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 analyzing 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 thus sampled pressure signals into pressure-related digital data with a time reference, 
 wherein for selectable time sequences the method comprises the further 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 sequences, and    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) balanced position of amplitude (ΔP)/latency (ΔT) combinations,    c2) balanced position of rise time coefficients (ΔP/ΔT),    c3) absolute mean pressure for said single pressure waves of said time sequence.    
     
     
         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 2 , wherein said selected time duration lies in the range 5-15 seconds.  
     
     
         4 . A method according to  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 5 , 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 1 , 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 (ΔP) of the single pressure wave,    latency (ΔT) of the single pressure wave,    rise time coefficient (ΔP/ΔT) of the single pressure wave,    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  claim 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 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 of said single pressure waves within said individual time sequence must have its ending diastolic minimum pressure value (P min ) within said individual time sequence.  
     
     
         16 . A method according to  claim 14 , wherein said selected criteria define that a last of said single pressure waves within said individual time sequence must have both its starting (P min ) and ending (P min ) diastolic minimum pressure values within said individual time.  
     
     
         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: 
 c1) balanced position of amplitude (ΔP)/latency (ΔT) combinations,    c2) balanced position of rise time coefficients (ΔP/ΔT),    c3) absolute mean pressure for said single pressure waves of said time sequence.    
     
     
         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 absolute 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 27 , wherein 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 1 , wherein said establishing step c) yields output of analysis of parameters c1)-c3) 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 establishing step c) yields output of analysis of one or more of said parameters c1)-c3), said analysis output being presented as numerical values on a display for each of said time sequences during ongoing sampling of said pressure-related signals.  
     
     
         32 . A method according to  claim 1 , wherein establishing step c) yields output of analysis of one or more of parameters c1)-c3), said analysis output being presented as histogram distribution of values of said parameters c1)-c3) for a selectable number of time sequence windows of said pressure-related signal.  
     
     
         33 . A method according to  claim 1 , wherein establishing step c) yields output of analysis of one or more of parameters c1)-c3), said analysis output being presented as a quantitative matrix for a selectable number of time sequences of said pressure-related signal.  
     
     
         34 . A method according to  claim 33 , wherein said quantitative matrix is created based on determining numbers of one of said parameters c1)-c3) with selected parameter values, wherein one axis of the quantitative matrix is related to an array of selected parameter values, wherein the other axis is related to an array of selected numbers of consecutive included time sequences, and wherein indicating for each matrix cell at respective intersections in said quantitative matrix a number of occurrence of matches between a specific parameter value and a specific number of time sequences.  
     
     
         35 . A method according to  claim 34 , wherein said parameter values are categorized into groups, said groups reflecting ranges of said parameter values.