What is one evidence of loss of cerebral auto regulation?

Cushing's response is a significant clinical indication of loss of cerebral autoregulation, particularly in the context of increased intracranial pressure (ICP). This response is characterized by a classic triad of symptoms: hypertension, bradycardia, and irregular respirations. When autoregulation fails, the brain is unable to maintain consistent cerebral blood flow despite changes in systemic blood pressure. As a result, the body attempts to compensate by increasing systemic blood pressure to ensure that adequate perfusion reaches the brain, despite the problematic conditions. The presence of Cushing's response indicates that the body's compensatory mechanisms are being activated due to an underlying pathological condition, such as brain injury or mass effect, which disrupts normal autoregulation.

In this context, the other symptoms presented in the choices, while they may also relate to changes in cerebral function, do not specifically indicate loss of autoregulation as definitively as Cushing's response. Widening pulse pressure can result from various cardiovascular conditions, decreased level of consciousness may be due to multiple factors including drugs or metabolic issues, and bradycardia alone does not indicate loss of cerebral autoregulation without the context of increased ICP.