Ischemic tissue, which is tissue that is not receiving adequate blood supply, often presents noticeable signs. While swelling can occur later as a result of inflammation or other processes, the first and most acute indicator of ischemia is usually pain in the affected area. This occurs due to the lack of oxygen and nutrients delivered by the blood, which triggers a pain response in the body.
Other signs, such as color changes in the skin or loss of sensation, typically follow as the ischemia persists or worsens. Color changes may be indicative of more severe ischemia and loss of sensation often indicates that nerve function is being compromised due to prolonged hypoxia. Thus, while pain may lead to awareness of the ischemic condition, swelling is not typically the first sign of ischemia experienced.