Hyperemic

Hyperemic is an adjective used in medicine to describe tissue that shows hyperemia, an increased flow of blood through the regional vasculature. It is typically associated with redness (rubor) and warmth and results from dilation of arterioles and increased perfusion of capillary beds. Hyperemia can be physiological or pathological and may be localized to a skin area or to internal organs.

Physiological (active) hyperemia occurs when blood flow rises to meet metabolic demand or thermal needs. Examples include increased perfusion to exercising muscles, postprandial flow to the gut, and functional hyperemia in the brain during neural activity. Reactive hyperemia describes a transient rise in blood flow following a period of ischemia, as vessels dilate to restore tissue perfusion.

Pathological hyperemia arises from inflammatory processes. Inflammation causes arteriolar dilation and increased perfusion mediated by mediators such as nitric oxide, histamine, and prostaglandins. This type of hyperemia is often accompanied by signs of inflammation and may contribute to tissue redness and warmth in affected areas.

Localization and examples include cutaneous hyperemia (redness of the skin), conjunctival hyperemia (red eye), mucosal hyperemia, and cerebral or splanchnic hyperemia in various disease states. Hyperemia is distinct from edema, which involves fluid accumulation, and from venous congestion, which is due to impaired outflow rather than increased inflow.

Clinically, hyperemic tissue indicates increased blood supply and can reflect normal physiological responses or underlying pathology such as infection, injury, or inflammatory conditions.