Apparatus for monitoring metabolism in body organs

• US 4,321,930 A
• Filed: 09/18/1980
• Issued: 03/30/1982
• Est. Priority Date: 06/28/1977
• Status: Expired due to Term

• Current Assignee: Duke University Inc (Duke University)
• Original Assignee: Duke University Inc (Duke University)
• Inventors: Overaker, Ronald F., Jobsis, Frans F., Keizer, Johannes H.
• Primary Examiner(s): Kamm, William E.
• Application Number:
  US06/188,578
• Time in Patent Office: 558 Days
• Field of Search: 128/633, 128/634, 128/664, 128/665, 128/687, 128/688, 128/689
• US Class Current: 600/344
• CPC Class Codes: A61B 5/0059 using light, e.g. diagnosis by transillumination, diascopy, fluorescence A61B5/0093, A61B5/1455, A61B5/02416 and A61B5/0261 take precedence
• CPC Class Codes: A61B 5/0073 by tomography, i.e. reconstruction of 3D images from 2D projections A61B5/0066 takes precedence
• CPC Class Codes: A61B 5/14551 for measuring blood gases
• CPC Class Codes: A61B 5/14552 Details of sensors specially adapted therefor
• CPC Class Codes: A61B 5/14553 specially adapted for cerebral tissue
• CPC Class Codes: A61B 5/6833 Adhesive patches
• CPC Class Codes: A61K 49/0004 Screening or testing of compounds for diagnosis of disorders, assessment of conditions, e.g. renal clearance, gastric emptying, testing for diabetes, allergy, rheuma, pancreas functions

Abstract

A mounting structure secures to a selected portion of the human body, e.g., the head, a limb, or the torso, and incorporates light source and light detecting means adapted for association with spectrophotometric circuitry for in situ, in vivo monitoring of local metabolism in the area of the body where the structure is secured.

Claims

1. A spectrophotometric reflectance apparatus for measuring in situ, in vivo, non-invasively, atraumatically, harmlessly, rapidly and continuously a local metabolic oxygen dependent activity of a selected portion of the body such as the brain of a body where such activity bears a measureable relation to an oxygen dependent absorption characteristic of the selected portion for a particular wavelength of light transmitted therethrough, comprising:

(a) circuitry means including;

(i) a plurality of near-infrared light sources located external of the body and having light emissions of different wavelengths in the 700 to 1300 nanometer spectral range and of an intensity below the level damaging to the body and said selected portion but sufficient to be detectable by a light sensor after transmission through any skin, bone and tissue included in an optical transmission-reflectance path including said selected portion thereof and extending for several centimeters between points of light entry and exit laterally spaced several centimeters apart and located on contiguous skin surface areas of the body and after scattering in and deep reflectance from said selected portion along said path, said emissions including at least one measuring wavelength and at least one reference wavelength within said spectral range, each said measuring wavelength being selected such that said selected portion exhibits a selected absorption therefore, the extent of which is dependent upon a specific state of a local metabolic, oxygen dependent activity of said selected portion; and

(ii) means operatively associated with said light sources to produce emissions representing at least one said measuring wavelength and at least one said reference wavelength within said spectral range for transmission along said path to said selected portion and at levels of intensity below that which would be damaging to the body and said selected portion;

(b) first optical cable coupling means for receiving transmitting and directing the output light emissions of said light sources at said measuring and reference wavelengths to a light entry point proximate said body;

(c) a detachable, body mountable apparatus associated with said circuitry means including;

(i) a flexible, elongated support member adapted to be releasably secured to the body proximate a said selected portion of the body having a selected set of said light entry and exit points, said support member being adapted to provide ambient light shielding over said light entry and exit points and to conform to the curvature and shape of the body at the location thereof;

(ii) a mounting structure secured to said support member and adapted to deform in shape in correspondence with the curvature assumed by said support member when secured to the body;

(iii) a first preformed light guide means mounted in said mounting structure and optically coupled to said first optical cable means and having an optical face for light exit adapted to be mated in a substantially pressed fit relation with said selected point of light entry for entry of light in said wavelengths to be transmitted, deeply reflected and scattered along said path and to said selected portion;

(iv) a first preformed light detector assembly mounted in said mounting structure proximate said first light guide means and having first light collector means adapted to be mated in a substantially pressed fit relation with said selected point of light entry for receiving deeply penetrating light emissions reflected directly back from any skin, bone and tissue at or within a few millimeters of said selected point of light entry; and

(v) a second preformed light detector assembly mounted in said mounting structure and having second light collecting means spaced several centimeters away from said first collector means and adapted to be mated in a substantially pressed fit relation with said selected point of light exit for receiving deeply penetrating light emissions reflected and scattered to said selected point of light exit from said selected portion of said body;

(d) second coupling means operatively coupling the output of said first light detector assembly to said circuitry means;

(e) third coupling means operatively coupling the output of said second light detector assembly to said circuitry means; and

(f) processing means operatively associated with said circuitry means adapted to produce from the outputs of said first and second light detector assemblies an electrical output signal corrected for changes in blood volume of said skin, bone and tissue during the measuring cycle and representing the difference in absorption of said measuring and reference wavelengths by said selected body portion as a function of the state of said local metabolic oxygen dependent activity and further adapted to convert said electrical output signal to a signal providing a substantially continuous and rapid measure of said activity.

2. An apparatus as claimed in claim 1 wherein said support member is formed as an elastic strap with adjustable securing means thereon, said mounting structure is secured to said strap in a manner enabling said strap when mounted on said body to exert pressure on said mounting structure and thereby orient said first light guide means optical face and said first and second light detector assemblies'"'"' first and second light collector means in said press fit relation with respect to said selected light entry and exit points.

3. An apparatus as claimed in claim 1 wherein said first and second light collector means comprise second and third preformed light guide means with light collecting optical faces thereon and being mounted in said mounting structure, and said second and third coupling means comprise second and third optical cable means connected to said second and third light guide means.

4. An apparatus as claimed in claim 3 wherein said first preformed light guide means and said second preformed light guide means are formed as an integral coaxial optical cable terminal.

5. An apparatus as claimed in claim 1 wherein said first and second light collector means comprise photo diode means and said first and second light detector assemblies include associated circuitry for converting light emissions received by said photo diodes to electrical signals representative thereof and said second and thid coupling means comprise a pair of electrical cabling means operatively connected to the respective said assemblies for conducting said photo diode developed signals to said circuitry means.

6. An apparatus as claimed in claim 1 including auxiliary ambient light-shielding means in the nature of a flexible cap adapted to cover said selected portion of the body and to be detachably secured to said support member.

7. An apparatus as claimed in claim 1 wherein said mounting structure is formed in a manner enabling the spacing between said first light guide means and said second light detector assembly to be adjusted.

8. An apparatus as claimed in claim 1 wherein said first light guide means and said first light detector assembly comprise a single integral preformed optical cable terminal with selected optical fibers and the faces thereof being allocated and adapted to be utilized for transmitting and entry of light in said wavelengths to said point of entry with the remainder of the optical fibers and the faces thereof being allocated and adapted to be utilized for receiving said light emissions reflected directly back from any skin, bone and tissue at or within a few millimeters of said selected point of light entry and wherein said first and second coupling means comprise optical cable means coupled at one end to said single cable terminal and at the opposite end being branched with separate couplings to said circuitry means with those fibers allocated to transmitting said wavelengths to said point of light entry having one coupling to said circuitry means and with the said remainder of said optical fibers having another coupling for transmitting said light emissions to said circuitry means.

9. An apparatus as claimed in claim 1 wherein said first light guide means and said first and second light detector assemblies are provided with operatively associated detachable coupling means enabling said body mountable apparatus to be installed on and removed from the body as a unitary replaceable structure.

10. An apparatus as claimed in claim 1 including resilient capping means effective under the pressure of said support member to establish resilient body conforming light guides adjacent the skin adjacent each said point of light entry and exit.

11. In a spectrophotometic reflectance apparatus for measuring in situ, in vivo, non-invasively, atraumatically, harmlessly, rapidly and continuously a local metabolic oxygen dependent activity of a selected portion of the body where such activity bears a measurable relation to an oxygen dependent absorption characteristic of the selected portion for a particular wavelength of light transmitted therethrough having:

(a) circuitry means including;

(i) a plurality of near-infrared light sources located external of the body and having light emissions of different wavelengths in the 700-1300 nanometer spectral range and of an intensity below the level damaging to the body and said selected portion but sufficient to be detectable by a light sensor after transmission through any skin, bone and tissue included in an optical transmission-reflectance path including said selected portion thereof and extending for several centimeters between selected points of light entry and exit laterally spaced several centimeters apart and located on contiguous skin surface areas of the body and after scattering in and deep reflectance from said selected portion along said path, said emissions including at least one measuring wavelength and at least one reference wavelength within said spectral range, each said measuring wavelength being selected such that said selected portion exhibits a selected absorption therefore, the extent of which is dependent upon a specific state of a local metabolic, oxygen dependent activity of said selected portion; and

(ii) means operatively associated with said light sources to produce emissions representing at least one said measuring wavelength and at least one said reference wavelength within said spectral range for transmission along said path to said selected portion and at levels of intensity below that which would be damaging to the body and said selected portion;

(b) first optical cable means providing a bundle of optical fibers with selected fibers connected for receiving, transmitting and directing the output light emissions of said light sources at said measuring and reference wavelengths to a selected light entry point proximate said body and other selected fibers connected for receiving deeply penetrating light emissions reflected directly back from any skin, bone and tissue at or within a few millimeters of said selected point of light entry and coupling such emissions to a processing means;

(c) second optical cable means providing a bundle of optical fibers adapted for receiving deeply penetrating light emissions reflected and scattered to said selected point of light exit from said selected portion of said body and coupling such exit light emissions to a processing means; and

(d) processing means operatively associated with said circuitry means adapted to produce from the outputs of said first and second optical cable means an electrical output signal corrected for changes in blood volume of said skin, bone and tissue during the measuring cycle and representing the difference in absorption of said measuring and reference wavelengths by said selected body portion as a function of the state of said local metabolic oxygen dependent activity and further adapted to convert said electrical output signal to a signal providing a substantially continuous and rapid measure of said activity;

12. (e) an improved detachable, body mountable apparatus associated with said circuitry, coupling and processing means comprising:

(i) a flexible, elongated support member adapted to be releasably secured to the body proximate a said selected portion of the body having a selected set of said light entry and exit points, said support member being adapted to provide ambient light shielding over said light entry and exit points and to conform to the curvature and shape of the body at the location thereof;

(ii) a mounting structure secured to said support member and adapted to deform in shape in correspondence with the curvature assumed by said support member when secured to the body;

(iii) a first preformed right angled light guide means supported in said structure and formed by a bundle of optical fibers optically coupled to said first optical cable means and having an optical face adapted to be mated in a substantially pressed fit relation with said selected point of light entry utilizing selected fibers of said bundle for entry of light in said wavelengths to be transmitted, deeply reflected and scattered along said path and to said selected portion and other selected fibers for receiving deeply penetrating light emissions reflected directly back from any skin, bone and tissue at or within a few millimeters of said selected point of light entry; and

(iv) a second right angled light guide means formed by a bundle of optical fibers optically coupled to said second optical cable means and having a second optical face spaced several centimeters away from said first optical face and adapted to be mated in a substantially pressed fit relation with said selected point of light exit for receiving deeply penetrating light emissions reflected and scattered to said selected point of light exit from said selected portion of said body.