EP3041410A1

EP3041410A1 - Catheter

Info

Publication number: EP3041410A1
Application number: EP14755832.4A
Authority: EP
Inventors: Oliver Sawodny; Michael Ederer; Philipp RAPP; Mario Klünder
Original assignee: Universitaet Stuttgart
Current assignee: Universitaet Stuttgart
Priority date: 2013-09-05
Filing date: 2014-08-28
Publication date: 2016-07-13
Also published as: DE102013014685A1; DE102013014685B4; WO2015032677A1

Abstract

The invention relates to an urinary catheter having a sensor means for detecting the pressure in the urethra and a determination means for determining the arrangement of the catheter in the urethra. According to the invention, the determination means comprises a triaxial accelerometer in order to determine how the catheter is oriented in the urethra during pressure detection.

Description

CATHETER

The present invention relates to what is claimed in the preamble and accordingly deals with measuring instruments for the treatment of incontinence.

Incontinence is the unwanted escape of urine. Incontinence can vary greatly; for instance, in mild cases, urine may escape unintentionally only if the heavily filled bladder of the affected person is exposed to a sudden increase in pressure in the body, for instance as a result of coughing or sneezing; In particularly serious cases of incontinence, on the other hand, unintentional urine loss may already occur while lying down and without additional stress. Incontinence can also have a number of causes. For example, incontinence may be the result of damage to various muscles involved in bladder emptying or their associated nerves; These muscles include, among others, the muscles surrounding the bladder and the muscles of the urethra.

In women, for example, births can lead to a lowering of organs in the female pelvis, whereupon, with increased pelvic pressure, the closing pressure of the urethra involved in the closure of the bladder as a muscle is no longer sufficient; In males, for example, damage due to surgery, e.g. Prostate surgery, occur and in patients of both sexes, incontinence may occur due to nerve diseases such as Alzheimer's, multiple sclerosis, Parkinson's.

Since incontinence can be very uncomfortable for those affected and may significantly reduce the quality of life, it is desirable to be able to treat incontinence efficiently.

However, this requires a thorough diagnosis that accompanies its precise characterization. In addition to urinary stream measurements, in which the amount of effluent urine is detected during urination over time, for diagnostic purposes, especially the measurement of pressure in the urinary bladder or urethra of importance, where as pressure in part even the pressure difference to other locations in the body and / or the behavior during filling or emptying of the bladder should be determined.

Pressure measurement can be accomplished by introducing a catheter fitted with a pressure sensing sensor through the urethra into the urinary bladder (or back out of the bladder) and taking pressure measurements along the way. With suitable uroceters pressure profiles of the urethra and urinary bladder can be determined.

A pressure-measuring ureteral catheter is e.g. known from US 2009 / 0306539A1. Here, the pressure in the urethra to be determined by inflating a balloon, which is arranged on the catheter circumference and whose interior communicates via a lumen with a pressure sensor.

There are already urological catheters in which the signal of the pressure sensor is digitized and processed computer-aided. In some cases, such systems are advertised with the claim that the examiner, assuming correspondingly large measuring ranges, does not need to worry about the exact position of the pressure transducers.

In addition, there are other medical catheters in which the exact positioning and alignment of the catheter is attributed considerable importance.

It is known from US 2012/0035467 AI to detect the twist of a cardiac catheter when inserted into the patient by the cumulative angle of rotation is determined. This is intended to counteract a twist. Among other things, an accelerometer is to be arranged in the catheter for the purpose of measurement.

From US 2009/0306736 AI is an accelerometer-based monitoring of the frequency dynamics of the isovolumic contraction phase and pathological cardiac vascular known. With a one-, two- or three-axis accelerometer, which is to be inserted in a guide catheter, thereby information about the heart condition are determined. It is also stated that a plurality of acceleration sensors, even multiple multi-axis acceleration sensors, can be used in order to be able to detect vibrations of specific frequency ranges better. It is also known from the state of cardiac catheterization that acceleration sensors are well suited for measuring vibrations and displacement movement. It is also discussed that more accurate acceleration measurements can be obtained if the influence of gravity on the acceleration sensors is taken into account.

An intercranial catheter, which also uses an accelerometer as one of several sensors to navigate the catheter through the brain to a desired location, is known from US 2012/0302875. It is desirable to allow a better diagnosis of incontinence causes.

The object of the present invention is to provide new products for commercial use. The solution to this problem is claimed in an independent form. Preferred embodiments can be found in the subcransprints.

The present invention thus proposes a first basic idea

A urethral catheter comprising sensing means for sensing urethral pressure and determining means for determining the location of the catheter in the urethra, wherein the determining means is comprised of a triaxial accelerometer to determine how the catheter is to be subjected to pressure sensing in the urethra the urethra is oriented. According to a basic idea, this does not just allow pressure in a particular one

Insertion depth at any unknown location, but to specifically determine how high the pressure actually is for a given orientation of the catheter. This seems at first absurd, since a pressure prevailing in a liquid should initially be the same in all directions. In practice, however, it is the case that the catheter will lie comparatively close to the urethra and is therefore at least partially sealed off from it to such an extent that only a local pressure at a certain point is measured. In this case, the pressure can also be sensibly measured locally at a specific point only if a plurality of sensors or the small windows leading to them are distributed on the catheter jacket surface with a spacing from one another, since the sensors are then measured locally. The measured values with the various sensors can be detected simultaneously or also shortly one after the other, if for example only one analog-digital converter is available, to which successive sensor values from different pressure sensors are fed for digitization.

The size of the area for which the pressure is determined locally depends on various factors. Thus, the actual pressure sensor will typically be located inside the catheter and communicate with the fluid in the urethra via a breakthrough or a window in the catheter wall. The size of such a window thus has a clear influence on the area at which the pressure is determined locally. Furthermore, such a window is sealed by the urethra attached to the catheter. How close to the window the urethra nestles and how small or large it is the area at which the pressure is recorded locally depends on the interaction between the urethra and the catheter. For example, the bending of the typically flexible catheter in the urethra, which varies over the length of the larethra, may result in the urethra abutting the catheter better at certain points and at certain orientations than at other points. Such effects may cause the area for which the pressure is actually measured to be larger than the window leading to the pressure sensor in the catheter interior.

In addition, when measuring during a catheter movement, for example, during a rotation, oversampling may be performed in one area. It should also be noted that irrespective of the tissue structure of the urethra, which has longitudinal folds in the unfilled state, a seal is achieved through the urethra which is only slightly larger than the respective opening leading to a pressure sensor in the catheter wall. Typically, this area will not be substantially greater than three times the length along any distance defined on the catheter jacket surface However, in many cases, the urethra is so close to the catheter that the opening size practically corresponds to the measuring surface, but it will be appreciated that in preferred variants of the catheter, in which a plurality of sensors to the Are distributed around the circumference of the catheter, for example, egg-shaped, the sensors at equal angular intervals relative to each other

Cross-sectional projection will be arranged. Depending on the sensor window size and

Catheter diameters may be reduced upon implementation of preferred non-overlapping sensors e.g. approximately eight sensors are arranged along the circumference of a (projected) cross-section in a non-overlapping manner. The arrangement along the circumference of only one projected cross section is typically necessary because the sensors in the interior of the catheter together with the associated lines and signal conditioning circuits occupy so much space that they can not all be arranged at the same axial position, but axially offset from each other Need to become. The pressure can also be applied at e.g. equiangularly distributed around the circumference sensors are detected by rotation of the sensor. This allows oversampling in the direction of rotation.

It is therefore possible that a local pressure is measured at only one specific point. By then determining how the catheter is actually oriented upon pressure sensing in the urethra, it becomes possible to detect how a particular pressure sensor is currently oriented, eg, oriented ventrally or dorsally, ie, facing the tummy or the dorsal direction , This is advantageous because now the distribution of the pressure ratios (not only) along the length of the urethra between urinary bladder and end of the urethra can be determined, but also it can be accurately determined how the pressure ratios are in a particular direction. This makes it possible to accurately determine the pressure conditions over the entire surface of the ureter. This was not readily possible in the prior art, in any case, since the catheters must be flexible enough to be introduced without injury; However, the flexibility causes not, at least not readily and not exactly, can be determined how the possibly tordicrende catheter is oriented straight in a certain insertion depth. It has to do with it can be calculated that a catheter without special measures is not exactly pulled straight out of the urethra, but even if per se the attempt is made to pull it out as straight as possible from the urethra, a rotation is subjected. Thus, it is advantageous in any case, at least to determine the rotation; In addition, it may be advantageous to rotate in each case in a targeted manner so that the twisting that occurs when it is pulled out is not subjected to accidental influences. Targeted rotation can then also be good over oversampling in the circumferential direction can be achieved, etc., which in turn improves the ability to take measures to reduce the sensor noise.

It should also be mentioned that, if necessary, a slightly rotating movement can be comparatively more comfortable for the patient and a unidirectional rotation can provide advantages in modeling the urethral surface because it may provide a scan that is robust to disturbances and the like , If the aim is, for example, to model the inner surface of the tube on the basis of the measured values, it is first of all noteworthy that the measured values are never recorded in an ideal position where a grid point should preferably be located for the model. The algorithms for converting from the actual actual positions at which measured values were recorded to the nominal positions at which grid points are located are differently sensitive to different influences such as the exact position of the measuring points, shape of the urethra, etc. As advantageous for the conversion has been proven when certain pitch heights, ie Rotations per extension distance of the catheter from the lariat tube can be selected. It will be appreciated that the preferred pitch heights depend on e.g. of the number of sensors around the circumference, the spacing along the axis, the modeling to be laid out, etc. Therefore, it is desirable for the pitch height to be predeterminable. It should be noted, moreover, that at typical urethral catheter withdrawal rates of a few mm per second, e.g. 1 Omm / s, and conventional sampling rates of e.g. 1kHz, enough measurements can be taken to apply noise reduction techniques without causing excessive loss of information.

By now acceleration sensors are used, from the current components of the gravitational acceleration, ie from the components of gravity, the act on the individual sensors of the multiaxial accelerometer, as well as from the moment of insertion by the integration of asster motion state changes are closed to the urethra location. Even without integration of the total movement of the catheter since insertion (taking into account only the current force components caused by gravitation), the alignment of the catheter in the urethra or the bladder can still be detected, in some cases even very well. Optionally, by detecting deflections of the catheter at the location of the accelerometer, anatomical peculiarities such as the end of the urethra on the bladder, etc., may also be deduced. The detection of deflections of the catheter in the urethra is on the one hand advantageous because it allows the urethral profile in the sagittal plane to be determined and ergo anomalies can be detected. In addition, it has already been pointed out that the presence of the urethra on the catheter means that pressure can even be measured locally, but that, for example, the bend of the catheter in the urethra can lead to the urethra not resting evenly. Deviations can be taken into account here; this is possible, on the one hand, in modeling in which the surface of the hamming tube is to be detected. On the other hand, it is also possible without such modeling, a doctor information about the

To provide ureteral flexion at a particular location, such as by displaying a bare bending profile, where the bend radius determined by the accelerometer is plotted over the extension, so that the physician can then better associate, assess, and assess anomalies in the pressure history. This can cause artifact reduction.

It should be noted that the patient will lie in the examination and / or at least take a tilt, but will not stand if optimal use of the

Gravitational force on the acceleration sensors is desired. This allows high accuracies without the need for abrupt movements.

The measurement of pressure in a given direction also significantly improves the diagnostic possibilities. The intramedullary tube is partly fused with other organs or attached to them. The recording of the pressure conditions over the total The lateral surface therefore provides valuable information for identifying lesions, etc., which in turn is very helpful in the treatment of incontinence causes.

It may be mentioned that, where appropriate, the signals obtained with the accelerometer can also be used to determine an insertion depth. However, alternatively and / or additionally, it is possible to detect the insertion depth to other ^"way and to use the accelerometer signals only to determine the catheter orientation in the urethra or the urinary bladder. Is this regard, explicitly mentioned the possibility of designing a traction device for pulling out so This rotary motion can be oscillatory, ie, pivoting the catheter in a circumferential direction, or under steady rotation in one direction If the use of rotary joints on the catheter can be advantageous, eg for fluid lines and signal lines, it is particularly preferable if a gradient height, ie rotation per mm extension, can be set or selected during continuous rotation in order, in particular, when lateral surfaces are to be modeled. Measurement artifacts or measurement errors to ve It should be noted in this regard that in the modeling of the urethral surface certain slopes are advantageous over other gradients, as far as the stability of the calculation is concerned.

The catheter will typically have a flexible and at least slightly twistable body in its entirety. He is preferred to be so stiff that the introduction is facilitated, but at the same time so slippery that it introduced to the patient is not too uncomfortable and bending-related artifacts are minimal. It is preferred if the pressure sensors of the pressure sensor means are arranged close to the accelerometer, so that only a limited torsion between accelerometer and pressure sensor means is possible. It is understood that a possible twist between

Accelerometer and pressure sensor means will affect the accuracy of the measurement. Therefore, it is preferred that the possible typical torsion between pressure sensing means and accelerometer be limited to 5 ° to 10 ° (a 360 ° full circle). It should be explicitly pointed out that the term torsion in this case refers to the rotation of the cathe- Tcrs in itself and not for example as the rotation of the catheter about its axis meant for helical or helical measurement.

Per se, it may be sufficient if a single pressure sensor is provided and thus the urethra is characterized by means of a device according to the invention Urokatheters; However, if the pressure conditions on the urethral surface are to be determined, this may require the very wide or very rapid twisting of the catheter in order to be able to determine the pressure in a respectively desired direction. This twisting can be uncomfortable for a patient. Therefore, it is often preferred if the sensor means comprises a plurality of pressure sensors which are distributed over the circumference and / or in the axial direction. Not all pressure sensors must be at the same axial height. Full detection of urethral sheath area pressure ratios is thus possible with less total catheter movement. Also, where several sensors are distributed along the circumference (possibly in cross-sectional projection), a rotation of the sensor may be advantageous, which may need to be less rotated in order to achieve the same measuring point density around the circumference. This also applies where a helical movement is desired. In addition, it should be pointed out that the modeling of the lateral surface can take into account, using measurement data of a catheter which moves in a helical manner with a plurality of sensors distributed over the circumference, that the sensors often do not rest on one and the same helix, because the sensors may indeed be arranged helically on the lateral surface of the catheter, but the spiraling of the sensor arrangement on the catheter jacket surface may have a different pitch than the pitch height of the helical movement of the catheter (for example effected by a suitable pulling device and with a predetermined pitch height) Urethra. While in general pulling out completely without turning would be particularly advantageous for the modeling, it will be appreciated that - since a slight rotation already occurs by the typical insert pull-out motion - even without external deliberate specification of a rotating one

Pulling out a slightly helical pulling out results. Since, however, unfavorable incline heights are possibly obtained, it is advantageous if, notwithstanding the actually favorable rotational freedom, a non-zero rotation is selected from the outset and then at least one particularly advantageous pitch height is selected which can not cause information loss during signal processing

Sensor trajectory overlap and so on.

It is possible to axially space the pressure sensors (viewed in cross-sectional perspective) circumferentially. This optionally allows the accommodation of slightly larger pressure sensors or more sensors and thus also a higher resolution in the circumferential direction. Even if several pressure sensors are provided on the catheter, the pressure will be measured locally, namely typically locally at each sensor.

It should be noted that it is possible to interpolate signals of circumferentially distributed sensors even if they are axially spaced from each other to detect a complete ureteral coat surface characterization. Among other things, it can be exploited that in many cases static pressure conditions in the urethra should be determined. The pressures detected at different times at different sites of the urethra can thus be treated as if they were taken at the same time. It should be noted, moreover, that the arrangement of several pressure sensors at axially spaced locations on a rigid or only partially limp catheter portion can lead to artifacts, because the urethra will fit differently at different axial positions. Regardless of any such artifacts but the measurement results will be very meaningful and easier diagnosis. Such artifacts can also be well corrected, at least as far as the urethra is modeled. The fact that the elastostatic properties of the catheter can also be taken into account for the modeling, ie that the evaluation stage is designed to take into account the modeling taking into account the properties of the catheter used for the measurement, in particular the elastostatic properties of the catheter, should be mentioned , Incidentally, it has already been mentioned that the urethral profile can be displayed or made accessible to the physician in various ways. It is understood from consideration of the different anatomy that the determination of the urethral profile in men may be particularly advantageous. It is preferred if the pressure is measured simultaneously with all pressure sensors. This increases the available resolution with only a short intervention time.

The pressure sensors are typically mounted near the proximal end of the catheter, i. close to the tip of the catheter to be inserted into the patient. In this case, a small distance of the pressure sensors to the tip can be provided in order to ensure greater flexibility there, to allow a rounding of the tip and thus to allow a simpler and above all painless insertion of the catheter. However, the sensors are typically placed so close to the proximal end of the catheter that measurement of pressure conditions within the urinary bladder is possible.

The arrangement of a plurality of pressure sensors close to one another contributes to approximately similar bending conditions occurring in each sensor, that is scanned in a rotational or helical movement of the catheter through the urethra very shortly in succession to all orientations around a given location, so that the dynamic Behavior of the urethra, at least in part, can be disregarded and that the arrangement is easier to produce st.

It is further preferred if the urological catheter according to the present invention is assigned an evaluation unit which has an input for accelerometer-based signals, an input for signals based on measurements with at least one pressure sensor and preferably an input for signals related to a depth of insertion. The depth of penetration will typically be digitized by means of the pulling device, which is a clear advantage even where no urethral surface is considered. It should be noted that the evaluation unit can work completely digitally and so if appropriate only a single physical port is provided for serially received, digitized conditioned signals. The evaluation unit will preferably be designed to determine the pressure conditions on a urethral surface in response to pressure sensor and accelerometer signals. In this case, even a determination of the pressure ratio on a urethral sheath outer surface can preferably be made, i. modeling a typical 1-lam tube behavior that is determined inside the urethra by the pressure conditions prevailing in it

- Π - is, can be closed on the surface given on the outer surface conditions.

The invention will now be described by way of example only with reference to the drawings. In this is represented by

Fig. 1 shows a urethral catheter according to the present invention; Fig. 2 shows a pressure profile taken with the urological catheter of the present invention as it moves in a model of a urethra.

Referring to Figure 1, a urethral catheter 1, generally designated 1, includes a urethral pressure sensing means 2 and a urethral urinary catheter determining means 3, the sensing means 3 comprising a triaxial accelerometer to determine. how urological catheter 1 is oriented when pressure is detected in the urethra. In the present exemplary embodiment, the urethral catheter 1 is dimensioned such that its front end 1a can be advanced into the interior of the bladder in a male adult patient. The patient side. towards the inside of the body (proximal) tip lal of the urological catheter 1 is rounded in order to avoid injury to the urethra during insertion and to facilitate a less painful and less unpleasant insertion for the patient. Near the proximal tip lal of the urological catheter 1, a pressure sensor for measuring the I Iarn bubble internal pressure is provided, compare la2.

The materials used to make the urethra catheter, which come into direct contact with the patient or, via body fluids, in indirect contact with the patient, are selected according to the applicable criteria and regulations for the approval of medical products. The skilled person understands that this is readily possible is. In particular, the proximal tip will be formed of medical grade stainless steel or the like. For the pressure sensor which detects the urinary bladder pressure, an opening will be provided therein; the sensor itself is placed inside the tip. This will allow the sensor to communicate with the port itself and not measure the pressure exerted on a balloon or the like. The sensor but could be upstream of a membrane above. Like the other pressure sensors described below, the sensor on the catheter tip will also be located very close to the opening.

In the embodiment of Fig. 1 is further between the pressure sensor la2 for detecting the bubble internal pressure and the sensor means 2 for detecting the pressure in the

Urethral flexible catheter area la3 provided whose length is dimensioned here so that the adult male patient, for whom in the described embodiment, the Urokatheter 1 is designed, the ürucksensoren 2 a to 2 c can be pushed into the bladder, without passing through the proximal tip Lal injury to the urinary bladder occur. This is easily feasible. It is understood that in the design of the urological catheter 1 for children, the distance la3 corresponding to the body size and the not yet fully grown organs will be shorter, as well as there the catheter diameter will be smaller. Further, without this being absolutely necessary for a first aspect of the invention, electrodes 3 a, 3 b, 3 c are provided on the urological catheter 1 between the pressure sensor provided at the proximal end 11 a and the pressure sensors 2 for determining the pressure in the lacrimal tube. While the pressure sensor is provided lal on a metal tip and the section la3 will be formed of flexible plastic, the electrodes are typically formed of mutually insulated metal rings, so that the urethra inside or the transition from urinary bladder to iliary tube (ostium-Urethrae- Internum ) can be electrically stimulated. It is understood that in the interior of the catheter leads are led to the electrodes 3a, 3b, 3c, via which suitable voltages can be applied to the electrodes. In this way, what is preferred, with the catheter, a muscle stimulation can be effected and in particular also be recorded how the pressure in the urethra or at the output of 1 Harnblase changes to urethra, if there (the smooth, ie the conscious will not subject) Musculature is excited. This can make the diagnosis much easier. It is therefore to be regarded as inventive to provide one or more stimulation electrodes, optionally in conjunction with an accelerometer on a urological catheter. This is especially true when - deviating from the above - no electrode rings, but locally in a certain direction towards stimulating electrodes (surfaces) are provided and / or a multiaxial, especially triaxial acceleration sensor is provided. It is understood that can be applied to the three electrodes 3a, 3b, 3c AC voltage pulses, different DC voltage pulses of different polarity and / or waveforms, etc. depending on the desired excitation pattern.

The sensor means 2 for detecting the pressure in the urethra is now realized with a here about 1, 2 cm to 3 cm long metal tube on the catheter, which carries a total of eight pressure sensors, of which in the figure only three (2a, 2b, 2c) are shown. For each of the eight pressure sensors, an opening is provided in the metal tube, so that the pressure sensor located inside the catheter can detect the pressure acting at the respective opening. The openings for the eight pressure sensors are helically wound around the circumference of the catheter. It will be understood from the figure and from the entirety of the available documents that the here eight pressure sensors around the catheter circumference around - or the projections of the eight pressure sensors here on a perpendicular to the catheter axis cross-section - here are preferably distributed as equiangular , Each center of a sensor is thus removed by an arc of 45 ° from the nearest sensor on the cross-sectional project. The eight sensors will not all be arranged at the same axial height, but be axially offset from each other. This may be the case, but a number of sensors may also be provided so that e.g. always pairs of pressure are provided in diametrically opposite directions sensing sensors at a given axial position.

In the case of a helical arrangement, the axial offset of the windows for the pressure sensors in the tube is such that the distal end of a window lies slightly farther toward the interior of the body than the proximal end of the pressure sensor window next following in the helical direction. It should be noted, however, that other geometries than the can be used here as preferred helical. This may also depend on the overall size allowed for a given patient's dummy. It is also possible, for example, to use fewer or even more than eight sensors in children. Moreover, for common and usable pressure sensors, a window size of, for example, 1 mm x 2 mm sufficient and useful; while the larger edge of the window is oriented in the axial direction. The arrangement of 8 sensors of this size on the circumference of a catheter with a good usable size of 8 French, ie about 8.3 mm circumference, is easily possible. In the direction away from the interior of the body, ie more distally to the outside, a segment with an acceleration sensor 3 follows after a short further transition piece 1 a4 on the catheter after the tip, the intermediate piece, the muscle stimulation electrodes and the pressure sensors Pressure sensors relative to the acceleration sensor and that of at least corresponding to the anatomically required in the urethra radii of curvature, but allows at most a slight twist, ie rotation about the catheter axis, between the segment 3 and 2. In order for a rotation of the catheter 1 outside the patient, a same rotation of the section 3 and the section 2 is ensured. The placement of the Accclerometer on a section away from the pressure sensors is not mandatory.

The acceleration sensor 3 is formed as a tri axial accelerometer, i. With the acceleration sensor arranged in the interior of the tube segment, it is possible to determine three components of an acceleration vector that are mutually orthogonal to one another.

Not shown in the figure, that the pressure sensors Ia2, 2 and the acceleration sensor 3 signal lines and S ignalkonditioniermittel are assigned to feed outside of the Urokatheters 1 and outside of the patient, where the Urokatheter to be used, the respective signals to a data evaluation unit , Depending on the requirements of the clinic or practice, a signal amplification, an impedance conversion, a digitization, if necessary a consideration of calibration or calibration data, signal filtering and / or other conditioning, a conversion to appropriate data protocols each within the Urokatheters using highly integrated circuits of low power or outside the Urokatheters done. In a preferred variant, however, the signals of the pressure sensors and the acceleration sensor are in any case digitized for further data processing.

The Urokatheter 1 is otherwise provided with marks l a5, which allow a determination of the insertion depth without reference to the signals, possibly integrated and processed signals, the acceleration sensor. This contributes to the fact that even in case of failure of the acceleration sensors, the catheter is not inserted too deeply and, moreover, a plausibility check of the integrated signals by the attending physician during the treatment can take place at any time. For this purpose, the evaluation unit can be designed for either a modeling in real time or at least to a display of the current pressure values in certain directions in real time, preferably in graphical form, such as display of excellent directions towards determined pressure and the Hanrröhrenprofils in the sagittal plane.

The urethral catheter 1 of the present invention is now used as follows: After preparing the patient and optionally applying lubricants, etc., to the catheter, the urethral catheter 1 is inserted into the patient's urethra until the pressure sensors 2 lie within the bladder. It will generate a certain bubble level. The catheter is then successively withdrawn from the urethra, here in sections in each case by a little less than the length of the section 2 of the catheter. After each extraction movement by a distance which is slightly shorter than the length of the section 2, the catheter is rotated by approximately 360 ° and it is the pressure detected with each of the eight pressure sensors, and, at least initially, and the pressure inside the bladder. The three components of the acceleration sector are permanently recorded, ie they are repeatedly scanned, digitized and written off or stored as required, ie also recorded during the rotation. It is understood that, if necessary, a rotation in a clockwise direction alternately, a withdrawal of the catheter to a stretch that is slightly shorter than the length of section 2, and thereafter counterclockwise rotation can be made 360 °, etc. This prevents the catheter as a whole from being twisted massively with associated conduits, etc. Next is the possibility of a helical

Turn mentioned. In the case of a rotation, a plurality of knife values can be detected during the rotation, and from each j ene can be selected, for which the accelerometer indicates that they were picked up at a certain rotational position. It should be noted that, if necessary, the rotation during extraction, i. superimposed to can take place and insofar as a helical movement can be selected. In a particularly preferred variant of the invention, a pulling device is provided, which causes such a helical movement and the catheter is designed for a continuous rotation in one direction, to which it can be provided with suitable rotary joints for the electrical supply and signal lines, which in its interior, ie e.g. a free lumen, or its catheter wall are guided and for the fluid lines with which fluid into the bubble or out of this can be performed. This traction device has the particular advantage that a constant pitch height can thus be achieved and insofar additional difficulties in the modeling can be avoided. The pressure signals obtained during extraction and gating can now be displayed, after signal conditioning and integration of the acceleration sensor signals, as if all openings for the pressure sensors were arranged along a straight line parallel to the catheter axis and with each pressure sensor in each outlet. peg position measurements would be detected with full rotation. It is thus made by reference to the signals of the acceleration sensor, an assignment of the pressure detection to the exact (rotational) position of the sensors in the urethra and measured the pressure at respective points of the urethral surface. At the same time it is also corrected that the catheter was not pulled out by exactly the same distance from measurement to measurement.

This is also possible by integration of the tri axial acceleration sensor components over time. Thus, with the triaxial acceleration sensor, on the one hand, the direction of rotation can be detected and, on the other hand, if necessary, the depth of extension. However, it should be noted that sensors, including the acceleration sensors used here, have a drift component. When integrating the acceleration components, in particular double integration for purposes of determining a route, this drift has a strong disruptive effect. Therefore, it may be preferable to detect the feed or extension depth in another way, in particular in a manner known per se.

Incidentally, it is advantageous for adapting to fluctuations in measured value recording, etc., if a model is chosen which is particularly robust against the expected variations and inaccuracies. For example, instead of a model that relies on lattice points arranged at fixed axial distances along the circumference, a model may instead be used in which equidistant tangents to the idealized helix are considered, and then again lattice points are defined on these tangents. Such grids have advantages in terms of boundary conditions, because for the interpolation of the real measured values on functions with others

Can be resorted to and not the otherwise compelling cyclical continuation must be chosen at the edges. In this regard, reference may be made, by way of example, to D. Grishin et al., "Almost Scattered Data Approximation with Neumann and Other Boundary Conditions." Linear algebra and its applications, Vol. 391 No 0, S, 99-123, 2004. It should be noted that with this the possibility exists to determine suitable pitch heights for a selected model by considering the robustness, ie the insensibility to outliers.

It should be further mentioned that there is the possibility to pull the catheter with an optionally motorized pulling device from the urethra and by the

Pulling movement caused to detect what can be done on the catheter itself or about the drive of the pulling device. In this respect, the preferred and in particular under suitable evaluation for the modeling preferred catheter movements can also be implemented mechanically well.

It is also possible to detect the depth only at certain points in other ways than with the acceleration sensor and to interpolate between them. It should be noted that the suggested extraction by just less than an entire section 2 and full 360 ° rotation is merely exemplary. Optionally, a slightly shorter distance, for example, to just about the length of a Drucköffnungsfensters be pulled out and to (something) more than one-eighth of a full circle oscillating rotational movement are made, so that in total so every point on the inside of the urethra at least once a pressure sensor was swept over. It can be measured continuously, but a measured value can be used only after passing through a certain angle of rotation. So a discretization is achieved. It should be mentioned that oversampling can also be present in the case of a two-dimensional scan, ie that there is an optimal measured value density even in the case of two-dimensional measurements in the surface if the structures to be detected do not fall below a certain spatial size. Incidentally, it will be appreciated that the eight sensors will be calibrated to give the same signals at the same pressure. If necessary, this can be done by pre-calibration and storage of calibration curves or the like. Such pre-calibration can be done by determining the air pressure before the actual examination. In this case, the air pressure does not necessarily have to be determined absolutely exactly, but rather a measurement is to be made with all pressure sensors, in particular all sensors communicating via openings in the wall of the catheter with fluid in the urethra, which will result in identical measured values independently of position, and thus an adjustment of the Sensors with each other easier. As far as the calibration is concerned, it should be noted, among other things, that the sensors are in front of

Measurement of urethral characteristics are typically inserted into the urinary bladder. In addition, as a rule, the bladder is filled with a defined amount of liquid. This makes it possible during the filling, if the catheter according to the invention has a corresponding lumen for the filling or emptying of the bladder, to carry out the calibration during the filling in the case of several filling states. As a result, a calibration that is normally at least usable is usually automatic without special features. achieved. If desired, it is also possible to measure completely without catheter rotation.

If the circumferential pressure profile which was recorded with the sensors when being pulled out is then plotted in such a way that the pressure windows were corrected for the different orientation, the result is a drag surface profile, as illustrated by way of example in FIG. FIG. 2 shows a pressure profile 1 obtained on the model. This model comprises a silicone tube instead of the urethra. In doing so, the sphincter muscle was modeled on a cord loop model. The silicone tube is oriented horizontally for the trial to model a recumbent patient. Iiier the pressure curves are plotted, which were detected for the respective sensors 2a, 2b ... 2h of the eight pressure sensors between 0 ° and 360 ° rotation, when the zero point of rotation for each sensor 2a to 2h on the same line parallel to the catheter axis through Considering the signals of the triaxial accelerometer is set. It can be seen that in a typical patient in a certain area, namely towards the rectum, an increase in pressure can be detected in the model. The graphs shown indicate that the maximum applied pressure from the calibrated sensor to the calibrated sensor and thus along the modeled urethra can vary. The quasi-continuous measurement in the axial direction and the discretization of the catheter drawn without rotation can also be clearly recognized. A doctor can already infer from such a representation very well on defects and anomalies. The reconstruction of the geometry of - here model-like - urethra especially in the sagittal plane is readily possible.

However, it is possible to investigate defects, for example in the sphincter muscle, even more precisely by determining not only the pressure on the inside of the urethra, as detected with the sensors, but also modeling the elastic urethra beyond that with the measured data. This can be done automatically and using in particular partially precalculated tables and matrices in such a way that a model of the urethra outer sheath considered to be elastostatic is created with the pressure data. It should be noted that such modeling also suggests that urethral pressure conditions may be considered invariable during measurement, possibly due to catheter-related urethral deflection.

It is preferred if a finite element model is used for such elasto static modeling, in which at least four times more points around the circumference are (equidistant) as sensors are distributed around the circumference. In the present example, with eight sensors distributed around the circumference, at least thirty-two nodes of a finite element model should be determined around the circumference of the urethra being modeled. Measuring points are used, which are recorded after one-eighth of the rotation.

In this way, scanning problems resulting from the Nyquist theories and the finite sensor width can be considered. In addition, filtering of spatial noise may be preferred, which is most easily achieved by spatial Fourier transformation and truncation of higher frequency components in the

Fouriertransformierten and subsequent back transformation can be done. In this way, a very steep bandpass can be realized. The cutoff frequency will typically be about 1.5 times the spatial Nyquist frequency. If such modeling is desired, it is understood that the use of equidistant sensors is particularly preferred because this simplifies the mapping of the data to the nodes. After modeling, the examining doctor receives not only a curve according to FIG. 2, but also a modeling of the outer surface of the hernia which makes it even easier to detect defects.

It should be noted that although a catheter for an adult male patient has been described above, this is by no means mandatory. It is readily possible to use the catheter described also for female adult patients or, if appropriate, make a resizing for female patients or adolescents or children gender-neutral or sex-specific fish. It should be noted, moreover, that under Wakrang's preferred balloon catheterization of the preferred catheter, but regardless of the preferred arrangement of the pressure sensors immediately behind the windows provided in the catheter sheath surface for communication with the fluid in the Urnröhe if necessary, nevertheless a fluid connection from the opening to a further away and in particular outside the body of the patient located pressure sensor could be performed. Such a design would be advantageous if, for example, the catheter is desired for measurement during an examination with a magnetic resonance imaging apparatus (MRI). It will be appreciated that, in such a case, it must be ensured that the orientation sensor, ie, the triaxial accelerometer and leads there, etc., must be usable in the catheter irrespective of the MRI conditions. Otherwise, it should be noted that the catheter of the present invention is preferably operated with a pulling device which imparts rotation to the catheter simultaneously to withdraw the catheter from the bladder, preferably with a selectable pitch. It should also be noted that the pulling-out distance can preferably be determined with the pulling device in order to make the digitized values available in the modeling and / or the measuring value preparation.

What has been described above, inter alia, is thus a urocatheter having a sensor means for detecting urethral pressure and determining means for determining the location of the catheter in the urethra, characterized in that the determining means comprises a triaxial accelerometer to determine how of the

Catheter is oriented at pressure detection in the urethra.

Furthermore, such a urocatheter has been described, wherein the catheter has a flexible and / or twistable basic body, on which sensor means and accelerometers are arranged. Furthermore, such a Urokather has been described, wherein the sensor means are only relatively twistable and / or movable relative to the accelerometer.

Furthermore, such a urocatheter has been described, wherein the sensor means has a plurality of pressure sensors distributed in cross-sectional projection over the circumference.

It has also been described such a urological catheter, wherein the sensors distributed over the circumference are axially spaced apart.

Further, such a urocatheter has been described, wherein the sensor means for simultaneously detecting the pressure in the urethra is formed with a plurality, preferably all, of the sensors.

Such a urocatheter has also been described, the sensors being provided near the patient-side end of the catheter.

Furthermore, such a urocatheter has been described, wherein the sensors are arranged so close to the patient-side end of the catheter that a measurement within the bladder is possible. Furthermore, such a urocatheter has been described, wherein a means for measuring the insertion probes is provided.

Also described was a urocatheter arrangement with such a urethra catheter and an evaluation unit comprising an input for signals obtained with the accelerometer, an input for signals based on signals obtained with at least one pressure sensor, and preferably an input for signals of a processing unit related to a insertion depth, in response to pressure sensor and

Accelerometersignale make a determination of the pressure conditions on a H urrthröhrenman- tcl surface, and an output for outputting a relation to these pressure conditions output signal

Claims

A urological catheter having a sensor means for detecting urethral pressure and a determining means for determining the location of the urethral urethral catheter, characterized in that the sensor means is adapted to

the pressure

locally on the circumference of the catheter

to measure and the determining agent

tri axial accelerometer,

that for the determination of a

caused by gravity

Force component is suitable,

so as to detect the rotational orientation of the catheter in the urethra when draining,

2. Urokatheter according to the preceding claim, characterized in that the catheter has a flexible and / or twistable base body on which the sensor means and the accelerometer are arranged.

3. Urokather according to the preceding claim, characterized in that the sensor means are relatively twistable relative to the accelerometer only limited.

4. Urokathctcr according to one of the preceding claims, characterized in that the sensor means comprises a plurality of distributed in Querschmttsprojektion over the circumference pressure sensors.

5. Urokathctcr according to the preceding claim, characterized in that the circumferentially distributed pressure sensors are axially spaced from each other,

6. Urokatheter according to one of the two preceding claims, characterized in that the sensor means for the simultaneous detection of the pressure in the urethra with a plurality, preferably all of the pressure sensors is formed.

7. Urokatheter according to any one of the preceding claims, characterized in that the pressure sensors are provided near the patient-side end of the catheter.

8. Urokatheter according to any one of the preceding claims, characterized in that the pressure sensors are arranged so close to the patient-side end of the catheter, that a measurement within the bladder is possible.

9. Urokatheter according to any one of the preceding claims, characterized in that a means for measuring the insertion depth is present.

10. Urokatheter according to any one of the preceding claims, characterized in that an opening in the catheter is provided in front of the pressure sensor and the catheter surface is formed around the opening so that the urethra sealing a local area can abut the catheter. Urokalheteranordnung with a Urokatheter according to any one of the preceding claims, and an evaluation unit comprising at least

an input for signals obtained with the accelerometer, and

an input for signals that

on with

at least one

Pressure sensor based signals that are designed to respond in response to

Accelerometersignale

by determining a

force component caused by gravity

the rotation orientation

of the catheter in the urethra

at pressure detection

to capture and thereby respond to

Pressure sensor signals

a provision

the pressure conditions on a tube surface

make, as well as with

an output to output a

related to these pressure conditions

Output signal.

12. Urokatheteranordnung with a Urokatheter according to one of the preceding claims, and an evaluation unit comprising at least