What vital sign may indicate a serious head injury?

Widening pulse pressure is a crucial vital sign that can indicate a serious head injury, particularly in cases of increased intracranial pressure. When there is significant trauma to the head, the body's compensatory mechanisms can lead to changes in blood pressure. A widening pulse pressure—defined as an increase in the difference between systolic and diastolic blood pressure—may suggest that the brain is struggling to maintain adequate blood flow due to increased pressure within the skull. This scenario is commonly associated with conditions such as traumatic brain injury or cerebral hemorrhage, where the brain tissue may be swollen or bleeding.

In contrast, an increased heart rate may occur due to anxiety, pain, or shock but is not specific to head injuries. Low blood pressure can indicate shock but is less directly tied to head trauma compared to widening pulse pressure. Similarly, a high temperature can result from various infections or inflammatory processes but does not specifically indicate a serious head injury. Thus, widening pulse pressure is a more reliable and specific indicator that medical personnel should monitor closely in the context of potential head trauma.