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Cerebral hypoxia is a form of hypoxia (reduced supply of oxygen), specifically involving the brain; when the brain is completely deprived of oxygen, it is called cerebral anoxia. There are four categories of cerebral hypoxia; they are, in order of increasing severity: diffuse cerebral hypoxia (DCH), focal cerebral ischemia , cerebral infarction ...
An alternative definition of CPP is: [1] = where: MAP is mean arterial pressure ICP is intracranial pressure JVP is jugular venous pressure. This definition may be more appropriate if considering the circulatory system in the brain as a Starling resistor, where an external pressure (in this case, the intracranial pressure) causes decreased blood flow through the vessels.
A cascade is a series of events in which one event triggers the next, in a linear fashion. Thus "ischemic cascade" is actually a misnomer, since the events are not always linear: in some cases they are circular, and sometimes one event can cause or be caused by multiple events. [4]
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.
Similar failure processes are involved in brain failure following reversal of cardiac arrest; [3] control of these processes is the subject of ongoing research. Repeated bouts of ischemia and reperfusion injury also are thought to be a factor leading to the formation and failure to heal of chronic wounds such as pressure sores and diabetic foot ...
If the swelling is untreated, it causes death by brain herniation. [4] The brain swelling is likely a result of vasogenic edema, the penetration of the blood–brain barrier by fluids. [16] This process has been observed in MRI studies. Hypoxia increases extracellular fluid, which passes through the vasogenic endothelium in the brain.
An increase in carbon dioxide causes tension of the arteries, often resulting from increased CO 2 output (hypercapnia), indirectly causes the blood to become more acidic; the cerebrospinal fluid pH is closely comparable to plasma, as carbon dioxide easily diffuses across the blood–brain barrier.
The lack of oxygen (hypoxia) causes cell death in a localized area which is perfused by blood vessels failing to deliver primarily oxygen, but also other important nutrients. While ischemia in most tissues of the body will cause coagulative necrosis, in the central nervous system ischemia causes liquefactive necrosis , as there is very little ...