Hyperemia

Hyperemia is an excessive amount of blood or an increase in blood volume within an organ or a tissue that can be caused by vasodilation or diminished venous outflow.

Types of hyperemia

Hyperemia is divided into two types:

1. Active hyperemia is an active process in which the affected tissues are redder than normal because of engorgement with oxygenated blood.
2. Congestion (passive hyperemia): these tissues have an abnormal blue-red color that due to accumulation of deoxygenated blood in the affected area. Congestion is further devided into acute and chronic.

Causes of hyperemia

Each type of hyperemia has a different cause:

1. Active hyperemia: This is caused by an arteriolar dilation and increased blood inflow (e.g., blushing, inflammation, exercising).
2. Congestion (passive hyperemia): it is caused by obstructed venous return or increased back pressure from congestive heart failure (resulting from impaired outflow of venous blood).
   • Acute passive congestion occurs in sudden right-sided heart failure, shock or acute inflammation.
   • Chronic passive congestion of lung is caused most often by left-sided heart failure, while Chronic passive congestion of the liver and lower extremities is most often caused by right-sided heart failure

Symptoms

Generally the symptoms involve:

• swelling
• redness
• affected area warmer than normal