Method for analysis of single pulse pressure waves

Abstract

This invention relates to a method for analysing pressure-signals derivable from pressure measurements on or in a body of a human being or animal, comprising the steps of identifying during given time sequences in a series of time sequences the single pressure waves, including related parameters [pressure amplitude ΔP latency (ΔT), rise time coefficient (ΔP/ΔT)], determining numbers of single pressure waves with pre-selected combinations of two or more of said single pressure wave parameters during said time sequence. For the time sequences is further determined the balanced positions of single wave parameters. Two-dimensional values of balanced position may be presented as a one dimensional value after weighting of the matrix cells. The signal processing method may be used for more optimal detection of single pressure waves by means of non-invasive sensor devices.

1 . A method for analysing pressure-signals derivable from pressure measurements on or in a body of a human being or animal, comprising the steps of sampling said signals at specific intervals and converting the pressure-signals into pressure related digital data with a time reference, 
 wherein for selectable time sequences the method further comprises the steps of    a) identifying from said digital data single pressure waves related to cardiac beat-induced pressure waves,    b) computing time sequence parameters of said single pressure waves during individual of said time sequence,    c) establishing an analysis output selected from one or more of said time sequence parameters of said single pressure waves during individual of said time sequences:    c1)—absolute mean pressure for each identified single pressure wave (wavelength P min -P min ) within said time sequence,    c2)—mean of mean pressure for all identified single pressure waves (wavelength P min -P min ) within said time sequence,    c3)—standard deviation of absolute mean pressure for all identified single pressure waves (wavelength P min -P min ) within said time sequence,    c4)—number of single pressure waves during said time sequence,    c5)—single pressure wave derived heart rate during said time sequence,    c6)—relative pressure amplitude (ΔP) value for each identified single pressure wave (wavelength P min -P min ) within said time sequence,    c7)—standard deviation of relative pressure amplitude (ΔP) values for all identified single pressure waves (wavelength P min -P min ) within said time sequence,    c8)—relative latency (ΔT) value for each identified single pressure wave (wavelength P min -P min ) within said time sequence,    c9)—standard deviation of relative latency (ΔT) values for all identified single pressure waves (wavelength P min -P min ) within said time sequence,    c10)—rise time (ΔP/ΔT) coefficient for each identified single pressure wave (wavelength P min -P min ) within said time sequence,    c11)—standard deviation of rise time (ΔP/ΔT) coefficients for all identified single pressure waves (wavelength P min -P min ) within said time sequence,    c12)—balanced position within a first matrix for combinations of single pressure wave amplitude (ΔP) and latency (ΔT) values within said time sequence,    c13)—balanced position within a second matrix for combinations of single pressure wave rise-time (ΔP/ΔT) coefficient values within said time sequence,    d) establishing a deliverable first control signal related to an analysis output in step c) for a selectable number of said time sequence windows, said first control signal being determined according to one or more selectable criteria for said analysis output, and    e) modifying said deliverable first control signal into a regulator deliverable second control signal said second control signal corresponding to said first deliverable control signal, and    f) to provide a performance modifying signal.    
   
   
       2 . A method according to  claim 1 , wherein each of said selectable time sequences is a selected time duration of said pressure-related digital data with a time reference.  
   
   
       3 . A method according to  claim 1 , wherein said selected time duration lies in the range 3-15 seconds.  
   
   
       4 . A method according to anyone of  claim 1 , wherein the method is applied to each of said selectable time sequences in a continuous series of said time sequences during a recording.  
   
   
       5 . A method according to  claim 1 , wherein said identifying step a) includes identification of peaks and valleys in said sampled signal.  
   
   
       6 . A method according to  claim 1 , wherein all minimum and maximum values are identified and represented with an amplitude value and a location value or time stamp.  
   
   
       7 . A method according to  claim 1 , wherein said identifying step a) includes identification of included pair combinations of peaks and valleys in said signal.  
   
   
       8 . A method according to  claim 2 , wherein said identifying step a) includes identification of included pair combinations of valleys and peaks in said signal, corresponding to included pair combinations of diastolic minimum pressure (P min ) and systolic maximum pressure (P max ), characterizing single pressure waves created by the cardiac beat-induced pressure waves.  
   
   
       9 . A method according to  claim 1 , wherein said identifying step a) excludes for further analysis pressure waves during said time sequences with single pressure wave parameters outside selected criteria for thresholds and ranges of said parameters, said parameters selected from the group of: 
 starting diastolic minimum pressure defining the start of the single pressure wave (P min ),    ending diastolic minimum pressure defining the end of the single pressure wave (P min ),    systolic maximum pressure of the single pressure wave (P max ), amplitude of the single pressure wave (ΔP),    latency of the single pressure wave (ΔT),    rise time coefficient of the single pressure wave (ΔP/ΔT),    wave duration of the single pressure wave, and    absolute mean pressure of said single pressure wave.    
   
   
       10 . A method according to  claim 1 , wherein said identifying step a) includes for further analysis single pressure waves having single pressure wave parameters within selected criteria for thresholds and ranges of said single pressure wave parameters.  
   
   
       11 . A method according to  claim 1 , wherein said identifying step a) excludes for further analysis time sequences with time sequence parameters outside selected criteria for thresholds and ranges of said parameters, said parameters selected from the group of: 
 number of single waves (N SW ),    single pressure wave derived heart rate,    absolute mean pressure,    standard deviation for mean pressure of mean pressure for the individual single waves,    standard deviation for diastolic minimum (P min ),    standard deviation for systolic maximum (P max ),    standard deviation for amplitude (ΔP) of all individual single pressure waves,    standard deviation for latency (ΔT) of all individual single pressure waves,    standard deviation for rise time coefficient (ΔP/ΔT) of all individual single pressure waves,    balanced position of amplitude (ΔP)/latency (ΔT) combinations,    balanced position of rise time coefficients (ΔP/ΔT).    
   
   
       12 . A method according to  claim 1 , wherein said identifying step a) includes for further analysis time sequences having time sequence parameters within selected criteria for thresholds and ranges of said time sequence parameters.  
   
   
       13 . A method according to  1 , wherein said identifying step a) is applied to each consecutive time sequence in a continuous series of time sequences of a signal.  
   
   
       14 . A method according to  claim 1 , wherein said identifying step a) further includes selecting single pressure waves which occur between two consecutive ones of said time sequences and placing such waves in one or the other of said two consecutive individual time sequences according to selected criteria.  
   
   
       15 . A method according to  claim 14 , wherein said selected criteria define that a first one of said single pressure waves within said individual time sequence has its ending diastolic minimum pressure value (P min ) within said individual time sequence.  
   
   
       16 . A method according to  claim 15 , wherein said selected criteria define that a last one of said single pressure waves within said individual time sequence has both its starting (P min ) and ending (P min ) diastolic minimum pressure values within said individual time sequence window.  
   
   
       17 . A method according to  claim 1 , wherein said computing step b) for accepted time sequences further includes determining said time sequence parameters, said parameters selected from the group of: 
 number of single waves (N SW ),    single pressure wave derived heart rate,    absolute mean pressure,    standard deviation for mean pressure of mean pressure for the individual single waves,    standard deviation for diastolic minimum (P min ),    standard deviation for systolic maximum (P max ),    standard deviation for amplitude (ΔP) of all individual single pressure waves,    standard deviation for latency (ΔT) of all individual single pressure waves,    standard deviation for rise time coefficient (ΔP/ΔT) of all individual single pressure waves,    balanced position of amplitude (ΔP)/latency (ΔT) combinations,    balanced position of rise time coefficients (ΔP/ΔT).    
   
   
       18 . A method according to  claim 1 , wherein said establishing step c) includes determining balanced position of amplitude (ΔP)/latency (ΔT) combinations, said determining comprising the steps of creating a first matrix based on determining number of single pressure waves with pre-selected values related to amplitude (ΔP) and latency (ΔT), one axis of said first matrix being related to an array of pre-selected values of pressure amplitude (ΔP) and the other axis of said first matrix being related to an array of pre-selected values of latencies (ΔT), and indicating for each matrix cell at respective intersections in said first matrix a number of occurrences of matches between a specific pressure amplitude (ΔP) and a specific latency (ΔT) related to successive measurements of single pressure waves over said individual time sequences.  
   
   
       19 . A method according to  claim 18 , wherein the single pressure wave parameters of amplitude (ΔP) and latency (ΔT) are categorized into groups, said groups reflecting ranges of said single wave parameter values.  
   
   
       20 . A method according to  claim 18 , wherein the occurrence of matches in said first matrix is indicated through actual number of matches during individual of said time sequence windows.  
   
   
       21 . A method according to  claim 18 , comprising the further step of computing balanced position for a number of occurrences of said single pressure wave parameters of amplitude (ΔP) and latency (ΔT) values during individual of said time sequences in said first matrix.  
   
   
       22 . A method according to  claim 21 , wherein said balanced position of said first matrix of numbers of amplitude (ΔP) and latency (ΔT) combinations corresponds to mean frequency distribution of the different occurrences of amplitude (ΔP) and latency (ΔT) during said individual time sequences.  
   
   
       23 . A method according to  claim 1 , wherein said establishing step c) includes determining balanced position of rise time coefficients (ΔP/ΔT), said determining comprising the steps of creating a second matrix based on determining number of single pressure waves with pre-selected values related to rise time coefficient (ΔP/ΔT), the axis in said second matrix being related to an array of pre-selected values of rise time coefficient (ΔP/ΔT), and wherein for each matrix cell in said second matrix indicating a number of occurrences of pre-selected rise time coefficients (ΔP/ΔT) related to successive measurements of single pressure waves during said individual time sequences.  
   
   
       24 . A method according to  claim 23 , wherein the single pressure wave parameter rise time coefficient (ΔP/ΔT) is categorized into groups, said groups reflecting ranges of said single wave (ΔP/ΔT) parameter values.  
   
   
       25 . A method according to  claim 23 , comprising the further step of computing balanced position for a number of occurrences of said single pressure wave parameter rise time coefficient (ΔP/ΔT) in said second matrix, to yield an analysis output.  
   
   
       26 . A method according to  claim 25 , wherein said balanced position of said second matrix of numbers of rise time coefficient (ΔP/ΔT) combinations corresponds to the mean frequency distribution of rise time coefficient (ΔP/ΔT) of said time sequence.  
   
   
       27 . A method according to  claim 1 , wherein said establishing step c) yields analysis output related to the parameter c2) mean of mean pressure for said single pressure waves of said time sequence, corresponding to the sum of mean pressure values for all individual single pressure waves during said time sequence divided by number of said individual single pressure waves during said individual time sequence.  
   
   
       28 . A method according to  claim 1 , wherein the parameter c1) absolute mean pressure for an individual of said single pressure waves is the sum of sample values during the time of a wave duration, i.e. from starting diastolic minimum pressure (P min ) to ending diastolic minimum pressure (P min ) divided by number of samples.  
   
   
       29 . A method according to  claim 11 , wherein said establishing step c) yields output of analysis of one or more of parameters c1)-c13) during each individual of said time sequence windows in a continuous series of said time sequence windows of said pressure-related signal.  
   
   
       30 . A method according to  claim 1 , wherein the duration of each selectable time sequence window lies in a time range of 3-15 seconds.  
   
   
       31 . A method according to  claim 1 , wherein said establishing step c) relates to obtaining an analysis output based on said time sequence parameters for a selectable number of said individual time sequence windows.  
   
   
       32 . A method according to  claim 1 , wherein said analysis output is a mean value of balanced position of amplitude (ΔP)/latency (ΔT) combinations for a selectable number of said individual time sequence windows.  
   
   
       33 . A method according to  claim 1 , wherein said analysis output is a mean value of balanced position of rise-time (ΔP/ΔT) coefficient values for a selectable number of said individual time sequence windows.  
   
   
       34 . A method according to  claim 1  wherein said analysis is performed by a processing unit, said processing unit delivering a first control signal to a regulator, said first control signal being determined according to selectable criteria for output of said analysis.  
   
   
       35 . A method according to  claim 1 , wherein output of said analysis of single pressure wave related digital data for a given time sequence yields modification of said deliverable first control signal  
   
   
       36 . A method according to  claim 1 , wherein features of said first control signal are selectable when output of said single pressure wave analysis derivable from a subsequent pressure monitoring meet specific criteria.  
   
   
       37 . A method according to  claim 1 , wherein said selected criteria of single pressure wave related parameters relate to criteria for optimum single pressure wave detection.  
   
   
       38 . A method according to  claim 1 , wherein said selectable first control signal is determined during each individual time sequence in a continuous series of time sequences, according to output of said single pressure wave analysis for each time sequence in said continuous series of time sequences.  
   
   
       39 . A method according to  claim 1 , wherein said first control signal is converted within a regulator to a deliverable second control signal, said selectable second control signal corresponding to said selectable first control signal.  
   
   
       40 . A method according to  claim 39 , wherein said regulator deliverable second control signal provides a performance modifying signal, said performance modifying signal causing modifications in the performance of a sensor-regulating device.  
   
   
       41 . A method according to  claim 40 , wherein said sensor-regulating device is adjustable according to a regulator deliverable second control signal.  
   
   
       42 . A method according to  claim 40 , wherein said sensor-regulating device modifies the mode by which the sensor is able to sample signals indicative of pressure.  
   
   
       43 . A method according to  claim 1 , wherein there is feedback between a processing unit performing single pressure wave analysis controlling a deliverable first control signal to a regulator, and a regulator controlling a deliverable second control signal to a sensor-regulating device, said feedback signal being restorable at selected intervals during an ongoing pressure measurement.  
   
   
       44 . A method according to  claim 43 , wherein output of said single pressure wave analysis for a given time sequence is related to said second deliverable control signal.  
   
   
       45 . A method according to claims  44 , wherein output of said single pressure wave analysis is determined for each individual time sequence during a series of continuous time sequences, wherein said second control signal is modified to another level between each of said individual time sequences, and the level of said second control signal is related to said analysis output for each of said time sequences.  
   
   
       46 . A method according to claims  44 , wherein said first control signal is determined according to said second control signal, or said second control signal is determined according to said first control signal.  
   
   
       47 . A method according to  claim 1 , wherein the deliverable first and second control signals relate to output of said single pressure wave analysis indicative of optimum single pressure wave detection, said first and second control signals being used during the subsequent pressure monitoring.  
   
   
       48 . A method according to  claim 1 , wherein said human or animal body pressure is one or more of intracranial pressure, arterial blood pressure, cerebrospinal fluid pressure, cerebral perfusion pressure, ocular pressure, gastrointestinal pressure, urinary tract pressure, or any type of soft tissue pressure.  
   
   
       49 . A system for analysing pressure-signals derivable from pressure measurements on or in a body of a human being or animal, said system comprising: 
 a) control means which on basis of said pressure signals receivable from a pressure sensor via pressure transducer means is configured to control performance of a pressure sensor regulating device to optimize single pressure wave detection,    b) a processing unit having means for analyzing said pressure signals, said processing unit including sampling means for sampling said pressure signals at specific intervals,    c) converter means for converting the sampled pressure signals into pressure related digital data with a time reference,    d) identifying means operative during selectable time sequences to identify from said digital data single pressure waves related to one of: cardiac beat-induced pressure waves, artifacts, and a combination of cardiac beat-induced waves and artifacts,    e) analyzing means for analysis of said digital data single pressure waves during said selectable time sequences,    f) output means configured to output to a regulator device one or more first control signals derivable from one or more time sequence parameters related to a selectable number of time sequences elected from the group of: 
 f1) absolute mean pressure for each identified single pressure wave (wavelength P min -P min ) within said time sequence,  
 f2) mean of mean pressure for all identified single pressure waves (wavelength P min -P min ) within said time sequence,  
 f3) standard deviation of absolute mean pressure for all identified single pressure waves (wavelength P min -P min ) within said time sequence,  
 f4) number of single pressure waves during said time sequence,  
 f5) single pressure wave derived heart rate during said time sequence,  
 f6) relative pressure amplitude (ΔP) value for each identified single pressure wave (wavelength P min -P min ) within said time sequence,  
 f7) standard deviation of relative pressure amplitude (ΔP) values for all identified single pressure waves (wavelength P min -P min ) within said time sequence,  
 f8) relative latency (ΔT) value for each identified single pressure wave (wavelength P min -P min ) within said time sequence,  
 f9) standard deviation of relative latency (ΔT) values for all identified single pressure waves (wavelength P min -P min ) within said time sequence,  
 f10) rise time (ΔP/ΔT) coefficient for each identified single pressure wave (wavelength P min -P min ) within said time sequence,  
 f11) standard deviation of rise time (ΔP/ΔT) coefficients for all identified single pressure waves (wavelength P min -P min ) within said time sequence,  
 f12) balanced position within a first matrix for combinations of single pressure wave amplitude (ΔP) and latency (ΔT) values within said time sequence, and  
 f13) balanced position within a second matrix for combinations of single pressure wave rise-time (ΔP/ΔT) coefficient values within said time sequence, and  
   g) regulator means connectable to said processing unit for receiving at least one of said first control signals, said regulator means being capable of establishing a device performance modifying second control signal by means of at least one of said first control signals or establishing a combination effect obtained from using at least two of said first control signals, wherein said performance modifying second control signal deliverable from said regulator means being capable of controlling said sensor regulating device.    
   
   
       50 . A system according to  claim 49 , wherein said sensor provides for sensing pressure signals related to arterial blood pressure.  
   
   
       51 . A system according to  claim 49 , wherein said sensor provides for sensing pressure signals related to ocular bulb pressure.  
   
   
       52 . A system according to  claim 49 , wherein said sensor provides for sensing pressure signals related to intracranial pressure.  
   
   
       53 . A system according to  claim 49 , wherein said pressure-signals are arterial applanation pressure signals, being transformable into pressure signals indicative of arterial blood pressure signals.  
   
   
       54 . A system according to  claim 49 , wherein said pressure signals are ocular applanation pressure signals, being transformable into pressure signals indicative of ocular bulb pressure signals.  
   
   
       55 . A system according to  claim 49 , wherein said pressure-signals are fontanel applanation pressure signals, being transformable into pressure signals indicative of intracranial pressure signals.  
   
   
       56 . A system according to  claim 49 , wherein said pressure signals are Doppler signals, being transformable into pressure signals.  
   
   
       57 . A system according to  claim 49 , wherein said pressure signals are acoustic signals, being transformable into pressure signals.  
   
   
       58 . A system according to  claim 49 , wherein said selectable time sequences are selected time durations of said pressure-related digital data with a time reference.  
   
   
       59 . A system according to  claim 58 , wherein said selected time duration lies in the range 3-15 seconds.  
   
   
       60 . A system according to  claim 49 , wherein said analysis is performed by a processing unit, said processing unit delivering a first control signal to a regulator, said first control signal being determined according to selectable criteria for output of said analysis.  
   
   
       61 . A system according to  claim 49 , wherein output of said analysis of single pressure wave related digital data for a given time sequence yields modification of said deliverable first control signal.  
   
   
       62 . A system according to  claim 49 , wherein features of said first control signal are selectable when output of said single pressure wave analysis derivable from a subsequent pressure monitoring meet specific criteria.  
   
   
       63 . A system according to  claim 49 , wherein said selected criteria of time sequence parameters relate to criteria for optimum single pressure wave detection.  
   
   
       64 . A system according to  claim 49 , wherein said selectable first control signal is determined during each individual time sequence in a continuous series of time sequences, according to output of said single pressure wave analysis for each time sequence in said continuous series of time sequences.  
   
   
       65 . A system according to  claim 49 , wherein said regulator means is configured to convert said first control signal into a deliverable second control signal, said selectable second control signal corresponding to said selectable first control signal.  
   
   
       66 . A system according to  claim 49 , wherein said second control signal delivered by said regulator constitutes a performance modifying signal, said performance modifying signal being an input to a sensor-regulating device to cause modifications of performance thereof.  
   
   
       67 . A system according to  claim 49 , wherein said sensor-regulating device is adjustable according to a regulator deliverable second control signal.  
   
   
       68 . A system according to  claim 49 , wherein said sensor-regulating device is operable to modify a mode by which the sensor is able to sample signals indicative of pressure.  
   
   
       69 . A system according to  claim 49 , wherein said processing unit is operable to perform single pressure wave analysis in order to control a first control signal which is deliverable to a regulator, said regulator operable to control a second control signal which is deliverable to a sensor-regulating device, and wherein a feedback signal is provided between said processing unit said regulator, said feedback signal being restorable at selected intervals during an ongoing pressure measurement.  
   
   
       70 . A system according to  claim 49 , wherein output of said single pressure wave analysis for a given time sequence is related to said second deliverable control signal.  
   
   
       71 . A system according to claims  49 , wherein determining means are provided to determine an output of said single pressure wave analysis for each individual time sequence during a series of continuous time sequences, and wherein modifying means are operative to modify said second control signal into another level between each of said individual time sequences, said level of said second control signal being related to said analysis output for each of said time sequences.  
   
   
       72 . A system according to claims  49 , wherein said first control signal is a function of said second control signal, or said second control signal is a function of said first control signal.  
   
   
       73 . A system according to  claim 49 , wherein the deliverable first and second control signals relate to output of said single pressure wave analysis which is indicative of optimum single pressure wave detection, said first and second control signals being for use during the subsequent pressure monitoring.  
   
   
       74 . A system according to  claim 49 , wherein said human or animal body pressure is selected from one or more of: intracranial pressure, arterial blood pressure, cerebrospinal fluid pressure, cerebral perfusion pressure, ocular pressure, gastrointestinal pressure, urinary tract pressure, any type of soft tissue pressure.