What vital sign change would you expect in a young adult with an infected hand and swelling up to their elbow?

In the context of a young adult with an infected hand and significant swelling up to the elbow, a febrile response is a common physiological reaction to infection. When the body detects the presence of pathogens, it typically initiates an immune response, which often results in the release of pyrogens. These substances can elevate the body's temperature set point, leading to fever. A febrile response indicates that the body is fighting an infection, making it a vital sign change to anticipate in this scenario.

Fever can serve several important functions, including creating a less favorable environment for pathogens and enhancing the effectiveness of immune responses. Therefore, among the potential vital sign changes associated with an infection, an increase in body temperature is the most expected result.

The other options, while they might be relevant in discussions of infection management, do not directly correlate with the typical physiological response to an infection localized to a hand. For instance, bradycardia, hypotension, and decreased respiratory rate are not usually expected to emerge as initial signs in a young adult experiencing a localized infection unless there are significant systemic complications or other underlying health issues. Thus, the febrile response stands out as the correct and most pertinent indication in this clinical context.