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Ischemia, Causes, Signs and Symptoms, Diagnosis and Treatment.

. Chapters 0:00 Introduction 1:03 Causes of Ischemia 2:15 Symptoms of Ischemia 3:00 Diagnosis and Treatment of Ischemia Ischemia or ischaemia is a restriction in blood supply to tissues, causing a shortage of oxygen that is needed for cellular metabolism (to keep tissue alive).[3] Ischemia is generally caused by problems with blood vessels, with resultant damage to or dysfunction of tissue i.e. hypoxia and microvascular dysfunction.[4][5] It also means local anemia in a given part of a body sometimes resulting from constriction (such as vasoconstriction, thrombosis or embolism). Ischemia comprises not only insufficiency of oxygen, but also reduced availability of nutrients and inadequate removal of metabolic wastes. Ischemia can be partial (poor perfusion) or total. Since oxygen is carried to tissues in the blood, insufficient blood supply causes tissue to become starved of oxygen. In the highly metabolically active tissues of the heart and brain, irreversible damage to tissues can occur in as little as 3–4 minutes at body temperature. The kidneys are also quickly damaged by loss of blood flow (renal ischemia). Tissues with slower metabolic rates may undergo irreversible damage after 20 minutes. Clinical manifestations of acute limb ischemia (which can be summarized as the "six P's") include pain, pallor, pulseless, paresthesia, paralysis, and poikilothermia.[6] Without immediate intervention, ischemia may progress quickly to tissue necrosis and gangrene within a few hours. Paralysis is a very late sign of acute arterial ischemia and signals the death of nerves supplying the extremity. Foot drop may occur as a result of nerve damage. Because nerves are extremely sensitive to hypoxia, limb paralysis or ischemic neuropathy may persist after revascularization and may be permanent.[7]