3-0.7 U/mL), PT, PTT (target 1.5-2.5 times control), fibrinogen (maintain >200 mg/dL), platelet count, and antithrombin III levels 2
• Do not rely exclusively on ACT; use PTT and anti-Factor Xa as confirmatory tests 2
• Monitor for antithrombin III deficiency, especially in patients <1 year of age, and supplement if increasing heparin is needed to maintain target ACT 2
• Monitor for acquired von Willebrand syndrome, which develops in nearly all ECMO patients and contributes to bleeding complications 4

Metabolic Panel and Organ Function

• Monitor renal and hepatic function daily, as ECMO circuitry and organ dysfunction alter medication pharmacokinetics 2
• Monitor lactate levels serially; absolute lactate levels outperform lactate clearance for prognostication 4
• Distinguish between lactate from hemolysis versus inadequate tissue perfusion—inadequate ECMO flow causing tissue hypoperfusion remains the most critical reversible cause 4
• Monitor mixed venous oxygen saturation (SvO₂) continuously, maintaining >66% 4

Hemolysis Markers

• Check plasma-free hemoglobin levels immediately to quantify hemolysis 4
• Monitor for signs of mechanical hemolysis including dark discoloration of tubing 4

---

Neurological Monitoring

Clinical Assessment Frequency

• Perform bedside nursing neurological assessments every 1-4 hours based on acute brain injury risk 2, 1
• Conduct daily assessment by a neurologist or neurointensivist when available 2, 1
• Use standardized scoring tools including Glasgow Coma Scale and Confusion Assessment Method 2, 1
• Assess mental status, brainstem reflexes (pupillary light response, oculocephalic, corneal, cough/gag reflexes), and motor examination when sedation is lightened 2

Continuous Neuromonitoring

• Implement continuous cerebral oximetry (rSO₂) for all ECMO patients, especially those on peripheral VA ECMO at risk for differential hypoxia 2, 3, 1
• Use pupillometry if available for objective pupil assessment 2, 1
• Obtain intermittent EEG and somatosensory evoked potentials (SSEP) in all comatose patients 2, 1
• Use continuous EEG when available to detect non-convulsive seizures in comatose patients 2, 1

Neuroimaging

• Perform early neuroimaging for ECMO patients at risk of acute brain injury based on physical examination and neuromonitoring tools 2

---

Temperature Management

• Continuously monitor core temperature and actively prevent fever (>37.7°C) 2, 3, 1
• Consider mild-moderate hypothermia (33-36°C) for 24-48 hours in VA ECMO patients, especially those undergoing ECPR 2, 3, 1
• Hypothermia is not recommended in VV ECMO patients 2

---

Sedation Monitoring

• Use standardized sedation protocols with validated scoring systems such as the Richmond Agitation Sedation Scale 2, 1
• Prefer intermittent (as-needed) analgo-sedation over continuous infusion 1
• Perform daily reassessment of sedation goals, stepwise sedation weaning, and sedation interruptions to improve neurological examinations and acute brain injury diagnosis 1

---

Fluid Balance

• Strive for daily negative fluid balance after ECMO flows are optimized and the patient is hemodynamically stable 3, 1
• Monitor for fluid overload, which is associated with increased mortality by the third day of ECMO 3, 1

---

Critical Pitfalls to Avoid

• Do not rely solely on ACT for anticoagulation management; always confirm with PTT and anti-Factor Xa levels 2
• Do not assume all elevated lactate is from hemolysis—inadequate tissue perfusion must be ruled out first 4
• Do not use continuous thermodilution or pulse contour cardiac output monitoring as these are unreliable in ECMO patients 4
• Do not rely on fixed, dilated pupils before cannulation as an absolute contraindication to ECMO, as patients receiving epinephrine during CPR frequently have this finding but can achieve favorable outcomes 1
• Recognize that acute brain injury incidence (19% in VA ECMO) is likely higher than clinical detection, with autopsy studies showing 68% of ECMO non-survivors had developed acute brain injury 1
• Balance anticoagulation carefully, as 42% of VV-ECMO patients experience thrombotic events, 37% experience bleeding events, and 21% experience both 1