System for noninvasive hematocrit monitoring
US6681128B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jun 13, 2001 |
| Grant date | Jan 20, 2004 |
| Priority date | — |
| Expiry date | Jun 20, 2021 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N2021/036
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A system determines heamtocrit transcutaneously and noninvasively. Disclosed are a finger clip assembly and an earlobe clip assembly, each including at least a pair of emitters and a photodiode in appropriate alignment to enable operation in either a transmissive mode or a reflectance mode. At least two, and preferably three, predetermined wavelengths of light are assed onto or through body tissues such as the finger, earlobe, or scalp, etc. and the extinction of each wavelength is detected. Mathematical manipulation of the detected values compensates for the effects of body tissue and fluid and determines the hematocrit value. If a fourth wavelength of light is used which is extinguished substantially differently by oxyhemoglobin and reduced hemoglobin and which is not substantially extinguished by plasmas, then the blood oxygen saturation value, independent of hematocrit, maybe determined. It is also disclosed how to detect and analyze multiple wavelengths using a logarithmic DC analysis technique. Then a pulse wave is not required. So this method may be utilized in states of low blood pressure or low blood flow.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.