CVP Hemodynamics and Monitoring — Questions and Answers
Question 1: What is mean arterial pressure (MAP) and what is the target during bypass?
- The average arterial pressure during a cardiac cycle, typically maintained at 50-80 mmHg during bypass (Correct answer)
- Maximum systolic pressure, maintained above 120 mmHg
- Minimum diastolic pressure
- Central venous pressure
Correct answer: The average arterial pressure during a cardiac cycle, typically maintained at 50-80 mmHg during bypass
MAP represents the average pressure driving blood through organs. During bypass, it is typically maintained between 50-80 mmHg to ensure adequate organ perfusion.
Question 2: What does mixed venous oxygen saturation (SvO2) indicate during bypass?
- The balance between oxygen delivery and consumption (Correct answer)
- Arterial oxygen levels only
- The amount of carbon dioxide in the blood
- Heart rate adequacy
Correct answer: The balance between oxygen delivery and consumption
SvO2 reflects the balance between oxygen delivery and tissue consumption. Low values indicate inadequate perfusion or increased oxygen demand.
Question 3: What is the normal range for blood gas pH during cardiopulmonary bypass?
- 7.35 to 7.45 (Correct answer)
- 7.0 to 7.2
- 7.5 to 7.6
- 6.8 to 7.0
Correct answer: 7.35 to 7.45
Maintaining pH in the normal range of 7.35-7.45 during bypass is essential for proper enzyme function and cellular metabolism.
Question 4: What does a rising lactate level during bypass indicate?
- Inadequate tissue perfusion or oxygen delivery (Correct answer)
- Excellent perfusion
- Normal metabolic activity
- Excessive anticoagulation
Correct answer: Inadequate tissue perfusion or oxygen delivery
Rising lactate indicates that tissues are not receiving adequate oxygen and are relying on anaerobic metabolism, suggesting inadequate perfusion.
Question 5: What is the purpose of monitoring hematocrit during bypass?
- To assess blood dilution and oxygen-carrying capacity (Correct answer)
- To measure clotting time
- To determine blood type
- To monitor kidney function
Correct answer: To assess blood dilution and oxygen-carrying capacity
Hematocrit reflects the proportion of red blood cells in the blood, indicating oxygen-carrying capacity. Excessive hemodilution may require blood transfusion.
Question 6: What is venous reservoir volume and why is it monitored?
- The volume of blood in the venous reservoir that serves as a safety buffer preventing air embolism (Correct answer)
- The total blood volume of the patient
- The amount of cardioplegia remaining
- The fluid in the IV bags
Correct answer: The volume of blood in the venous reservoir that serves as a safety buffer preventing air embolism
The venous reservoir holds blood returned from the patient and provides a safety buffer. Low levels risk introducing air into the circuit.
CVP Hemodynamics and Monitoring
What is mean arterial pressure (MAP) and what is the target during bypass?