Fiber optic monitor using interferometry for detecting vital signs of a patient

• US 6,498,652 B1
• Filed: 02/08/2000
• Issued: 12/24/2002
• Est. Priority Date: 02/08/2000
• Status: Expired due to Term

• Current Assignee: Tamiras Per Pte Ltd LLC (Intellectual Ventures LLC)
• Original Assignee: Deepak Varshneya
• Inventors: Maida, John L. Jr., Varshneya, Deepak
• Primary Examiner(s): Turner, Samuel A.
• Assistant Examiner(s): CONNOLLY, PATRICK J
• Application Number:
  US09/499,889
• Time in Patent Office: 1,050 Days
• Field of Search: 356/477, 356/478, 356/479, 356/481, 356/483, 250/227.19, 250/227.27
• US Class Current: 356/477
• CPC Class Codes: A61B 2503/06 Children, e.g. for attention deficit diagnosis
• CPC Class Codes: A61B 2562/0266 Optical strain gauges
• 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 5/0205 Simultaneously evaluating both cardiovascular conditions and different types of body conditions, e.g. heart and respiratory condition
• CPC Class Codes: A61B 5/024 Detecting, measuring or recording pulse rate or heart rate A61B5/0205, A61B5/021 take precedence
• 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 5/113 occurring during breathing
• CPC Class Codes: A61B 5/14551 for measuring blood gases
• CPC Class Codes: A61B 5/318 Heart-related electrical modalities, e.g. electrocardiography [ECG]
• CPC Class Codes: A61B 5/412 Detecting or monitoring sepsis
• CPC Class Codes: A61B 5/4818 Sleep apnoea
• CPC Class Codes: A61B 5/6805 Vests
• CPC Class Codes: A61B 5/6887 mounted on external non-worn devices, e.g. non-medical devices
• CPC Class Codes: A61B 5/6892 Mats

Abstract

A fiber optic monitor that utilizes optical phase interferometry to monitor a patient'"'"'s vital signs such as respiration, cardiac activity and body'"'"'s physical movement. The monitor, which is non-invasive, comprises an optical fiber interferometer that includes an optical fiber proximately situated to the patient so that acousto-mechanical signals from the patient are coupled into the optical fiber. Responsive thereto, the interferometer generates a time-varying serial train of fringes which is detected by a photo-detector. A signal processor coupled to the optical detector provides one or more processed output signals indicative of the vital functions. The monitor system has broad applicability, from routine monitoring of infants at home to apnea, arrhythmia and trauma situations. The system can be implemented in embodiments ranging from a low cost in-home monitor for infants to a high end product for in hospital use to monitor infants in nenonatalogy laboratories or at home by physician'"'"'s prescription. The monitor can be integrated with other sensors such as an EKG, a camera, an oxygen sensor, a carbon-di-oxide sensor, temperature sensor or a microphone to get additional required information depending on the application. When integrated and combined with EKG information, the monitor provides ballisto-mechanical information of the heart for early diagnosis or prediction of cardiac conditions or events. In some embodiments of the monitor, the system can be made portable so that the patient can walk around while still being continuously monitored.

Claims

1. A fiber optic, interferometric monitor for detecting vital functions in a patient, comprising:

an optical fiber interferometer that generates an optical signal responsive to acousto-mechanical signals generated by vital functions of said patient, including

optical fiber means for defining two optical paths including a first optical path and a second optical path;

said first optical path including an optical fiber proximately situated to said patient so that said acousto-mechanical signals are coupled to said optical fiber, thereby modulating a physical parameter of said optical fiber responsive to said acousto-mechanical signals,

an optical source coupled to supply optical radiation into an input end of said first and second optical paths,

means for creating a serial train of fringes from the optical radiation emitted from an output end of said two optical paths;

a photo-detector arranged to sense an optical signal provided by time variations in said fringe train, said photo-detector providing a raw electrical signal responsive thereto;

a signal processor coupled to said optical detector to process said raw electrical signal to provide one or more processed output signals indicative of said vital functions; and

an output system for said one or more processed signals.

2. The monitor of claim 1 wherein said modulated physical parameter comprises the length of said optical fiber, such that said acousto-mechanical signals modulate the length of said optical fiber.

3. The monitor of claim 1 wherein said output signals indicative of said vital functions include heartbeat, respiration, and movement.

4. The monitor of claim 3 wherein said signal processor comprises a digital signal processor for providing separate output signals indicative of heartbeat rate, respiration rate, and physical movement.

5. The monitor of claim 3 wherein said output signals include a combined signal indicative of heartbeat and respiration rates.

6. The monitor of claim 3 wherein said signal processor comprises means for generating an alarm responsive to at least one of said heartbeat, respiration, and physical movement.

7. The monitor of claim 1 further comprising a pad within which said optical fiber sensor is situated, said pad being positioned proximate to said patient.

8. The monitor of claim 7 wherein said pad has a mat configuration, and said patient rests on said mat.

9. The monitor of claim 7 wherein said pad has a garment configuration such that said patient wears said pad.

10. The monitor of claim 1 wherein said output system includes a transmission system that transmits at least one of said signals to a receiver situated remotely from said patient.

11. The monitor of claim 10 wherein said receiver includes a portable receiver unit and means for providing an alarm responsive to said at least one of said output signals.

12. The monitor of claim 1 further comprising a depolarizer for reducing polarization-induced signal fading.

13. The monitor of claim 1 wherein said fiber interferometer comprises a Sagnac interferometer configuration.

14. The monitor of claim 1 wherein said fiber interferometer comprises a Mach-Zehnder interferometer configuration.

15. The monitor of claim 1 wherein said fiber interferometer comprises a Fabry-Perot interferometer configuration.

16. The monitor of claim 1 wherein said fiber interferometer comprises a Michelson interferometer configuration.

17. The monitor of claim 1 further comprising one or more additional sensors arranged to monitor physical parameters in said patient.

18. The monitor of claim 17 wherein said one or more additional sensors are selected from a group comprising:

a microphone, a camera, an oxygen sensor, a carbon dioxide sensor, a temperature sensor, an EKG monitor and a second fiber optic interferometer.

19. A method for detecting vital functions of a patient utilizing an optical fiber interferometer, comprising:

coupling optical radiation into a first end of a first optical path and a second optical path, said first optical path including a first section of optical fiber;

situating said first section of optical fiber proximate to said patient;

coupling acousto-mechanical signals indicative of vital signs generated by said patient into said first section of optical fiber to modulate a physical parameter of said optical fiber responsive to said acousto-mechanical signals;

creating a serial train of fringes from the optical radiation emitted from a second end of said two optical paths;

detecting time variations of said fringes and providing a time-varying electrical signal responsive thereto; and

signal processing said time-varying electrical signal to provide one or more output signals indicative of said vital functions.

20. The method of claim 19 wherein said step of modulating a physical parameter comprises modulating the phase of said optical fiber.

21. The method of claim 19 wherein said signal processing step comprises providing output signals indicative of vital functions including heartbeat rate, respiration rate, and physical movement.

22. The method of claim 21 wherein said signal processing step comprises digitally processing said time-varying electrical signal to provide separate output signals indicative of heartbeat rate, respiration rate, and physical movement.

23. The method of claim 21 wherein said signal processing step comprises processing said time-varying electrical signal to provide a combined signal indicative of heartbeat and respiration rates.

24. The method of claim 21 wherein said signal processing step comprises processing said time-varying electrical signal to generate an alarm signal responsive to at least one of said heartbeat rate, respiration rate, and physical movement.

25. The method of claim 19 wherein said step of situating said first section of optical fiber proximate to said patient further comprises positioning said patient on a pad in a bed.

26. The method of claim 19 said step of situating said first section of optical fiber proximate to said patient further comprises wearing a garment including said first section of optical fiber.

27. The method of claim 19 further comprising the step of communicating said output signals.

28. The method of claim 27 wherein said step of communicating said signals further comprises transmitting said signal to a receiver positioned remotely from said patient.

29. The method of claim 19 further comprising the step of simultaneously monitoring one or more physical parameters of said patient with a second sensor.

30. The method of claim 29 comprising the step of monitoring the oxygen level in said patient.

31. A fiber optic, interferometric infant monitor for detecting vital functions in an infant within a crib, comprising:

a pad having an optical fiber situated therein, said pad arranged within said crib proximate to said infant so that acousto-mechanical signals generated by said infant are coupled into said optical fiber;

a fiber interferometer that generates an optical signal responsive to acousto-mechanical signals generated by vital functions of said infant, including

optical fiber means for defining two optical paths including a first optical path and a second optical path, said first optical path including said optical fiber situated within said pad;

an optical source coupled to supply optical radiation into an input end of said first and second optical paths,

an optical system for creating a serial train of fringes from the optical radiation emitted from an output ends of said two optical paths; and

a photo-detector arranged to sense an optical signal provided by time variations in said fringe train, said photo-detector providing a raw electrical signal responsive thereto;

a signal processor coupled to said optical detector to process said raw electrical signal to provide one or more processed output signals indicative of heartbeat rate, respiration rate, and physical movement; and

an output system that communicates said one or more output signals.

32. The monitor of claim 31 further comprising an audio system that detects and transmits sounds, including a microphone arranged to detect sounds generated by the infant.

33. The monitor of claim 31 wherein said pad has a mat configuration, and said infant rests on said mat.

34. The monitor of claim 31 wherein said output system includes a transmission system that transmits at least one of said signals to a receiver situated remotely from said infant.

35. The monitor of claim 34 wherein said receiver includes a portable receiver and means for providing an alarm responsive to said at least one of said output signals.

36. The monitor of claim 34 wherein said receiver includes a speaker to provide sounds generated by the infant.

37. The monitor of claim 31 wherein said output signals include a combined signal indicative of heartbeat and respiration rates.

38. The monitor of claim 31 wherein said signal processor comprises means for generating an alarm responsive to at least one of said heartbeat rate, respiration rate, and physical movement.

39. The monitor of claim 31 wherein said signal processor comprises a digital signal processor for providing separate output signals indicative of heartbeat rate, respiration rate, and physical movement.

40. The monitor of claim 31 wherein said pad has a garment configuration such that said infant wears said pad.

41. The monitor of claim 31 further comprising a means for reducing polarization-induced signal fading.

42. The monitor of claim 31 wherein said fiber interferometer comprises a Sagnac interferometer configuration.

43. The monitor of claim 31 wherein said fiber interferometer comprises a Mach-Zehnder interferometer configuration.

44. The monitor of claim 31 wherein said fiber interferometer comprises a Fabry-Perot interferometer configuration.

45. The monitor of claim 31 wherein said fiber interferometer comprises a Michelson interferometer configuration.

46. The monitor of claim 31, further comprising one or more additional sensors arranged to monitor physical parameters in said patient.

47. The monitor of claim 46 wherein said one or more additional sensors are selected from a group comprising:

a microphone, a camera, an oxygen sensor, a carbon dioxide sensor, a temperature sensor an EKG monitor and a second (or more) fiber optic interferometer.