A
system for determining a biologic constituent including
hematocrit transcutaneously, noninvasively and continuously. A finger clip
assembly includes 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 one predetermined
wavelength of light is passed onto or through body tissues such as a finger,
earlobe, or
scalp, etc. and attenuation of light at that
wavelength is detected. Likewise, the change in
blood flow is determined by various techniques including optical, pressure, piezo and strain gage methods. Mathematical manipulation of the detected values compensates for the effects of
body tissue and fluid and determines the
hematocrit value. If an additional
wavelength of light is used which attenuates light substantially differently by oxyhemoglobin and
reduced hemoglobin, then the blood
oxygen saturation value, independent of
hematocrit may be determined. Further, if an additional wavelength of light is used which greatly attenuates light due to
bilirubin (440 nm) or glucose (1060 nm), then the
bilirubin or glucose value may also be determined. Also how to determine the hematocrit with a
two step DC analysis technique is provided. Then a
pulse wave is not required, so this method may be utilized in states of low
blood pressure or low
blood flow.