JPH0356050B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an intracranial pressure measuring device, and particularly to an intracranial pressure measuring device for measuring intracranial pressure in patients with hydrocephalus, etc. The present invention relates to a reservoir that constitutes a ventricle-peritoneal shunt or a ventricle-atrial shunt (hereinafter referred to as "ventricular shunt") that is surgically implanted into the body.

[Conventional technology]

Generally, in neurosurgical diseases associated with increased intracranial pressure, accurate measurement of intracranial pressure is necessary to elucidate the pathological picture.

In the past, various methods have been proposed for measuring intracranial pressure, one example of which is Japanese Patent Application Laid-Open No. 1983-1999.
There is one described in the 115538 issue.

As shown in FIGS. 6 to 8, there is an implant A buried inside the patient's body, and an implant A placed outside the patient's body that connects to the intracranial pressure measurement reservoir 11 of the implant A through the scalp 16. It consists of a pressure detection device B that can be contacted.

The implant A includes a tubular ventricular catheter 12 whose tip end 12b can be inserted into the ventricle 19 of a patient to drain cerebrospinal fluid from the ventricle 19, and the catheter 12.
a reservoir 11 connected to the scalp 16;
It consists of a buried object main body 22 made of a soft wall made of silicone resin or the like fixed on the skull 17 at the bottom, and a thin film-like flexible curved dome 11a for measuring intracranial pressure is formed on the upper part of the reservoir 11. has been done.

The pressure detection device B includes a pressure detector 23, an amplifier 25 that receives and amplifies a pressure detection signal from a pressure sensor 23e of the pressure detector 23 via a lead wire 24, and an amplified signal from the amplifier 25. It is comprised of a recorder 27 such as a printer for receiving and recording the information via a lead wire 26 and a display device 28 such as a CTR for displaying the information.

The pressure detector 23 is configured as a transcutaneous cerebral pressure sensor, and includes a case 23a, an outer cylinder 23b of a predetermined length connected to the detection end side of the case 23a,
A presser plate 23c connected to the back side of the case 23a
and a columnar pressure receiving plate 23d slidably inserted into the outer cylinder 23b, which is connected to the pressure receiving plate 23d, converts the pressure from the pressure receiving plate 23d into an electrical signal, and outputs it via the lead wire 24. A diffusion-type semiconductor pressure sensor (or load sensor) 23e whose surface is molded with silicon for the purpose of servicing, and a hard spring 2 that applies a biasing force to the pressure sensor 23e inside the case 23a.
3f, and a zero adjuster 23g for positioning the pressure sensor 23e.

Note that the reference numeral 20 in the figure indicates the brain and 21 the dura mater.

This device can measure intracranial pressure using the following steps.

(1) The cerebrospinal fluid is guided through the ventricular catheter 12 to the intracranial pressure measurement reservoir 11 buried under the scalp 16 and above the skull 17, and the pressure of the cerebrospinal fluid causes the upper dome 11 of the reservoir 11 to be
Expand a so that it protrudes outward.

(2) Turn on pressure detection device B and start measurement [see sensor depth L _A at time t _A in FIG. 7 a and FIG. 8]. At this time, the detection end 29
is separated from the scalp 16 and is in a non-contact state.

Therefore, in this state, no pressure is applied to the dome 11a from the outside.

(3) By bringing the detection end 29 of the pressure detection device B into contact with the upper dome 11a through the scalp 16 [see sensor depth L _B at time t _B in FIGS. 7b and 8], the pressure is detected. Start measuring P.

(4) Next, push the detection end 29 into the upper dome 11a until the center of the upper surface becomes flat [see sensor depth L _C at time t _C in FIG. 7 c and FIG. 8].

In this state, the tip surface of the pressure receiving plate 23d and the scalp 1
6, the upper surface of the curved dome 11a becomes a co-plane, and the curve is curved in the relationship between the indentation depth L and the detected pressure P (hereinafter, the point of inflection is referred to as "BP ₁ "). occurs.

(5) Further, the pushing is continued until the upper surface of the upper dome 11a is crushed [see sensor depth L _D at time t _D in FIG. 7 d and FIG. 8].

In this state, the tip surface of the pressure receiving plate 23d is on the scalp 1.
6, the curved dome 11a begins to sink into the curved dome 11a, and a curve (hereinafter the inflection point will be referred to as "BP ₂ ") occurs in the relationship between the indentation depth L and the detected pressure P.

(6) The pressure detected by the pressure detection device B during this pushing process is measured by recording it with the recorder 27 or displaying it on the display device 28.
A section (inflection points _BP1 to _BP2 ) in which the detected pressure P does not change even if the indentation depth L is slightly changed is detected, and the detected pressure P in this section is taken as the intracranial pressure.

[Problem to be solved by the invention]

By the way, the above-mentioned transcutaneous intracranial pressure measurement is based on the following principle.

That is, as shown in FIG. 6, the intracranial pressure is derived directly below the scalp 16, and the "soft"
It is assumed that a pressure equal to the intracranial pressure exists in the dome 11a.

In this case, the object to be measured is the pressure within the implant body 22 (ventricular shunt body) embedded under the scalp 16, and this pressure is indirectly measured from outside the scalp 16. At this time, it is assumed that there is almost no change in intracranial pressure even if the scalp 16 and reservoir 11 are lightly compressed.

At this time, the following measurement principle is derived from Laplace's theorem.

As shown in FIG. 9, when the scalp 16 and the dome 11a of the implant body 22 (ventricular shunt body) are considered to be part of a sphere with radius r, the sphere has an internal pressure (brain pressure) Pi, External pressure (usually atmospheric pressure) P
and the dome 11 of the scalp 16 and the implant body 22
Laplace's theorem holds true between a and the tension T.

That is, the following relationship holds true.

Pi−P=2T/r (1) Here, when measuring the internal pressure Pi from outside the dome 11a, it is sufficient that the condition such that Pi=P is satisfied under equation (1).

Based on Laplace's theorem, the following measurement principle is established.

Now try pressing the outside of the dome 11a with a plate 29' as shown in FIG. The upper surface of the dome 11a is made flat by the plate 29'. If the area of the planar portion of this plate 29' is D, then in the area of D,
Based on Laplace's theorem, this corresponds to r becoming infinite.

That is, if r is set to ∞, the right side of equation (1) becomes 0, and in this case, Pi=P holds true. From this, when the dome 11a and the scalp 16 are compressed with an appropriate external pressure, the external pressure applied to the flattened part is:
It can be seen that it is equal to the internal pressure.

However, in actual measurements, dome 1
The conditions for accurately compressing the dome 11a only in the necessary areas are: compressing the dome 11a flatly detecting external pressure only in the region D above, avoiding crushing the dome 11a more than necessary. The problem is that it requires skill.

The present invention attempts to solve these problems by inserting a flexible curved dome for measuring intracranial pressure, which is formed to protrude outward from the upper part of the reservoir, from the outside through the scalp. The pressure on the dome is gradually increased using a probe, and the intracranial pressure is determined from the pressure when the dome begins to curve inward, which requires special measurement techniques. The purpose is to provide an intracranial pressure measuring device that does not require

[Means to solve the problem]

In order to achieve the above object, claim 1 of the present invention
The invention described in 2003-12-12 discloses a ventricular catheter whose distal end can be inserted into a ventricle to introduce cerebrospinal fluid from the same ventricle, and a ventricular catheter which is connected to the proximal end of the ventricular catheter to guide the cerebrospinal fluid and to introduce the cerebrospinal fluid from the scalp. A reservoir for intracranial pressure measurement buried below and above the skull, and a flexible reservoir formed so as to protrude outward at the upper part of the reservoir, which is expanded by the pressure of the cerebrospinal fluid and can be bent in response to external pressure. It consists of a curved dome for measuring sexual intracranial pressure, and a pressure measuring probe equipped with a pressing part that can press the curved dome from the outside through the scalp, and the curved dome receives the pressing force from the pressing part of the probe. The curved dome is characterized in that an annular cross-sectionally deformed portion is formed on the curved dome so that the curved dome begins to concavely curve inward.

In addition, the invention described in the same 2 provides a ventricular catheter whose distal end is inserted into the ventricle to draw out the cerebrospinal fluid from the ventricle, and a ventricular catheter which is connected to the proximal end of the ventricular catheter to draw out the cerebrospinal fluid from the ventricle. A reservoir for intracranial pressure measurement is buried under the scalp and on the skull, and a reservoir is formed in the upper part of the reservoir to protrude outward, and is expanded by the pressure of the cerebrospinal fluid, and is expanded in response to pressure from the outside. A flexible curved dome for measuring intracranial pressure that can be bent;
a pressure measuring probe equipped with a pressing part that can press the curved dome from the outside through the scalp, and directing the pressing part of the probe toward the dome,
A pressing part driving means that presses at a constant speed, a pressure transducer capable of measuring the pressing force on the dome by the pressing part of the probe are provided, and a liquid is filled inside the tip of the pressing part. It is characterized by being provided with a flexible membrane.

[Effect]

In the above-described intracranial pressure measuring method and device of the present invention, the flexible curved dome for intracranial pressure measuring is formed to protrude outward from the upper part of the reservoir.
The probe is pressed from outside through the scalp with gradually increasing pressure, and the pressure of the probe is read when it begins to curve inward, making measurement simple and easy. .

In addition, since the curved dome is formed with an annular cross-sectional deformation section, when the difference in pressure acting on the inner and outer surfaces of the dome reaches a certain value, the cross-section deformation section instantly bends concavely. In other words, the cutting is done with good precision, and the point at which the curved dome becomes concave can be clearly measured.

Furthermore, a flexible membrane filled with liquid is provided at the tip of the pressing part of the probe.
When the curved dome is concavely curved (or restored) inward, the pressing part can immediately deform to accommodate this, so the liquid pressure inside the flexible membrane also changes immediately, and this causes the dome to curve inward. Inward concave curve points can be accurately measured.

〔Example〕

Hereinafter, an intracranial pressure measuring device as an embodiment of the present invention will be explained with reference to the drawings.
are schematic side views showing the measurement procedure, Fig. 3 is a graph explaining its action, Fig. 4 is a vertical cross-sectional view showing a modified example of the curved dome, and Fig. 5 is measurement using the device shown in Fig. 1. It is a graph showing the results. Note that the same reference numerals in FIGS. 1 to 5 as in FIGS. 6 to 10 indicate substantially the same members.

The intracranial pressure measuring device of this embodiment can also contact an implant A buried inside the patient's body and an intracranial pressure measurement reservoir 11 of the implant A placed outside the patient's body through the scalp 16. It is composed of a pressure detection device B.

The implant A includes a tubular ventricular catheter 12 whose tip end 12b can be inserted into the ventricle 19 of a patient to drain cerebrospinal fluid from the ventricle 19, and the catheter 12.
a reservoir 11 connected to the scalp 1;
6 and a buried object main body 22 consisting of a soft wall made of silicone resin or the like fixed on the skull 17 at the bottom of the reservoir 11, and a flexible thin film formed on the upper part of the reservoir 11 so as to protrude to the outside. A curved dome 11a for intracranial pressure measurement is formed.

The pressure detection device B includes a probe 1 that is removably attached to a frame 3, and the probe 1 is connected to a curved dome 11 by a screw rod 4 that rotates at a constant speed.
It is configured to be pushed toward a at a constant speed, and a liquid (for example,
A pressing portion 6 is provided with a flexible membrane 5 such as a urethane membrane filled with silicone oil (2).

A pressure transducer 7 for measuring the pressing force of the pressing part 6 is provided, and its output signal is connected to a meter (not shown) via a lead wire 8. 9 indicates a return spring.

Next, to explain the intracranial pressure measurement method using the intracranial pressure measuring device configured as described above, the intracranial pressure is measured as shown in Figs. 2 and 3 with the buried object A buried in a predetermined position. can do.

(1) The cerebrospinal fluid is guided through the ventricular catheter 12 to the intracranial pressure measurement reservoir 11 buried under the scalp 16 and above the skull 17, and the curved dome 11 of the reservoir 11 is caused by the pressure of the cerebrospinal fluid.
a to protrude outward (at this time, the cerebrospinal fluid pressure inside the curved dome 11a is
Let it be Pi. ) (2) Turn on pressure detection device B and start measurement [time t _A in Figure 3]. At this time, the pressing part 6 is separated from the scalp 16 and is in a non-contact state.

Therefore, in this state, no pressure is applied to the dome 11a from the outside.

(3) By pressing the probe 1 of the pressure detection device B at a constant speed and bringing the pressing part 6 into contact with the upper dome 11a through the scalp 16 [Fig.
and time t _B in FIG. 3], measurement of the pressure Po of the liquid in the pressing part 6 is started.

(4) Continue extruding the probe 1 at a constant speed, and continue pushing the curved dome 11a with the pressing part 6. In this state, the hydraulic pressure Po inside the pressing part 6 is
gradually rises under the reaction force of the cerebrospinal fluid within the curved dome 11a [the state shown in FIG. 2b]. At this time,
Pi > Po, but Po gradually approaches Pi.

(5) If the pushing is continued further and Po≒Pi, the curved dome 11a becomes flat (the state shown in Figure 2 c), and eventually when Pi<Po, the curved dome 11a begins to curve inward. [Second
Figure d, time t _C in Figure 3].

As the curved dome 11a curves inward, the volume of the pressing portion 6 increases.
The hydraulic pressure inside the tank suddenly drops temporarily (time td in Figure 3).

(6) After continuing to push in further, pull out the probe 1 at a constant speed (the turning point is time te in Figure 3).

(7) Then, in the withdrawal process of probe 1,
When Pi≒Po is reached, the curved dome 11a, which had been curved concavely inward, begins to restore its shape, and the curved dome 11
As a is restored, the pressing part 33 is compressed, and the internal hydraulic pressure temporarily increases (time tg in Fig. 3).
However, as the probe 1 continues to be pulled out, the hydraulic pressure Po inside the pressing part 6 gradually decreases, and when it leaves the curved dome 11a (at the time shown in FIG.
th), return to the initial pressure.

By the above operations, time tc, td, tf and tg
The detection pressure in Poc, Pod, Pof and Pog,
The intracranial pressure can be determined by calibrating the data measured in advance using the probe.

In order to quickly perform the above-mentioned concave bending and restoration of the curved dome 11a, the curved dome 11a is
An annular cross-sectional deformation portion as shown in FIG. 4 is formed in 1a. That is, the above-mentioned concave bending and restoration are performed quickly when the pressure difference acting on the inside and outside of the curved dome 11a reaches a certain value, in other words, the concave bending with good sharpness can be performed. , along the circular edge of the curved dome 11a, an annular thin-walled part 11b (annular cross-sectional deformation part)
is formed.

It goes without saying that the same effects can be obtained even if instead of forming a thin part, a thick part or a cross-sectionally deformed part such as a pleat is formed.

FIG. 5 is a graph showing the measurement results obtained by the device shown in FIG. 1. The horizontal axis shows time, the vertical axis shows the pressing force Po of the pressing part, and points a, b, and c are all tc,
This is the inflection point of the pressing force at td, tf, and tg.

This graph case the pressure Pi inside the curved dome
When increasing the pressure from case (A) to case (E), points (a) to (d) in each case also show higher pressures in sequence, and the pressure at points (a) to (d) corresponds to Pi. It shows that.

〔Effect of the invention〕

As explained above, according to the intracranial pressure measuring method and apparatus of the present invention, the following effects and advantages can be obtained.

(1) A flexible curved dome for measuring intracranial pressure, which is formed to protrude outward from the upper part of the reservoir, is pressed from the outside with a probe through the scalp while gradually increasing the pressing force; Since the pressing force of the probe is read when the probe begins to curve inward, the measurement is simple and easy.

(2) Since the curved dome is formed with an annular cross-sectional deformation part, when the difference in pressure acting on the inner and outer surfaces of the dome reaches a certain value, the cross-sectional deformation part instantly becomes concave. In other words, it is possible to accurately measure the point at which the curved dome becomes concave.

(3) A flexible membrane filled with liquid is provided at the tip of the pressing part of the probe, so when the curved dome curves inward (or restores its shape), the pressing part immediately responds to this. The flexible membrane can be deformed in a conforming manner, and the liquid pressure inside the flexible membrane changes immediately, which makes it possible to accurately measure the point of inward concave curvature of the dome.

(4) Since it uses a ventricular shunt reservoir, it is advantageous in terms of cost.

[Brief explanation of drawings]

Figures 1 to 5 show an intracranial pressure measuring device as an embodiment of the present invention. Figure 1 is a schematic vertical sectional view showing its measurement state, and Figures 2 a to d are its measurement procedure. FIG. 3 is a graph illustrating its function, FIG. 4 is a longitudinal sectional view showing a modified example of the curved dome, and FIG. 5 is a graph showing the measurement results using the device shown in FIG. 1. , FIGS. 6 to 10 show a conventional intracranial pressure measuring means, and FIG. 6 is a schematic longitudinal sectional view showing its measurement state, and FIGS.
d is a schematic side view showing the measurement procedure;
FIG. 8 is a graph for explaining its action, and FIGS. 9 and 10 are a schematic perspective view and side view for explaining its measurement principle. DESCRIPTION OF SYMBOLS 1... Probe, 2... Liquid, 3... Frame, 4... Screw rod, 5... Flexible membrane, 6... Pressing part, 7... Transducer, 8... Lead wire,
9... Return spring, 11... Reservoir, 11a...
Curved dome, 12...ventricular catheter, 12a...
...Proximal end, 12b...Distal end, 16...Scalp, 1
7...Skull, 21...Dura mater, 22...Body of buried object.

Claims (1)

[Claims] 1. A ventricular catheter whose distal end is inserted into a ventricle and can lead out cerebrospinal fluid from the ventricle, and a ventricular catheter which is connected to a proximal end of the ventricular catheter to guide the cerebrospinal fluid. A reservoir for intracranial pressure measurement buried under the scalp and on the skull, and a reservoir formed in the upper part of the reservoir so as to protrude outward so that it can be expanded by the pressure of the cerebrospinal fluid and deflected in response to external pressure. It consists of a flexible curved dome for intracranial pressure measurement, and a pressure measurement probe equipped with a pressing part that can press the curved dome from the outside through the scalp, and the curved dome absorbs the pressing force from the pressing part of the probe. An intracranial pressure measuring device, characterized in that an annular cross-sectionally deformed portion is formed in the curved dome so that the curved dome begins to curve concavely inward in response to the curved dome. 2. A ventricular catheter whose tip is inserted into the ventricle and can draw out cerebrospinal fluid from the same ventricle, and a ventricular catheter which is connected to the proximal end of the ventricular catheter to guide the cerebrospinal fluid and place it under the scalp and on the skull. An embedded reservoir for intracranial pressure measurement, and a flexible intracranial pressure measurement device that is formed in the upper part of the reservoir to protrude outward and is expanded by the pressure of the cerebrospinal fluid and can be bent in response to external pressure. The pressure measuring probe is composed of a curved dome and a pressure measuring probe that is capable of pressing the curved dome from the outside through the scalp, and the pressure measuring probe is configured to direct the pressure part of the probe toward the dome and press it at a constant speed. A driving means and a pressure transducer capable of measuring the pressing force of the dome by the pressing part of the probe are provided, and a flexible membrane filled with liquid is provided at the tip of the pressing part. An intracranial pressure measuring device characterized by: