Device, method and system for monitoring pressure in body cavities

• US 7,198,602 B2
• Filed: 10/30/2002
• Issued: 04/03/2007
• Est. Priority Date: 04/30/2001
• Status: Expired due to Fees

• Current Assignee: Dpcom As
• Original Assignee: Sensometrics As
• Inventors: Eide, Per Kristian
• Primary Examiner(s): Marmor, II; Charles A
• Assistant Examiner(s): Mallari; Patricia C
• Application Number:
  US10/283,245
• Publication Number:
  US 20030100845A1
• Time in Patent Office: 1,616 Days
• Field of Search: None
• US Class Current: 600/485
• CPC Class Codes: A61B 5/021 Measuring pressure in heart or blood vessels A61B5/0205 takes precedence
• CPC Class Codes: A61B 5/02108 from analysis of pulse wave characteristics
• CPC Class Codes: A61B 5/03 Detecting, measuring or recording fluid pressure within the body other than blood pressure, e.g. cerebral pressure; Measuring pressure in body tissues or organs A61B5/205 takes precedence
• CPC Class Codes: A61B 5/031 Intracranial pressure
• CPC Class Codes: G16H 15/00 ICT specially adapted for medical reports, e.g. generation or transmission thereof

Abstract

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 from said digital data features related to single pressure waves, and determining at least one parameter of the single wave parameters elected from the group of: pressure amplitude ΔP, latency (ΔT), rise time coefficient ΔP/ΔT, and wavelength of the single wave, as well as determining numbers of single pressure waves with pre-selected combinations of two or more of said single pressure wave parameters during said given time sequence. In another aspect of the invention, the method is capable of identifying from said digital data features related to absolute pressures relative to atmospheric pressure a number of different pressure levels and duration thereof, and presenting the numbers of levels of various time durations in said matrix format.

Claims

1. A method for analysing pressure-signals derivable from pressure measurements on or in a body of a human being or animal, comprising sampling said signals at specific intervals, converting the pressure signals into pressure-related digital data with a time reference,

identifying from said digital data features related to single pressure waves in said pressure signals,

said identifying step including determination of a minimum pressure value related to diastolic minimum value and a maximum pressure value related to systolic maximum value, and

determining at least one parameter of the single wave parameters elected from the group of:

pressure amplitude=Δ

P=[(maximum pressure value)−

(minimum pressure value)], latency (Δ

T), rise time or rise time coefficient=Δ

P/Δ

T, and wavelength of the single wave, and

determining numbers of said single pressure waves occurring during a given time sequence,

wherein said determining of numbers includes;

determining numbers of single pressure waves with pre-selected values of one or more of said single pressure wave parameters during said given time sequence, and

further includes determining numbers of single pressure waves with pre-selected combinations of two or more of said single pressure wave parameters during said given time sequence.

2. A method according to claim 1, wherein the latency Δ

T is defined as the time elapsed from occurrence of the minimum pressure value to the maximum pressure value.

3. The method according to claim 1, wherein the amplitude Δ

P is defined as the pressure difference between the systolic maximum pressure and the diastolic minimum pressure during a series of increasing pressures of single pressure wave.

4. The method according to claim 1, wherein said maximum pressure value is one of three peak values occurring in said single pressure wave.

5. The method according to claim 4, wherein

a first (P1) of said three peak values in said single pressure wave has an amplitude Δ

P1 representing relative pressure difference between systolic maximum pressure and diastolic minimum pressure,

a second (P2) of said three peak values has an amplitude Δ

P2 related to a tidal wave portion of said single pressure wave, and

a third (P3) of said three peak values has an amplitude Δ

P3 related a dichrotic wave portion of said single pressure wave.

6. The method according to claim 3, further comprising calculation of one or more rise time coefficients between said amplitude and latency values.

7. The method according to claim 1, wherein in said single pressure wave said amplitude and latency values are relative values only, respectively.

8. The method according to claim 1, wherein said single pressure wave amplitudes and latency values are relative values not related to a zero pressure level.

9. The method according to claim 1, wherein numbers of single pressure waves during a said time sequence corresponds to the heart rate during said time sequence of said human being or animal.

10. The method according to claim 1, comprising in said determining step defining related limits within which at least one of said parameters, i.e. amplitude, latency, rise time coefficient, and heart rate are expected to lie.

11. The method according to claim 10, said determining step further comprising rejecting a value of a specific one of said parameters not lying within related, given threshold values.

12. The method according to claim 10, wherein rejection of an amplitude related parameter value involves rejection of related false minimum pressure and false maximum pressure values.

13. The method according to claim 10, wherein calculated values of Δ

P/Δ

T outside given threshold values are rejected.

14. The method according to claim 1, wherein any determined value of Δ

P less than the threshold value is discarded.

15. The method according to claim 1, wherein a matrix is created based on determination of numbers of single pressure waves with pre-selected values of one or more parameters related thereto during a given recording sequence, said parameters elected from pressure amplitude Δ

P, latency Δ

T, and rise time coefficient Δ

P/Δ

T.

16. The method according to claim 15, wherein one axis of the matrix is related to an array of pre-selected values of pressure amplitude (Δ

P), and wherein the other axis is related to an array of pre-selected values of latency (Δ

T).

17. The method according to claim 15, wherein numbers in said matrix relate to numbers of occurrence of matches between specific pressure amplitude (Δ

P) and specific latency (Δ

T) values, related to successive measurements of single pressure waves over a specific measurement period.

18. The method according to claim 17, wherein the occurrence of matches is indicated through actual number or standardisation based number of matches during the specific measurement period.

19. The method according to claim 17, wherein the occurrence of matches is indicated through percentage of matches during the specific measurement period.

20. The method according to claim 18, wherein said standardisation of said numbers or percentages of occurrence of matches is a function of the length of the specific measurement period.

21. The method according to claim 18, wherein said standardisation is related to single pressure wave wavelength (heart rate).

22. The method according to claim 21, wherein said standardisation is expressed through use of ratio numbers or percentages.

23. The method according to claim 15, wherein the matrix undergoes statistical analysis for subsequent graphical presentation.

24. The method according to claim 22, wherein said statistical analysis of the matrix ratio numbers or percentages includes computation of balanced position of said ratio numbers or percentages.

25. The method according to claim 24, wherein said balanced position is centroidal axis or centre of mass of said matrix.

26. The method according to claim 24, wherein said balanced position in said matrix is represented by amplitude (Δ

P) and latency (Δ

T) values.

27. The method according to claim 24, comprising the further step of reiterating updates of said balanced positions during ongoing pressure measurements.

28. The method according to claim 27, wherein reiterated updating is made at regular intervals.

29. The method according to claim 28, wherein said regular intervals occur at each 5 seconds.

30. The method according to claim 15, wherein reiterated updating of occurrence of matches in matrix form is made, e.g. every five seconds or every one minute, during ongoing measurements taken over said specific measurement period.

31. The method according to claim 1, wherein data related to single pressure waves obtained from measurements of a) arterial blood pressure and b) elected other internal body pressure, e.g. intra-cavity pressure are compared within identical time reference.

32. The method according to claim 31, wherein numbers of single pressure waves from different pressures are compared within said identical time reference.

33. The method according to claim 31, wherein standardised numbers or percentages of single pulse pressure waves from different pressures are compared within said identical time reference.

34. The method according to claim 31, wherein said comparisons are related to number of relationships between rise time coefficient of intra-cavity pressure waves, e.g. intra-cranial pressure waves, and blood pressure waves.

35. The method according to claim 31, wherein said comparisons are made between matrixes for the different pressure waves.

36. The method according to claim 31, wherein relative duration of each single pressure wave corresponds to heart rate, and wherein a heart rate parameter is indicative of abnormality of intercranial pressure.

37. The method according to claim 31, wherein said internal body pressure is one or more of intra-cranial pressure, blood pressure, cerebrospinal fluid pressure and cerebral perfusion pressure.

38. The method according to claim 1, wherein the data from measurements of single pressure waves are compared against data derived from a continuous or interval-based measurement of absolute pressures made over a same total measurement period, said absolute pressures being relative to atmospheric pressure.

39. The method according to claim 15, wherein said matrix is based on updating occurrences of matches at regular intervals.