Classifications

• • G—PHYSICS
  • G06—COMPUTING OR CALCULATING; COUNTING
  • G06F—ELECTRIC DIGITAL DATA PROCESSING
  • G06F17/00—Digital computing or data processing equipment or methods, specially adapted for specific functions
  • G06F17/10—Complex mathematical operations
  • G06F17/14—Fourier, Walsh or analogous domain transformations, e.g. Laplace, Hilbert, Karhunen-Loeve, transforms
  • G06F17/141—Discrete Fourier transforms
  • G06F17/142—Fast Fourier transforms, e.g. using a Cooley-Tukey type algorithm
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B5/00—Measuring for diagnostic purposes; Identification of persons
  • A61B5/02—Detecting, measuring or recording for evaluating the cardiovascular system, e.g. pulse, heart rate, blood pressure or blood flow
  • A61B5/021—Measuring pressure in heart or blood vessels
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B5/00—Measuring for diagnostic purposes; Identification of persons
  • A61B5/02—Detecting, measuring or recording for evaluating the cardiovascular system, e.g. pulse, heart rate, blood pressure or blood flow
  • A61B5/021—Measuring pressure in heart or blood vessels
  • A61B5/02108—Measuring pressure in heart or blood vessels from analysis of pulse wave characteristics
  • A61B5/02125—Measuring pressure in heart or blood vessels from analysis of pulse wave characteristics of pulse wave propagation time
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B5/00—Measuring for diagnostic purposes; Identification of persons
  • A61B5/03—Measuring fluid pressure within the body other than blood pressure, e.g. cerebral pressure ; Measuring pressure in body tissues or organs
  • A61B5/031—Intracranial pressure
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B5/00—Measuring for diagnostic purposes; Identification of persons
  • A61B5/72—Signal processing specially adapted for physiological signals or for diagnostic purposes
  • A61B5/7235—Details of waveform analysis
  • A61B5/7253—Details of waveform analysis characterised by using transforms
  • A61B5/7257—Details of waveform analysis characterised by using transforms using Fourier transforms

Definitions

• the present invention relates to the field of methods and equipment for the analysis of biological signals representative of variations in intracranial pressure and blood pressure, and for the latter in particular in the skull.
• the purpose of such analysis is to assist the clinician in-interpreting the data provided by sensors providing 'signals representative of the intracranial pressure.
• ICP - intracranial Pressure ICP - intracranial Pressure
• related signals blood pressure, speed of arterial or venous circulation, and gas concentrations.
• the PCT patent WO132076 describes for example a monitoring device making it possible to determine a physiological parameter in a patient.
• This apparatus includes a calibration device configured to provide a calibration signal representative of the physiological parameter.
• a non-invasive sensor is placed on the vessel, this non-invasive sensor being configured to detect a blood parameter and to produce a signal representative of the blood parameter.
• a blood parameter such as blood pressure, flow, volume, speed, movement and position of the vessel wall and other related parameters.
• a processor is configured to determine the relationship between a characteristic of the received exciter wave and a characteristic of the physiological parameter.
• PCT patent WO9849934 describes an apparatus and a non-invasive method for measuring intracranial pressure.
• the measurement system emits acoustic signals passing through the skull by means of the transmitters and provides an indication of the intracranial pressure as a function of the acoustic signal received after interaction with the brain. Properties such as acoustic transmission impedance, resonant frequency, resonant characteristics, speed of sound, and the like can be measured and correlated with intracranial tension.
• Acoustic signals have, for example, characteristic frequencies of less than 100 kHz, in the audible and infrasonic ranges. The intensity of the acoustic signal used to measure intracranial tension is relatively low, with little or no health hazards during short or long exams.
• PCT patent WO068647 relates to a method for non-invasively monitoring the intracranial pressure of a patient.
• said anatomical characteristic is the third cerebral ventricle.
• a quantitative measurement of intracranial pressure is inferred from at least two diagnostic characteristics, such as hours of diagnosis, associated with the oscillogram.
• a qualitative measurement of the intracranial pressure is obtained from the shape of the respiratory curve imposed on the wave train by the patient's breathing.
• PCT patent WO9926529 describes a fast Fourier transform processing unit applied to frequency analysis at a waveform (MHj) without body movement and provides waveform analysis data (MKD).
• MHj waveform
• MKD waveform analysis data
• a falling wave extraction unit and a wave extraction unit linked to an incision provide tide wave data (TWD) and dicrotic wave data linked to an incision respectively.
• DWD dicrotic wave data linked to an incision.
• a pulse assessment unit provides pulse state (ZD) data based on the TWD and DWD data, whereby a reporting unit reports on the subject's pulse state.
• the invention aims to remedy this problem by proposing a system for the representation and analysis of pressure variables comprising pressure sensors
• Frequency analysis to extract information relating to slow waves constitutes an essential improvement of the equipment of the prior art, because it offers the clinician new possibilities of interpretation.
• the frequency analysis means are constituted by a computer applying a Fast Fourier transform (FFT).
• the frequency analysis means consist of a computer applying a wavelet analysis.
• said range of recorded target frequencies comprises frequencies between 8.10 "3 Hertz and 50.10 " 3 Hertz.
• the system comprises a sampling circuit performing a sampling of each of the input signals at a first frequency, and a resampling circuit at a sampling frequency lower than the first frequency, for recording of time-stamped signals in a memory.
• it comprises a local signal acquisition and processing module and at least one remote monitoring station connected to said local acquisition module by a telecommunications network.
• the invention also relates to a method for analyzing biological pressure signals comprising a sampling step characterized in that it further comprises a step of frequency analysis with respect to a range of target frequencies corresponding to slow waves of type B and UB.
• the method further comprises a step of determining the time offset between the signals corresponding to two separate inputs.
• FIG. 1 shows a schematic view of a system according to the invention
• FIG. 2 represents a view of a screen for displaying the information displayed by the system
• the equipment according to the invention is composed of three main modules: an acquisition module (1), generally placed close to the patient - a treatment module (2), generally placed at the clinician, an operating module and display which can be placed close to the patient in the form of equipment (3), or in the form of a local workstation (4) connected to the treatment module by an internal network or even be constituted by a workstation remote work station (5) connected to the processing module (2) by a telecommunications network, for example the Internet.
• the first module (1) has a plurality of input channels, for receiving signals from different pressure sensors: arterial blood pressure sensor (ABP) cerebral blood pressure sensor (CBF) sensor intracranial pressure (ICP - intracranial pressure).
• ABSP arterial blood pressure sensor
• CBF cerebral blood pressure sensor
• ICP - intracranial pressure ICP - intracranial pressure
• the module (1) has 8 channels. It comprises an 8-channel input-output interface circuit (6) delivering a reference signal and analog signals corresponding to the different channels, in parallel or multiplexed form. The analog signals are then sampled by a circuit (7) controlled by a clock (8). Each signal is preferably sampled at 100 samples per second.
• the module also includes means for entering free information in the form of a marker. This information is associated with the recorded information, to describe for example an event, or to annotate the curve of one of the signals observed.
• the analysis module (2) performs a frequency analysis of the signals sampled from a target frequency chosen from: slow waves of type "B", corresponding to a frequency between
• Frequency analysis can be performed by a Fast Fourier transform (FFT).
• FFT Fast Fourier transform
• Discrete (DCT) characterizes each frequency by multiplying the input signal by an example of the target frequency or basic function, chosen from the frequencies of slow waves, and by integrating the product obtained.
• DSP electronic circuits
• samplingRate a sampling rate determined by the clinician, by selection of one of the frequencies of slow waves observed.
• the parameter N of the number of samples in the analyzed record is predetermined, for example 256, or variable by choice of the user.
• Discrete Fourier transform algorithms convert a function of time with complex sampled values into a function with complex values of frequency, also sampled. They provide information such as:
• the table of sinus coefficients in the Fourier formula (imaginary part of the result). * The first output element of each table contains the average value of all the inputs. The variant of this element is displayed on a monitor, and is the subject of comparative processing from one signal to another.
• Slow waves are extracted from the amplitude (and power) spectrum and are carried out by detecting the frequency (F) whose amplitude (or the power) is maximum (P) for the frequency bands B, UB, and IB.
• the analysis module (2) comprises means for calculating the offset between the slow waves of two signals, and for representing these offsets on the display of a monitor.
• FIG. 2 represents the view of a display screen coming from a system according to the invention.
• the screen is subdivided into a plurality of display zones for the representation: of the temporal variation of the intracranial pressure (zone (20)) of the temporal variation of the arterial pressure (zone (21)) of the variation of the component corresponding to the slow wave B, with a curve (22) corresponding to the frequency in millihertz and a curve (23) corresponding to the amplitude of the pressure of the correlation rate between the intracranial pressure signals (or of the circulatory velocity (20) and arterial pressure (21), in the form of the curve (24) of the time offset between the slow waves of the intracranial pressure or circulatory velocity (20) and arterial pressure (21) signals, in the form of the curve (25)

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• 2002
  • 2002-07-23 EP EP02774824A patent/EP1416848A1/de not_active Withdrawn
  • 2002-07-23 US US10/484,566 patent/US7160250B2/en not_active Expired - Fee Related
  • 2002-07-23 CA CA002455397A patent/CA2455397A1/fr not_active Abandoned
  • 2002-07-23 WO PCT/FR2002/002633 patent/WO2003009756A1/fr not_active Ceased

Non-Patent Citations (1)

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