What effect does neurogenic shock due to a spinal injury have on cardiac function?

Neurogenic shock occurs as a result of a spinal cord injury that disrupts the autonomic pathways, particularly the sympathetic nervous system. This disruption leads to the loss of vascular tone, causing widespread vasodilation or the widening of blood vessels. As the blood vessels become more dilated, the total peripheral resistance decreases, which can lead to insufficient blood flow and oxygen delivery to the organs.

In terms of cardiac function, when the vascular tone is lost and there is significant vasodilation, the heart struggles to maintain adequate blood pressure and perfusion. This often results in a decreased venous return to the heart, known as preload. With less blood returning to the heart, the volume of blood being pumped out with each heartbeat – or stroke volume – is reduced. Consequently, with reduced stroke volume and decreased vascular resistance, overall cardiac output diminishes.

This is why a decreased cardiac output is associated with neurogenic shock. The body’s compensatory mechanisms, such as increasing heart rate to maintain blood pressure, may not be sufficient to counteract the effects of the low vascular resistance and reduced venous return. Therefore, the chosen answer accurately reflects the physiological impact of neurogenic shock on cardiac function.