Florida State Paramedic Practice Exam

Which physiological change occurs below a spinal cord injury leading to neurogenic shock?

1. Vasoconstriction of blood vessels

2. Complete dilation of blood vessels

3. Increased heart rate

4. Increased blood volume

The correct answer is: Complete dilation of blood vessels

Neurogenic shock occurs as a result of a spinal cord injury, particularly when the injury disrupts the nerve pathways that control vascular tone. This leads to a significant physiological change characterized by complete dilation of the blood vessels below the level of the injury. When the sympathetic nervous system is impaired due to the trauma, it can no longer regulate vascular resistance effectively. This results in a loss of vascular tone and widespread vasodilation. Consequently, the blood vessels cannot constrict appropriately, leading to hypotension and a decrease in effective circulating blood volume, despite the overall blood volume in the body remaining unchanged. The potential for vasoconstriction is diminished or completely lost because the nerves that would typically stimulate such a response are no longer functioning below the level of the injury. This state of increased vessel diameter will lead to pooling of blood in the periphery and a serious reduction in perfusion pressure, which is characteristic of neurogenic shock. Understanding this mechanism is crucial for recognizing and managing the implications of spinal cord injuries in clinical settings, as it directly affects treatment protocols and emergency response strategies.