ECMO Nutrition and Metabolic Management in ECMO 2 — Questions and Answers
Question 1: Which electrolyte disturbance is particularly problematic when using continuous renal replacement therapy (CRRT) concurrently with ECMO?
- Hypernatremia
- Hypomagnesemia and hypophosphatemia (Correct answer)
- Hypercalcemia
- Hyperkalemia
Correct answer: Hypomagnesemia and hypophosphatemia
CRRT removes magnesium and phosphate from the blood continuously; without supplementation, patients on combined ECMO-CRRT are at high risk for hypomagnesemia and hypophosphatemia.
Question 2: What is the primary concern with administering lipid emulsions (as part of parenteral nutrition) to ECMO patients?
- Lipids cause hemolysis by altering red cell membrane fluidity
- Lipid particles can coat and degrade the oxygenator membrane, reducing gas transfer efficiency (Correct answer)
- Lipids bind to heparin and reduce anticoagulation efficacy
- Lipid emulsions cause vasospasm at the cannulation site
Correct answer: Lipid particles can coat and degrade the oxygenator membrane, reducing gas transfer efficiency
Fat emulsion particles can deposit on the oxygenator membrane and circuit components, degrading gas transfer performance and potentially clogging the circuit.
Question 3: Refeeding syndrome in ECMO patients is characterized by a critical drop in which electrolyte after nutrition initiation?
- Potassium
- Phosphate (Correct answer)
- Sodium
- Calcium
Correct answer: Phosphate
Refeeding syndrome is primarily characterized by hypophosphatemia due to rapid intracellular phosphate uptake when anabolic metabolism resumes after a period of starvation or catabolic stress.
Question 4: Which condition most commonly leads to enteral feeding intolerance in ECMO patients receiving VA ECMO?
- Hypoxic gut ischemia due to retrograde aortic flow and reduced splanchnic perfusion (Correct answer)
- Circuit recirculation reducing mesenteric oxygen delivery
- High ECMO flows causing mesenteric venous hypertension
- Anticoagulation causing mucosal hemorrhage and diarrhea
Correct answer: Hypoxic gut ischemia due to retrograde aortic flow and reduced splanchnic perfusion
In VA ECMO, retrograde aortic flow can reduce antegrade pulsatile flow to mesenteric vessels, leading to gut hypoperfusion and feeding intolerance.
Question 5: What blood glucose target range is currently recommended for ECMO patients to balance glycemic control with hypoglycemia risk?
- 60–100 mg/dL
- 100–140 mg/dL
- 140–180 mg/dL (Correct answer)
- 180–220 mg/dL
Correct answer: 140–180 mg/dL
Current critical care guidelines, applicable to ECMO patients, recommend a blood glucose target of 140–180 mg/dL to reduce hypoglycemia risk while avoiding severe hyperglycemia.
Question 6: How does ECMO most significantly alter zinc and selenium homeostasis?
- ECMO promotes renal retention of trace elements
- Adsorption of trace elements onto the circuit and oxygenator leads to reduced plasma levels (Correct answer)
- ECMO increases hepatic synthesis of metallothionein, depleting free zinc
- Circuit-induced hemolysis releases intracellular zinc into plasma, causing toxicity
Correct answer: Adsorption of trace elements onto the circuit and oxygenator leads to reduced plasma levels
Selenium and zinc are adsorbed onto circuit components and consumed by the inflammatory response during ECMO, leading to clinically significant depletion requiring supplementation.
Question 7: What nutritional intervention has been shown to be harmful and is NOT recommended in critically ill ECMO patients?
- Enteral glutamine supplementation at high doses in multi-organ failure (Correct answer)
- Vitamin C supplementation to reduce oxidative stress
- Early enteral feeding within 48 hours
- Protein supplementation at 1.5 g/kg/day
Correct answer: Enteral glutamine supplementation at high doses in multi-organ failure
High-dose enteral glutamine supplementation was associated with increased mortality in critically ill patients with multi-organ failure in the REDOXS trial and is not recommended.
ECMO Nutrition and Metabolic Management in ECMO 2
Which electrolyte disturbance is particularly problematic when using continuous renal replacement therapy (CRRT) concurrently with ECMO?