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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).
The cause of inadequate tissue perfusion (blood delivery to tissues) in distributive shock is a lack of normal responsiveness of blood vessels to vasoconstrictive agents and direct vasodilation. [4] There are four types of distributive shock.
Hypovolemia can be recognized by a fast heart rate, low blood pressure, [12] and the absence of perfusion as assessed by skin signs (skin turning pale) and/or capillary refill on forehead, lips and nail beds. The patient may feel dizzy, faint, nauseated, or very thirsty. These signs are also characteristic of most types of shock. [13]
By widening the blood vessels, the tissue allows greater perfusion. By contrast, in the lungs , the response to hypoxia is vasoconstriction. This is known as hypoxic pulmonary vasoconstriction , or "HPV", and has the effect of redirecting blood away from poorly ventilated regions, which helps match perfusion to ventilation, giving a more even ...
Coronary artery bypass surgery during mobilization (freeing) of the right coronary artery from its surrounding tissue, adipose tissue (yellow). The tube visible at the bottom is the aortic cannula (returns blood from the HLM). The tube above it (obscured by the surgeon on the right) is the venous cannula (receives blood from the body).
Ventilation Scan is abnormal but perfusion scan is normal indicating abnormal airway suggesting COPD or asthma. Ventilation Scan is normal but perfusion is abnormal indicating any obstruction to the blood flow (perfusion), may be because of the pulmonary embolism obstructing the flow. Both scans are abnormal. It may be found in pneumonia or COPD.
Physiologic dead space cannot change as it is ventilation without perfusion. A shunt is a perfusion without ventilation within a lung region. [citation needed] Low tidal volume ventilation was the primary independent variable associated with reduced mortality in the NIH-sponsored ARDSNet trial of tidal volume in ARDS.
Cerebral perfusion pressure, or CPP, is the net pressure gradient causing cerebral blood flow to the brain (brain perfusion).It must be maintained within narrow limits because too little pressure could cause brain tissue to become ischemic (having inadequate blood flow), and too much could raise intracranial pressure (ICP).