6. If available, record the three-digit zero reference
number provided by the ICP Monitor. Mark this
number on the catheter connector housing and the
patient's chart for future reference.
General Surgical Procedure
The following is a general guide for informational
purposes only. The surgeon may wish to alter details
in accordance with his or her own clinical experience
and medical judgment. The CODMAN Cranial Access
Kit is recommended for this procedure. This device
is not designed, sold, or intended for use as a
therapeutic device.
Measuring Subdural Pressure
1. Following craniotomy and bone flap
removal connect and zero the transducer.
Refer to Connecting and Zeroing the
MICROSENSOR Transducer.
2. Choose the burr hole through which the
transducer will be placed and bevel the
edge on the side the transducer will exit
to facilitate removal.
3. Use the Tuohy needle to tunnel under the scalp
from the craniotomy site to the desired transducer
exit site.
4. Remove the Tuohy needle stylet and thread the
transducer from the tip of the needle until the
approximate length for desired placement exits
from the hub. See Figure 2.
CAUTION: The inner edges of the Tuohy needle
are sharp; exercise caution when threading the
catheter.
5. Gently remove the needle and estimate the length
of the transducer from the tip to the first bend.
6. Fold back the transducer once completed at the
desired bend site to leave a kink in the catheter.
Verify that the kink is on the opposite side of the
transducer from the transducer sensing element,
as shown in Figure 3.
7. Place the tip of the transducer on the brain tissue
under the dura opposite the beveled burr hole.
The kink must be placed at the bottom of the burr
hole so that the transducer sensing element faces
the cortex, as shown in Figure 4.
CAUTION: To ensure accurate ICP
measurements, position the sensing element
of the transducer tip towards the cortex during
subdural pressure monitoring.
CAUTION: To minimize movement artifacts of
the bone flap, place the transducer under the
intact skull.
8. Close and suture down the dura following
standard neurosurgical procedure.
9. Replace the bone flap and close the scalp incision.
10. Secure the catheter to the scalp. To provide
additional strain relief, make a small loop with the
catheter and tie the loop down.
11. Close and dress the incision site.
Measuring Intraparenchymal Pressure
NOTE: The CODMAN Cranial Hand Drill, catalog
no. 82-6607, is recommended for this procedure.
1. Connect and zero the transducer.
Refer to Connecting and Zeroing the
MICROSENSOR Transducer.
2. Perform craniotomy and retraction procedures
required to expose the skull. Put the 2.7 mm
drill bit into the drill chuck and make a drill hole
through the outer table.
CAUTION: Proceed gently through the inner
table with care to avoid injury to the dura
or parenchyma.
3. Carefully bevel the bone at the incision site
towards the side from which the catheter will exit.
4. Use the Tuohy needle to make a cruciate puncture
in the dura.
5. Use the Tuohy needle with stylet in place to tunnel
under the scalp from the incision site to the exit
site.
6. Remove the stylet and thread the transducer from
the tip of the needle until approximately twice the
placement length exits from the hub. See Figure 5.
CAUTION: The inner edges of the Tuohy needle
are sharp; exercise caution when threading the
transducer.
7. Gently remove the needle and estimate the length
of the transducer from the tip to where it will bend
upon exiting the skull.
8. Fold the transducer once completely at the
desired bend site to leave a kink in the transducer.
9. Place the tip of the transducer into the
parenchyma through the puncture in the dura until
the kink is at the edge of the hole, as shown in
Figure 6.
10. Carefully pull back the excess transducer.
11. Remove the retractor, verify hemostasis in the
insertion area, and then suture the incision
site closed.
12. Secure the catheter to the scalp. For additional
strain relief, make a small loop with the catheter
and tie the loop down.
13. Close and dress the incision site.
Specifications
Probe Specifications
Note: All performance specifications based on 5 VDC
excitation voltage
Sensing element ........................ Strain gauge silicon
Probe usable length .................. 100 cm nominal
Probe material ........................... Nylon, titanium,
Probe tip diameter ..................... 1.3 mm maximum
Probe tubing diameter ............... 0.8 mm maximum
Functional pressure range ......... –50 mmHg
4
microchip
silicone, epoxy
to +250 mmHg