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home - Colon - Colonic Vascular Disorders - Mesenteric perfusion Written by Dr Sebastian Zeki

Mesenteric perfusion

Arteriolar smooth muscle relaxtion Decreased perfusion pressure Mucosal ischaemia Adenosine and other metabolites of mucosal ischaemia Sympathetic nervous system Renin-angiotensin axis Venoconstricion Arteriolar smooth muscle contriction Venodilatation Vasopressin (ADH) Mesenteric perfusion (10 to 35 % of cardiac output) -Physiol-ogy Intestines can compensate for 75 % acute reduction in mesenteric blood flow for up to 12 hours without substantial injury, in part because of increased oxygen extraction Collateral circulation opens immediately Progressive vasoconstriction develops in the obstructed bed, increasing its pressure and thereby reducing collateral flow. Ischaemia may persist after restoration so therapeutic infusion of papaverine (a vasodilator) during angiography often given After several hours Early ischaemic damage is due to reperfusion injury -It is initiated by an increased release of oxygen free radicals, other toxic byproducts of ischemic injury, and neutrophil activationHypoxia is main mechanism if longer ischaemic time Written by Dr Sebastian Zeki

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