Apparatus and method for monitoring respiration

• US 5,273,036 A
• Filed: 04/20/1993
• Issued: 12/28/1993
• Est. Priority Date: 04/03/1991
• Status: Expired due to Fees

• Current Assignee: E for M Corp. (General Electric Company)
• Original Assignee: PPG Industries Incorporated (Nouryon BV)
• Inventors: Kronberg, Harald, Leist, Helmut
• Primary Examiner(s): Cohen, Lee S.
• Assistant Examiner(s): NASSER, ROBERT L
• Application Number:
  US08/049,965
• Time in Patent Office: 252 Days
• Field of Search: 128/633, 128/665-666, 128/716, 364/413.03
• US Class Current: 600/310
• CPC Class Codes: A61B 5/02427 Details of sensor
• CPC Class Codes: A61B 5/0816 Measuring devices for examining respiratory frequency measuring frequency of electric signals G01R23/00
• CPC Class Codes: A61B 5/14552 Details of sensors specially adapted therefor
• CPC Class Codes: A61B 5/1491 Heated applicators

Abstract

The apparatus for monitoring respiration comprises a photoplethysmographic sensor whose LED transmitter element(s) is/(are) excited by a monitoring unit with a specified control power and/or control signal sequence or frequency. By means of a signal processing unit, both the frequency and depth of respiration can be measured, as can the pulse frequency or oxygen saturation of the peripheral blood. The use of such an apparatus guarantees significantly more reliable monitoring of respiration than the impedance pneumographic methods of the prior art.

Claims

1. An apparatus for monitoring respiration of a patient by peripheral measurement of vital factors relevant to respiration, comprising:

a sensor to be applied on a surface tissue of an organ containing blood vessels;

said sensor including;

at least one radiation transmitter means which emits electromagnetic radiation into the organ tissue, and

at least one radiation receiver means which receives a portion of the radiation after the radiation passes through the organ tissue and blood components and generates an output signal;

a control means which excites said radiation transmitter with a desired control output, control signal sequence and control signal sequence frequency; and

a means for signal processing which receives said signal output from said radiation receiver means and determines therefrom measurements for the patient'"'"'s respiratory activity of at least one of the following;

temporal curve of the respiratory excursion, the frequency, and the depth of respiration.

2. The apparatus according to claim 1 wherein said control means includes means to excite said radiation transmitter means to emit electromagnetic radiation on at least two different frequencies (wavelengths), said radiation receiver means delivers output signals for said at least two radiation frequencies received after passing through said organ tissue and blood components, and said means for signal processing also can determine at least one of the following:

1) measurements for the specified blood components, and

     2) blood circulation values based on said output signals.

3. The apparatus according to claim 2 wherein said means for signal processing includes a pulse oximeter means for the determination of at least the oxygen saturation of the peripheral arterial blood in the organ tissue.

4. The apparatus according to claim 2 wherein the means for signal processing can determine the pulse frequency as a blood circulation value.

5. The apparatus according to claim 2 wherein said means for signal processing includes a bandpass filter selected from the group consisting of:

fixed bandpass filters, adjustable bandpass filters, and bandpass filters with automatically adaptable cutoff frequencies.

6. The apparatus according to claim 5 wherein said cutoff frequencies of said bandpass filter are selected in the range of 8 to 50 periods/min. and approximately in the ratio 4:

1.

7. The apparatus according to claim 1 wherein said means for signal processing includes a high pass filter means to eliminate gradual signal drift.

8. The apparatus according to claim 1 wherein said means for signal processing includes a preamplifier means to normalize said output signals to values selected from the group consisting of:

their mean values and peak values.

9. The apparatus according to claim 8 wherein said preamplifier means normalizes to values selected form the group consisting of:

means values and peak values measured over moving limited time segments.

10. The apparatus according to claim 1 wherein said radiation transmitter means is a light emitting diode of a specified radiation frequency (radiation wavelength) in the visible and near-infrared range.

11. The apparatus according to claim 10 wherein said light emitting diode radiates at a radiation frequency of approximately 805 nm.

12. The apparatus according to claim 1 wherein said radiation receiver means is a photodiode with spectral sensitivity adapted to the radiation frequency (wavelength) of the radiation transmitter.

13. The apparatus according to claim 1 wherein said sensor includes a heating means and said means for signal processing includes means to provide for the thermostatic control of said sensor to the hyperemization temperature of adjacent bodily tissue.

14. The apparatus according to claim 13 wherein said means for signal processing includes means to display a measurement for blood perfusion derived by heating the sensor to a constant temperature and making the determination calorimetrically.

15. The apparatus according to claim 1 wherein said sensor includes a heating means, and said means for signal processing includes a temperature control which heats said surface tissue of said organ at the application point of said sensor to a temperature corresponding to the subsurface body temperature and means to display said subsurface body temperature.

16. A method of monitoring respiration of a patient by peripheral measurement of vital factors relevant to respiration, comprising:

applying a sensor to the surface tissue of an organ containing blood vessels;

emitting electromagnetic radiation at a desired control output, control signal sequence and control signal sequence frequency, from said sensor into the organ tissue;

receiving a portion of said radiation after said radiation passes through said organ tissue and blood components;

generating an output signal based on said received portion of said radiation; and

processing said signal output to determine from the received portion of the radiation measurements for the patient'"'"'s respiratory activity of at least one the of the following;

temporal curve of the respiratory excursion, the frequency, and the depth of respiration.

17. The method according to claim 16 wherein said emitting step includes the step of emitting electromagnetic radiation on at least two different frequencies (wavelengths), said generating step includes the step of generating output signals for the at least two radiation frequencies received after passing through said organ tissue and said processing step includes at least one of the steps of determining measurements for the specified blood components, and determining blood circulation values.

18. The method according to claim 17 wherein said emitting step includes the step of emitting radiation from light emitting diodes of a specified radiation frequency (radiation wavelength) in the visible and near-infrared range and said receiving step includes the step of receiving said portions of said radiation with photodiodes with spectral sensitivities adapted to the radiation frequencies (wavelengths) of said light emitting diodes.

19. The method according to claim 18 further including the steps of heating the surface tissue of said organ at the application point of said sensor to a temperature corresponding to the subsurface body temperature and displaying said subsurface body temperature.