NSE 22A/B Lecture : Pathophysiology - CNS disorders
16 Dec 2011
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Alteration d/t: changes in intracranial pressure (icp, changes in cerebral blood flow. Cerebral perfusion pressure(cpp) of pressure exerted by the brain tissue, blood volume & csf within the skull. 60-130 mm hg (average 80-90) is required to maintain adequate blood flow to. Mean systemic vascular pressure (msvp) of 60- 160 mm hg (= diastolic + 1/3 of pulse press. ) is required to maintain normal icp below 30 mm hg. Auto-regulation ceases when the cpp is less than 40 mm hg (a cpp of less than 30 mm hg is incompatible with life) Msap of less than 60 mm hg reduces cerebral perfusion. Cardiac output ( bld flow if co is decreased by 1/3) Extensive anastamotic channels in the circle of willis become patent (normally not patent) if blood flow to an area is disrupted blood supply to the affected area. Ability of brain to regulate its own blood supply is maintained by 3 physiological mechanisms.
