JPH0342A - Method and device for measuring cranial internal pressure - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an intracranial pressure measuring method and a measuring device, and particularly to an intracranial pressure measuring method and a measuring device for measuring the intracranial pressure of a patient suffering from hydrocephalus, etc. A ventricular-peritoneal shunt or a ventricular-atrial shunt (hereinafter referred to as "ventricular shunt") is surgically implanted into the body of a patient suffering from hydrocephalus, etc.
Relating to the use of reservoirs that make up the.

[Conventional technology]

Generally, in neurosurgical diseases associated with increased intracranial pressure,
Accurate measurement of intracranial pressure is necessary to elucidate these pathological conditions.

Conventionally, various methods for measuring intracranial pressure have been proposed; one example is Japanese Patent Application Laid-Open No. 115538/1983.
There are 0 entries in the bulletin.

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 IZ whose distal end 12b can be inserted into the ventricle 19 of a patient to drain cerebrospinal fluid from the ventricle 19, and a reservoir 11 connected to the catheter 12. It also 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 under the scalp 16, and above the reservoir 11 is a thin film-like flexible curved dome for measuring intracranial pressure. lla is formed.

The pressure detection device B includes a pressure detector 23 and a pressure detector 2.
Pressure detection signal from pressure sensor Z3e of No. 3 is connected to lead wire 2.
4, and an amplifier 25 that receives the signal and amplifies it via the amplifier 25.
It is comprised of a recorder 27, such as a printer, for receiving and recording the amplified signal from through a lead wire 26, and a display device 28, such as a CRT, for displaying the information.

The pressure detector 23 is configured as a transcutaneous cerebral pressure sensor, and includes a case 23i, an outer cylinder 23b of a predetermined length connected to the detection end side of the case 23a, and an outer cylinder 23b connected to the back side of the case 23a. The presser plate 23c, the columnar pressure receiving plate Z3d slidably inserted into the outer cylinder 23b, and the lead wire 24 are connected to the pressure receiving plate 23d to convert the pressure from the pressure receiving plate 23d into an electric signal. A diffusion type semiconductor pressure sensor (or load sensor) 23e whose surface is molded with silicon for output through the case 23a, a hard spring 23f that applies a biasing force to the pressure sensor 23e in the case 23a, and the pressure sensor 23e are positioned. It consists of a zero adjuster 23g.

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 on the skull 17, and the upper dome 1111 of the reservoir 11 is directed outward by the pressure of the cerebrospinal fluid. Expand it so that it protrudes toward.

(2) Turn on pressure detection device B and start measurement [
See sensor depth LA at time 1A in FIGS. 7(a) and 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 Ila from the outside.

(3) Connect the detection end 29 of the pressure detection device B to the upper dome l.
Measurement of the pressure P is started by making contact with the sensor la through the scalp 16 [see sensor depth at time t in FIG. 7(b) and FIG. 8].

(4) Next, push the detection end Z9 into the upper dome lla until the center of the upper surface becomes flat [Fig. 7(c) and 8
See sensor depth Lc at time tc in the figure].

In this state, the tip surface of the pressure receiving plate 23d and the upper surface of the curved dome lla via the scalp 16 are in a co-planar state.
e), the inflection point in the relationship between the indentation depth L and the detected pressure P is called rBPIJ)
occurs.

(5) Further, the pushing is continued until the upper surface of the upper dome 111L is collapsed [see FIG. 7(d) and the sensor depth LD at time t in FIG. 8].

In this state, the tip end surface of the pressure receiving plate 23d has begun to sink into the curved dome l1m through the scalp 16,
A curvature (hereinafter, the point of inflection is referred to as rBP2J) 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, and even if the pushing depth of the detection end 29 is slightly changed, the detected pressure The section where P does not change (inflection point B
P l-B P2) 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.
Assume that there is a pressure equal to the intracranial pressure at

In this case, the measurement target is the pressure within the implant body 22 (ventricular shunt body) embedded under the scalp 16,
This pressure is measured indirectly from the outside of 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, the scalp 16 and the implant body 22 (
When considering the dome lla of the ventricular shunt body as part of a sphere with radius r, the sphere has internal pressure (brain pressure) Pi, external pressure (usually atmospheric pressure) P, the scalp 16 and the implant body. Laplace's theorem is established between the tension T of the dome Ila of No. 22 and the tension T of the dome Ila of No. 22.

In other words, the following relationship is established.

P i −P = 2 T / r・・・・・・・・・
(1) Here, when measuring the internal pressure Pi from outside the dome lla, the condition that Pi=P should be satisfied under the equation (1).

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

Now, the outside of the dome l1m is covered with a board 2 as shown in Figure 10.
Try applying pressure at 9'. The upper surface of the dome lla is made flat by the plate 29'. Letting the area of the planar portion of this plate 29' be D, in the area of D, based on Laplace's theorem mentioned above, it corresponds to `` becoming infinite.

That is, when r is set to ■, the right side of equation (1) becomes O, and in this case, Pi=P holds true. From this, it can be seen that when the dome lla and the scalp 16 are compressed with an appropriate external pressure, the external pressure applied to the planar portion becomes equal to the internal pressure.

However, during actual measurement, the conditions for accurately compressing the dome 11a only in the necessary areas are: ■ Pressing the dome 11a flat ■ Detecting external pressure only in the above areas ■ Excessive pressure on the dome 11a than necessary l
There is a problem in that it requires a great deal of skill to do something that does not destroy la.

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. By gradually increasing the pressing force on the dome using a probe, and calculating the intracranial pressure from the pressing force when the dome begins to concavely curve inward,
The purpose of the present invention is to provide an intracranial pressure measurement method and device that does not require special measurement techniques.

[Means to solve the problem]

In order to achieve the above-mentioned object, the invention as set forth in claim 1) of the present invention provides a ventricular catheter whose distal end can be inserted into the ventricle to lead out cerebrospinal fluid from the ventricle; An intracranial pressure measurement reservoir connected to the proximal end of the catheter to guide the cerebrospinal fluid and buried under the scalp and on the skull, and a flexible skull formed to protrude outward from the upper part of the reservoir. When measuring intracranial pressure using a pressure measuring probe equipped with a flexible pressing part that can press the curved dome for internal pressure measurement from the outside through the scalp, the pressure on the curved dome by the pressing part is The method is characterized in that the pressure is gradually increased, and the intracranial pressure is determined from the pressing force when the dome begins to concavely curve inward.

In addition, the invention described in (2) above provides a ventricular catheter whose tip end can be inserted into the ventricle to draw out cerebrospinal fluid from the ventricle;
A reservoir for intracranial pressure measurement is connected to the proximal end of the ventricular catheter to guide the cerebrospinal fluid and is buried under the scalp and on the skull. When measuring intracranial pressure using a pressure measuring probe equipped with a flexible pressing part capable of pressing the flexible curved dome for measuring intracranial pressure from the outside through the scalp, the curved dome is pressed by the pressing part. The intracranial pressure is determined from the pressing force when the dome begins to concavely curve inward, and the probe The intracranial pressure is determined by calibrating the pressing force when the dome begins to concavely curve inward, based on data previously measured by the method.

Furthermore, the invention described in (3) above provides a ventricular catheter whose distal end can be inserted into the ventricle to draw out cerebrospinal fluid from the ventricle, and a ventricular catheter which is connected to the proximal end of the ventricular catheter. A reservoir for measuring intracranial pressure that is buried under the scalp and on the skull while guiding cerebrospinal fluid, and a reservoir that is formed at the upper part of the reservoir to protrude outward and is expanded by the pressure of the cerebrospinal fluid and responds to pressure from an external force. It consists of a flexible curved dome for intracranial pressure measurement that can be bent and a pressure measurement probe that is equipped with a pressing part that can press the curved dome from the outside through the scalp, and the dome is bent by the pressing part of the probe. It is characterized by being formed with a ring-shaped cross-sectional deformation part that begins to concavely curve inward in response to a pressing force.

Furthermore, the invention described in (4) above provides a ventricular catheter whose distal end can be inserted into the ventricle to draw out cerebrospinal fluid from the ventricle, and a ventricular catheter connected to the proximal end of the ventricular catheter. A reservoir for intracranial pressure measurement is embedded under the scalp and on the skull to guide the cerebrospinal fluid, 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 resists pressure from external forces. It consists of a flexible curved dome for measuring intracranial pressure that can be bent accordingly, and a pressure measuring probe equipped with a pressing part that can press the curved dome from the outside through the scalp,
A pressing part driving means for directing the pressing part of the probe toward the dome and pressing it at a constant speed, and a pressure transducer capable of measuring the pressing force on the dome by the pressing part of the probe are provided. It is characterized by having a flexible membrane at its tip that is filled with liquid inside.

[For production]

In the above-described intracranial pressure measurement method and device of the present invention,
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, and Since the pressure of the probe is read when the probe starts to curve concavely, the measurement is simple and easy.

In addition, since the curved dome is formed with a ring-shaped 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 becomes concave. 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, since a flexible membrane filled with liquid is provided at the tip of the pressing part of the probe, when the curved dome curves inward (or restores its shape), the pressing part immediately responds to this. Since it can be deformed in a conforming manner, the liquid pressure inside the flexible membrane changes immediately, and from this it is possible to accurately measure the point of inward concave curvature of the dome.

〔Example〕

Hereinafter, an intracranial pressure measuring method and device thereof 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 a curved dome, and Fig. 5 is a diagram using the apparatus shown in Fig. 1. It is a graph showing measurement results. In addition, 6th to 1st of the 1st to 5th wards
The same reference numerals as in Figure 0 indicate substantially the same members.

The intracranial pressure measuring device of this embodiment also includes an implanted elA that is implanted inside the patient's body, and an implanted M that is placed outside the patient's body.
The pressure detection device B is capable of contacting the intracranial pressure measurement reservoir 11 of A through the scalp 16.

The implant A includes a tubular ventricular catheter 12 whose distal end 12b can be inserted into a patient's ventricle 19 to drain cerebrospinal fluid from the ventricle 19, and a reservoir 11 connected to the catheter 12. , and a buried object main body 22 made of a soft wall made of silicone resin or the like fixed on the skull 17 under the scalp 16.
At the upper part of the reservoir 11, a thin film-like flexible curved dome l1g for intracranial pressure measurement is formed so as to protrude to the outside.

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

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 on the skull 17, and the curved dome lla of the reservoir 11 is guided outward by the pressure of the cerebrospinal fluid. (The cerebrospinal fluid pressure in the curved dome lla at this time is Pi.) (2) Pressure detection device B is turned on and measurement is started [time 1A in Fig. 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 lla from the outside.

(3) By pushing out 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 lla through the scalp 16 [time t6 in FIGS. 2(a) and 3] ], measurement of the pressure Pa 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 lla with the pressing part 6. In this state, the hydraulic pressure P in the pressing part 6 is low. gradually rises due to the reaction force of the cerebrospinal fluid in the curved dome lla [shape R in Fig. 2(b)]. At this time, Pi > Pa, but gradually Po becomes P
approach i.

(5) When the pushing is continued and the state of PoζPi is reached, the curved dome lla becomes flat [Fig. 2(c)]
shape fi], and eventually Pi < Po, the curved dome l
la begins to concavely curve inward [time tc in FIG. 2(d) and FIG. 3].

As the curved dome lla curves inward, the pressing portion 6
As the volume increases, the hydraulic pressure within the pressing portion 6 suddenly drops temporarily (at time td in FIG. 3).

(6) After further pushing in, the probe 1 is pulled out at a constant speed (the turning point is time Le in FIG. 3).

(7) Then, in the withdrawal process of the probe 1, Pi
A curved dome that is not concavely curved inward when it reaches the slope Pa.
a starts to restore, and as the curved dome lla restores, the pressing part 33 is compressed, and the internal hydraulic pressure temporarily increases (
At time Lg in FIG. 3, 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 lla (time t11 in FIG. 3)
, return to the initial pressure.

By the above operations, the times tc, td, tf and tg
The detected pressures Poc, Pod, Pof and P
By calibrating og with data previously measured by the probe, intracranial pressure can be determined.

The modified example of the curved dome Ila shown in Fig. 4 is
In order for the above-mentioned concave curve and restoration to be performed quickly when the pressure difference acting on the inside and outside of the curved dome 11a reaches a certain value, in other words, to perform the concave curve with good sharpness, A ring-shaped thin part ub is formed along the circular edge of the curved dome lla.

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 by the device shown in FIG. 1, in which the horizontal axis shows time and the vertical axis shows the pressing force Po of the pressing part, and points a, Jc, and d are all tctd, t
f, is the inflection point of the pressing force at tg.

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

[Effects of the Invention] As detailed above, according to the intracranial pressure measuring method and its device of the present invention, the following effects and advantages can be obtained.

(1) A flexible curved dome for intracranial pressure measurement, which is formed so as 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. , the pressing force of the probe when it begins to curve inward is simple and easy.

(2) Since the curved dome is formed with a ring-shaped 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 itself), 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 the reservoir of the ventricular shunt is used, it is advantageous in terms of cost.

[Brief explanation of the drawing]

1 to 5 show an intracranial pressure measuring device as an embodiment of the present invention. FIG. 1 is a schematic longitudinal sectional view showing its measurement state, and FIGS. 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 shows the measurement results using the device shown in Fig. 1. Sections 6 to 10 show conventional intracranial pressure measuring means, and FIG. 6 is a schematic vertical cross-sectional view showing its measurement state, and FIGS. 7(a) to (d) are A schematic side view showing the measurement procedure, FIG. 8 is a graph to explain its action, and FIG.
, 10 are a schematic perspective view and a side view for explaining the measurement principle. 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, lla... Curved dome, 12... Ventricular catheter, 12a... Base end part,
12b... tip, 16... scalp, 17... skull, 21... dura mater, 22... buried object body. Figure Figure Figure Figure (b) (C) (d) Figure

Claims (4)

[Claims] (1) 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 skull. Flexibility that allows the reservoir for intracranial pressure measurement embedded above and the flexible curved dome for intracranial pressure measurement formed to protrude outward from the upper part of the reservoir to be pressed from the outside through the scalp. When measuring intracranial pressure using a pressure measurement probe equipped with a pressing part, the pressing force of the pressing part against the curved dome is gradually increased, thereby causing the dome to curve inward. A method for measuring intracranial pressure, characterized in that the intracranial pressure is determined from the pressing force at the time of initiation. (2) Based on the data previously measured by the probe for various known internal pressures in the reservoir, the pressing force when the dome begins to concavely curve inward is calibrated; The intracranial measurement method according to claim 1, characterized in that intracranial pressure is determined. (3) 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 is placed under the scalp and skull. a reservoir for intracranial pressure measurement buried therein; and a flexible intracranial pressure measurement device formed in the upper part of the reservoir so as to protrude outward, and which is expanded by the pressure of the cerebrospinal fluid and can be bent in response to pressure from an external force. It consists of a curved dome and a pressure measurement probe equipped with a pressing part that can press the curved dome from the outside through the scalp, and the dome moves inwardly under the pressure of the pressing part of the probe. An intracranial pressure measuring device, characterized in that a ring-shaped cross-sectional deformation section is formed to begin concavely curving. (4) A ventricular catheter whose tip is inserted into the ventricle to 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 is placed under the scalp and skull. a reservoir for intracranial pressure measurement buried therein; and a flexible intracranial pressure measurement device formed in the upper part of the reservoir so as to protrude outward, and which is expanded by the pressure of the cerebrospinal fluid and can be bent in response to pressure from an external force. Composed of a curved dome and a pressure measuring probe equipped with a pressing part that can press the curved dome from the outside through the scalp, the pressing part of the probe is directed toward the dome and pressed at a constant speed. part driving means;
A pressure transducer capable of measuring the pressing force of the dome by the pressing part of the probe is provided, and
An intracranial pressure measuring device characterized in that a flexible membrane filled with liquid inside is provided at the tip of the pressing part.