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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).
Intracranial hypertension (IH), also called increased ICP (IICP) or raised intracranial pressure (RICP), refers to elevated pressure in the cranium. 20–25 mmHg is the upper limit of normal at which treatment is necessary, though it is common to use 15 mmHg as the threshold for beginning treatment.
Traumatic brain injury can cause dangerously raised intracranial pressure. Pressure reactivity index or PRx is a tool for monitoring cerebral autoregulation in the intensive care setting for patients with severe traumatic brain injury or subarachnoid haemorrhage, in order to guide therapy to protect the brain from dangerously high or low cerebral blood flow.
Incidence is estimated to 0.3–3% in patients older than 60 years and raising with older age. [38] Its prevalence is reported to be less than 1% in persons under the age of 65, and up to 3% for persons aged 65 or older. No difference in incidence is seen between men and women or amongst differing ethnicities.
This part of coronary circulatory regulation is known as auto regulation and it occurs over a plateau, reflecting the constant blood flow at varying CPP & resistance. The slope of a CBF (coronary blood flow) vs. CPP graph gives 1/Resistance. Autoregulation maintains a normal blood flow within the pressure range of 70–110 mm Hg.
It is more common in older people and females. [7] It is the reason for 2–5% of visits to emergency departments and admissions to hospital. [7] Up to half of women over the age of 80 and a third of medical students describe at least one event at some point in their lives. [7]
For most substances presented, the optimal levels are the ones normally found in the population as well. More specifically, optimal levels are generally close to a central tendency of the values found in the population. However, usual and optimal levels may differ substantially, most notably among vitamins and blood lipids, so these tables give ...
The variation in pressure in the left ventricle (blue line) and the aorta (red line) over two cardiac cycles ("heart beats"), showing the definitions of systolic and diastolic pressure Blood pressure is classified as normal blood pressure, prehypertension , hypertension (stages I and II), and isolated systolic hypertension , which is a common ...