WO2002003860A1

WO2002003860A1 - Pressure regulator for stabilizing cerebrospinal fluid pressure

Info

Publication number: WO2002003860A1
Application number: PCT/EP2001/006955
Authority: WO
Inventors: Wolfgang Barnikol
Original assignee: Glukomeditech Ag
Priority date: 2000-07-07
Filing date: 2001-06-20
Publication date: 2002-01-17
Also published as: AU2001272492A1; DE10033138A1

Abstract

The invention relates to a device for measuring and regulating the pressure in the human body, comprising a thin tube (1.9) with one chamfered end, comprising a miniaturized pressure sensor (1.1) arranged on the tip thereof. Electrical lines (1.6) are disposed in the wall of said tube and transmit the signals measured by the pressure sensor (1.1). The device is further provided with a measuring amplifier (1.2) that picks up the signals measured by the pressure sensor (1.1), amplifies and transmits them. A recording and control device (4) receives and processes the electrical signals of the measuring amplifier (1.2). An adjusting, gauging and measuring device (2) regulates the supply or discharge of a gas or liquid flow and is provided with a flow sensor (2.2). Said adjusting, gauging and measuring device (2) may preferably be provided with a puncture system (2.6) with a diaphragm (2.7) that allows gauging, monitoring and correction of the signals of the pressure sensor (1.1) via a cannula introduced through the skin and a pressure sensor coupled therewith. The inventive device is preferably used for measuring and regulating the cerebrospinal fluid pressure and in the artificial respiration of children.

Description

PRESSURE REGULATION FOR STABILIZING LIQUOR PRESSURE

Device for measuring and regulating pressure in the human body, in particular for adjusting and stabilizing the cerebrospinal fluid pressure for the therapy of hydrocephalus and for diagnostic purposes

The invention relates to a device for pressure measurement and regulation in the human body with the features of claim 1 for use in various medical applications.

One embodiment of the invention relates to a device in a totally implantable microtechnical embodiment, which can be an integral part of a liquor pressure ^' drainage (so-called liquor "shunt") and with the help of which one is in the cerebrospiral liquor (brain water) in the therapy mode Pressure sensor by changing an artificial CSF drain resistance can keep a person's CSF pressure stable at a desired value and can determine a long-term profile of brain pressure in the diagnostic mode artificial respiration, cyclically discontinued.

The very soft brain of the human being swims, as it were, in the cerebrospinal fluid (cerebrospinal fluid); the volume of the cerebrospinal fluid is about 150 ml. This protects the sensitive brain tissue. The liquor is in the pair, so-called. The choroid plexus of the 1st and 2nd ventricles is formed and flows into the venous blood in various ways: via the arachnoid granulation and the interventricular foramina in the 3rd ventricle and further via the cerebral aqueduct in the 4th brain ventricle.

The formation and drainage of the brain water are usually coordinated so that there is a real overpressure in the brain water. This so-called intracranial intracranial pressure also depends on the position and is physiologically 10 ± 5mmHg in the lying adult. The CSF flow amounts to about 350 ml per day. Various disturbances can lead to pressure deviations from the norm, in particular to increases. These cause considerable complaints and (Cerebral) disorders for the wearer. An ongoing increase in pressure also leads to the irreversible loss of nerve cells, especially in the cortex, ie to the debarking of the person concerned. The reason for this is, among other things, that the cerebral perfusion pressure (ZPD) decreases, since this is the difference between the blood pressure and the cerebral pressure. The cerebral perfusion pressure, in turn, is the decisive driving force for the blood supply to the brain and thus for its supply.

The cerebrospinal fluid pressure also increases due to a decrease in cerebrospinal fluid absorption (Hydrocephalus aresorptivus) after meningitis or encephalitis; the

Increases also arise from an increase in the discharge resistance (hydrocephalus occlucus) in the event of malformations, from tumors, and again from inflammation; finally, the intracranial pressure increases with increased CSF production (Hydrocephalus hypersecretorius), for example due to toxic influences on the brain. Further detailed explanations on pathophysiology, the clinic but also measurement technology and their problems can be found in S. Schwab, D. Krieger, W. Müllgas, G. Haman, W. Hacke (ed.), "Neurological Intensive Care Medicine", Springer-Verlag, 1999, ISBN 3-54065412-7.

In order to prevent further irreversible destruction of brain cells in cases of corresponding clinical cerebral symptoms, such as short-term memory loss and / or imperative urge to urinate and / or walking disorders (unsafe walking), a thin tube with an outer diameter of approximately 2.5 mm is used a CSF drainage (so-called, cerebral "shunt"). The tube is located at one end in one of the two lateral and paired intracerebral CSF spaces (so-called brain ventricles) and leads out through the skull cap; it usually runs under the skin to the abdomen.

The current state of the art is that - in order to be able to set a physiological CSF pressure - an artificial resistance is usually placed in the drainage tube of the CSF drainage below the clavicle. The size of the resistance can be set transcutaneously in a few discrete steps using a magnet. One problem with these fixed discharge resistances is the positional dependence of the CSF pressure. A critical overview of the adjustable drainage resistances of this type currently available can be found in A. Aschoff, "In Vitro Testing of Hydrocephalus Valves", Habil.-Schrift, Heidelberg, 1994. The resistance is set according to clinical experience, taking into account the above symptoms. There is currently no way for clinical routine to measure the intracranial pressure without a transcutaneous probe and even to record a long-term profile of this pressure (diagnostic working mode), which would be of the greatest diagnostic and consequently therapeutic interest for the patient concerned. Likewise, it would be of great advantage if the CSF flow could also be measured with the pressure stabilized (therapeutic mode of operation). So far it has not been possible to keep the intracranial pressure stable at a desired value.

Since the targeted system for stabilizing the intracranial pressure is to be integrated into a cerebrospinal fluid drainage, only a micro pressure sensor can be used for pressure measurement, which is best integrated at the tip of the implanted catheter of the cerebrospinal fluid drainage in such a way that its pressure-sensitive surface is facing the cerebral cerebrospinal fluid space. Stabilization should function properly for years; for this it is particularly important that the signal of the fully integrated and implanted pressure sensor remains stable for years - a problem that cannot be solved practically, even if the pressure sensors are constructed as stable as possible. Therefore, the fully implanted system must have a device by means of which the calibration of the pressure sensor can be checked and, if necessary, corrected.

Another embodiment of the invention relates to pressure measurement in other medical applications. For example, in medicine it is of great interest to use micro sensors to directly and continuously measure the pressure at the tip of a child's tube, which has an outer diameter of only 2.5 mm and less, in order to achieve this so-called endotracheal pressure during artificial ventilation of a child, so that a ventilator could also be controlled with this signal. A ventilator could then control the signal of the tube sensor in such a way that on the one hand the ventilated lung does not experience any volumetric and / or baro-trauma and on the other hand it is adequately ventilated in order to supply the person concerned with sufficient oxygen. Here, too, a measurement mode (diagnostic mode) and a regulation mode (therapeutic mode) would be extremely desirable. The problems described with regard to intracranial pressure can be solved according to the invention in such a way that a micro-pressure sensor is incorporated in a special way into the tip of a thin tube; the thin tube also serves for liquid conduction, for example into the abdomen. The signal - wireless or wired - arrives at a controllable flow resistance, which is found in the CSF.

Discharge hose is located. The resistance is adjusted so that the cerebrospinal fluid pressure stabilizes at a desired value. The controllable flow resistance is followed by a flow sensor, which can measure the CSF flow quantitatively. Thus, the method described below allows an additional artificial controlled CSF drain in the case of a restricted CSF drain

Build up compliance with a physiological intracranial pressure. This also solves the problem of the positional dependence of the pressure on the brain, as well as the problem of the reference pressure during the measurement of the intracranial pressure.

Between the pressure sensor and the controllable flow resistance, very close to this, a miniaturized subcutaneous puncture system with a diaphragm is switched on in the liquor discharge tube, via which the intracranial one is connected with the help of a cannula to which an externally calibrated pressure sensor is connected via a tube (here: intraventricular) pressure can be checked and verified if necessary. The controllable flow resistance is an important aid here: firstly, it can be used to check the flowability of the implanted drainage tube, and secondly, after closing the flow resistance, which in turn can be controlled via the downstream flow sensor, the signal of the pressure sensor located in the brain ventricle can be obtained.

In the case of the children's tube, the pressure signal passes from the pressure sensor at the tip of the tube to a ventilator, which ensures the desired ventilation. A flow sensor is located in the connector of the children's tube, which allows the ventilation set by the ventilator to be determined.

The device is explained in more detail below and advantageous embodiments for it are described.

Fig. 1 shows the scheme for the process of CSF pressure stabilization. The pressure measuring device (1) consists of the sensor (1.1) and the measuring amplifier (1.2). The sensor (1.1) is located in the 1st or 2nd brain ventricle. The sensor (1.1) and the measuring amplifier (1.2) are electrically coupled to one another via the lines 1.6. Number 5 identifies a hose route.

The sensor (1.1), the measuring amplifier (1.2) and the lines (1.6) are implanted, the measuring amplifier (1.2) is preferably directly subclavicular. From time to time, the electrical energy source (1.2.1) of the measuring amplifier (1.2) can be charged telemetrically via the non-implanted external device (3). The implanted measuring amplifier (1.2) transmits the measuring signal to the non-implanted external registration, control and regulating device (4) by means of a transmitter (1.2.2).

In the case of the pediatric sensor tube, the sensor (1.1) is located in a child's windpipe and part 5 identifies an airway. All other parts of the device are not implanted. The external device (3) is omitted, the energy source (1.2.1) likewise, the measuring amplifier (1.2) can be supplied with electrical energy via lines.

The device (1, 3, 4 and 5) explained can work as a whole; in the case of cerebrospinal fluid, the intracranial pressure, in the case of the pediatric sensor tube, the endotracheal pressure is recorded continuously.

The actuating, calibrating and measuring device (2) can be implanted or replaced at any time in the application of the intracranial pressure measurement - preferably subclavicularly, i.e. directly below the clavicle - or switched and electrically connected. It includes a controllable flow resistance (2.1), a subcutaneous one

Puncture system (2.6) with diaphragm (2.7), for example made of silicone, and a flow sensor (2.2), whose signal via the transmitter (2.4) from the receiver (4.2) of the non-implanted external registration, control and regulating device (4) can be recorded telemetrically. The actuating and measuring device (2) can also be supplied with electrical energy via the transmitter (3.1) of the external device (3) and the receiver (2.5) of the actuating and measuring device (2). Via the subcutaneous puncture system (2.6), the pressure inside the liquor discharge tube (5) can be measured with the help of a cannula, which reaches the tip of the skin through the skin and the diaphragm (2.7) with the tip into the inner fluid of the liquor drain tube (5). measure directly. The pressure measuring device (1) and the adjusting, calibrating and measuring device (2) can be used in two different function modes:

1.Measurement mode (diagnostic mode) In this mode, the liquor path (5) is determined with the help of the registration, control and regulating device (4) via the receiver (2.5) of the actuating, calibration and measuring device (2). closed by the controllable flow resistance (2.1), which can be controlled with the flow sensor (2.2): In this case, the signal of the flow sensor (2.2) must remain zero. This mode allows the detection of a pressure profile in the ^{'cerebrospinal} fluid, for example, over 24 hours, and permitted a characterization of the disease condition.

2. Controller mode (therapeutic mode)

In this case, the external registration, control and regulating device (4) works as a controller with negative feedback: it sets the flow resistance via its transmitter (4.1)

(2.1) continuously such that the measured pressure - its signal to the registration,

Control and regulating device (4) is transmitted telemetrically by the transmitter (1.2.2) - a desired value preselected in the registration, control and regulating device (4) is the same.

This corresponds to a cerebrospinal fluid pressure regulation. The measured quantity and thus the medical observation quantity is now the CSF flow, the value of which is transmitted from the flow sensor (2.2) via the transmitter (2.4) to the external registration, control and regulating device (4) by means of its receiver (4.2).

The pressure sensor (1.1) can be checked and re-calibrated using the subcutaneous puncture system (2.6) as follows: A cannula is inserted into the puncture system (2.6) from the outside through the skin and the diaphragm (2.7), which is filled with a liquid Hose is connected to an external calibrated pressure sensor. Now the adjustable flow resistance (2.1) is completely closed. The flow sensor (2.2) must set its zero signal here: this is an indication that the CSF drain hose (5) is continuous. In the subcutaneous puncture system (2.6) there is - since there is no longer any flow in the discharge tube - pressure compensation with the pressure sensor (1.1), which is located in the brain ventricle. The pressure signals from this sensor (1.1) and the external sensor that is coupled to the cannula can thus be compared directly. In the event that the pressure sensor (1.1) is at the top of a children's tube, part (2) represents a respirator with a fan (2.1) and a gas flow meter (2.2); In this case, the device (2.6) is omitted. There are also two operating modes:

1.Measurement mode (diagnostic mode)

The doctor sets the ventilator (2.1) according to clinical experience and the flow sensor (2.2) quantitatively detects the ventilation. The pressure sensor (1.1) continuously determines the endotracheal ventilation pressure, the signal of which is transmitted from the measuring amplifier (1.2) to the registration, control and regulating device (4).

2. Controller mode (therapy mode)

In this case, the registration, control and regulating device (4) monitors the endotracheal pressure. If this does not have the desired course in the breathing cycle, which is defined in this device, the mode of operation of the fan (2.1) is changed accordingly. The flow sensor (2.2) always provides the respiratory flow and thus the ventilation as a measurement.

Fig. 2 shows schematically an embodiment of the pressure sensor (1.1) at the tip of a thin tube (1.9) as a longitudinal section. The thin hose (1.9) is roughly cut off at the end. On the long part of the slope (1.12), the micro-pressure sensor (1.1) is placed inside a bead (1.13). The sensor (1.1) has a pressure-sensitive membrane (1.4) on the outside. On the back of the sensor (1.1) begins a flat air shaft (1.5) in the hose wall, which runs lengthways in the hose wall. The cable connections (1.6) of the micro pressure sensor are located in the flat shaft (1.5). The pressure sensor can work, among other things, piezoelectric, resistive, inductive or capacitive. In the case of the CSF pressure sensor, the flat shaft (1.5) can also be filled with material. There may be one or more additional side openings (1.7), one of which is shown, near the hose tip.

A variant of this embodiment can include that the end of the hose is filled with solid material (1.8) and the thin hose (1.9) then necessarily has some lateral openings (1.7). Fig. 3 shows a section along the line I of Fig. 2 again. Here the micro pressure sensor (1.1), the pressure sensitive membrane (1.4) and the flat channel (1.5) are shown.

Fig. 4 shows the cross section II of Fig. 2 again with the flat channel (1.5) and with the cable connections (1.6). In addition, the hose in the wall can be provided with further hollow channels (1.10; 1.11).

5 shows schematically in longitudinal section an embodiment of the controllable flow resistance (2.1) and FIG. 6 shows a cross section along line I of FIG. 5.

The hose (1.9) is located between the two legs (5.1) and (5.2) of a clamp (5.3). The cross-section of the hose (1.9) can be reduced by the clamp (5.3), thus increasing its flow resistance. The hose (1.9) is firmly connected to the legs (5.1; 5.2) at points (5.4) and (5.5). This means that the hose resistance can be safely reduced again. The two legs (5.1; 5.2) of the clamp (5.3) can be moved against each other with a threaded rod (5.6). The threaded rod (5.6) has two opposing threads (5.7) and (5.8), the transition (5.9) of which is located in the middle of the screw between the legs. The threaded rod (5.6) can be moved, for example, with a motor (5.10), controllable in both directions of rotation and at different speeds. The threaded rod (5.6) runs in two nuts (5.11) and (5.12) corresponding to the threads, which are articulated at the ends of the two legs (5.1) and (5.2).

7 and 8 schematically show embodiments of the flow sensor (2.2) in longitudinal section. The flow sensor (2.2) consists of a tubular constriction (6.1), which is equipped with two pressure measuring points (6.2) and (6.3) in the wall at a suitable distance. The difference in the pressures measured at the points gives a measure of the flow of the medium through the pipe. The pressure measuring points can each consist of the pressure-sensitive membrane of a pressure microsensor. Then the difference between the two (electrical) signals is a measure of the flow.

However, as illustrated in FIG. 8, the pressure measuring points can also be the end of pressure transmission lines (6.4) and (6.5), which lead to a differential pressure Guide sensor (6.6). These lines can consist, for example, of liquid-filled tubes. In this case the signal from the differential pressure sensor (6.6) is a measure of the flow.

The inside of the tubular constriction is provided with an inert coating (6.7), which prevents interaction with molecules that are dissolved in the brain water, so that the flow resistance of the constriction (6.1) does not change. A diamond-like carbon coating can preferably be used for this purpose.

The flow sensor can be made of metal or plastic, but in any case from a cell-compatible material.

Claims

claims

1. Device for pressure measurement and regulation in the human body, consisting of 1.1.1 a thin tube (1.9) cut at one end at an angle with a miniaturized pressure sensor arranged at its tip

(1 -1). 1.1.2 in the wall of which the electrical signals (1.6) transmitting the measurement signals of the pressure sensor (1.1) are arranged, 1.1.3 a measuring amplifier which receives, amplifies and transmits the measurement signals of the pressure sensor (1.1) (1.2), 1.1.4 a recording, control and regulating device (4) receiving and processing the electrical signals of the measuring amplifier (1.2) and 1.1.5 an actuating, calibrating and measuring device (2) for regulating the supply or discharge of a gas or liquid flow, which is provided with a flow sensor (2.2), the inner surface of which is coated with a biologically inert material.

2. Device according to claim 1, characterized in that the pressure sensor (1.1) on the inside of the obliquely cut thin tube (1.9) is arranged.

3. Device according to claims 1 or 2, characterized in that the opening of the thin tube (1.9) is sealed at the obliquely cut end with solid material (1.8).

4. Device according to one of claims 1 to 3, characterized in that the thin tube (1.9) has several lateral openings (1.7) at its sensor end.

5. Device according to claims 1 to 4, characterized in that a channel (1.5) extends from the pressure sensor (1.1) in the wall of the thin tube (1.9).

6. Device according to claims 1 to 5, characterized in that in the channel (1.5) are the lines (1.6) leading from the pressure sensor (1.1) to the measuring amplifier (1.2).

7. Devices according to claims 1 to 6, characterized in that in the wall of the thin tube (1.9) still further channels (1.10; 1.11) are arranged.

8. Device according to claims 1 to 7, characterized in that the measuring amplifier (1.2) contains a transmitter (1.2.2), the signals of which

Registration, control and regulating device (4) can be received via its receiver antenna (4.2).

9. Device according to claims 1 to 8, characterized in that the actuating and measuring device (2) bidirectionally telemetrically with the registration,

Control and regulating device (4) is coupled.

10. Device according to claims 1 to 9, characterized in that the actuating, calibration and measuring device (2) contains a telemetrically controllable flow resistance (2.1).

11. The device according to claims 1 to 10, characterized in that electrical memory (2.3; 1.2.1) of the measuring device (2) and the measuring amplifier (1.2) are charged by an external device (3).

12. Device according to claims 1 to 11, characterized in that the controllable flow resistance (2.1) from a clamping device (5.3) with a straight (5.1) and an L-shaped (5.2) clamping part with the threaded stand (5.6) are connected, and the two free ends of the clamping parts bear nuts (5.11 and 5.12), which are driven by the motor (5.10)

Thread stand (5.6) with opposing threads (5.7 and 5.8) can be moved towards and away from each other.

13. Device according to claims 1 to 12, characterized in that the thin hose (1.9) on the clamping parts (5.1; 5.2) of the clamping device at the points (5.4; 5.5) is attached.

14. Device according to claims 1 to 13, characterized in that the flow sensor (2.2) consists of a tubular constriction (6.1).

15. Device according to claims 1 to 14, characterized in that the inert inner coating (6.7) of the flow sensor (2.2) is a diamond-like material.

16. The device according to claims 1 to 15, characterized in that the flow sensor (2.2) works on the principle of the pressure difference of two sensors.

17. The device according to claims 1 to 16, characterized in that the flow sensor (2.2) has two pressure measuring points (6.2 and 6.3).

18. Device according to claims 17, characterized in that the pressure sensors (6.2 and 6.3) used work electrically, resistively, capacitively or inductively.

19. Device according to one of claims 1 to 18, characterized in that in the actuating, calibration and measuring device (2) between the flow sensor (2.2) and the controllable flow resistance (2.1) near the latter a puncture system (2.6 ) is arranged with a diaphragm (2.7)

20. Use of the device according to one of claims 1 to 19 for external control and calibration of the pressure sensor (1.1).

21. Use according to claim 20, characterized in that the pressure sensor (1.1) is arranged in the 1st or 2nd brain ventricle.

22. Use according to one of claims 20 to 21, characterized in that the measuring amplifier (1.2) is preferably implanted directly under the skin subclavicularly.

23. Use according to claims 20 to 22, characterized in that the adjusting and measuring device (2) is implanted directly subclavicularly under the skin and is switched on serially in the thin tube (1.9).

24. Use of the device according to one of claims 1 to 19 for controlling the artificial respiration of a person, in particular a child.

25. Use according to claim 24, characterized in that the thin tube (1.9) with the pressure sensor (1.1) is arranged in the trachea.

26. Use according to claim 24 or 25, characterized in that the adjusting, calibration and measuring device (2) is a fan (2.1) with a gas flow meter (2.2).

27. Use according to one of claims 20 to 26 in the diagnostic mode.

28. Use according to one of claims 20 to 26 in controller mode.