What hemodynamic change often occurs in patients with excessive bleeding post CABG?

In the context of excessive bleeding following coronary artery bypass grafting (CABG), a significant hemodynamic change is a decrease in cardiac output. This can occur due to several factors. Excessive bleeding leads to a reduction in blood volume, which can compromise venous return to the heart. As less blood returns to the heart, the stroke volume decreases because there is less blood available to be pumped with each heartbeat.

This reduction in stroke volume directly affects cardiac output, which is calculated as the product of stroke volume and heart rate. With a compromised blood volume and reduced stroke volume, the body may struggle to maintain adequate cardiac output, leading to potential organ hypoperfusion and hemodynamic instability.

With regard to other options, conditions such as high central venous pressure (CVP) and pulmonary wedge pressure (PWP) can be reflections of fluid overload or heart failure, rather than direct indicators of the hemodynamic response to bleeding. Increased stroke volume is not expected, as significant blood loss would typically hinder ventricular filling and output. Improved blood pressure in a state of significant hemorrhage is also unlikely; instead, blood pressure may decrease as a compensatory mechanism continues to fail.