Method and device for determining local distribution of a measuring parameter

• US 20030050543A1
• Filed: 06/25/2002
• Published: 03/13/2003
• Est. Priority Date: 12/14/1999
• Status: Active Grant

• Current Assignee: Perimed AB
• Original Assignee: Perimed AB
• Inventors: Hartmann, Paul
• Granted Patent: US 6,970,729 B2
• Time in Patent Office: Days
• US Class Current: 600/317
• CPC Class Codes: A61B 5/14542 for measuring blood gases A61B5/14551 takes precedence
• CPC Class Codes: A61B 5/14552 Details of sensors specially adapted therefor
• CPC Class Codes: A61B 5/14556 by fluorescence A61B5/14555 takes precedence
• CPC Class Codes: G01N 21/6408 with measurement of decay time, time resolved fluorescence

Abstract

The invention relates to a method and a device for determining local distribution of a measuring parameter relative to or in a predefined, flat measuring area pertaining to a biological sample, preferably of an organ surface or the epidermis. In a first measuring method for determining a first measuring parameter, a sensor film with a luminescence indicator reacting to the measuring parameter with modification of at least one optical characteristic is applied to a flat measuring area and a first measuring parameter is detected by imaging means. A second optical measurement method is carried out, wherein the sensor film is used to determine the local distribution of at least one second measuring parameter in the same measuring range either simultaneously or directly afterwards.

Claims

1. Method for determining the local distribution of a quantity to be measured relative to or present in a predefined measurement area of a biological sample, preferably the surface of an organ or the epidermis, where in a first measuring process for determining a first measurement variable a sensor film with a luminescence indicator reacting to this variable by a change of at least one optical characteristic, is applied to the measurement area and the first measurement variable is detected by imaging means, characterized in that a luminescence-optical method is used as first measuring process, in which luminescence decay time or a quantity derived therefrom as a function of a first measurement variable is recorded by an imaging technique, and that for simultaneous or immediately following determination of the local distribution of at least one further variable in the same measurement area a second optical measuring process using an imaging technique is employed which is effective through the sensor film.

2. Method according to claim 1, characterized in that as first quantity to be measured local distribution of oxygen concentration (tcPO₂), and preferably transcutaneous oxygen concentration, or local distribution of oxygen flow (O₂-flux) through the organ surface, preferably the skin surface, will be determined.

3. Method according to claim 1, characterized in that as first quantity to be measured local distribution of CO₂ concentration or CO₂ flow will be determined.

4. Method according to claim 1, characterized in that as first quantity to be measured local distribution of temperature, glucose concentration, or an ionic concentration, such as pH level will be determined.

5. Method according to any of claims 1 to 4, characterized in that a Laser Doppler imaging (LDI) process is used as second measuring process, by means of which the perfusion rate in the measurement area is determined.

6. Method according to any of claims 1 to 5, characterized in that a photometric or photographic method is used as second or further measuring process, where the measurement area is recorded as an image in a predefined range of wavelengths.

7. Method according to claim 6, characterized in that autofluorescence in the measurement area is recorded as an image.

8. Method according to claim 6, characterized in that infrared radiation in the measurement area is recorded as an image.

9. Method according to any of claims 1 to 8, characterized in that a profilometric method, e.g., an interferometric method is employed as second or further measuring process.

10. Method according to any of claims 1 to 9, characterized in that the measurement area is assessed by visual inspection through the sensor film as second or further measuring process.

11. Method according to any of claims 1 to 9, characterized in that any errors in the measured results of the second optical measuring process, which are due to the sensor film, are corrected by a computing procedure or suitable calibrating parameters.

12. System for determining the local distribution of a quantity to be measured in a predefined measurement area (m) of a biological sample (8), preferably the surface of an organ or the epidermis, comprising a first measuring device with an excitation unit (1, 2) for supply of excitation radiation (11), and an image-producing detection unit (3, 4) including an evaluation unit (16), and a sensor film (7) to be applied to the measurement area (m), whose diffusion properties concerning the variable to be measured are known, the sensor film (7) featuring a luminescence indicator reacting to said measurement variable by a change of at least one optical characteristic, characterized in that a second image producing optical measuring device (5;

6;

17) is provided for whose excitation and emission radiation (9, 10) the sensor film (7) of the first optical measuring device is transparent, so that two independent optical measuring means will cover the same measurement area (m).

13. System according to claim 12, characterized in that the second optical measuring device is provided with a unit (17) for separation of radiations (10, 12) emitted by the two optical measuring devices, such as a filter wheel with different emission filters (3, 3′

) for the two radiations (10, 12).

14. System according to claim 12 or 13, characterized in that the second optical measuring device is provided with a separate excitation light source (5).

15. System according to claim 12, characterized in that the second optical measuring device is provided with a separate excitation light source (5) and a separate image-producing detection unit (6).