| abstract |
A system for determining the hematocrit transcutaneously and noninvasively. Disclosed are a finger clip assembly (6) and an earlobe clip assembly (10), each including at least a pair of emitters (1, 2) and a photodiode (3) in appropriate alignment to enable operation in either a transmittion mode or a reflectance mode. At least two, and preferably three, predetermined wavelengths of light are passed onto or through body tissues such as the finger (7), earlobe (11), 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 plasma, then the blood oxygen saturation value, is determinable independently of the hematocrit value. It is also within the scope of the present invention to detect and analyze multiple wavelengths using a logarithmic DC analysis technique. In this embodiment, a pulse wave is not required. Hence, this embodiment may be utilized in states of low blood pressure or low blood flow. |