Certified Registered Nurse Anesthetist (CRNA) Practice Exam

What does wedge pressure indirectly measure?

1. Right ventricular pressure

2. Mean left atrial pressure

3. Systemic artery pressure

4. Pulmonary artery pressure

The correct answer is: Mean left atrial pressure

Wedge pressure, often referred to as pulmonary capillary wedge pressure (PCWP), is a valuable clinical measurement that indirectly assesses the left atrial pressure. When a catheter is positioned in the pulmonary artery and a balloon is inflated to occlude a small pulmonary artery branch, the pressure recorded reflects the pressure in the left atrium. This measurement is significant because it serves as an indicator of left ventricular function and preload status. Elevated wedge pressures suggest conditions such as heart failure or fluid overload, where the left atrium may be under increased pressure due to inadequate pumping by the left ventricle. Recognizing the importance of wedge pressure in diagnosing cardiac conditions emphasizes that it is a specific marker of left atrial dynamics rather than directly measuring pressures in the right ventricle, systemic arteries, or pulmonary arteries. Each of those measurements corresponds to different physiological aspects and is assessed through separate methods, distinguishing the value of wedge pressure in cardiology and critical care settings.