BLOOD OXIMETER

• US 20100240973A1
• Filed: 09/24/2008
• Published: 09/23/2010
• Est. Priority Date: 09/27/2007
• Status: Active Grant

• Current Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Such, Olaf, Garcia Molina, Gary N., Hooft, Gert, Heinks, Carsten, Presura, Cristian
• Granted Patent: US 8,417,307 B2
• Time in Patent Office: Days
• US Class Current: 600/335
• CPC Class Codes: A61B 5/14551 for measuring blood gases
• CPC Class Codes: A61B 5/721 using a separate sensor to detect motion or using motion information derived from signals other than the physiological signal to be measured

Abstract

The invention relates to a blood oximeter for measuring the oxygenation and at least one other parameter of flowing blood in living tissue. According to the invention, the blood oximeter comprises two lightsources (2, 3) emitting light of different wavelengths into tissue, and preferably a light detector (4) for detecting a transmitted and/or reflected part of the light emitted into the tissue, wherein at least one of the light sources is a laser with a laser cavity emitting a laser beam, the laser being adapted to allow a part of the laser beam which is scattered by the tissue to re-enter into the laser cavity, and wherein a laser beam sensor (7, 8) for measuring the light emitted from the laser is provided, the laser beam sensor (7, 8), thus, obtaining a signal which varies in accordance with the self-mixing interferometric effect between the original laser beam and the scattered laser beam. Accordingly, such a blood oximeter is provided that performs well at low perfusion and which further allows for reliable measurements

Claims

1. A blood oximeter for measuring the oxygenation and at least one other parameter of flowing blood in living tissue, comprising

two light sources emitting light of different wavelengths into the tissue, wherein

at least one of the light sources is a laser with a laser cavity emitting a laser beam, the laser being adapted to allow a part of the laser beam which is scattered by the tissue to re-enter into the laser cavity, and wherein

a laser beam sensor for measuring the light emitted from the laser is provided, the laser beam sensor, thus, obtaining a signal which varies in accordance with the self-mixing interferometric effect between the original laser beam and the scattered laser beam.

2. The blood oximeter according to claim 1, wherein a lens is provided for illuminating the laser beam into the tissue through the lens, the lens having a focal length of equal or less than 2 mm.

3. The blood oximeter according to claim 2, wherein the lens is adapted to directly contact the illuminated tissue.

4. The blood oximeter according to claim 1, wherein a pulse controller for a pulsed operation of the laser is provided.

5. The blood oximeter according to claim 1, wherein a force actuator is provided for pressing the laser against the illuminated tissue with a predefined pressure.

6. The blood oximeter according to claim 5, wherein a pressure controller is provided for applying a predefined pressure changing in time.

7. The blood oximeter according to claim 1, wherein a light detector for detecting a transmitted and/or reflected part of the light emitted into the tissue is provided.

8. The blood oximeter according to claim 7, wherein a motion detector is provided for detecting a motion of the irradiated tissue on the basis of the signal of the laser beam sensor and the signal of the light detector.

9. The blood oximeter according to claim 8, wherein a motion processing unit is provided for rejecting a measurement due to detected motions of the tissue or for correcting a measurement based on detected motions of the tissue.

10. The blood oximeter according to claim 1, wherein both light sources are designed as a laser with a laser beam sensor, respectively.

11. The blood oximeter according to claim 10, wherein a SO2 unit is provided for determining and indicating an SO2 value based on the signals of both of the laser beam sensors.