So the next thing we're going to talk about is
Increased Intracranial Pressure. Our brain is
contained within a box. And within that box
there are only a few substances.
There is Blood. There's Intracellular
fluid. There's Interstitial
Fluid, which is the fluid between the cells.
And there's Cerebrospinal Fluid that is
the fluid that bathes the brain cells within
the brain, and goes down through
the spinal column and bathes
cells within the spinal column.
Any increase in any one of those without a corresponding
decrease in one of the others, results
in an increase pressure within the cranium.
And that increased pressure,
if it goes to its worst level, can result
in the brain, actually the brainstem, being
forced out of the skull through the Foramen
Magnum at the base of the skull,
which is almost always associated with sudden
death. Intubation by the anesthesiologist
increases intracranial pressure, usually by increasing
blood pressure and heart rate. Unfortunately,
that can be quite a serious problem, but we
can correct it by inducing anesthesia
with our normal induction agents, which
tend to lower blood pressure and may also
reduce cerebral blood flow and increase the probability
of ischemic brain damage if we drop the blood
pressure too much. The careful use of anesthetic
drugs to reduce pressure, but maintain
cerebral perfusion, is a real art. And people who are
neuro anesthetists spend all their time discussing
this issue. Diuretics such as loop diuretics,
Furosemide, and osmotic agents,
such as Mannitol, basically suck water
out of the cells and cause it to be lost
through the kidney. So they reduce the size
of the brain and reduce the pressure in the skull.