Physiological parameter monitoring system and sensor assembly for same

• US 20040267103A1
• Filed: 04/21/2004
• Published: 12/30/2004
• Est. Priority Date: 10/22/2001
• Status: Active Grant

• Current Assignee: Nellcor Puritan Bennett Ireland
• Original Assignee: Cardiodigital Inc. (Medtronic Plc)
• Inventors: Sun, Ming, Li, Luya, Sethi, Rakesh Kumar
• Granted Patent: US 7,248,910 B2
• Time in Patent Office: Days
• US Class Current: 600/323
• CPC Class Codes: A61B 2560/0276 Determining malfunction
• CPC Class Codes: A61B 2562/085 combined with means for recording calibration data
• CPC Class Codes: A61B 5/00 Measuring for diagnostic purposes radiation diagnosis A61B6/00; diagnosis by ultrasonic, sonic or infrasonic waves A61B8/00; Identification of persons
• CPC Class Codes: A61B 5/1455 using optical sensors, e.g. spectral photometrical oximeters
• CPC Class Codes: A61B 5/14552 Details of sensors specially adapted therefor
• CPC Class Codes: A61B 5/1495 Calibrating or testing of in-vivo probes

Abstract

A detachable sensor assembly for use in monitoring a physiological parameter of a subject includes an information containing circuit and a timer. The sensor assembly stores time varying information in the information containing circuit. The information may include cumulative use times for the detachable sensor assembly and/or for components in the detachable sensor assembly.

Claims

1. A detachable sensor assembly for supplying a signal to a device for monitoring a physiological parameter of a subject, the detachable sensor assembly comprising:

a sensor;

an information containing circuit;

a timer; and

,

a connector comprising one or more signal conductors connected to carry information from the sensor and information from the information containing circuit to a device for monitoring a physiological parameter;

wherein the information containing circuit is configured to store time-varying information in response to timing signals from the timer and to transmit the time varying information by way of the connector.

2. The detachable sensor assembly of claim 1 wherein the time varying information comprises one or more of:

a cumulative time during which power has been applied to the sensor;

a cumulative time during which an active component in the sensor has been operating;

a cumulative time during which the sensor has been acquiring data from a subject;

a cumulative time since a sensor reset;

a cumulative time since a sensor error;

a cumulative time since the sensor was calibrated; and

,

a cumulative time since an interruption in a signal detected by the sensor.

3. The detachable sensor assembly of claim 2 wherein the information containing circuit comprises a microprocessor.

4. The detachable sensor assembly of claim 3 wherein the timer comprises a clock of the microprocessor.

5. A detachable sensor assembly according to claim 1 wherein the sensor comprises a pulse oximetry sensor.

6. A detachable sensor assembly according to claim 1 wherein the information containing circuit comprises one or more memory locations for storing information received by way of one or more of the one or more signal conductors from a device for monitoring a physiological function.

7. A detachable sensor assembly according to claim 6 wherein the one or more memory locations store information including a time that the detachable sensor assembly is being used.

8. A detachable sensor assembly according to claim 6 wherein the one or more memory locations store information including a duration during which the detachable sensor assembly is being used.

9. A detachable sensor assembly according to claim 1 wherein the information containing circuit comprises stored information comprising one or more of:

information identifying a manufacturer of the detachable sensor assembly;

information identifying a model of the detachable sensor assembly;

information identifying a type of the detachable sensor assembly;

a unique serial number for the detachable sensor assembly;

information identifying a date of manufacture of the detachable sensor assembly;

information identifying a location on a subject'"'"'s body at which the sensor is intended to be placed; and

,

calibration information for the sensor.

10. A detachable sensor assembly according to claim 1 wherein the information containing circuit is configured to transmit the time varying information in response to a request signal received by way of the connector.

11. A detachable sensor assembly according to claim 10 wherein the information containing circuit is configured to transmit the time varying information periodically in response to a timing signal from the timer.

12. A detachable sensor according to claim 11 wherein the information containing circuit comprises a non-volatile memory.

13. A system for determining a value of a physiological parameter comprising a detachable sensor assembly according to claim 1 connected by way of the connector to a monitoring device.

14. A system according to claim 13 wherein the monitoring device is configured to:

retrieve a first instance of the time varying value from the information containing circuit at a first time;

store the first instance of the time varying value in a memory;

retrieve a second instance of the time varying value from the information containing circuit at a second time later than the first time; and

,

compare the first and second instances of the time varying value to a difference between the first and second times.

15. A system according to claim 14 wherein the time varying value comprises a cumulative use time for a component in the detachable sensor assembly and the monitoring device is configured to energize the component at or before the first time.

16. A system according to claim 15 wherein the monitoring device is configured to:

retrieve from the information containing circuit information identifying a date of manufacturing the detachable sensor assembly;

compare the date of manufacture to a current date maintained in the monitoring device; and

,

signal an error if the date of manufacture of the sensor assembly is longer before the current date than a threshold time.

17. A system according to claim 16 wherein the monitoring device is configured to:

retrieve from the information containing circuit information identifying a cumulative use time of the detachable sensor assembly; and

signal an error if the cumulative use time exceeds a threshold.

18. A system according to claim 17 wherein the monitoring device is configured to:

retrieve from the information containing circuit information identifying a cumulative on time of a component in the detachable sensor assembly; and

,

signal an error if the cumulative on time exceeds a threshold.

19. A system according to claim 18 wherein the component comprises a light emitting element.

20. A system according to claim 19 wherein the monitoring device is configured to:

retrieve information from the information containing circuit;

compare the retrieved information to information stored in the monitoring device which was previously retrieved from the information containing circuit; and

,

signal an error if the retrieved information is not consistent with the stored information.

21. A system according to claim 20 wherein the monitoring device comprises a data store holding stored information identifying one or more acceptable sensor combinations, each of the acceptable sensor combinations comprising a plurality of sensor locations required for the determination of a physiological parameter;

and,

a plurality of sensors detachably connected to the monitoring device, each of the sensors intended for application to a different location on a subject'"'"'s anatomy, each of the sensors comprising a circuit containing stored information indicating the intended location for the sensor;

wherein the monitoring device comprises a processor connected to retrieve the stored information from each of the plurality of sensors, and to determine from the retrieved stored information whether the plurality of sensors includes all sensors of at least one of the acceptable sensor combinations.

22. A system according to claim 21 wherein the monitoring device comprises stored calibration information corresponding to each of the acceptable sensor combinations and the processor is configured to determine a value for the physiological parameter by applying the calibration information corresponding to the identified acceptable sensor combination to process signals from a plurality of the plurality of sensors corresponding to the identified acceptable sensor combination.

23. A system according to claim 22 wherein the physiological parameter comprises a blood pressure.

24. A system according to claim 23 wherein the sensors each comprise a pulse oximetry sensor.

25. Apparatus for monitoring a physiological parameter of a subject, the apparatus comprising:

a monitoring device comprising stored information identifying one or more acceptable sensor combinations, each of the acceptable sensor combinations comprising a plurality of sensor locations required for the determination of a physiological parameter; and

,

a plurality of sensors detachably connected to the monitoring device, each of the sensors intended for application to a different location on a subject'"'"'s anatomy, each of the sensors comprising a circuit containing stored information indicating the intended location for the sensor;

wherein the monitoring device comprises a processor connected to retrieve the stored information from each of the plurality of sensors, and to determine from the retrieved stored information whether the plurality of sensors includes all sensors of at least one of the acceptable sensor combinations.

26. The apparatus of claim 25 wherein the monitoring device comprises stored calibration information corresponding to each of the acceptable sensor combinations and the processor is configured to determine a value for the physiological parameter by applying the calibration information corresponding to the identified acceptable sensor combination to process signals from a plurality of the plurality of sensors corresponding to the identified acceptable sensor combination.

27. The apparatus of claim 26 wherein the physiological parameter comprises a blood pressure.

28. The apparatus of claim 27 wherein the sensors each comprise a pulse oximetry sensor.

29. A method for operating a detachable sensor assembly comprising a sensor for supplying a signal to a monitoring device for monitoring a physiological parameter of a subject, the method comprising:

determining in the detachable sensor assembly a time varying value;

storing the time varying value in a data store on the detachable sensor assembly a time varying value; and

,

transmitting the time varying value to a monitoring device detachably connected to the detachable sensor assembly.

30. The method of claim 29 wherein the time varying value comprises one of:

a cumulative time during which power has been applied to the sensor;

a cumulative time during which an active component in the sensor has been operating;

a cumulative time during which the sensor has been acquiring data from a subject;

a cumulative time since a sensor reset;

a cumulative time since a sensor error;

a cumulative time since the sensor was calibrated; and

,

a cumulative time since an interruption in a signal detected by the sensor.

31. The method of claim 30 comprising, at a monitoring device connected to the detachable sensor assembly:

retrieving a first instance of the time varying value from the detachable sensor assembly at a first time;

storing the first instance of the time varying value in a memory;

retrieving a second instance of the time varying value from the detachable sensor assembly at a second time later than the first time;

comparing a difference between the first and second instances of the time varying value to a difference between the first and second times; and

,

signaling an error if the difference between the first and second instances of the time varying value does not match the difference between the first and second times.

32. The method of claim 31 wherein the time varying value comprises a cumulative use time for a component in the detachable sensor assembly and the method comprises energizing the component at or before the first time.

33. A method according to claim 32 comprising, at the monitoring device, retrieving from the detachable sensor assembly information identifying a date of manufacturing the detachable sensor assembly;

comparing the date of manufacture to a current date; and

,

signaling an error if the date of manufacture of the sensor assembly is longer before the current date than a threshold time.

34. A method according to claim 33 comprising, at the monitoring device,

retrieving from the detachable sensor assembly information identifying a cumulative use time of the detachable sensor assembly;

and

signaling an error if the cumulative use time exceeds a threshold.

35. A method according to claim 34 comprising, at the monitoring device:

retrieving from the detachable sensor assembly information identifying a cumulative on time of a component in the detachable sensor assembly; and

,

signaling an error if the cumulative on time exceeds a threshold.

36. A method according to claim 35 comprising, at the monitoring device:

retrieving information from the detachable sensor assembly;

comparing the retrieved information to information stored in the monitoring device which was previously retrieved from the detachable sensor assembly; and

,

signaling an error if the retrieved information is not consistent with the stored information.

37. A method according to claim 36 comprising computing the time varying information in a processor located in the detachable sensor assembly.