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| INSTRUCTIONS FOR USE
GB
FUNCTION OF THE VALVE
The operating principle of the paediGAV is illus-
trated in fig. 3 and fig. 4.
Fig. 3 a shows the paediGAV in a horizontal
position. The ball-cone unit is closed and the
drainage is blocked. In fig. 3 b, the paediGAV
is shown when it is open. The increased IVP of
the patient overcomes the spring force, which
otherwise would keep the ball-cone unit closed.
The closing ball is pushed away from the cone
seal and a gap opens for fluid drainage. The
gravitational unit is always open in the horizon-
tal position and does not present any resistance
to the drainage flow.
ball-cone unit
gravitational unit
a)
b)
Fig. 3: paediGAV in horizontal position
a) closed b) open
As soon as the patient raises to a vertical po-
sition, the gravitational unit closes and the drai-
nage is interrupted (fig. 4 a). In this position, the
sum of the IVP and the hydrostatic pressure
surpasses the spring force of the ball-cone unit.
Therefore this valve is open now. But only when
the sum of the IVP and the hydrostatic pressure
exceeds the gravitational force on the tantalum
ball in the gravitational unit, the drainage path is
open again (fig. 4 b).
a)
b)
Fig. 4: paediGAV in a vertical position
a) closed b) open
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paediGAV
SELECTING THE APPROPRIATE VALVE
The paediGAV operates in different modes de-
pending on the physical position of the patient.
It features two different opening pressures, one
for the patient in a horizontal position and one
for a vertical position.
Percutaneous readjustments of the valve ope-
ning pressure become unnecessary through
this design, as a higher opening pressure in the
vertical position counteracts any unintentional
overdraining, while the lower opening pressure
required for when the patient is lying down rules
out any underdrainage.
Horizontal position:
For the horizontal position, two different ope-
ning pressure settings are available (4 and 9
cmH
O). Selection of the appropriate pressure
2
rating should be made in accordance with indi-
cation (age of the patient).
Vertical position:
The opening pressure for the vertical body
position depends upon the size of the patient
(hydrostatic parameter). If an infant is being tre-
ated, a low pressure rating should be selected.
If, on the other hand, a larger child is being tre-
ated, a paediGAV with a higher pressure rating
should be applied. (see recommendation of
pressure settings at www.miethke.com)
READING THE PRESSURE SETTING FROM
AN X-RAY IMAGE
Each paediGAV is calibrated under strict quality
control. The following pressure combinations
are available:
Opening pressure
Coding
horizontal
vertical
4 cmH
O
24 cmH
O
2
2
9 cmH
O
24 cmH
O
2
2
9 cmH
O
29 cmH
O
2
2
4 cmH
O
14 cmH
O
2
2
4 cmH
O
19 cmH
O
2
2
9 cmH
O
19 cmH
O
2
2
paediGAV
Recommendation of pressure levels:
Opening pressure
Recommendation
horizontal
vertical
4 cmH
O
24 cmH
O
children up to 6 months
2
2
9 cmH
O
24 cmH
O
children from 6 months to
2
2
5 years
9 cmH
O
29 cmH
O
children over 5 Years
2
2
The pressure settings selected can be checked
postoperatively on x-ray images, on which the
corresponding coding is visible.
Fig. 5: Radiograph of a paediGAV (9/24 cmH
O)
2
POSSIBLE SHUNT COMPONENTS
The paediGAV is available with different shunt
accessories. These variants consist of a varie-
ty of components, which are described briefly
below:
The borehole reservoir is positioned in the
cranial borehole. It allows measuring the in-
traventricular pressure, injecting drugs and
extracting CSF. Its solid titanium base is highly
puncture-resistant. All reservoirs are availa-
ble with integrated catheters or connectors.
A special borehole reservoir is the SPRUNG
RESERVOIR. As additional new feature of this
reservoir CSF can be flushed towards the val-
ve because of a one-way valve in the bottom
of the reservoir. By this mechanism a flow
in the direction of the ventricular catheter is
avoided during the pumping procedure. The
opening pressure of the shunt system is not
INSTRUCTIONS FOR USE |
increased by the implantation of the SPRUNG
RESERVOIR.
The prechamber is positioned on the craniu m.
It allows measuring the intraventricular pressu-
re, injecting drugs, extracting CSF and perfor-
ming a palpatory ventricle inspection. Its solid
titanium base is highly puncture-resistant.
A puncture of the prechamber or the CONTROL
RESERVOIR should be performed as perpendi-
cular to the reservoir surface as possible with
a cannula of max. 0,9 mm. 30 times of punc-
tures are able without any restrictions. A special
prechamber is the CONTROL RESERVOIR. As
an additional new feature of this reservoir, CSF
can be flushed towards the valve because of a
one-way valve in the proximal inlet of the reser-
voir. By this mechanism a flow in the direction
of the ventricular catheter is avoided during the
pumping procedure. The opening pressure of
the shunt system is not increased by the im-
plantation of the CONTROL RESERVOIR.
Warning note: Frequent pumping can lead
to overdrainage and thus to unphysiological
pressure conditions. The patient should be
informed about the risk.
Due to its tight fit on the ventricular catheter, the
deflector allows choosing the length of catheter
penetrating into the skull prior to implantation.
The ventricular catheter is deflected at a right
angle in the borehole
TUBE SYSTEMS
The paediGAV has been designed to ensure the
optimal ventricular pressure. It is available as a
shunt system or as individual valve units with
or without an integrated distal catheter (internal
diameter 1.2 mm, external diameter 2.5 mm).
Individual valve units should be used with ca-
theters of approx. 1.2 mm internal diameter and
approx. 2.5 mm external diameter.
The connector on the valve allows using ca-
theters of 1.0 mm to 1.5 mm internal diameter.
The external diameter of the catheter should
be about double the internal diameter. In any
case, the catheters must be carefully fixed, with
a ligature, to the valve connectors. Kinks in the
catheter have to be avoided.
The provided catheters have virtually no effect
on the Pressure-flow characteristics.
GB
17
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