ECMO Foundations of ECMO and ECMO Management 3 — Questions and Answers
Question 1: A patient on VV-ECMO has a pre-oxygenator saturation of 75% and a post-oxygenator saturation of 99%. This indicates:
- Significant recirculation
- Adequate oxygenator function with normal circuit performance (Correct answer)
- Oxygenator failure requiring replacement
- Excessive pump speed causing hemolysis
Correct answer: Adequate oxygenator function with normal circuit performance
A large step-up in saturation across the oxygenator (75% to 99%) confirms the membrane lung is functioning correctly and fully oxygenating the blood.
Question 2: Which anticoagulant is most commonly used to maintain circuit patency during ECMO?
- Warfarin (Coumadin)
- Unfractionated heparin (UFH) (Correct answer)
- Bivalirudin
- Enoxaparin
Correct answer: Unfractionated heparin (UFH)
Unfractionated heparin is the most widely used anticoagulant in ECMO due to its titrability, reversibility with protamine, and availability of established monitoring assays.
Question 3: The ACT (activated clotting time) target range typically used for monitoring anticoagulation during ECMO is:
- 100–140 seconds
- 180–220 seconds (Correct answer)
- 300–350 seconds
- 50–80 seconds
Correct answer: 180–220 seconds
An ACT of 180–220 seconds is the most common target range for ECMO anticoagulation, balancing thrombosis prevention against bleeding risk.
Question 4: Plasma-free hemoglobin (pfHgb) elevation on ECMO is a marker of:
- Adequate red cell transfusion
- Circuit-induced hemolysis (Correct answer)
- Improving renal function
- Normal ECMO priming
Correct answer: Circuit-induced hemolysis
Elevated plasma-free hemoglobin indicates red blood cell destruction within the circuit, signaling hemolysis that can cause renal injury and must be investigated.
Question 5: In ECMO management, 'chatter' of the venous drainage cannula or tubing typically indicates:
- Excessive pump flow causing high pressures
- Hypovolemia or inadequate venous return to the circuit (Correct answer)
- Oxygenator membrane failure
- Air embolism in the arterial limb
Correct answer: Hypovolemia or inadequate venous return to the circuit
Chatter (intermittent collapse) of the venous drainage line reflects inadequate preload or hypovolemia limiting the circuit's ability to maintain continuous blood flow.
Question 6: Which condition is considered an absolute contraindication to initiating ECMO support?
- Age greater than 70 years
- Irreversible condition with no bridge or recovery option (Correct answer)
- Mild coagulopathy correctable with FFP
- Recent thoracic surgery within 72 hours
Correct answer: Irreversible condition with no bridge or recovery option
ECMO is contraindicated when the underlying condition is irreversible and no transplantation, device therapy, or meaningful recovery is possible, as it would only prolong the dying process.
Question 7: The ELSO (Extracorporeal Life Support Organization) Registry primarily serves to:
- Certify individual ECMO specialists
- Collect multicenter outcomes data to guide ECMO practice and quality improvement (Correct answer)
- Regulate ECMO equipment manufacturing standards
- Manage ECMO organ allocation protocols
Correct answer: Collect multicenter outcomes data to guide ECMO practice and quality improvement
The ELSO Registry is an international database that collects ECMO case data from member centers to support research, benchmarking, and evidence-based practice improvement.
ECMO Foundations of ECMO and ECMO Management 3
A patient on VV-ECMO has a pre-oxygenator saturation of 75% and a post-oxygenator saturation of 99%.
This indicates: