SYSTEM FOR DETECTING AND MONITORING VITAL SIGNS

• US 20080005838A1
• Filed: 07/05/2007
• Published: 01/10/2008
• Est. Priority Date: 07/05/2006
• Status: Active Grant

• Current Assignee: Stryker Corporation
• Original Assignee: Stryker Corporation
• Inventors: Wan Fong, David, Dionne, Jean-Paul
• Granted Patent: US 7,699,784 B2
• Time in Patent Office: Days
• US Class Current: 005/600
• CPC Class Codes: A61B 5/02444 Details of sensor A61B5/02427 takes precedence
• CPC Class Codes: A61B 5/1102 Ballistocardiography
• CPC Class Codes: A61B 5/113 occurring during breathing
• CPC Class Codes: A61B 5/4094 Diagnosing or monitoring seizure diseases, e.g. epilepsy
• CPC Class Codes: A61B 5/6887 mounted on external non-worn devices, e.g. non-medical devices
• CPC Class Codes: A61B 5/7257 using Fourier transforms
• CPC Class Codes: A61G 2203/32 for force

Abstract

A system and method for determining and monitoring various characteristics of a patient positioned on a patient support apparatus, such as a bed, stretcher, or cot, is disclosed. The system and method involve monitoring the forces exerted by the patient on one or more force sensors, which may be load cells on the support apparatus. These force sensors will detect vibrations that correspond to various conditions of the patient, including the patient'"'"'s heart rate, breathing rate, and/or the seizure status of a patient. These vibrations may be analyzed, such as by Fast Fourier Transforms, in order to determine the various conditions of the patient.

Claims

1. A patient support apparatus comprising:

a support adapted to at least partially support a weight of a patient;

a force sensor adapted to detect a force exerted from said support onto said force sensor, said force sensor outputting a signal corresponding to said force; and

a controller in communication with said force sensor, said controller adapted to determine from said signal at least one of a breathing rate and heart rate of a patient positioned on said support.

2. The apparatus of claim 1 wherein said controller is adapted to calculate a Fast Fourier Transform of said signal and use said Fast Fourier Transform to determine said at least one of the breathing rate and the heart rate.

3. The apparatus of claim 2 wherein said controller determines the breathing rate, and said controller identifies a peak frequency in said Fast Fourier Transform in order to determine the breathing rate.

4. The apparatus of claim 3 wherein the controller determines the breathing rate to be equal to said peak frequency.

5. The apparatus of claim 2 wherein said controller determines the heart rate of the patient and said controller analyzes a peak in said Fast Fourier Transform in order to determine the heart rate.

6. The apparatus of claim 5 wherein said controller calculates the heart rate by dividing said peak by an integer.

7. The apparatus of claim 5 wherein said controller analyzes a pair of peaks in said Fast Fourier Transform to determine the heart rate, said pair of peaks located at integer multiples of the heart rate.

8. The apparatus of claim 1 further including a low pass filter adapted to filter out frequencies in said signal that exceed a selected frequency.

9. The apparatus of claim 1 wherein said controller is further adapted to analyze said signal to determine if the patient is experiencing a seizure.

10. The apparatus of claim 2 further including a second force sensor adapted to detect a second force exerted from said support onto said second force sensor, said second force sensor outputting a second signal corresponding to said second force;

wherein said controller is in communication with said second force sensor and said controller is further adapted to make a second determination of said at least one of the breathing rate and heart rate of the patient positioned on said support based upon said second signal.

11. The apparatus of claim 1 wherein said controller is further adapted to monitor said at least one of the breathing rate and heart rate and issue a notification to an attendant if said at least one of the breathing rate and heart rate meets a criteria.

12. The apparatus of claim 1 further including a frame positioned between said support and said force sensor.

13. A patient support apparatus comprising:

a support deck adapted to support a patient;

a frame adapted to support said support deck;

a force sensor interconnected between said frame and said support deck, said force sensor adapted to detect a force exerted from said support deck onto said force sensor, said force sensor outputting a signal corresponding to said force; and

a controller in communication with said force sensor, said controller adapted to determine from said signal a breathing rate of a patient positioned on said support deck.

14. The apparatus of claim 13 wherein said controller is adapted to calculate a Fast Fourier Transform of said signal and use said Fast Fourier Transform to determine the breathing rate.

15. The apparatus of claim 13 wherein said controller is further adapted to monitor said breathing rate and issue a notification to an attendant if the breathing rate meets a criteria.

16. The apparatus of claim 15 wherein said controller allows said criteria to be changed by the attendant.

17. The apparatus of claim 15 wherein said controller is in communication with at least one computer located outside of a room in which the patient support apparatus is located.

18. The apparatus of claim 17 wherein said controller is further adapted to determine a heart rate of the patient using said Fast Fourier Transform.

19. The apparatus of claim 13 wherein said controller is further adapted to use said signal to determine whether the patient is having a seizure or not.

20. A patient support apparatus comprising:

a support adapted to at least partially support a weight of a patient;

a force sensor adapted to detect a force exerted from said support onto said force sensor, said force sensor outputting a signal corresponding to said force; and

a controller in communication with said force sensor, said controller adapted to analyze said signal to determine if a patient positioned on said support is experiencing a seizure or not.

21. The apparatus of claim 20 wherein said controller is further adapted to calculate a Fast Fourier Transform of said signal and to determine from said Fast Fourier Transform a breathing rate of the patient.

22. The apparatus of claim 21 wherein said controller is further adapted to determine from said Fast Fourier Transform a heart rate of the patient.

23. A method of collecting data about a patient comprising:

providing a support that supports at least a portion of a patient'"'"'s weight;

providing a force sensor that senses a force exerted by said support on said force sensor, said force sensor generating a signal corresponding to said force;

performing a Fast Fourier Transform on said signal; and

analyzing said Fast Fourier Transform.

24. The method of claim 23 wherein said support includes a surface of a bed that supports an entire weight of the patient.

25. The method of claim 24 further including using said signal from said force sensor to determine the patient'"'"'s weight.

26. The method of claim 25 further including determining a breathing rate of the patient from said Fast Fourier Transform.

27. The method of claim 25 further including determining a heart rate of the patient from said Fast Fourier Transform.

28. The method of claim 25 further including determining whether the patient is experiencing a seizure or not from said signal.

29. The method of claim 23 further including low-pass filtering said signal prior to performing said Fast Fourier Transform.

30. The method of claim 23 further including providing a frame positioned between said support and said force sensor.

31. A method of monitoring a condition of a patient comprising:

providing a support that at least partially supports a patient'"'"'s weight;

providing a force sensor that senses a force exerted by said support on said force sensor, said force sensor generating a signal corresponding to said force; and

determining at least one of a heart rate, a breathing rate, and a seizure status of the patient from said signal.

32. The method of claim 31 further including performing a Fast Fourier Transform on said signal and determining from said Fast Fourier Transform at least one of said heart rate and breathing rate.

33. The method of claim 32 further including:

performing a second Fast Fourier Transform on said Fast Fourier Transform; and

using said second Fast Fourier Transform to determine at least one the heart rate and the breathing rate of the patient.

34. The method of claim 31 further including:

providing a second force sensor that senses a second force exerted by said support on said second force sensor, said second force sensor generating a second signal corresponding to said second force;

performing a second Fast Fourier Transform on said second signal; and

using said second Fast Fourier Transform and said Fast Fourier Transform to determine at least one of the heart rate and the breathing rate of the patient.

35. A method of analyzing forces exerted by a patient onto a patient support in communication with a force sensor wherein the force sensor outputs a signal corresponding to said forces, said method comprising:

processing said signal to produce a processed output;

using a second sensor different from said force sensor to determine at least one of a patient'"'"'s breathing rate and heart rate; and

determining a correlation between said processed output and said at least one of the patient'"'"'s breathing rate and heart rate determined by said second sensor.

36. The method of claim 35 further including storing said correlation in an electronic memory for future use in situations where said second sensor is not used.

37. The method of claim 36 wherein said processing includes performing a Fast Fourier Transform on said signal.