Apparatus and method for reducing the risk of decubitus ulcers

• US 6,646,556 B1
• Filed: 06/09/2000
• Issued: 11/11/2003
• Est. Priority Date: 06/09/2000
• Status: Expired due to Term

• Current Assignee: Bed-Check Corporation (Stanley Black & Decker, Inc.)
• Original Assignee: Bed-Check Corporation (Stanley Black & Decker, Inc.)
• Inventors: Cooper, Craig L., Smith, Toby E.
• Primary Examiner(s): MULLEN, THOMAS J
• Application Number:
  US09/591,887
• Time in Patent Office: 1,250 Days
• Field of Search: 340/573.1, 340/529, 340/309.15, 340/666, 340/667, 340/309.16, 340/309.7
• US Class Current: 340/573.1
• CPC Class Codes: A61B 2562/0247 Pressure sensors
• CPC Class Codes: A61B 2562/0266 Optical strain gauges
• CPC Class Codes: A61B 2562/046 in a matrix array
• CPC Class Codes: A61B 5/1115 Monitoring leaving of a patient support, e.g. a bed or a wheelchair
• CPC Class Codes: A61B 5/1118 Determining activity level
• CPC Class Codes: A61B 5/447 specially adapted for aiding the prevention of ulcer or pressure sore development, i.e. before the ulcer or sore has developed
• 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: A61G 2203/44 for weight
• CPC Class Codes: A61G 2203/46 for temperature
• CPC Class Codes: A61G 7/057 Arrangements for preventing bed-sores or for supporting patients with burns, e.g. mattresses specially adapted therefor ventilation openings in mattresses A47C21/042; pneumatic or hydraulic mattresses A47C27/08

Abstract

There is provided herein a sensor for use in patient monitoring situations, wherein the level of patient motion activity is tracked for purposes of determining whether or not that patient has exhibited sufficient activity to merit eliminating a scheduled assisted relocation to a new position. The instant device broadly operates to sense the length of time since a patient has last moved from a previous sitting or lying position. If the patient has not moved during some predetermined time interval, it is preferred that the nursing staff be notified that it is time to manually reposition the patient. On the other hand, if the patient has changed position within the specified time period, the device will note that fact and inform the attending nurse or other caregiver that the patient need not be moved at the next scheduled relocation, thereby eliminating the need in some cases to rouse the patient from an otherwise sound sleep. In either case, the instant invention operates to reduce the risk that a patient will develop bed sores by helping ensure that the patient is manually moved as frequently as is medically necessary, but no more often than is actually necessary.

Claims

1. An apparatus for reducing the risk of occurrence of decubitus ulcers in a patient at rest on a support surface, wherein is provided a predetermined patient turn interval, comprising:

(a) a patient location sensor for determining at least approximately an “

X” and

a “

Y”

location of the patient on the support surface;

(b) a time circuit;

(c) a CPU in electronic communication with said patient location sensor and said time circuit, said CPU at least for

(c1) determining from said patient location sensor an initial “

X” and

an initial “

Y”

location of the patient on the support surface,

(c2) determining a start time associated with said determination of said initial “

X”

location and said initial “

Y”

location,

(c3) thereafter repeatedly determining from said patient location sensor a then-current “

X”

location and a then-current “

Y”

location of the patient on the support surface,

(c4) determining from said time circuit, said start time, said initial “

X” and

“

Y”

locations, and a plurality of said then-current “

X” and

“

Y”

locations, a time since the patient last significantly changed location, wherein a significant change of location is one which persists for at least a predetermined time interval, and,

(c5) initiating a signal indicative of a state of the patient if said time since the patient last significantly changed location is greater than said patient turn interval; and

,

(d) an alarm in electronic communication with said CPU and responsive thereto, said alarm at least for responding to said signal indicative of a state of the patient to produce an alarm signal.

2. An apparatus for reducing the risk of occurrence of decubitus ulcers in a patient according to claim 1, wherein said patient location sensor is a bed mat.

3. An apparatus for reducing the risk of occurrence of decubitus ulcers in a patient according to claim 1, wherein said patient location sensor is a chair mat.

4. An apparatus for reducing the risk of occurrence of decubitus ulcers in a patient according to claim 1, wherein said patient location sensor is selected from a group consisting of a plurality of accelerometers, an infrared sensor, a video camera, and an ultrasonic sensor.

5. An apparatus for reducing the risk of occurrence of decubitus ulcers in a patient according to claim 1, wherein said alarm is a speaker.

6. An apparatus for reducing the risk of occurrence of decubitus ulcers in a patient according to claim 1, wherein said alarm is selected from a group consisting of a light, a buzzer, and a beeper.

7. An apparatus for reducing the risk of occurrence of decubitus ulcers in a patient according to claim 1,

wherein said apparatus is for use with a bed, said bed having at least four legs, and

wherein said location sensor includes at least one weight sensor positioned under at least one of said bed legs.

8. An apparatus for reducing the risk of occurrence of decubitus ulcers in a patient according to claim 7, wherein said bed has four legs and wherein said location sensor includes at least four weight sensors, one weight sensor being positioned under each of said four bed legs.

9. An apparatus for reducing the risk of occurrence of decubitus ulcers in a patient according to claim 1, wherein

said patient location sensor is a mat containing a plurality of sensor points thereon,

each of said plurality of sensor points being separately readable by said CPU,

said sensor points being for use in determining at least approximately a location of the patient.

10. An apparatus for reducing the risk of occurrence of decubitus ulcers in a patient according to claim 9, wherein said sensor points are temperature sensors.

11. An apparatus for reducing the risk of occurrence of decubitus ulcers in a patient according to claim 9, wherein said sensor points are piezoelectric elements.

19. An apparatus for reducing the risk of occurrence of decubitus ulcers in a patient according to claim 11, wherein said bed has four legs and wherein said location sensor includes at least four weight sensors, one weight sensor being positioned under each of said four bed legs.

12. A method for reducing the risk of occurrence of decubitus ulcers in a patient at rest on a support surface, comprising the steps of:

(a) selecting a patient turn interval and a persistence time period said persistence time period being less than said patient turn interval and greater than zero;

(b) sensing a signal from a patient sensor representative of a first position of the patient on the support surface, wherein said signal representative of the first position of the patient comprises at least an approximate first “

X” and

first “

_Y”

location of the patient;

(c) sensing a signal from said patient sensor representative of a current position of the patient on the support surface wherein said signal representative of said current position of the patient comprises at least an approximate current “

X” and

current “

_Y”

location of the patient;

(d) comparing at least said first “

X” and

said first “

Y”

with said current “

X” and

said current “

Y”

, thereby forming a differential movement measure;

(e) examining said differential movement measure to determine whether the patient has moved from said first position;

(f) determining a differential time interval since said signal representative of said first position of the patient was sensed;

(g) if the patient has not moved from said first position,

(g1) comparing said differential time interval with said selected turn interval, and,

(g2) activating an alarm if said differential time interval exceeds said selected turn interval;

(h) if the patient has moved from said first position,

(h1) monitoring the current patient position to ascertain whether the patient returns at least approximately to said first position within said persistence time period,

(h2) if the patient does not return at least approximately to said first position within said persistence time period, determining that the patient has moved significantly from said first position,

(h3) if the patient does return to approximately said first position within said persistence time period,

(i) comparing said differential time interval with said selected turn interval,

(ii) activating an alarm if said differential time interval exceeds said selected turn interval, and,

(iii) performing steps (i) and (ii) until either the patient moves again or until said differential time interval exceeds said selected turn interval; and

,

(i) performing steps (b) through (h) as necessary to reduce the risk of occurrence of decubitus ulcers in the patient.

13. A method for reducing the risk of occurrence of decubitus ulcers in a patient according to claim 12, wherein said patient sensor of step (c) is a pressure sensitive mat.

14. A method for reducing the risk of occurrence of decubitus ulcers in a patient according to claim 12, wherein step (e) includes the steps of:

(e1) examining said differential movement measure to determine whether the patient has moved from said first position, and,

(e2) determining that the patient has not moved from said first position if said differential movement measure does not exceed a predetermined threshold value.

15. A method for reducing the risk of occurrence of decubitus ulcers in a patient at rest on a support surface, comprising the steps of:

(a) selecting a patient turn interval;

(b) selecting a persistence time period less than said patient turn interval and greater than zero;

(c) determining a first position of the patient on the support surface, said first position comprising at least a first “

X”

position and a first “

Y”

position;

(d) continuously obtaining a position of the patient and continuously determining an elapsed time since said first position was determined,

(e) repeating step (d) until either a movement of the patient from said first position is detected, or until said determined elapsed time exceeds said selected patient turn interval,

(e1) if said determined elapsed time exceeds said selected patient turn interval, activating an alarm, else,

(e2) if the patient moves from said first position,

(i) continuously monitoring the current patient position to ascertain whether the patient returns at least approximately to said first position within said persistence time period,

(ii) if the patient does not return at least approximately to said first position within said persistence time period, determining that the patient has moved significantly from said first position,

(iii) if the patient does return to approximately to said first position within said persistence time period,

(A) comparing said elapsed time with said selected turn interval,

(B) activating an alarm if said elapsed time exceeds said selected turn interval, and,

(C) performing steps (A) and (B) until either the patient moves again or until said elapsed time exceeds said selected turn interval; and

,

(f) performing steps (c) through (e) as necessary to reduce the risk of occurrence of decubitus ulcers in the patient.

16. A method for reducing the risk of occurrence of decubitus ulcers in a patient according to claim 15, wherein is provided a movement threshold, and the step of repeating step (d) until movement of the patient from said first position is detected comprises the step of repeating step (d) until movement of the patient from the first position in excess of said movement threshold is detected.

17. An apparatus for reducing the risk of occurrence of decubitus ulcers in a patient, comprising:

(a) a patient location sensor for determining at least approximately a location of the patient;

(b) a time circuit;

(c) a CPU in electronic communication with said patient location sensor and said time circuit, said CPU at least for determining from said time circuit and said patient location sensor a time since the patient last changed location;

(d) an alarm in electronic communication with said CPU and responsive thereto, said alarm for signaling a state of said patient depending on at least said patient location and said time since the patient last changed location, wherein said patient location sensor is selected from a group consisting of a chair mat, a plurality of accelerometers, an infrared sensor, a video camera, and an ultrasonic sensor.

18. An apparatus for reducing the risk of occurrence of decubitus ulcers in a patient, wherein said apparatus is for use with a bed, said bed having at least four legs, comprising:

(a) a patient location sensor for determining at least approximately a location of the patient, said location sensor including at least one weight sensor positioned under at least one of said bed legs;

(b) a time circuit;

(c) a CPU in electronic communication with said patient location sensor and said time circuit, said CPU at least for determining from said time circuit and said patient location sensor a time since the patient last changed location; and

,

(d) an alarm in electronic communication with said CPU and responsive thereto, said alarm for signaling a state of said patient depending on at least said patient location and said time since the patient last changed location.

20. An apparatus for reducing the risk of occurrence of decubitus ulcers in a patient, comprising:

(a) a patient location sensor for determining at least approximately a location of the patient;

(b) a time circuit;

(c) a CPU in electronic communication with said patient location sensor and said time circuit, said CPU at least for determining from said time circuit and said patient location sensor a time since the patient last changed location; and

,

(d) an alarm in electronic communication with said CPU and responsive thereto, said alarm for signaling a state of said patient depending on at least said patient location and said time since the patient last changed location, wherein, said patient sensor is a mat containing a plurality of sensor points thereon,

each of said plurality of sensor points being separately readable by said CPU,

said sensor points being for use in determining at least approximately a location of the patient,

and wherein said sensor points are selected from a group consisting of temperature sensors and piezoelectric elements.

21. An apparatus for reducing the risk of occurrence of decubitus ulcers in a patient, wherein said patient is at rest on a support surface, comprising:

(a) a patient location sensor for determining at least approximately a location of the patient, wherein said patient location sensor is selected from a group consisting of a chair mat, a plurality of accelerometers, an infrared sensor, a video camera, and an ultrasonic sensor;

(b) a time circuit;

(c) a CPU in electronic communication with said patient location sensor and said time circuit, said CPU at least

(c1) for determining from said time circuit and said patient location sensor a time since the patient last significantly changed location, and,

(c2) for initiating a signal indicative of a state of the patient depending on at least said patient location and said time since the patient last significantly changed location; and

,

(d) an alarm in electronic communication with said CPU and responsive thereto, said alarm at least for responding to said signal indicative of a state of the patient to produce an alarm signal.

22. An apparatus for reducing the risk of occurrence of decubitus ulcers in a patient at rest on a support surface, wherein the support surface is a bed, said bed having at least four legs, comprising:

(a) a patient location sensor for determining at least approximately a location of the patient, said location sensor including at least one weight sensor positioned under at least one of said bed legs;

(b) a time circuit;

(c) a CPU in electronic communication with said patient location sensor and said time circuit, said CPU at least

(c1) for determining from said time circuit and said patient location sensor a time since the patient last significantly changed location, and,

(c2) for initiating a signal indicative of a state of the patient depending on at least said patient location and said time since the patient last significantly changed location; and

,

(d) an alarm circuit in electronic communication with said CPU and responsive thereto, said alarm circuit at least for responding to said signal indicative of a state of the patient to produce an alarm signal.

23. An apparatus for reducing the risk of occurrence of decubitus ulcers in a patient according to claim 22, wherein said bed has four legs and wherein said location sensor includes at least four weight sensors, one weight sensor being positioned under each of said four bed legs.

24. An apparatus for reducing the risk of occurrence of decubitus ulcers in a patient at rest on a support surface, comprising:

(a) a patient location sensor for determining at least approximately a location of the patient on the support surface,

(a1) wherein said patient sensor is a mat containing a plurality of sensor points thereon,

(a2) wherein each of said plurality of sensor points is separately readable by said CPU, said sensor points being for use in determining at least approximately a location of the patient on the support surface, and,

(a3) wherein said sensor points is are selected from a group consisting of temperature sensors and piezoelectric elements;

(b) a time circuit;

(c) a CPU in electronic communication with said patient location sensor and said time circuit, said CPU at least

(c1) for determining from said time circuit and said patient location sensor a time since the patient last significantly changed location, and,

(c2) for initiating a signal indicative of a state of the patient depending on at least said patient location and said time since the patient last significantly changed location; and

,

(d) an alarm circuit in electronic communication with said CPU and responsive thereto, said alarm circuit at least for responding to said signal indicative of a state of the patient to produce an alarm signal.

25. A method for reducing the risk of occurrence of decubitus ulcers in a patient at rest on a support surface, wherein is provided a predetermined movement time period comprising the steps of:

(a) selecting a patient turn interval;

(b) determining a first position of the patient on the support surface;

(c) continuously monitoring a position of the patient and continuously determining an elapsed time since said first position was determined, until either a significant movement of the patient from said first position is detected, or until said determined elapsed time exceeds said selected patient turn interval,

(c1) if said significant movement of the patient from said first position is detected,

(i) continuing to monitor the patient for a period of time at least as long as said predetermined movement time period,

(ii) if the patient moves next to a location substantially the same as said first position before said predetermined movement time period has passed, determining that the patient has not moved, and,

(iii) if the patient does not move next to a location substantially the same as said first position before said predetermined movement time period has passed,

determining that the patient has moved, and

determining anew said first position of the patient;

(c2) if said determined elapsed time exceeds said selected patient turn interval, activating an alarm; and

,

(d) performing steps (b) and (c) as necessary to reduce the risk of occurrence of decubitus ulcers in the patient.