Which two conditions can lead to a decrease in preload?

A decrease in preload refers to a reduction in the volume of blood returning to the heart during diastole, which can impair cardiac output and overall heart function. Hemorrhage and dehydration are two conditions that can significantly lead to a decrease in preload.

Hemorrhage results in a loss of blood volume, directly diminishing the amount of blood that returns to the heart. This reduced venous return causes a decrease in preload, as there is less blood available to fill the heart's ventricles. Similarly, dehydration causes a reduction in plasma volume, leading to a decrease in circulating blood volume and a direct impact on preload.

Understanding these mechanisms is crucial in cardiology, as they can inform treatment strategies. For instance, managing volume status in patients experiencing hemorrhage or dehydration involves fluid administration to restore adequate preload and improve cardiac output.