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Physiology and Principles Flashcards

7 cards from real ECMO practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

Read the first 7 Physiology and Principles flashcards as text

  1. What is the significance of the 'venous inlet pressure' (P-in) alarm during ECMO, and what does it indicate?

    Answer: Highly negative P-in indicates inadequate venous return, risking cavitation and hemolysis

    A very negative inlet (drainage) pressure indicates hypovolemia, cannula malposition, or kinking, and can cause circuit cavitation, hemolysis, and 'chatter' (intermittent collapse of the venous line).

  2. In the context of ECMO physiology, what is 'sweep gas' and what is its primary purpose?

    Answer: A blend of O2 and air passed through the oxygenator to facilitate gas exchange across the membrane

    Sweep gas (typically blended O2 and air) flows through the gas side of the membrane oxygenator, creating the concentration gradient needed for O2 loading and CO2 removal from the blood.

  3. Why is systemic anticoagulation required during ECMO, and what is the most common agent used?

    Answer: To prevent circuit thrombosis from blood-surface contact activation; unfractionated heparin is most common

    Blood contact with the artificial circuit surfaces activates the coagulation cascade; unfractionated heparin is the most widely used anticoagulant to prevent life-threatening circuit thrombosis.

  4. What is the 'oxygen delivery index' (DO2I) target during ECMO, and why is it important?

    Answer: Approximately 520-600 mL/min/m² to match normal physiologic oxygen demand

    Targeting physiologic DO2I (approximately 520-600 mL/min/m²) ensures adequate tissue oxygenation while avoiding excessive flow that could increase hemolysis and recirculation.

  5. How does the position of the return (reinfusion) cannula relative to the drainage cannula affect recirculation in single-access dual-lumen VV-ECMO?

    Answer: The return jet must be directed toward the tricuspid valve to minimize recirculation

    In dual-lumen cannulas (e.g., Avalon), proper positioning directs the return jet toward the tricuspid valve, propelling oxygenated blood into the right ventricle rather than back toward the drainage holes.

  6. What does 'circuit compliance' refer to in ECMO, and how does it affect blood pressure waveform dampening?

    Answer: The ability of circuit tubing to expand and store energy, which attenuates pulse pressure

    Compliant (flexible) ECMO tubing absorbs kinetic energy during each pump stroke, damping the arterial pulse waveform and contributing to reduced pulsatility during VA-ECMO.

  7. What is the physiological consequence of severe 'LV distension' that can occur during VA-ECMO, and how does it manifest clinically?

    Answer: Increased LV wall stress, subendocardial ischemia, pulmonary edema, and thrombus formation in the stagnant LV

    LV distension from afterload increase and blood accumulation raises wall stress and myocardial oxygen demand, worsens pulmonary edema, and creates stagnant LV blood prone to thrombus formation.