Certified Registered Nurse Anesthetist (CRNA) Practice Exam

What is the function of the catheter used to measure wedge pressure?

1. To deliver medication to the pulmonary arteries

2. To measure oxygen saturation in the blood

3. To permit indirect measurement of mean left atrial pressure

4. To assess right ventricle function directly

The correct answer is: To permit indirect measurement of mean left atrial pressure

The function of the catheter used to measure wedge pressure is to permit an indirect measurement of mean left atrial pressure. When the catheter, typically a pulmonary artery catheter, is inserted into the pulmonary artery, it can be "wedged" into a smaller branch of the artery. This wedging occludes the artery and allows for the measurement of pressure that reflects the pressure in the left atrium. This measurement is crucial in assessing cardiac function and the hemodynamic status of a patient. The left atrial pressure gives insights into the left heart's ability to receive blood from the lungs and can indicate conditions such as heart failure or fluid overload. By measuring this pressure, clinicians can make informed decisions about treatment and management strategies. Understanding this function also helps clarify why the other options do not fit. Delivering medication to the pulmonary arteries pertains to a different function of catheters, primarily used for therapeutic purposes. Measuring oxygen saturation involves different types of sensors and techniques and does not directly relate to wedge pressure. Lastly, while assessing right ventricle function is important in cardiology, it involves different assessments rather than the indirect measurement that wedge pressure provides for the left atrium.