System for the measurement of the content of a gas in blood, in particular the oxygen saturation of blood

• US 4,890,619 A
• Filed: 04/14/1987
• Issued: 01/02/1990
• Est. Priority Date: 04/15/1986
• Status: Expired due to Fees

• Current Assignee: Avl Medical Instruments AG (Roche Holding AG)
• Original Assignee: Rudolf A. Hatschek
• Inventors: Hatschek, Rudolf A.
• Primary Examiner(s): Wayner, William E.
• Application Number:
  US07/038,296
• Time in Patent Office: 994 Days
• Field of Search: 356/39-41, 128/633, 128/661.04, 128/635, 128/24 A
• US Class Current: 600/323
• CPC Class Codes: A61B 5/14552 Details of sensors specially adapted therefor

Abstract

The system comprises a mounting device and two holding members detachably fastened to the mounting device, each holding member comprising a measuring head. Each measuring head comprises a light receiver and light sources adapted to emit light signals at various wave lengths and at least one heat radiator adapted to heat the bodily region, and particularly the skin region in which the oxygen saturation of the blood is measured, by the irradiation of waves. If the two measuring heads are positioned during measurement on opposite sides of the bodily part to be examined, then each light receiver will be able to receive reflection light dispersed back from the bodily part as well as transmission light permeating through the bodily part, thus yielding a good measurement accuracy. The power output of the waves emitted by the radiator is controlled by pulse width control in a way to have a parameter representing a measure for the heart pulse cause changes in the intensity of light coming out of the body and reaching at least one of the light receivers so as to have a predetermined desired value. An adequate heating of the bodily region is thus guaranteed, without any tissue damages occurring due to overheating.

Claims

1. System for the measurement of the content of a gas in the blood of a living being in a region of the body thereof, the system comprising:

radiation means adapted to radiate waves into the region of the body for heating the region;

controlling means provided for controlling the power output of the waves radiated by said radiating means;

at least one light receiver for optically measuring the gas, and wherein said controlling means are adapted to control said radiating means in a way to have a value representing a measure for the changes in the intensity of light emitted from the bodily region and received by said light receiver which, at least one of, lie within a predetermined desired value range and equal a desired value.

2. System as claimed in claim 1, where said controlling means are further adapted such that said value represents a measure for light intensity changes caused by the pulse of the living being subjected to the measurement process.

3. System as claimed in claim 1, wherein said radiating means comprises at least one ultrasonic radiator.

4. System as claimed in claim 1, further comprising at least one measuring head provided with light emitting means for emitting light of various wave lengths directed toward said region of the body and serving for the optical measurement of the blood gas with at least one light receiver, the measuring head further comprising wall means bounding a hollow space provided on the side of the measuring head and destined to make contact with a bodily part during measurement, and a pump being provided for pumping liquid through said hollow space.

5. System as claimed in claim 4, wherein said pump and said hollow space are arranged to form a circuit.

6. System as claimed in claim 4, comprising a temperature control device adapted to control the temperature of said liquid.

7. System as claimed in claim 4, wherein said radiating means comprise at least one ultrasonic radiator and wherein the latter and said hollow space are so arranged, that during the measuring process at least some part of the hollow space is located between the ultrasonic radiator and the bodily part, and wherein liquid provided in said hollow space is adapted to transmit onto the bodily part ultrasonic waves generated by said ultrasonic radiator and is adapted to match the wave resistance of the ultrasonic radiator to the wave resistance of the bodily part.

8. System as claimed in claim 1, wherein said radiating means are adapted for radiating pulsed waves.

9. System claimed in claim 1, wherein said controlling means are adapted for pulse width control of the radiated waves.

10. System for the optical measurement of oxygen saturation of blood in a region of the body of a living being, the system comprising:

two measuring heads, each of which being provided with light emitting means adapted to emit light of various wave lengths;

at least one light receiver;

a mounting device adapted to detachably support the two measuring heads; and

at least one additional mounting device equally adapted to datachably support the two measuring heads, said mounting device and said at least one additional mounting device being of dissimilar construction, thereby enabling the two measuring heads to be mounted as required onto the various mounting devices in different positions in relation to each other whereby the different positions depend on the specific mounting device selected.

11. System as claimed in claim 10, wherein at least two dissimilar mounting devices are adapted to support the measuring heads in a way to have their sides serving for emitting and receiving light to be disposed on opposing sides of a bodily part and arranged to face each other.

12. System as claimed in claim 10, wherein at least one mounting device is adapted to support the two measuring heads in a way to have their sides serving for emitting and receiving light disposed on opposing sides of a bodily part and arranged to face each other, another mounting device being adapted to support the measuring heads to have their sides serving for emitting and receiving light face away from each other.

13. System as claimed in claim 10, wherein each measuring head is fastened onto one end of an elongated holding member detachable connectable with at least some of the mounting devices in a way to have its side serving for emitting and receiving light define a plane parallel to the longitudinal direction of the holding member.

14. System for the optical measurement of oxygen saturation of blood in a region of the body of a living being, the system comprising:

two measuring heads, each of which being provided with light emitting means adapted to emit light of various wave lengths;

at least one light receiver; and

electronic circuit means connected to said measuring heads to process electrical signals supplied by said at least one light receiver to determine therefrom the oxygen saturation, wherein said circuit means are adapted to utilize light which originates from the light emitting means pertaining to the same measuring head as the light receiver which receives said light does, as well as light received by the light receiver in question and originating from the light emitting means of the other measuring head.

15. System for the optical measurement of oxygen saturation of blood in a region of the body of a living being, the system comprising:

two measuring heads, each of which being provided with light emitting means adapted to emit light of various wave lengths;

at least one light receiver; and

electronic circuit means electrically connected with said measuring heads to process electrical signals supplied by the light receiver to said measuring heads and to determine therefrom the oxygen saturation, wherein at least when the two measuring heads are positioned on opposing sides of a bodily part, said circuit means is adapted to determine the oxygen saturation on the basis of the electrical signals supplied to said circuit means by said light receivers of both said measuring heads.

16. System for the measurement of the content of a blood gas, the system comprising:

at least one measuring head, for measuring said gas content optically, comprising a support, a shell disposed on the support, at least one light receiver, and at least one light source, the shell surrounding said at least one light receiver and said at least one light source, said measuring head being adapted to contact a bodily part and being open on the side designated to contact said bodily part wherein an edge of the shell designated to contact said bodily part is provided with a gasket of rubber-like elastic material; and

at least one ultrasonic radiator, also disposed within the shell and adapted to radiate ultrasonic waves into a region of the bodily part.

17. System for the measurement of the content of a blood gas, the system comprising:

at least one measuring head for measuring said gas content optically comprising a support, a shell, disposed on said support, at least one light receiver, and at least one light source, the shell surrounding said at least one light receiver and said at least one light source, said measuring head being adapted to contact a bodily part and being open on the side designated to contact said bodily part; and

at least one ultrasonic radiator comprising a plateshaped, piezoelectric element, also disposed within the shell and adapted to radiate ultrasonic waves into a region of the bodily part, and

an ultrasonic wave transmitter consisting of a gelatinous mass disposed in a space enclosed by the shell on that side of the piezoelectric element that is designated to face the bodily part.

18. System as claimed in claim 17, wherein said gelatinous mass is pervious to visible and infrared light.

19. System for the measurement of the content of a blood gas, the system comprising:

at least one measuring head, for measuring said gas content optically, adapted to contact a bodily part, said at least one measuring head including a support, at least one light receiver, at least one light source and ultrasonic radiators, adapted to radiate ultrasonic waves into a region of the bodily part arranged on opposite sides of the at least one light receiver;

said at least one light receiver, said light source, and said ultrasonic radiators being supported by said support.