ECMO Patient Monitoring and Assessment 3 — Questions and Answers
Question 1: What does a persistently elevated lactate during ECMO most commonly indicate?
- Adequate sedation
- Insufficient systemic oxygen delivery or utilization (Correct answer)
- Therapeutic anticoagulation
- Normal liver metabolism
Correct answer: Insufficient systemic oxygen delivery or utilization
Elevated lactate (>2 mmol/L) persisting on ECMO reflects ongoing tissue hypoxia or impaired lactate clearance, signaling inadequate support.
Question 2: During ECMO, urine output less than 0.5 mL/kg/hr for more than 2 hours suggests:
- Therapeutic fluid balance
- Acute kidney injury or inadequate perfusion (Correct answer)
- Appropriate diuresis
- Excessive anticoagulation
Correct answer: Acute kidney injury or inadequate perfusion
Oliguria below 0.5 mL/kg/hr is a standard marker of inadequate renal perfusion or acute kidney injury requiring prompt assessment of ECMO flows and hemodynamics.
Question 3: Which hemodynamic finding on a pulmonary artery catheter would indicate left ventricular distension in a VA-ECMO patient?
- Low pulmonary capillary wedge pressure (PCWP)
- High PCWP with low cardiac output (Correct answer)
- High mixed venous saturation only
- Low central venous pressure
Correct answer: High PCWP with low cardiac output
Elevated PCWP with low native cardiac output in VA-ECMO indicates LV distension from afterload mismatch, potentially requiring LV unloading.
Question 4: How frequently should ACT (activated clotting time) be checked during routine ECMO management?
- Every 15 minutes
- Every 1-2 hours (Correct answer)
- Once per shift
- Only when bleeding occurs
Correct answer: Every 1-2 hours
ACT is typically monitored every 1-2 hours during ECMO to maintain anticoagulation within the target range (usually 180-220 seconds) and balance thrombosis vs. bleeding risk.
Question 5: A 'chatter' or 'flutter' in the ECMO tubing during a drainage phase typically signals:
- Adequate preload
- Venous inflow obstruction or hypovolemia (Correct answer)
- Systemic hypertension
- Membrane oxygenator failure
Correct answer: Venous inflow obstruction or hypovolemia
Tubing chatter occurs when the centrifugal pump generates intermittent high negative pressure due to inadequate venous return, indicating hypovolemia or cannula obstruction.
Question 6: In ECMO patients, which chest X-ray finding most concerns the clinician for cardiac tamponade?
- Bilateral infiltrates
- Rapidly enlarging cardiac silhouette (Correct answer)
- Atelectasis in the left lower lobe
- Air bronchograms
Correct answer: Rapidly enlarging cardiac silhouette
A rapidly enlarging cardiac silhouette on serial chest X-rays, especially post-cannulation, suggests pericardial effusion and possible tamponade requiring urgent intervention.
Question 7: What is the purpose of monitoring the pre- and post-oxygenator pressure differential (ΔP) during ECMO?
- To assess patient blood pressure
- To detect clot formation within the membrane oxygenator (Correct answer)
- To titrate sweep gas flow
- To measure cardiac output
Correct answer: To detect clot formation within the membrane oxygenator
An increasing ΔP across the membrane oxygenator indicates rising resistance from thrombus formation, signaling the need for oxygenator inspection or replacement.
ECMO Patient Monitoring and Assessment 3
What does a persistently elevated lactate during ECMO most commonly indicate?