Cerebral Blood Volume

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1. Cerebral blood volume (total of 60 mL) is influenced by arterial inflow, venous drainage and cerebrovascular tone. Hypercarbia and hypoxemia result in pH-mediated cerebral vasodilation and must be avoided. Hyperventilation causes an alkalosis-mediated increase in cerebrovascular resistance and decrease in cerebral blood volume, thereby transiently decreasing ICP. This is particularly helpful for 'emergency' response to impending or ongoing cerebral herniation syndrome. Unfortunately, hyperventilation also may cause brain ischemia and secondary injury due to reduced cerebral blood flow. Hyperventilation may be still be useful in a subset of patients with damaged autoregulation of cerebral blood vessels and hype-remic intracranial hypertension, but it is no longer widely recommended.

2. Elevation of the head to 30 degrees above the heart, in order to improve venous outflow and reduce intracerebral hydrostatic pressure, is traditionally advocated in severe head injury. This measure is now also controversial and some centers evaluate head position by its effects on ICP in each individual patient. This measure should be avoided in hypovolemic patients.

3. Neutral position of the neck to avoid compression of jugular venous outflow helps to avoid intracranial hypertension related to venous congestion.

4. Sedative drugs, narcotics and pharmacological paralytics may be used to avoid valsalva maneuver due to pain or tracheal irritation, which can reduce venous outflow and raise ICP.

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Blood Pressure Health

Blood Pressure Health

Your heart pumps blood throughout your body using a network of tubing called arteries and capillaries which return the blood back to your heart via your veins. Blood pressure is the force of the blood pushing against the walls of your arteries as your heart beats.Learn more...

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