External patient reference sensors

• US 5,810,735 A
• Filed: 05/01/1997
• Issued: 09/22/1998
• Est. Priority Date: 02/27/1995
• Status: Expired due to Term

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Carney, James K., Turi, Michael, Beck, Robert C., Halperin, Louis E.
• Primary Examiner(s): Lacyk, John P.
• Assistant Examiner(s): GILBERT, SAMUEL G
• Application Number:
  US08/848,764
• Time in Patent Office: 509 Days
• Field of Search: 128/847-899, 128/903, 607/27, 600/301, 600/483-486, 600/509, 600/511, 600/522
• US Class Current: 600/486
• CPC Class Codes: A61B 2560/0257 using atmospheric pressure
• CPC Class Codes: A61B 5/0002 Remote monitoring of patients using telemetry, e.g. transmission of vital signals via a communication network A61B5/07 takes precedence; transmission systems for measured values G08C; transmission H04B; transmission of digital information H04L; wireless communication networks H04W
• CPC Class Codes: A61B 5/0031 Implanted circuitry
• CPC Class Codes: A61B 5/02156 Calibration means
• 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 5/1455 using optical sensors, e.g. spectral photometrical oximeters
• CPC Class Codes: A61B 5/7475 User input or interface means, e.g. keyboard, pointing device, joystick
• CPC Class Codes: G01L 19/02 Arrangements for preventing, or for compensating for, effects of inclination or acceleration of the measuring device; Zero-setting means for aneroid barometers G01L7/14

Abstract

A system for long term monitoring of an internal patient medical parameter having an external reference and means to correct the internal measurements of the parameter via external measurements taken by the external reference. A coordinating device makes the correction and makes available a histogram-based record of the parameter over time. This information can be used to reprogram an implantable device or for other therapeutic or diagnostic purposes. Pressure sensor embodiment is detailed.

Claims

1. A system for determining the absolute value of an implanted medical device sensor measurement where said implanted sensor measurement values are subject to significant biasing by external forces in the patient'"'"'s environment, said system comprising:

a systemwide program for pairing the storage of data sets of sensed values and times between an implanted sensor and measurement device and an external sensor and measurement device and enabling the later comparison of the two data sets, said program having portions thereof stored in memory of system devices for execution therein, said system devices comprising;

a) an implanted sensor and measurement device having a memory for storing sensor data and a portion of said program for execution in said implanted device, a clock, a sensor for generating measurement values and a processor, so arranged and disposed that the memory holds representations of sensor measurement values as coordinated by the processor, said coordinating the enabling of the sensor to generate and the memory to hold each new measurement value at appropriate times in accord with a predetermined processor run and clock driven program,

b) an external sensor and measurement device having a memory for storing sensor data and a portion of said program for execution in said external device, a clock, a sensor for generating measurement values and a processor, so arranged and disposed that the memory holds representations of sensor measurement values as coordinated by the processor, said processor coordinating the enabling of the sensor to generate and the memory to hold each new measurement value at appropriate times in accord with a predetermined processor run and clock driven program,

c) a coordinating programmer apparatus also having a memory for storing a portion of said program for execution in said apparatus, for initiating timing of paired programs for storing data in said implanted and external devices by way of two communications channels establishable between said programmer and said external device and between said programmer and said implanted device.

2. A system as set forth in claim 1 wherein at least one of said portions of program can be modified by user activities that control said programmer and wherein such modifications can be effected in one of said devices through programmer communication to such device prior to initiating sense gathering activity of the paired programs.

3. A system as set forth in claim 2 wherein one of said portions of program is either loaded into one of said devices, or turned on in one of said devices prior to initiation by said programmer.

4. A system as set forth in claim 1 wherein the implanted device and the external device establish a communications channel between said implanted and external devices for coordinating the initiation of a period for recording measurements by both said implanted and external devices.

5. A system as set forth in claim 4 wherein the communications channel between said programmer and said external device is a data carrying wire cable for conducting electrical signals therebetween.

6. A system as set forth in claim 1 wherein the real-time day and date are used to coordinate timing between the paired data sets of sensed values.

7. A system as set forth in claim 1 wherein each said sensor is a pressure sensor.

8. A system as set forth in claim 1 wherein said coordinating programmer subtracts pressure measurements taken at a given time by said external device from pressure measurements taken by said implanted device from approximately the same time to produce a corrected pressure reading indicative of absolute internal pressure.

9. A process of producing a long term series of gauge pressure readings from within a living body comprising:

measuring over a long term at specified intervals within said long term, internal pressure with an implanted sensor device that measures absolute pressure and recording said measurements with reference to the time they are taken so as to produce a measurement value for each interval,

at a time contemporaneous with said long term, and at intervals approximately contemporaneous with said specified intervals, measuring ambient pressure near the living body containing said implanted sensor device and recording said ambient pressure measurements with reference to the time they are taken so as to produce a measurement value for each interval,

coordinating the measurements for each approximately specified interval by subtracting the value of the ambient measurement for a given one of the specified intervals from the absolute pressure measurement value from said implanted sensor for the same specified interval, the result of such subtraction being an approximation of the gauge pressure reading for each said specified interval.

10. The process of claim 9, and further comprising the step:

reporting the results of said subtraction as a histogram trend graph for analysis of ventricular pressure with respect to time.

11. A process of producing a chronic histogram of measurement readings from within a living body comprising:

measuring over a long term at specified intervals within said long term, an internally sensed parameter with an implanted sensor device that measures said sensed parameter in absolute terms and recording said measurements with reference to the time they are taken so as to produce a measurement value for each interval,

at a time contemporaneous with said long term, and at intervals approximately contemporaneous with said specified intervals, measuring an external and ambient parameter near the living body containing said implanted sensor device and recording said ambient parameter measurements with reference to the time they are taken so as to produce a measurement value for each interval,

coordinating the measurements for each approximately specified interval by subtracting the value of the ambient measurement for a given one of the specified intervals from the absolute measurement value from said implanted sensor for the same specified interval, the result of such subtraction being an approximation of the internal measurement for each said specified interval.

12. A system for determining the absolute value of an implanted medical device sensor measurement where said implanted sensor measurement values are subject to significant biasing by changeable external conditions in the environment of the patient, said system comprising:

a) an implanted sensor and measurement device having a memory for storing sensor data, a clock, a sensor for generating measurement values and a processor, so arranged and disposed that the memory holds representations of sensor measurement values as coordinated by the processor, said processor coordinating the enabling of the sensor to generate and the memory to hold each new measurement value at appropriate times in accord with a predetermined processor run and clock driven program,

b) an external sensor and measurement device having a memory for storing sensor data, a clock, a sensor for generating measurement values and a processor, so arranged and disposed that the memory holds representations of sensor measurement values as coordinated by the processor, said processor coordinating the enabling of the sensor to generate and the memory to hold each new measurement value at appropriate times in accord with a predetermined processor run and clock driven program,

c) a coordinating program in said implanted device which, by way of two communications channels establishable between said implanted and said external device periodically corrects the internal measurement for said external conditions based on the measurement data transferred by said external device to said internal device.

13. A device as set forth in claim 12, and further comprising:

an adaptive program responsive to the corrected internal measurement to adaptively change the functioning of the implanted device.

14. A system for determining the absolute value of an implanted medical device sensor measurement where said implanted sensor measurement values are subject to significant biasing by external forces in the environment of the patient, said system comprising:

a) an implanted sensor and measurement device having a sensor for generating measurement values, a communications channel, and a processor, so arranged and disposed that the memory holds representations of sensor measurement values as coordinated by the processor, said processor coordinating the enabling of the sensor to generate and the communications channel to carry new measurement values at appropriate times in accord with a processor run and clock driven program,

b) an external sensor and measurement device having a memory for storing sensor data, a clock, a sensor for generating measurement values and a processor, so arranged and disposed that the memory holds representations of sensor measurement values as coordinated by the processor, said processor coordinating the enabling of the sensor to generate and the memory to hold each new measurement value at appropriate times in accord with a predetermined processor run and clock driven program,

c) a coordinating program in said external device which, by way of said communications channel establishable between said implanted and said external device periodically corrects the internal measurement for said external forces based on the measurement data transferred by said external device to said internal device.