Anesthesia Technologist Practice Exam

What effect can the trendelenburg position have on a patient's cardiac output and myocardial workload?

1. Increase both

2. Decrease cardiac output, increase myocardial workload

3. Decrease both

4. Increase cardiac output, decrease myocardial workload

The correct answer is: Decrease cardiac output, increase myocardial workload

The trendelenburg position, which involves tilting the patient so their head is lower than their feet, can lead to increased venous return to the heart. This position can momentarily enhance cardiac output due to the increased volume of blood that returns to the heart. However, this alteration in body position can also elevate intrathoracic pressure and potentially impede right ventricular output due to increased pressure on the heart and lungs. As venous return rises, the heart must work harder to pump the volume, leading to elevated myocardial workload. The increased workload occurs because the heart is adjusting to handle the augmented preload. Therefore, while cardiac output might temporarily rise, the simultaneous increase in myocardial workload can have significant implications for patients with existing cardiovascular issues. This can result in decreased cardiac efficiency and could ultimately affect overall cardiac function. In summary, adopting the trendelenburg position can produce a complex interaction whereby cardiac output may initially increase, but this comes at the cost of elevating myocardial workload, especially critical in patients with compromised cardiac function. This reflects why the assertion of decreasing cardiac output while increasing myocardial workload best captures the physiological realities of the trendelenburg position's effects.