Which of the following indicates a potential infection in a soft-tissue injury?

Swelling is a key indicator of a potential infection in a soft-tissue injury. When tissue becomes infected, the body's inflammatory response kicks in to deal with the invading pathogens. This response often includes swelling due to increased blood flow and the accumulation of fluid, immune cells, and other substances in the area. The presence of swelling can signal that the body is reacting to an infection within the tissue, making it an important sign for healthcare providers to monitor.

In cases of infection, the swelling may also be accompanied by other symptoms such as redness, warmth, and pain, which further highlight the underlying issue. On the other hand, other options like coldness, pain relief, and decreased heart rate do not typically indicate infection; in fact, coldness might suggest poor circulation or compromised blood flow, while pain relief usually indicates a reduction in the injury's severity or inflammation. Decreased heart rate is also not a common sign of infection and could signal a different set of physiological responses unrelated to soft-tissue injuries.