Device, method and system for monitoring pressure in body cavities

• US 20030100845A1
• Filed: 10/30/2002
• Published: 05/29/2003
• Est. Priority Date: 04/30/2001
• Status: Active Grant

• Current Assignee: Dpcom As
• Original Assignee: Dpcom As
• Inventors: Eide, Per Kristian
• Granted Patent: US 7,198,602 B2
• Time in Patent Office: Days
• US Class Current: 600/561
• 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

The present invention relates to a system and method for digital sampling, quantitative analysis and presentation of pressures in a body cavity. The invention also relates to a portable apparatus for monitoring, sampling and storing pressure and a software for analysis of pressures. The invention includes an algorithm for analysis and presentations of pressures and a software for performing the analysis. The computer software may be integrated in the portable apparatus and in a variety of systems. The software provides different quantitative presentations of pressure curves as a matrix of numbers of intracranial pressure elevations of different levels and durations and a matrix of numbers of single pulse pressure waves with preselected characteristics. The parameters may be standardised according to recording time and heart rate variability. The data may be presented in different ways, both on-line and off-line after pressure monitoring.

Claims

1. Method for measuring and analyzing pressure in a body cavity in a patient, comprising the steps of:

a) measuring pressure by means of at least one sensor during a period of time (hereinafter called recording period) to provide at least one signal representative of the pressure,

b) sampling, at selected intervals, said signal representative of said pressure, converting the sampled signal to digital form and storing the digital sample value along with a time reference,

c) analyzing the stored sample values in order to generate a presentation of at least one of the following;

c1) number of pressure elevations with any selected combination of level and duration,

c2) number of pressure changes with any selected combination of level difference and duration of change,

c3) number of single pulse pressure waves with preselected characteristics regarding minimum, maximum, amplitude, latency and rise time or any other single pulse wave parameter,

wherein said numbers are related to a time period and

wherein the analysis performed in c3) includes computation of relative differences of pressure and time not involving a zero reference level and/or computation of absolute pressures involving a zero reference level.

2. Method according to claim 1, wherein step a) involves implanting a sensor in a body cavity of the patient.

3. Method according to claim 1, wherein step a) involves applying a noninvasive technique with a sensor using acoustic or other measuring signals.

4. Method according to claim 1, where the at least one signal represents blood pressure, and other pressure signals subjected to steps c1)-c3) represent intracranial pressure, blood pressure, cerebrospinal fluid pressure, and cerebral perfusion pressure.

5. Method according to claim 1, wherein the measurements are made while the patient is free to move about.

6. Method according to claim 1, wherein step c) comprises:

c4) computation of the numbers of artifacts during a recording period,

c5) computation of the artifact ratio,

c6) exclusion of recording sequences of sampled values and time references when the artifact ratio is above a certain level.

7. Method according to claim 1, wherein the presentation in step comprises the steps of presenting the data in the form of absolute numbers, percentages or numbers per time period as follows:

absolute numbers or percentages during the actual recording period,

numbers or percentages during a standardized recording period (such as one minute, one hour or 10 hours)

numbers or percentages standardized to a selected heart rate (for example a standardized heart rate of 60 per minute)

numbers or percentages related to normative or reference data,

numbers or percentages computed repeatedly during a continuous recording period.

8. Method according to claim 1, wherein the sampling rate in step b) is at least 10 Hz, and the recording period is at least 24 hours.

9. Method according to claim 8, wherein the sampling rate in step b) is at least 100 Hz.

10. Method according to claim 8, wherein the sampling rate in step b) is at least 200 Hz.

11. Method according to claim 8, wherein the recording period is at least 48 hours.

12. Apparatus for recording and storing pressure recordings from a pressure sensor applied to a patient, comprising:

a first connector (4) for connecting the apparatus to a pressure sensor,

an analog-to-digital converter (7) for converting received pressure measurements to digital form,

processing means in communication with the analog-to-digital converter (8), capable of reading out samples of the digitally converted pressure measurements and storing said measurements in a data memory (9) connected to said processing means along with a time reference,

an input/output interface (10) in communication with the processing means and connected to a second connector (22) for connecting the apparatus to external computing means (6), and

a power source for supplying the apparatus with power.

13. Apparatus according to claim 12, further comprising:

a galvanic circuit connected to the first connector for preventing the transfer of electrical energy from the apparatus towards the sensor.

14. Apparatus according to claim 13, further comprising:

a signal conditioner for removing noise from the received pressure measurement signals.

15. Apparatus according to claim 14, wherein said signal conditioner is an analog filter connected between the first connector and the analog-to-digital converter.

16. Apparatus according to claim 15, wherein said signal conditioner is a digital filter connected to the output of the analog-to-digital converter.

17. Apparatus according to claim 16, further comprising:

an input control for entering control and calibration signals.

18. Apparatus according to claim 17, further comprising:

a display connected to said processing means.

19. Apparatus according to claim 12, wherein said data memory further contains instructions controlling the operation of the processing means.

20. Apparatus according to claim 12, further comprising an alarm circuit capable of generating an audible or visual alarm upon detection of low memory capacity in the data memory or low power capacity in the power source.

21. Apparatus according to claim 12, wherein said data memory is a random access memory (RAM) circuit.

22. Apparatus according to claim 12, wherein said data memory is a magnetic storage device.

23. Apparatus according to claim 12, wherein the processor and the analog-to-digital converter in combination are capable of sampling the received pressure measurements with a sampling rate of at least 10 Hz.

24. Apparatus according to claim 23, wherein the sampling rate is at least 100 Hz.

25. Apparatus according to claim 23, wherein the sampling rate is at least 200 Hz.

26. Apparatus according to claim 12, wherein the processor is programmable through input control means to operate with a sampling rate between a minimum sampling rate and a maximum sampling rate.

27. Apparatus according to claim 12, wherein said data memory has a capacity which allows the storage of at least 24 hours of continuous sampling of the received pressure measurements at maximum sampling rate.

28. Apparatus according to claim 12, wherein said data memory has a capacity which allows the storage of at least 48 hours of continuous sampling of the received pressure measurements at maximum sampling rate.

29. Apparatus according to claim 12, comprising a plurality of input connectors and means for multiplexing pressure signals from said input connectors for the simultaneous recording of pressure signals from more than one pressure sensors.

30. System for the analysis of recorded pressure data, comprising

a) a communication interface for receiving a set of digital pressure sample values;

b) a data memory for storing the received sample values along with time references;

c) processing means with access to said data memory, capable of analyzing said sample values in order to determine at least one of the following;

c1) number of pressure elevations with any selected combination of level and duration,

c2) number of pressure changes with any selected combination of level difference and duration of change,

c3) number of single pulse pressure waves with preselected characteristics regarding minimum, maximum, amplitude, latency and rise time, or any other single pulse wave parameter,

wherein said numbers are related to a time period as follow;

numbers or percentages of pressure elevations or changes or single wave parameters during an actual recording period,

numbers or percentages of pressure elevations or changes or single wave parameters during a standardized recording period (for example 1 minute or 1 hour),

numbers or percentages of pressure elevations or changes or single wave parameters during a recording time with a standardized heart rate,

wherein both real-time and on-line analysis/presentations are possible,

d) a video interface in communication with said processing means and capable of, in combination with the processor means, generating a visual presentation of the result of any analysis performed on the pressure sample values together with a graphical user interface capable of presenting the analyzed data;

repeatedly during the recording period, with comparisons of the repeatedly analyzed data,

along with normative or reference data,

e) a display for displaying the generated visual presentation; and

f) input means allowing a user of the system to enter and change parameters on which said analysis and said presentation should be based.

31. System according to claim 30, wherein said parameters include at least some of the following:

pressure intervals defining a number of pressure elevations,

pressure change intervals defining a number of pressure change step sizes,

time intervals defining a number of durations,

pressure wave characteristics including minimum, maximum, amplitude and latency,

selection of type of analysis, and

selection of presentation of numbers as absolute numbers, percentages or numbers/percentages during a standardized recording period or numbers/percentages with a given heart rate.

32. Computer program product for controlling a computer on which is stored a set of values representing pressure samples with a time reference, comprising program instructions for causing the computer to perform the steps of:

receiving from a user interface or as pre stored default values a set of parameters on which an analysis of said set of samples should be based;

analyzing said sample values in order to determine at least one of the following;

1) number of pressure elevations with any selected combination of level and duration,

2) number of pressure changes with any selected combination of level difference and duration of change,

3) number of single pulse pressure waves with pre-selected characteristics regarding minimum, maximum, amplitude, latency and rise time, where said numbers refer to a during a time period (recording period, standardized period, etc.) or a standardized heart rate.

generating a visual presentation of said analysis.

33. Computer program product according to claim 32, stored on a computer readable medium.

34. Computer program product according to claim 32, carried on a propagated signal.

35. Computer program product according to claim 32, integrated in a portable apparatus or in different systems such as medical device computers, computer servers or vital signs monitors.