Method and device for measurements in blood
We present an optical probe arrangement that surrounds blood in a receptacle. It comprises LED's and light detector arranged to overcome the variations when the receptacle is translucent medical tubing and the like. Also, a signal processing algorithm is used to average signals from a plurality of light detectors, to further enhance results when measuring hematocrit. The invention makes it possible to add the feature of hematocrit measurement into dialysis system without major alterations to the dialysis machine or transport tubing.
1. An optical sensor device for measuring blood constituents in an elongated vessel of tubing, said optical sensor device comprising at least two sets of light emitters and light detectors, each set comprising one light emitter and at least one detector, wherein a first set of light emitters are arranged as an array encircling the elongated vessel or tubing a longitudinal location along the vessel or tubing, and at least a second set light detectors are arranged as arrays encircling the elongated vessel or tubing at a longitudinally different location along the vessel or tubing, and said light emitters and said light detectors are aimed so that the detectors do not directly intercept light from the emitters.
2. The optical sensor device according to claim 1 , comprising four sets of light emitters and two or three light detectors in each set, wherein a light detector in each set represents a detector incorporated in an adjacent set.
3. The optical sensor device according to claim 1 , wherein a second array of light detectors are longitudinally located at a third location around said vessel's or tubing's circumference, and the light detectors are arranged to encircle the vessel or tubing at that circumferential location.
4. A method for processing signals from light detectors as claimed in claim 1 , including an amplifier for amplifying signals from the light detectors, which comprises employing a signal processing algorithm on the signals from said light detectors, to detect blood constituents.
5. The method for processing signals from light detectors as claimed in claim 4 , which comprises employing a signal processing algorithm on the signals from said light detectors, to detect hematocrit.
6. The method according to claim 5 , which comprises employing a multi variable analysis of signals from all light detectors engaged in the signaling process.
7. The method according to claim 4 , wherein signals are processed in a time domain.
8. The optical sensor device as claimed in claim 1 , wherein a third array of light detectors are longitudinally located at a fourth location around a receptacle's circumference, and the light detectors are arranged to encircle the receptacle at that circumferential location, and an second array of light emitters are longitudinally located at a fifth location around said receptacle's circumference, and the light detectors are arranged to encircle the receptacle at that circumferential location.
9. A method for processing signals from light detectors as claimed in claim 8 , including an amplifier for amplifying signals from the light detectors, and which comprises employing a signal processing algorithm on the signals from said light detectors, to detect blood constituents.
10. The method according to claim 9 , wherein signals are processed in a time domain.
11. The method of claim 10 , wherein the signals are processed sequentially.
12. A method for processing signals from optical sensor devices as claimed in claim 1 , including an amplifier for amplifying signals from the light detectors, which comprises employing a signal processing algorithm on the signals from said light detectors, to detect oxygen saturation in blood.
13. The method according to claim 12 , wherein signals are processed in a time domain.
14. The method of claim 13 , wherein the signals are processed sequentially.
15. The optical sensor device as claimed in claim 1 , further comprising a system to calculate hematocrit values from blood, and presenting the data to a display, and/or transferring data to another application.
16. The optical sensor device as claimed in claim 15 , characterized in that the measuring takes place in a vessel or tubing that is clamped in a holder with V-shaped recesses so that the vessel or tube is flattened to a square cross section, and that light sources and sensors are arranged at flattened surfaces of the vessel or tubing.
17. The optical sensor device as claimed in claim 1 , further comprising a system to calculate hematocrit values and oxygen saturation values from blood, and presenting the data to a display, and/or transferring data to another application.
18. The optical sensor device as claimed in claim 17 , characterized in that the measuring takes place in a vessel or tubing that is clamped in a holder with V-shaped recesses so that the vessel or tubing is flattened to a square cross section, and that light sources and sensors are arranged at flattened surfaces of the vessel or tubing.
19. The optical sensor device as claimed in claim 1 , characterized in that the measuring takes place in a vessel or tubing that is clamped in a holder with V-shaped recesses so that the vessel or tubing is flattened to a square cross section, and that light emitters and sensors are arranged at flattened surfaces of the vessel or tubing.
20. The optional sensor device as claimed in claim 1 , wherein the light emitters emit at different wavelengths.
21. A optical sensor device as claimed in claim 1 , further comprising a holder with V-shaped recesses for flattening the vessel or tubing to a square cross section, and the light emitters and sensors are arranged at flattened surfaces of the vessel or tubing.