miethke Shuntassistant 2.0 Patientenhandbuch Seite 25

SA 2.0 mechanism of action
SA 2.0 is a gravitational valve which makes use of gravity in order to achie-
ve an intracranial pressure independent of the body position of the patient
that is guided by pressure values of healthy subjects.
The SA 2.0 contains a gravitational unit, which can be combined with con-
ventional differential pressure valves. The SA 2.0 has a pre-set opening
pressure, selected by the neurosurgeon prior to implantation.
Differential pressure valve
A conventional differential pressure valve operates the same in all body
positions; for that reason, it has generally got a low opening pressure set
for the horizontal position to ensure that in case of increasing intracranial
pressure the valve permits the timely drainage of cerebrospinal fluid parti-
cularly in the horizontal position.
Gravitational unit
The gravitational unit makes use of the principle of gravity and operates
with the aid of a heavy tantalum ball in the inside of SA 2.0 In the upright
position, this ball presses down on a cone, thus closing the valve until a
specific opening pressure has been reached, which then dislocates the ball
from its position, thus permitting the drainage of cerebrospinal fluid. If the
intracranial pressure drops back below the pre-set opening pressure, the
ball once again closes the valve.
In the upright position, the gravitational unit operates in addition to the dif-
ferential pressure unit. In that way, SA 2.0 achieves in upright position the
desired opening pressure.
Warning notice: The shunt system may be fitted with a pumpa-
ble reservoir. As too frequent pumping can result in an exces-
sive drainage (overdrainage) and thus unfavourable pressure
conditions, this process should only be performed by a phy-
sician.
SA 2.0 PATIENT MANUAL //
25