EP0334859A1

EP0334859A1 - Process and device for eliminating the traumatic effects of the fragmentation of kidney stones

Info

Publication number: EP0334859A1
Application number: EP19870907418
Authority: EP
Inventors: Eberhard HÄUSLER
Original assignee: HOFFMAN MEDIZINISCHE TECHNIK GmbH
Current assignee: HOFFMAN MEDIZINISCHE TECHNIK GmbH
Priority date: 1986-11-29
Filing date: 1987-11-17
Publication date: 1989-10-04
Also published as: DE3723815A1; JPH02500720A; WO1988003782A1

Abstract

Pour éliminer les effets traumatiques ressentis lors de la destruction extracorporelle de calculs rénaux par concentration d'ondes de choc dans un liquide, ces dernières passent à travers un filtre passe-haut avant de pénétrer dans le corps humain. Ce filtre passe-haut est avantageusement configuré comme un guide d'ondes liquide à marge acoustique faible. On utilise à cet effet une plaque en mousse (5) avec une proportion élevée de bulles d'air, dans laquelle on pratique un alésage (4) destiné au guide d'ondes. Ce procédé et ce dispositif permettent d'éliminer du champ d'ondes de choc les composantes basse fréquence de ces dernières, de manière à concentrer les seules composantes haute fréquence. Il s'ensuit une thérapie par ondes de choc indolore et rendant superflue l'anesthésie du patient.To eliminate the traumatic effects felt during the extracorporeal destruction of kidney stones by concentration of shock waves in a liquid, the latter pass through a high-pass filter before entering the human body. This high-pass filter is advantageously configured as a liquid waveguide with a low acoustic margin. A foam plate (5) with a high proportion of air bubbles is used for this purpose, in which a bore (4) for the waveguide is made. This method and this device make it possible to eliminate from the shock wave field the low frequency components of the latter, so as to concentrate only the high frequency components. This results in painless shock wave therapy which eliminates the patient's anesthesia.

Description

Method and device for eliminating traumatic effects in the destruction of kidney stones

Description

The invention relates to a method for eliminating traumatic effects in extracorporeal kidney stone destruction with focused fluid shock waves, which are supplied to the body via a water bath. The invention also relates to an apparatus for carrying out the method with a water column with a soft sound and serving as a waveguide.

For the destruction of kidney stones in particular, it is known to use focusing shock wave generators, the shock waves having to be focused on the location of the kidney stone in order to have the mechanical energy required for the destruction available at the respective location. A water reservoir or water bath is used to transmit the focused shock wave. Various methods are known for generating the shock wave. The shock waves generated with these methods have different spectral components. In addition to the therapeutically mainly effective high-frequency spectral components, low-frequency spectral components may also be excited. These low-frequency spectral components are not only therapeutically ineffective, they are even associated with harmful side effects. For example, hematomas can arise in the vicinity of the body surface penetrated by the shock wave, which result from the sudden load caused by these low-frequency components. These low-frequency components occur primarily in processes in which the shock waves are generated by a gas discharge. (1) E. HÄUSLER, W. KIEFER: Excitation of shock waves in liquids by high-speed water drops. Negotiated DPG (VI) 6, p. 786, 1971

(2) B. FÖRSSMANN, W. HEPP, G. HOFF, Ch. CHAUSSY,

F. EISENBERG, K. WANNER: Development of a process for the contactless crushing of kidney stones by shock waves. Wiss. BMFT reports: Symposium: Biophys. Procedure for diagnosis and therapy of stone disorders of the urinary tract, Meersburg, 1976

(3) E. HÄUSLER, L. STEIN: Focusable underwater impulse sound sources. ACUSTICA, Vol. 49, 1981, No. 4

(4) D.A. RÜSSEL: Shock Dynamics of Noninvasive Fracturing of Kidney Stones. Proc. 15th Intern. Symp. On Chock Waves and Shock Tubes, Stanford, 1986

The invention is based on eliminating the task of round, di ered frequency shock wave components from the shock wave field in such a way that only the high frequency components are focused.

The object is achieved in that the shock wave is passed through a high-pass filter before entering the human body.

In this way, pain-free shock wave therapy is made possible, the need for anesthesia for the patient is eliminated. The high-pass filter eliminates the low-frequency components without significantly affecting the effectiveness of high-frequency components.

According to an expedient development of the method it is provided that several high-pass filters to one Filter plate combined and arranged parallel to the wavefront. This makes it possible to filter a directed shock wave field (eg collimated or focused shock wave field with a finite cross section) in a targeted manner. The juxtaposition of several high-pass filters at a short distance leads to a flat or curved, perforated plate which is adapted to the wavefront and is optimally suitable for the corresponding filtering.

It may make sense to filter the shock wave field before it is focused by an elliptical reflector or a sound lens by passing it through channels delimited by foam strips that are arranged in the immediate vicinity of the shock wave enquell e. In this way, it is possible to create channels with soft edges that provide the desired barrier damping.

Such a high-pass filter, that is to say a water column with a soft edge, is expediently realized by providing an air-filled foam plate, preferably a foam rubber plate, with a bore. The bore can be dimensioned according to the desired channel cross-section and thus the respective cut-off frequency. The size of the cutoff frequency depends on the cross section of the liquid waveguide. With a diameter of the waveguide channel of 10 mm, the cut-off frequency is around 200 kHz in water, whereby it decreases with increasing diameter. The damping of the foam plate for low-frequency spectral components is 40 d B / cm.

In the therapeutic application of shock waves, it can happen that in obese patients the shock wave amplitude on the way through the body happens so that it is no longer sufficient for stone crushing. Here you can by using a high pass Filters with a low cut-off frequency can be remedied because the low-frequency spectral component is weakened less. In this way, a compromise between the therapeutic and traumatic effects of the shock waves can be achieved.

For the filtering of a directional shock wave field, the invention provides that several high-pass filters combined to form a filter plate are arranged side by side and in a correspondingly shaped channel cross section in the foam plate. In this case, the individual channels are arranged as closely as possible next to one another, so that a perforated plate which is as flat as possible or which is adapted to the wavefront is obtained. By using channels with a non-circular, preferably rectangular cross-section, it is ultimately possible to decisively reduce the distance between the individual channels, as a result of which a very uniform filter plate is obtained. This filter plate is parallel to the wavefront normal and the axes of the individual channels are arranged perpendicular to it. In this way there is an optimal transmission loss, the transmission loss of the entire filter plate being given by the cross section of the sum of the channels, based on the total cross section of the wave field.

As a replacement for the filter plate, it is appropriate, depending on the application, for the high-pass filter to be arranged in the immediate vicinity of the shock wave source, preferably a spark gap, and to be formed by foam strips delimiting the channels. These foam strips also act as high-pass filters, but here the cut-off frequency and blocking attenuation are not as easy to calculate as with the filters or filter plates mentioned earlier. Due to the early filtering, however, there are advantages, which can be seen in particular in the structure of the overall device but also in the more targeted damping of the waves to be damped. The shape of the respective channels can be influenced in particular by the fact that the foam strips are arranged in the longitudinal and circumferential directions, which preferably results in rectangular or strip-shaped channels with soft edges.

The design of a device is particularly advantageous if the filter system formed by the foam strips and the shock wave generation system form a structural unit, because then the distances which are predetermined once are to be adhered to even during a long period of operation.

A particularly expedient embodiment of the foam strip forming the high-pass filter is that in which the sheet metal webs serving as the power supply line of the spark gap are covered with foam strips and arranged symmetrically to the axis and connected via zi rkumferenti al arranged foam rings. This results in a particularly stable design and a possibility of adapting the shape of the channels with soft edges to the circumstances.

Replacing the high-pass filter is facilitated according to the invention in that the sheet metal webs carrying the foam strips are detachably connected to the holder of the spark gap. In particular, these are inserted into the holder, so that a. easy connection and detachment is possible. The foam strips can be replaced after a long period of operation by removing the entire cage or the entire scaffold with the foam strips and replacing them with a new one. This is also facilitated by the fact that, after a further development, the foam strips are assigned to a cage-like support, preferably a plastic tube frame. In order to achieve long service lives for the device according to the invention, in particular the high-pass filter, it is provided that the high-pass filter, preferably in the form of the foam strips and foam rings, be designed to have the necessary stability against the shock waves. To do this, it is possible to wrap them with a film or to use foam strips and foam rings with a coated surface.

Foam rubber is well suited as a high-pass filter due to the high proportion of air bubbles. But it can also be advantageous that the high-pass filter is a dimensionally stable plastic plate with a high proportion of air bubbles. In terms of dimensional stability, such a plate has advantages over foam rubber.

To increase the dimensional stability of foam rubber plates, the invention additionally provides that the high-pass filter or the filter plate has a stiffening insert, preferably a thin sheet. This plate is inserted approximately in the middle of the filter plate.

Gas bubbles arising during shock wave excitation are advantageously prevented from getting stuck in the channels or the bore, in that the high-pass filter or the filter plate is covered by a film, the foam plate itself being filled with liquid.

The invention is characterized in particular in that a method and a device are specified with which the disadvantageous low-frequency shock wave components are effectively eliminated, so that no harmful side effects can be caused in the patient. Where, due to the patient's physical condition, complete elimination is not advisable because otherwise the high-frequency shock waves will not reach their destination, the sudden loading of the low-frequency waves is reduced to such an extent that a significant reduction in the traumatic effects can still be achieved. With the aid of the method according to the invention and the device according to the invention, it is not only possible to carry out the entire shock wave therapy painlessly, but at the same time it is also possible to shorten and simplify the entire treatment method.

Further details and advantages of the subject matter of the invention emerge from the following description of the associated drawings, in which preferred exemplary embodiments are shown with the details and individual parts required for this. Show it:

1 is a schematic, perspective view of a high-pass filter,

2 is a top view of a foam sheet,

3 shows a filter plate made of several high-pass filters,

Fig. 4 is a section through that shown in Fig. 3

High-pass filter, FIG. 5 a section through a stabilized high-pass filter, FIG. 6 a further embodiment of the spark gap and FIG. 7 a cage-like design of the spark gap.

Fig. 1 shows a water tank (1) with a high-pass filter (3) and the center of the high-pass filter through the bore (4) provided there running water column (2) as a waveguide. The water column (2) fills the bore (4) in the foam plate (5) designed as a foam rubber plate, the waveguide being delicately delimited by the foam rubber end. The water tank (1) is divided into two areas by the foam plate (5) designed as a foam rubber plate. A flat shock wave incident on the foam rubber plate from below is reflected on the foam plate (5), except for the area delimited by the bore (4). Only the low-frequency components of the shock wave are reflected in this area. The higher-frequency spectral components pass through the water column into the area above the foam plate (5). If the shock wave front is not flat, e.g. B. a focused shock wave, the foam plate (5) of the shape of the wavefront must be closely matched at this point, in the above case representing a spherical section. Fig. 2 shows a foam sheet (5). with a bore (4) for a waveguide, while the top view according to FIG. 3 provides a filter plate (76) with a plurality of bores, that is to say a filter plate (6) consisting of a plurality of high-pass filters (3). This filter plate (6) thus has a number of wavy conductors or water columns (52) with soft edges.

Fig. 4 shows a section through the high-pass filter (3) shown in Fig. 3 or the filter plate (6). To make the presentation clear, only a few channels (9, 10) are shown, the axes of which are perpendicular to the wavefront normal (11). With a corresponding filter plate (6), the number of corresponding channels (9, 10) can be considerably higher. The shape of the filter plate (6) adapted to the wavefront normal (11) can be clearly seen here in FIG. 4. The shown shock wave front (13) corresponds to a snapshot shortly after the shock wave excitation in the area of the spark gap (14) and within the ellipsoidal reflector (12). The focus is denoted by (15). Finally, FIG. 5 shows a section through a foam sheet (5) which is equipped with an insert (7) designed as a thin sheet to improve the dimensional stability and is enclosed by a film (8). This film (8) prevents the gas bubbles generated during shock wave excitation from settling in the channels (9, 10) or in the bore (4).

The embodiment shown in FIG. 6 shows a longitudinal section through a spark gap (14) serving as a shock source. The sheet metal webs (17, 18) serving as the power supply line, which are held in the holder (19), preferably inserted, are covered with foam strips (22, 23) and arranged symmetrically to the axis (A). This results in strip-shaped channels (9 ', 10') which are bordered by sound and which surround the electrodes (20, 21). These channels (9 ', 10') are subdivided by circumferentially arranged foam rings (24, 25) and a high-pass filter (3 ') is created, the cut-off frequency of which is determined by the cross section of the individual channels (9', 10 ') and its blocking attenuation by the expansion of the foam strips (22, 23) is given in the radial direction.

A system placed on the spark gap (14) and provided with foam strips (22, 23) in the axial and circumferential direction has similar properties (FIG. 7). The strip elements with sound-proof edges are fastened to a carrier (26), here a plastic tube frame (27). This plastic tube frame (27) sits around the two electrodes (2o, 21) and thus forms uniform channels (9 ', 10') on all sides, which are edged with a correspondingly soft sound.

Claims

Patent claims

1. Method for eliminating traumatic effects in extracorporeal kidney stone destruction with focused liquid shock waves, which are supplied to the body by a water bath, so that the shock wave before penetrating into the human

Body is passed through a high pass filter.

2. The method of claim 1, d a d u r c h g e k e n n z e i c h n e t that several high-pass filters are combined to form a filter plate and arranged parallel to the wavefront.

3. The method of claim 1, d a d u r c h g e k e n n z e i c h n e t that the shock waves or the shock wave field is filtered before focusing by passing through channels delimited by foam strips that are arranged in the immediate vicinity of the shock wave source.

4. An apparatus for performing the method according to claim 1 or claim 2 or claim 3, g e k e n n z e i c h n e t d u r c h serving as a high-pass filter (3), sound-edged, liquid waveguide.

5. The device according to claim 4, characterized in that the high-pass filter (3) is provided with a bore (4) for the waveguide, air-filled foam plate (5), preferably a foam rubber plate.

6. The device according to claim 4, d a d u r c h g e k e n n z e i c h n e t that several high-pass filter (3) to a filter plate (6) combined side by side and in a correspondingly shaped channel cross-section in the foam plate (5) is arranged.

7. The device according to claim 6, so that the filter plate (6) are arranged parallel to the wavefront normal (11) and the axes of the individual channels (9, lo) are arranged perpendicularly thereto.

8. The device according to claim 4 to claim 7, that the channel cross-section has a shape deviating from the circle, preferably that of a rectangle.

9. The device according to claim 4 and claim 8, characterized in that the high-pass filter (3 ') in the immediate vicinity of the shock wave source, preferably a spark gap (14) and arranged by the channels (9', lo ') delimiting foam strips (22, 23) is formed.

10. The device according to claim 9, so that the foam strips (22, 23) are arranged in the longitudinal and circumferential directions, which preferably results in rectangular or strip-shaped channels (9 ', 10') with soft edges.

11. The device according to claim 9 and claim 10, characterized in that the filter system formed by the foam strip (22, 23) and the shock wave generation system form a structural unit.

12. The apparatus of claim 9 and claim 10 and claim 11, characterized in that the sheet metal webs (17, 18) serving as the power supply line of the spark gap (14) covered with foam strips (22, 23) and arranged symmetrically to the axis (A) and about circumferential arranged foam rings (24, 25) are connected.

13. The apparatus of claim 9 and claim 12, d a d u r c h g e k e n e z e i c h n t that the foam strips (22, 23) carrying sheet metal webs (17, 18) are detachably connected to the holder (19) of the spark gap (14).

14. The apparatus of claim 9 and claim 11, that the foam strips (22, 23) are associated with a cage-like support (26), preferably a plastic tube frame (27).

15. The apparatus of claim 3 or claim 9 or one of the respective subordinate claims, characterized in that the high-pass filter (3, 3 ') preferably in the form of the foam strips (22, 23) and foam rings (24, 25) the necessary stability against the shock waves are trained.

16. The apparatus according to claim 15, characterized in that the foam strips (22, 23) and foam rings (24, 25) have a tempered surface.

17. The apparatus of claim 4, d a d u r c h g e k e n n z e i c h n e t that the high-pass filter (3) is a dimensionally stable plastic plate with a high proportion of air bubbles and preferably has an air bubble proportion corresponding to the foam rubber.

18. The apparatus of claim 4 or claim 9, d a d u r c h g e k e n e z e i c h n e t that the high-pass filter (3) or the foam strips (22. 23) have a stiffening insert (7) preferably a thin sheet.

19. The apparatus of claim 4, d a d u r c h g e k e n n z e i c h n e t that the high-pass filter (3) or the filter plate (6) is enveloped by a film (8), wherein the foam plate (5) is in turn liquid-filled.