WO2010079252A1

WO2010079252A1 - Apparatus, method and system for the ambulatory recording and analysis of intracranial pressure as well as for the automatic detection of associated pathologies

Info

Publication number: WO2010079252A1
Application number: PCT/ES2010/070005
Authority: WO
Inventors: Ruben Martin Laez; Juan Maria Perez Oria; Fernando Viadero Rueda; Luciano Alonso Renteria; Alfonso Vazquez Barquero; Lorena Santamaria Covarrubias
Original assignee: Fundación Marqués De Valdecilla
Priority date: 2009-01-09
Filing date: 2010-01-07
Publication date: 2010-07-15
Also published as: ES2379720B1; ES2379720A1

Abstract

Autonomous system for the ambulatory recording of the intracranial pressure of a patient, which system comprises an intracranial pressure sensor which transmits the intracranial pressure signal to a portable apparatus which may control the capture of the signal and may store the latter. The portable apparatus comprises a memory device for storing the intracranial pressure samples, a microcontroller for controlling the intracranial pressure sampling parameters and means for programming said microcontroller. Said parameters are optimized on the basis of experimental results, in accordance with a preset resolution, in order to minimize the power consumption of the system. The system comprises a PC which can be used to process the intracranial pressure samples stored in the memory device of the portable apparatus and can assist with the medical diagnosis of pathologies associated with said recordings.

Description

Apparatus, procedure and system for outpatient registration and analysis of intracranial pressure, as well as for the automatic detection of associated pathologies.

The present invention relates to a portable device for ambulatory registration (that is, outside the hospital) of the intracranial pressure of a patient through a pressure sensor, which transmits the intracranial pressure signal to said portable device, and a system comprising the sensor and the portable device. It also refers to a procedure for outpatient recording of said intracranial pressure.

STATE OF THE PREVIOUS TECHNIQUE

Dementia is an extremely frequent pathology in the general population, with an approximate prevalence of 5% in people over 65 years of age and reaching rates above 30% in samples that exceed 80 years of age. From a health point of view, dementias are a problem of great importance, generating an important economic expense, both direct (the annual cost of health care for each patient diagnosed with dementia in the United States is around $ 20,000) and indirect, given The pressure to which the people who take care of these patients are subjected. Approximately 10% of dementias present an effective treatment, and the detection of these cases is one of the cornerstones in the usual procedure when a doctor confronts a patient to whom the initial diagnosis of dementia is made.

Chronic adult hydrocephalus accounts for 1 in 10 patients with treatable dementia, and as such should become part of the battery of differential diagnoses in which a doctor has to think when diagnosing a dementia. The syndrome was described in 1965 by Hakim and Adams with the name of normal pressure hydrocephalus as the clinical triad that associated dementia, gait apraxia and urinary incontinence, with the radiological finding of dilated ventricular cavities and a normal cerebrospinal fluid pressure lumbar puncture measurement. The treatment by ventricular shunt resulted in an amazing improvement of the operated patients, and the image of this disease was quickly spread among the medical community as one of the dementias with better treatment response However, the initial euphoria gave way to skepticism, since the series showed uneven improvement rates and the complications of the implantation of a derivative system exceeded the benefits obtained in not a few patients.

At this point, the search for diagnostic procedures that allow the identification of patients who, meeting the clinical criteria to be diagnosed of hydrocephalus at normal pressure, had an adequate response to surgical treatment began. One of the procedures that has shown greater sensitivity and specificity has been the continuous recording of intracranial pressure (ICP). The first contribution of this technique has been the finding that at least one third of the patients presented a pathological mean ICP (greater than 15 mm Hg), invalidating the single measurement of pressure through a lumbar puncture as a diagnostic measure and making that the term normal pressure hydrocephalus be put in between, and that a large part of the authors reached the consensus of changing their name to that of chronic adult hydrocephalus.

The second contribution, and more important, has been the objectification of pathological waves - described by Lundberg in patients affected by intracranial hypertension due to other pathologies - in patients diagnosed with chronic adult hydrocephalus with a good response to ventricular shunt, especially during the REM sleep. Several authors have confirmed the prediction of the percentage of Lundberg B waves in the entire plot on the patient's response to the liqueur derivation, since those patients who present more than 10% of B waves in the continuous path have a probability of improvement after implantation of a ventricular shunt greater than 75%.

In general, the monitoring of intracranial pressure has become a necessary tool for the diagnosis and treatment of certain pathologies of the central nervous system, such as cerebrovascular accidents, craniocerebral trauma, hydrocephalus and various forms of intracranial hypertension.

However, the methodological complexity of the continuous recording of PIC makes that only a few groups have converted it into a routine procedure for the detection of this pathology, since it requires hospitalization of the patient for a variable period of time between 48 hours and 5 days. It is also necessary personnel trained in the reading of said register capable of identifying B waves and plateaus. The whole process consumes excessive time and too many health resources.

In its patent application published under the number US 2003/0100845, Per Kristian Eide presents a pressure sensor connected to a portable device to monitor, sample and store the PIC, and a software for the analysis of the PIC. The process parameters can be set according to the registration period, up to 48 hours, and the heart rate variability.

DESCRIPTION OF THE INVENTION

An objective of the present invention is to provide an apparatus for recording the intracranial pressure of a patient with a great autonomy of operation, which allows monitoring of the ICP for a relatively long period of time and in a non-restrictive manner, that is, without interfering with the normal activities of the patient.

Another objective of the invention is to provide a system for the subsequent analysis of the registered PIC samples.

According to one aspect of the invention, the apparatus, which is portable and serves to record the intracranial pressure of a patient through a pressure sensor, comprises a microcontroller to sample and store the intracranial pressure signal, and means to configure the parameters of sampling in said microcontroller, so that said parameters are optimized based on experimental results, in accordance with a pre-established resolution, to minimize the energy consumption of the autonomous system, which allows to extend the period of the outpatient registration of the PIC.

In one embodiment, among the sampling parameters, the sampling frequency is set at a constant value throughout the outpatient registration process. In this way it is not necessary to manipulate it during the period of the outpatient registry or, consequently, that the portable device incorporates a clock, which also translates into energy savings.

The portable apparatus preferably comprises a memory device, which in turn comprises a first repository (archive) in which the sampling configuration parameters are stored, a second repository in which the set of acquired intracranial pressure samples is stored by the microcontroller, and a third repository in which the autocalibration data of the pressure sensor is stored.

In one embodiment, the memory device is a removable device, such as a memory card, that can be edited by another computer system.

In one embodiment, the portable device weighs less than 200 grams, including the weight of a box whose dimensions are smaller than 10 cm ^* 6 cm * 3 cm and in which said portable device is housed. Thus, the operation of the device is non-restrictive and the patient can carry out his daily activities.

According to another aspect of the invention, a procedure for outpatient registration of the intracranial pressure of a patient is performed by a portable device as described in the previous paragraphs.

In one embodiment, said method comprises the steps of: - calibrating a pressure sensor connected to the portable apparatus;

- store the calibration data of the pressure sensor in the third repository of the memory device of the portable device;

- capture intracranial pressure samples from the pressure sensor, in accordance with the sampling parameters contained in the first repository of the memory device;

- store intracranial pressure samples, taken on an outpatient basis for a period of time, in the second repository of the memory device.

The invention includes a computer program comprising program instructions that are executed in the portable apparatus of the preceding paragraphs to perform the described procedure. Said program It is stored in storage media, preferably in an internal memory of the microcontroller, and can be carried by a carrier wave.

In general terms, a system for the outpatient recording of a patient's intracranial pressure comprises the portable device described above and a pressure sensor that can transmit in the form of a signal samples of the intracranial pressure to said portable device, which controls the capture of samples by the sensor and stores said samples in the memory device.

Preferably, said system comprises a computer system by means of which the memory device of the portable device can be edited. Thanks to the intervention of this computer system, it is not necessary for the portable device to incorporate a keyboard or screen.

According to another aspect of the invention, a procedure for recording and analyzing the intracranial pressure of a patient comprises the steps of:

- connect an external memory device to a computer system; - editing by means of said computing system a first repository of the memory device for configuration of a microcontroller connectable to said memory device;

- disconnect the memory device from the computer system and connect it, if the connection is not permanent, to said microcontroller; - implant a pressure sensor inside the cranial cavity of the patient;

- connect said sensor to the microcontroller;

- register intracranial pressure samples taken over a period of time in a second repository of the memory device;

- disconnect the sensor from the microcontroller;

- connect the memory device to the computer system;

- process the samples stored in said second repository of the memory device in the computer system.

As mentioned, the memory device may be a removable card, for example, or it may be integrated in the portable device, in which In this case, the portable device would have a direct connection to the computer system, for example of the USB type, for access to the data in said memory.

In one embodiment, the stage of processing in the computer system the intracranial pressure samples stored in the second repository comprises the digital processing of the signal for the extraction of statistical, temporal and frequency parameters, from the set of intracranial pressure samples.

In one embodiment, the stage of processing in the computing system the intracranial pressure samples stored in the second repository comprises the temporal, frequency and time-frequency graphical representation of said samples, and the statistical analysis thereof, optionally through of said graphic representation.

In one embodiment, the stage of processing intracranial pressure samples stored in the second repository in the computer system comprises the detection of symptomatic patterns of pathologies and the estimation of a clinical diagnosis with probability indication.

The invention has an autonomy such that the Vcapa of ambulatory recording of intracranial pressure samples lasts at least 60 hours, preferably at least 72 hours.

The invention includes a computer program comprising program instructions that are executed in the computer system to perform this procedure.

In one embodiment, said program comprises artificial intelligence tools for the detection of B waves.

In one embodiment, the program includes artificial intelligence tools to provide assistance in the detection of pathological patterns in the tracing of intracranial pressure samples.

The program is stored in storage media, and is carried by a carrier wave.

BRIEF DESCRIPTION OF THE DRAWINGS

Next, some embodiments of the invention will be described, by way of non-limiting example, with reference to the accompanying drawings, in which:

Figure 1A is a temporary graphic representation of a traditional analog PIC register;

Figure 1B is a temporary graphic representation of a PIC record obtained with the system of the invention; Y

Figure 2 is a graph of the power spectrum of a PIC signal obtained with the system of the invention.

DESCRIPTION OF PREFERRED EMBODIMENTS

A system for recording and processing intracranial pressure signals (PIC) comprises a portable device that is capable of recording PIC signals, from a standard sensor or probe implanted in the patient's skull, in a memory device, preferably A card from the device itself. The information stored in this memory is transferred to a computer or computer system, preferably a PC, for further processing by specific software.

The sensor may be based on a Wheatstone bridge.

The portable device comprises a microcontroller, provided with an analog to digital signal converter, specifically programmed for the correct acquisition of intracranial pressure signals and their storage in the memory device. The portable device may comprise hardware for the necessary conditioning of the signal from the sensor, or the microcontroller may include software for this purpose. The memory device is externally accessible for dump into the computer, which comprises software specifically developed for the subsequent processing of PIC signals, either by inserting said device into a memory reader, either by means of a USB connection between The portable device and the computer.

The microcontroller software is responsible for sampling the intracranial pressure signal at a frequency that allows, in subsequent processing, the extraction of the most significant characteristics of this signal, such as average, maximum values, deviations, etc., as well as the detection of the presence of B waves. This software can also be responsible for transferring the recorded data to the memory device.

The memory device comprises a first file in which the samples of the PIC signal are stored, a second file in which the sampling configuration parameters are stored, and a third file in which the self-calibration data of the sample is stored. sensor.

The portable device and the sensor are powered by a battery with high charge capacity and small size. The sampling parameters of the PIC signal, for example the sampling frequency, are calculated by means of an optimization algorithm whose objective is the minimization of the energy consumption of the whole of the portable apparatus and the sensor, with the condition that they must be suitable for Provide a preset resolution.

This optimization is based on experimental results related to the energy consumption of the set with different sampling configurations. The reduction in energy consumption makes it possible to extend the duration of the outpatient registration of the ICP to 60 or more hours, preferably up to at least 72 hours.

Thus, the portable device is configurable in the sense that the sampling parameters are programmable, but since this configuration is not manual, the device does not require keys or buttons, nor a screen with information on data capture or on the configuration of data. said capture, neither alarm nor real time clock.

By not having all these elements, the portable device is designed to effectively consume little energy, which allows the duration of the logs to be maximized. The sensor and the portable device can be powered at a voltage of less than 3.5 volts. The portable device, including the battery, is housed in a box that provides electrical insulation for possible electromagnetic interference. The approximate dimensions of the box are 10 cm • 6 cm - 3 cm, and it can be provided with connectors for the sensor and for the external charger of the battery. The box can also comprise an insertion slot of the memory card, a general power switch and an initialization / calibration button. You can also incorporate luminous indicators of operation and charge level of the battery.

The memory could also be non-removable, and in this case the portable device would have a connection to a PC, for example USB, for access to the data in that memory.

The outpatient recording system of the intracranial pressure is complemented with software stored in the computer, which allows the configuration of the acquisition of samples of the ICP, the formatting of the memory device and the dump of the data to the computer. Once the data is transferred, the computer software is capable of processing the PIC signals to obtain its most significant parameters, as well as automatically detecting the presence of B waves by signal processing, and also providing a help tool. to clinical diagnosis using artificial intelligence techniques.

To facilitate the analysis of the F ³ IC register, the computer software allows the on-screen graphic presentation and printing on a conventional printer of the PIC records in the format accepted as standard by neurologists and neurosurgeons, to facilitate interpretation without additional preparation. This is achieved technically by means of a signal processing that provides characteristics similar to those of the hardware filter that has been used so far, eliminating the need for its use.

The temporary graphic representation of the P! C register, also called "plotting", is performed according to the interpretation standards of the analog register. An emulation of the analogue inscriber is performed in such a way that a 1 mm Hg corresponds to 1 rnm on the screen, and that one hour of Registration is represented on 20, 30 or 60 cm screen. This is the standard of analog graphic representation accepted in the field of neurosciences.

In this way, the layout obtained with the system of the invention is substantially identical to the standard representation obtained by Lundberg with an analog monitor and an analog pen recorder. In Figure 1A a traditional analog plot is represented according to the Lundberg standard, and in Figure 1 B the plot obtained for the same PIC recording session is represented by the system of the invention.

Figure 2 shows a spectrum of powers of the ICP signal in a patient affected by chronic adult hydrocephalus obtained through the autonomous system of the invention by applying the fast Fourier transform. The X interval ranges from 0.008 Hz to 0.05 Hz and includes B waves; the Y range ranges from 0.15 Hz to 0.5 Hz and includes the waves due to the breath; and the Z range ranges from 0.6 Hz to 3 Hz and includes the waves due to the heart rate.

The computer software may include a functional management of a patient database, with the pertinent clinical information.

As explained, the system of the invention is specifically designed so that the surgical implantation of a traditional ICP sensor is possible and that the patient is discharged from the hospital, the ICP data being acquired through the sensor and the microcontroller during the minus 60 hours, preferably 72, at the patient's home, while the patient performs the activities of his daily life. After the patient is evaluated in external consultations, the sensor is explanted and the resulting plot is evaluated by means of the specific software of the computer, avoiding the patient's admission to the hospital.

The action procedure begins by editing the memory device configuration file of the portable device using the computer. Then the pressure sensor is connected to the portable device and it is started for self-calibration. Once the sensor is implanted in the patient, the portable device is ready to record and store the values of the intracranial pressure in the memory device. Once the PIC capture process is finished, the memory device is connected to the computer, in which the PIC signal analysis and treatment software is installed, including the intelligent clinical diagnostic support system. The software allows the calculation of statistical parameters of the PIC registry performed, the graphic representation in the domains of time, frequency and time-frequency thereof, the detection of symptomatic patterns of pathologies, and the estimation of a clinical diagnosis with indication of probability .

The computer software may also include artificial intelligence tools for the detection of E3 waves, and to provide assistance in the detection of pathological patterns in the plotting of ICP samples.

Although only particular embodiments of the invention have been represented and described herein, the person skilled in the art will know how to introduce modifications and replace some technical characteristics with equivalent ones, depending on the requirements of each case ?, without separating from the defined scope of protection by the appended claims.

Claims

1. Portable device for ambulatory recording of a patient's intracranial pressure through a pressure sensor, characterized by the fact that it comprises a microcontroller to sample and store the intracranial pressure signal, and means to configure the sampling parameters in said microcontroller, so that said parameters are optimized based on experimental results, in accordance with a preset resolution, to minimize the energy consumption of the autonomous system.

2. Portable device according to claim 1, characterized in that, among the sampling parameters, the sampling frequency is set at a constant value throughout the outpatient registration process.

3. Portable device according to claim 1 or 2, characterized in that it comprises a memory device, which comprises a first repository in which the sampling configuration parameters are stored, a second repository in which the set of intracranial pressure samples acquired by the microcontroller, and a third repository in which the autocalibration data of the pressure sensor is stored.

4. Portable device according to claim 3, characterized in that the memory device is a removable device.

5. Portable device according to any of the preceding claims, characterized in that the portable device weighs less than 200 grams, including the weight of a box whose dimensions are smaller than 10 cm * 6 cm ^* 3 cm and in which it houses said portable device.

6. Procedure for outpatient registration of the intracranial pressure of a patient, which is performed by a portable device according to any of claims 1 to 5.

7. Method according to claim 6, characterized in that it comprises the steps of:

- calibrate a pressure sensor connected to the portable device; - store the calibration data of the pressure sensor in the third repository of the memory device of the portable device,

- capture the intracranial pressure samples from the pressure sensor, in accordance with the sampling parameters contained in the first repository of the memory device;

8. Computer program comprising program instructions that are executed in a portable device according to any of claims 1 to 5 to perform the method according to claim 7.

9. Computer program according to claim 8, characterized in that it is stored in storage media.

10. Computer program according to claim 9, characterized in that it is stored in an internal memory of the microcontroller.

11. Computer program according to claim 8, characterized in that it is carried by a carrier wave.

12. System for the outpatient recording of the intracranial pressure of a patient, comprising a pressure sensor that can transmit in the form of a signal samples of the intracranial pressure, characterized in that it comprises a portable device according to any of claims 1 to 5, which can be connected to said sensor to control the capture of samples and store said samples.

13. System according to claim 12, characterized in that it comprises a computer system by means of which the memory device of the portable device can be edited.

14. Procedure for recording and analyzing the intracranial pressure of a patient, characterized by the fact that it comprises the stages of:

- connect an external memory device to a computer system;

- edit through said computer system a first repository of the memory device for configuring a microcontroller connectable to said memory device;

- connect said sensor to the microcontroller;

- disconnect the sensor from the microcontroller;

- connect the memory device to the computer system;

15. Method according to claim 14, characterized in that the stage of processing in the computer system the intracranial pressure samples stored in the second repository comprises the digital processing of the signal for the extraction of statistical, temporal and frequency parameters , from the set of intracranial pressure samples.

16. Method according to claim 14 or 15, characterized in that the stage of processing in the computer system the intracranial pressure samples stored in the second repository comprises the temporal, frequency and time-frequency graphical representation of said samples , and the statistical analysis of them.

17. Method according to any of claims 14 to 16, characterized in that the stage of processing in the computer system the intracranial pressure samples stored in the second repository comprises the detection of symptomatic patterns of pathologies and the estimation of a clinical diagnosis with indication of probability.

18. Method according to any of claims 14 to 17, characterized in that the step of registering outpatients Intracranial pressure samples have a duration of at least 60 hours.

19. Method according to claim 18, characterized in that the step of registering intracranial pressure samples outpatiently has a duration of at least 72 hours.

20. Computer program comprising program instructions that are executed in the computer system to perform the method according to any of claims 15 to 17.

21. Computer program according to claim 20, characterized in that it comprises artificial intelligence tools for the detection of B waves.

22. Computer program according to claim 20 or 21, characterized in that it comprises artificial intelligence tools to provide assistance in the detection of pathological patterns in the tracing of intracranial pressure samples.

23. Computer program according to any of claims 20 to 22, characterized in that it is stored in storage means.

24. Computer program according to any of claims 20 to 22, characterized in that it is carried by a carrier wave.