Which of the following conditions may result in a decreased cardiac output?

Decreased cardiac output refers to the amount of blood the heart pumps out to the body in a given time period. In cases of hypovolemic shock, there is a significant reduction in blood volume due to factors like excessive bleeding, dehydration, or fluid loss from burns. This low blood volume leads to decreased venous return to the heart, which in turn reduces stroke volume and ultimately lowers cardiac output.

In contrast, increased blood volume or hypervolemia generally supports higher venous return, which could enhance cardiac output if the heart is functioning well. High systemic vascular resistance could create more afterload, but it does not necessarily lead to decreased cardiac output—unless it is coupled with a compromised cardiac function. Thus, hypovolemic shock is the prime condition that directly correlates with a decrease in cardiac output due to inadequate blood volume.