Which of the following is a sign of cardiac tamponade?

A narrow pulse pressure is a sign of cardiac tamponade because it reflects the hemodynamic compromise experienced when fluid accumulates in the pericardial space. In this condition, the heart's ability to fill properly is impaired due to external pressure exerted by the fluid. This can result in decreased stroke volume and subsequently a diminished difference between systolic and diastolic blood pressures, leading to a narrow pulse pressure.

In contrast, fever is typically indicative of an infection or inflammatory process rather than directly related to cardiac tamponade. Increased blood pressure is generally not associated with cardiac tamponade; it tends to decrease due to the impaired cardiac output. A stable heart rhythm does not align with cardiac tamponade, as this condition often leads to disruptive hemodynamics that might result in variations in heart rhythms. Understanding these physiological changes is essential for the assessment and management of patients with cardiac tamponade.