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Ischemia, meaning insufficient blood flow to a tissue, can also result in hypoxia in the affected tissues. This is called 'ischemic hypoxia'. Ischemia can be caused by an embolism, a heart attack that decreases overall blood flow, trauma to a tissue that results in damage reducing perfusion, and a variety of other causes.
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. [9]
In hypoxic hypoxia 95–100% saturation is considered normal; 91–94% is considered mild and 86–90% moderate. Anything below 86% is considered severe. [8] Cerebral hypoxia refers to oxygen levels in brain tissue, not blood. Blood oxygenation will usually appear normal in cases of hypemic, ischemic, and hystoxic cerebral hypoxia.
Brain ischemia has been linked to a variety of diseases or abnormalities. Individuals with sickle cell anemia, compressed blood vessels, ventricular tachycardia, plaque buildup in the arteries, blood clots, extremely low blood pressure as a result of heart attack, and congenital heart defects have a higher predisposition to brain ischemia in comparison to the average population.
Tissue hypoxia refers to low levels of oxygen in the tissues of the body and the term hypoxia is a general term for low levels of oxygen. [2] Hypoxemia is usually caused by pulmonary disease whereas tissue oxygenation requires additionally adequate circulation of blood and perfusion of tissue to meet metabolic demands. [4]
Reperfusion injury, sometimes called ischemia-reperfusion injury (IRI) or reoxygenation injury, is the tissue damage caused when blood supply returns to tissue (re-+ perfusion) after a period of ischemia or lack of oxygen (anoxia or hypoxia).
Coagulative necrosis is a type of accidental cell death typically caused by ischemia or infarction. In coagulative necrosis, the architectures of dead tissue are preserved for at least a couple of days. [1] It is believed that the injury denatures structural proteins as well as lysosomal enzymes, thus blocking the proteolysis of the damaged cells.
Other factors in secondary damage are breakdown of the blood–brain barrier, edema, ischemia and hypoxia. [15] Ischemia is one of the leading causes of secondary brain damage after head trauma. [9] Similar mechanisms are involved in secondary injury after ischemia, trauma, and injuries resulting when a person does not get enough oxygen. [5 ...