Normalization method for a chronically implanted optical sensor
US6944488B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Apr 30, 2003 |
| Grant date | Sep 13, 2005 |
| Priority date | — |
| Expiry date | Oct 15, 2023 |
Classification
- Technology area (CPC A)Human Necessities
- CPC primaryA61B5/14532
- WIPO fieldMedical technology
- WIPO sectorInstruments
Abstract
A system and method are provided for accurately estimating blood oxygen saturation independent of tissue encapsulation of the optical sensor. The method includes determining a tissue overgrowth correction factor that accounts for the optical properties of the tissue that cause scattering of the emitted light to a light detector and the relative amplitudes of the emitted light wavelengths. A corrected time interval measured for infrared light is based on an infrared signal returned from fluid with no tissue overgrowth. A corrected time interval for red light is determined by subtracting a red light signal attributed to the presence of tissue overgrowth. The amount of red light signal attributed to the presence of tissue overgrowth is proportional to the total infrared signal less the nominal infrared signal. Oxygen saturation is estimated based on standard calibration factors and the ratio of the corrected infrared time interval and the corrected red time interval.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.