Possible Shunt Components; Tube Systems; Implantation; Valve Test - MIETHKE GAV 2.0 Mode D'emploi

| INSTRUCTIONS FOR USE
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POSSIBLE SHUNT COMPONENTS

The GAV 2.0 can be ordered as a shunt system
in a range of configurations. The configurations
can be combined with the accessories presen-
ted in brief below. In each case, versions for pa-
ediatric hydrocephalus and for normal pressure
hydrocephalus (NPH) in adults are available.
Reservoirs
The use of a reservoir in combination with shunt
systems provides options for the withdrawal of
cerebrospinal fluid, administration of drugs and
pressure control.
Thanks to the one-way flux (flow) system of
the SPRUNG RESERVOIR and the CONTROL
RESERVOIR, cerebrospinal fluid can be pum-
ped towards the valve, thus making it possible
to check the distal part of the drainage system
as well as (proximal) ventricular catheter. Duri-
ng the pump action, access to the ventricular
catheter is closed. The use of reservoirs does
not increase the opening pressure of the shunt
system. A puncture should be performed as
perpendicular as possible to the reservoir sur-
face with a maximum cannula diameter of 0.9
mm. 30 punctures are possible without any re-
strictions.
Warning notice: Frequent pumping can re-
sult in excessive drainage and thus lead
to pressure conditions outside the normal
physiological range. The patient should be
properly informed about this risk.
Burrhole deflector
Because of the tight fit on the ventricular cathe-
ter, the burrhole deflector makes it possible to
choose the length of catheter penetrating into
the skull prior to implantation. The ventricular ca-
theter is deflected at a right angle in the burrhole
(see chapter "Implantation").

TUBE SYSTEMS

The GAV 2.0 can be ordered as an individual
valve unit or as a shunt system with integrated
catheters (interior diameter 1.2 mm, exterior di-
ameter 2.5 mm). The supplied catheters do not
fundamentally change the pressure-flow cha-
racteristics. If catheters by other manufacturers
are used, a tight fit must be ensured. In any
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GAV 2.0
case, catheters have to be carefully fixed with a
ligature to the valve's titanium connectors.

IMPLANTATION

Positioning the ventricular catheter
Several surgical techniques are available for po-
sitioning the ventricular catheter. The required
skin incision should be made in form of a lo-
bule pedicled towards the draining catheter. If
a burrhole deflector is used, the skin incision
should not be located right above the reservoir.
To avoid CSF leakage, care should be taken
that the dura opening is kept as small as possi-
ble after applying the burrhole.
The GAV 2.0 is available in a range of different
configurations: If a burrhole reservoir is used,
the ventricular catheter is implanted first. Once
the introducing stylet has been removed, the
patency of the ventricular catheter can be te-
sted by checking if cerebrospinal fluid is drip-
ping out. The catheter is shortened and the re-
servoir is connected, whereby the connection
is secured with a ligature. A shunt system with
prechamber comes with a burrhole deflector.
The deflector is used for adjusting the length of
catheter to be implanted and for its positioning
inside the ventricle. The ventricular catheter is
deflected, connected to the prechamber, and
the prechamber is put into place. The position
of the ventricular catheter should be inspected
after the procedure by imaging (such as CT
or MRI).
Positioning the valve
The operating principle of the GAV 2.0 is po-
sture-dependent. For that reason, care must
be taken to implant the valve parallel to the
body axis. For VP drainage, a suitable posi-
tion for implantation is behind the ear. After
skin incision and tunnelling under the skin,
the catheter is pushed forward from the burr-
hole to the intended valve implantation site,
shortened where necessary and secured
with a ligature. For LP drainage, the valve is
placed in a subcutaneous skin pocket in the
abdominal or back region. The valve should
not be located directly under the skin incisi-
on. The valve is marked with an arrow indica-
ting the distal direction of flow.
GAV 2.0
Warning notice: The catheters should only
be blocked with a sheathed clamp and not
directly behind the valve as they might be
damaged otherwise.
Positioning the peritoneal catheter
The access site for the peritoneal catheter is
left to the surgeon's discretion. For example,
it can be applied para-umbically in a horizontal
direction or transrectally at the height of the epi-
gastrium. Likewise, various surgical techniques
are available for positioning the peritoneal ca-
theter. The recommendation is to pull the pe-
ritoneal catheter using a subcutaneous tunnel-
ling tool from the valve to the intended position,
if necessary with the aid of an auxiliary incision.
The peritoneal catheter which is usually secu-
rely attached to the valve has an open distal
end and no wall slits. Following the exposure
of the peritoneum or with the aid of a trocar,
the peritoneal catheter (shortened if necessary)
is pushed forward into the open space of the
abdominal cavity.
Reimplantation
Products that have previously implanted must
not subsequently be reimplanted into the same
or another patient.
INSTRUCTIONS FOR USE |

VALVE TEST

Preoperative valve test
The most careful way of filling the valve is by
aspiration through a sterile single-use syrin-
ge attached to the distal end of the catheter.
The distal end of the valve is connected and
immersed in a sterile physiological saline soluti-
on. The valve is patent if saline solution can be
extracted (Fig. 5).
Warning notice: Contamination in the soluti-
on used for testing can impair the product's
performance.
Fig. 5: Patency test
Warning notice: Pressurisation by the sin-
gle-use syringe should be avoided both at
the proximal and the distal end (fig. 6).
Fig. 6: Avoidance of pressurisation
Postoperative valve test
The GAV 2.0 has been constructed as a reliably
functioning unit without pump or test function.
The valve test can be performed by flushing,
pressure measurement or pumping.
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