ECMO Specialist Exam – 101 Practice
Questions with Complete Solutions
Q1: Which of the following terms best describes the primary physiological mechanism of
Veno-Venous (VV) ECMO?
A. Partial bypass providing cardiac and respiratory support
B. Intravenous gas exchange delivering oxygen to support end-organ perfusion [CORRECT]
C. Total circulatory replacement excluding native cardiac output
D. Direct arterial gas exchange independent of native lung function
Correct Answer: B
Rationale: VV ECMO functions as an "IV gas exchange" mechanism, providing respiratory
support by oxygenating blood and removing CO2, while the patient's native heart provides
the cardiac output. VA ECMO (Option A) provides both cardiac and respiratory support as
partial bypass.
Q2: What is the primary cardiovascular physiological difference between VV and VA ECMO?
A. VV ECMO relies on native cardiac output to propel blood, whereas VA ECMO returns
oxygenated blood to the arterial system to provide circulatory support. [CORRECT]
B. VV ECMO reduces cardiac preload, whereas VA ECMO increases cardiac preload.
C. VA ECMO relies on native cardiac output to propel blood, whereas VV ECMO provides
circulatory support.
D. Both modes provide identical circulatory support but differ in oxygenation mechanisms.
Correct Answer: A
Rationale: In VV ECMO, blood is drained from and returned to the venous system, requiring
native cardiac output to propel oxygenated blood to the tissues. In VA ECMO, blood is
returned to the arterial system, directly providing circulatory support and partially bypassing
the heart and lungs.
Q3: During VA ECMO, the term "partial capture" refers to:
,A. The oxygenator extracting only a partial volume of carbon dioxide from the blood
B. The drainage cannula withdrawing only a portion of the venous return [CORRECT]
C. The inability of the pump to generate pressures greater than 300 mmHg
D. The native lungs providing only a portion of the required oxygen
Correct Answer: B
Rationale: Partial capture describes the hemodynamic state where the ECMO pump drains
only a portion of the total venous return, allowing some blood to pass through the native
heart and lungs. The degree of capture determines the mix of ECMO-supported and native
blood ejected to the systemic circulation.
Q4: A patient on VV ECMO for severe ARDS has a continuous SvO2 of 48%. What is the most
immediate physiological concern?
A. Inadequate sweep gas flow
B. Transition to anaerobic metabolism and lactic acid accumulation [CORRECT]
C. Excessive oxygen delivery to peripheral tissues
D. Optimal oxygen consumption indicating successful support
Correct Answer: B
Rationale: An SvO2 below 50% indicates that tissues are extracting oxygen maximally, leading
to anaerobic metabolism and the production of lactic acid. Normal SvO2 is 65-75%. This
requires immediate intervention to increase oxygen delivery or decrease consumption.
Q5: The normal oxygen delivery (DO2) for a resting adult is approximately:
A. 200-250 mL/min
B. 500 mL/min
C. 1000 mL/min [CORRECT]
D. 1500 mL/min
Correct Answer: C
,Rationale: Normal DO2 is approximately 1000 mL/min. Option A represents the normal VO2
(oxygen consumption). The ideal DO2/VO2 ratio is 4:1, meaning the body delivers roughly 4
times the amount of oxygen it consumes at rest.
Q6: Which of the following is the correct formula for calculating Oxygen Delivery (DO2)?
A. CO x (SaO2 - SvO2) x Hgb x 1.34 x 10
B. CaO2 x CO x 10 [CORRECT]
C. [(Hgb x 1.34) x SaO2] + [PaO2 x 0.003]
D. (SpreO2 - SvO2) / (SpostO2 - SvO2) x 100
Correct Answer: B
Rationale: DO2 equals the arterial oxygen content (CaO2) multiplied by the cardiac output
(CO) and a conversion factor of 10. Option A is the formula for VO2, Option C is the formula
for CaO2, and Option D is the recirculation formula.
Q7: The normal oxygen consumption (VO2) for an adult is:
A. 100-150 mL/min
B. 200-250 mL/min [CORRECT]
C. 500-600 mL/min
D. 1000 mL/min
Correct Answer: A
Rationale: Normal adult VO2 is 200-250 mL/min. Values significantly above this indicate
increased metabolic demand, which may outstrip oxygen delivery on ECMO, leading to a
falling SvO2 and lactic acidosis.
Q8: How much oxygen does the heart consume from the oxygen supplied to it?
A. 30-40%
B. 50-60%
C. 70-75% [CORRECT]
, D. 85-90%
Correct Answer: C
Rationale: The heart is highly metabolically active and consumes 70-75% of the oxygen
supplied to it via the coronary arteries. This makes it highly susceptible to ischemia and
anaerobic metabolism if oxygen delivery drops or demand increases.
Q9: What is the ideal DO2/VO2 ratio in a resting adult?
A. 1:1
B. 2:1
C. 4:1 [CORRECT]
D. 10:1
Correct Answer: C
Rationale: The ideal DO2/VO2 ratio is 4:1, indicating that oxygen delivery is approximately
four times oxygen consumption, providing an adequate physiological reserve. A ratio
approaching 2:1 indicates critical supply-demand imbalance.
Q10: The formula CaO2 = [(Hgb x 1.34) x SaO2] + [PaO2 x 0.003] calculates:
A. Oxygen Consumption
B. Arterial Oxygen Content [CORRECT]
C. Oxygen Delivery
D. Mixed Venous Oxygen Saturation
Correct Answer: B
Rationale: This formula calculates the arterial oxygen content (CaO2), combining the oxygen
bound to hemoglobin (Hgb x 1.34 x SaO2) and the oxygen dissolved in plasma (PaO2 x 0.003).
It is a component of the DO2 formula.
Q11: A patient has a SvO2 of 60%. This value indicates:
A. Anaerobic metabolism
Questions with Complete Solutions
Q1: Which of the following terms best describes the primary physiological mechanism of
Veno-Venous (VV) ECMO?
A. Partial bypass providing cardiac and respiratory support
B. Intravenous gas exchange delivering oxygen to support end-organ perfusion [CORRECT]
C. Total circulatory replacement excluding native cardiac output
D. Direct arterial gas exchange independent of native lung function
Correct Answer: B
Rationale: VV ECMO functions as an "IV gas exchange" mechanism, providing respiratory
support by oxygenating blood and removing CO2, while the patient's native heart provides
the cardiac output. VA ECMO (Option A) provides both cardiac and respiratory support as
partial bypass.
Q2: What is the primary cardiovascular physiological difference between VV and VA ECMO?
A. VV ECMO relies on native cardiac output to propel blood, whereas VA ECMO returns
oxygenated blood to the arterial system to provide circulatory support. [CORRECT]
B. VV ECMO reduces cardiac preload, whereas VA ECMO increases cardiac preload.
C. VA ECMO relies on native cardiac output to propel blood, whereas VV ECMO provides
circulatory support.
D. Both modes provide identical circulatory support but differ in oxygenation mechanisms.
Correct Answer: A
Rationale: In VV ECMO, blood is drained from and returned to the venous system, requiring
native cardiac output to propel oxygenated blood to the tissues. In VA ECMO, blood is
returned to the arterial system, directly providing circulatory support and partially bypassing
the heart and lungs.
Q3: During VA ECMO, the term "partial capture" refers to:
,A. The oxygenator extracting only a partial volume of carbon dioxide from the blood
B. The drainage cannula withdrawing only a portion of the venous return [CORRECT]
C. The inability of the pump to generate pressures greater than 300 mmHg
D. The native lungs providing only a portion of the required oxygen
Correct Answer: B
Rationale: Partial capture describes the hemodynamic state where the ECMO pump drains
only a portion of the total venous return, allowing some blood to pass through the native
heart and lungs. The degree of capture determines the mix of ECMO-supported and native
blood ejected to the systemic circulation.
Q4: A patient on VV ECMO for severe ARDS has a continuous SvO2 of 48%. What is the most
immediate physiological concern?
A. Inadequate sweep gas flow
B. Transition to anaerobic metabolism and lactic acid accumulation [CORRECT]
C. Excessive oxygen delivery to peripheral tissues
D. Optimal oxygen consumption indicating successful support
Correct Answer: B
Rationale: An SvO2 below 50% indicates that tissues are extracting oxygen maximally, leading
to anaerobic metabolism and the production of lactic acid. Normal SvO2 is 65-75%. This
requires immediate intervention to increase oxygen delivery or decrease consumption.
Q5: The normal oxygen delivery (DO2) for a resting adult is approximately:
A. 200-250 mL/min
B. 500 mL/min
C. 1000 mL/min [CORRECT]
D. 1500 mL/min
Correct Answer: C
,Rationale: Normal DO2 is approximately 1000 mL/min. Option A represents the normal VO2
(oxygen consumption). The ideal DO2/VO2 ratio is 4:1, meaning the body delivers roughly 4
times the amount of oxygen it consumes at rest.
Q6: Which of the following is the correct formula for calculating Oxygen Delivery (DO2)?
A. CO x (SaO2 - SvO2) x Hgb x 1.34 x 10
B. CaO2 x CO x 10 [CORRECT]
C. [(Hgb x 1.34) x SaO2] + [PaO2 x 0.003]
D. (SpreO2 - SvO2) / (SpostO2 - SvO2) x 100
Correct Answer: B
Rationale: DO2 equals the arterial oxygen content (CaO2) multiplied by the cardiac output
(CO) and a conversion factor of 10. Option A is the formula for VO2, Option C is the formula
for CaO2, and Option D is the recirculation formula.
Q7: The normal oxygen consumption (VO2) for an adult is:
A. 100-150 mL/min
B. 200-250 mL/min [CORRECT]
C. 500-600 mL/min
D. 1000 mL/min
Correct Answer: A
Rationale: Normal adult VO2 is 200-250 mL/min. Values significantly above this indicate
increased metabolic demand, which may outstrip oxygen delivery on ECMO, leading to a
falling SvO2 and lactic acidosis.
Q8: How much oxygen does the heart consume from the oxygen supplied to it?
A. 30-40%
B. 50-60%
C. 70-75% [CORRECT]
, D. 85-90%
Correct Answer: C
Rationale: The heart is highly metabolically active and consumes 70-75% of the oxygen
supplied to it via the coronary arteries. This makes it highly susceptible to ischemia and
anaerobic metabolism if oxygen delivery drops or demand increases.
Q9: What is the ideal DO2/VO2 ratio in a resting adult?
A. 1:1
B. 2:1
C. 4:1 [CORRECT]
D. 10:1
Correct Answer: C
Rationale: The ideal DO2/VO2 ratio is 4:1, indicating that oxygen delivery is approximately
four times oxygen consumption, providing an adequate physiological reserve. A ratio
approaching 2:1 indicates critical supply-demand imbalance.
Q10: The formula CaO2 = [(Hgb x 1.34) x SaO2] + [PaO2 x 0.003] calculates:
A. Oxygen Consumption
B. Arterial Oxygen Content [CORRECT]
C. Oxygen Delivery
D. Mixed Venous Oxygen Saturation
Correct Answer: B
Rationale: This formula calculates the arterial oxygen content (CaO2), combining the oxygen
bound to hemoglobin (Hgb x 1.34 x SaO2) and the oxygen dissolved in plasma (PaO2 x 0.003).
It is a component of the DO2 formula.
Q11: A patient has a SvO2 of 60%. This value indicates:
A. Anaerobic metabolism
