Certified Registered Nurse Anesthetist (CRNA) Practice Exam

What does pulmonary artery occlusive pressure measure?

1. Right arterial pressure

2. Mean left atrial pressure

3. Pulmonary vascular resistance

4. Systolic pulmonary artery pressure

The correct answer is: Mean left atrial pressure

Pulmonary artery occlusive pressure, often referred to as pulmonary capillary wedge pressure (PCWP), provides an indirect measurement of the left atrial pressure. This measurement is critical because it reflects the pressure in the left atrium, which can give insights into left ventricular function and overall cardiac health. When the pulmonary artery catheter is advanced and wedged into a small pulmonary artery branch, it occludes that vessel, allowing the pressure recorded to be representative of the pressure in the left atrium. This is particularly useful in diagnosing and managing heart conditions, such as heart failure, and helps to assess the fluid status of patients. Understanding that PCWP acts as a surrogate for left atrial pressure is essential for clinical assessment, especially in critically ill patients undergoing monitoring for cardiac function and volume status. This direct correlation between PCWP and left atrial pressure helps healthcare providers make informed decisions on fluid management and in the evaluation of patients with cardiac conditions.