Ischaemia
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Abnormal reduction in blood supply to or drainage from an organ or tissue
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Infarction is the result of cessation of the blood supply to or drainage from an organ or tissue
Classification of causes
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Local
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Arterial obstruction: thrombus, embolus, artheroma, pressure, spasm
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Venous: thrombus, pressure, stasis
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Capillary obstruction: vasculitis (meningococcal septicaemia, drugs), obstruction (sickle cell)
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External pressure
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General
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Hypoxaemia
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Anaemia
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V/Q defect
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Factor determining the extent of ischaemic damage in arterial obstruction
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Tissue involved - brain low reserve
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Speed of onset
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Degree of obstruction
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Presence of collaterals
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Level of oxygenation
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Presence of concomitant heart failure
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State of microcirculation