Bed exit detection apparatus

• US 6,067,019 A
• Filed: 02/27/1998
• Issued: 05/23/2000
• Est. Priority Date: 11/25/1996
• Status: Expired due to Term

• Current Assignee: Hill-Rom Services Incorporated (Baxter International Inc.)
• Original Assignee: Hill-Rom Incorporated (Baxter International Inc.)
• Inventors: Scott, Thomas E.
• Primary Examiner(s): Hofsass, Jeffery A.
• Assistant Examiner(s): TRIEU, VAN THANH
• Application Number:
  US09/031,749
• Time in Patent Office: 816 Days
• Field of Search: 340/573.4, 340/573.5, 340/562, 340/572.2, 340/572.4, 340/686.1, 600/483, 600/484, 5/940
• US Class Current: 340/573.4
• CPC Class Codes: A61B 2562/0247 Pressure sensors
• CPC Class Codes: A61B 2562/046 in a matrix array
• CPC Class Codes: A61B 5/11 Measuring movement of the entire body or parts thereof, e.g. head or hand tremor, mobility of a limb for measuring pulse A61B5/02 ;A61B5/1038 takes precedence; motion detection to correct for motion artifacts in physiological signals A61B5/721
• CPC Class Codes: A61B 5/6887 mounted on external non-worn devices, e.g. non-medical devices
• CPC Class Codes: A61B 5/6892 Mats
• CPC Class Codes: G08B 21/22 responsive to presence or absence of persons

Abstract

A patient detection system including a plurality of sensors located adjacent the support surface and each sensor having an output signal variable in response to the change detected by the sensor. A processor monitors the output signals and provide an indication of change of position of the body relative to the support surface and to individually recalibrate each of the plurality of sensors. The automatic recalibration occurs upon sensing a substantial change due to an item being moved onto the surface. The processor may also sense changes in the support surface and recalibrate each of the sensors upon a detection of change in the support surface. The processor recalibrates all of the sensors for small changes existing for a pre-determined duration and for all large changes. The processor recalibrates all of the processors for a combination of changes in less than all of the sensors from the previous calibration for each sensor.

Claims

1. An apparatus for detecting and monitoring a body adjacent a support surface, the apparatus comprising:

a plurality of sensors located adjacent the support surface, each sensor having an output signal being variable in response to change detected by its corresponding sensor; and

a processor having inputs for receiving the output signals from the sensors, the processor monitoring individually the output signals from each sensor to provide an indication of change of position of the body relative to the support surface and to individually recalibrate each of the plurality of sensors.

2. The apparatus of claim 1, wherein the processor automatically recalibrates the sensors upon sensing substantial change due to an item being moved onto the support surface.

3. The apparatus of claim 1, wherein the support surface is located on an articulating bed having a bed position sensor, the bed position sensor having an output coupled to the processor, the processor automatically recalibrating the system in response to changes in bed position.

4. The apparatus of claim 1, wherein the processor detects when a body moves onto the support surface and the processor automatically recalibrating the system upon detection of the body moving onto the support surface.

5. The apparatus of claim 1, wherein the processor includes means for monitoring movement of the body within a detection region of each sensor.

6. The apparatus of claim 1, wherein the processor includes an output coupled to a communication port for providing a nurse call system with an indication of change of position of the body relative to the support surface.

7. The apparatus of claim 1, wherein the processor senses changes in the support surface and the processor recalibrates each of the plurality of sensors upon detection of changes in the support surface.

8. The apparatus of claim 7, wherein the processor includes an output coupled to a communication port, the processor transmitting an output signal through the communication port to a remote location upon detection of changes in the support surface.

9. The apparatus of claim 7, wherein the support surface is supported by a fluid.

10. The apparatus of claim 1, wherein the processor recalibrates all the sensors for small capacitive changes existing for a predetermined duration and for all large changes.

11. The apparatus of claim 1, wherein the processor recalibrates all the sensors for a predetermined set of individual changes from the previous calibration for each sensor.

12. A apparatus of claim 11, wherein the predetermined set of changes includes if a group of sensors, less than all the sensors, each have changes above a first value.

13. A apparatus of claim 12, wherein the predetermined set of changes includes if a group of sensors, less than all the sensors, in total have changes above a second value.

14. A apparatus of claim 11, wherein the predetermined set of changes includes if a group of sensors, less than all the sensors, in total have changes above a second value.

15. The apparatus of claim 1, wherein the plurality of sensors includes four corner sensors and a center sensor.

16. A method of calibrating a plurality of sensors located adjacent support surface in an apparatus for detecting and monitoring a body adjacent the support surface, each sensor providing a varying signal;

the method comprising;

determining an initial calibration value individually for each sensor;

determining a change of the signal of each sensor individually from its initial calibration value; and

individually recalibrating each of the plurality of sensors when a predetermined set of changes of the individual sensor signals have been determined.

17. A method of claim 16, wherein the predetermined set of changes includes if a group of sensors, less than all the sensors, each have changes above a first value.

18. A method of claim 17, wherein the predetermined set of changes includes if a group of sensors, less than all the sensors, in total have changes above a second value.

19. A method of claim 16, wherein the predetermined set of changes includes if a group of sensors, less than all the sensors, in total have changes above a second value.

20. A method of claim 16, wherein the predetermined set of changes includes if a group of sensors, less than all the sensors, in total or individually have changes above predetermined values;

and including determining a category of mass of body on the support surface and adjusting the predetermined values.

21. A method of claim 20, including individually recalibrating each of the plurality of sensors when a predetermined set of changes of the individual sensor signals have been determined.

22. A method of predicting that a patient is about to exit a support surface using a plurality of sensors located adjacent support surface and an apparatus for detecting and monitoring a body adjacent the support surface, each sensor providing a varying signal;

the method comprising;

determining an initial calibration value individually for each sensor;

determining a change of the signal of each sensor individually from its initial calibration value; and

predicting an exit when a predetermined set of changes of the individual sensor signals have been determined to indicate a significant shift of the patient on the support surface to one of the edges of the support surface since the last calibration.