Normalization method for a chronically implanted optical sensor
US7512431B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Sep 13, 2005 |
| Grant date | Mar 31, 2009 |
| Priority date | — |
| Expiry date | Jan 10, 2027 |
Classification
- Technology area (CPC A)Human Necessities
- CPC primaryA61B5/1459
- WIPO fieldMedical technology
- WIPO sectorInstruments
Abstract
A system and method are provided for estimating blood oxygen saturation independent of optical sensor encapsulation due to placement in blood, where the blood includes a blood flow characteristic of: a relatively low, a stasis, a stagnant value. The method includes determining tissue overgrowth correction factor that includes optical properties of the tissue that cause scattering of the emitted light to a detector and relative amplitudes of the emitted light wavelengths. A corrected time interval measured for infrared light is based on an infrared signal and a corrected time interval for red light is determined by subtracting red light signal due to presence of tissue overgrowth. The red light signal due to tissue overgrowth is proportional to total infrared signal less 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.