Patent ID: 6873865

Claim:
Apparatus for determining a desired biologic constituent concentration of the blood of a patient when the blood is flowing in a pulsatile fashion in a body part of the patient so as to be subjectable to transcutaneous examination in the body part, the body part defining a blood conduit, the comprising: (a) a blood conduit receiver for receiving the blood conduit with the blood flowing therein; (b) radiation-directing means for directing radiation into the flowing blood within the blood conduit, the radiation-directing means being situated within the blood conduit receiver, the radiation defining a directed radiation comprising a first quantity of radiation at a chosen radiation wavelength that, when directed into the flowing blood within the blood conduit, has: (A) a first attenuation value that varies with the desired biologic constituent concentration in the flowing blood and (B) a second attenuation value that varies with the concentration of components other than the desired biologic constituent in the flowing blood, which second attenuation value is at least ten times smaller than the first attenuation value, and (c) radiation-detecting means for detecting the portion of the directed radiation that passes through both the blood conduit and the flowing blood therein, the radiation-detecting means being situated within the blood conduit receiver, the detected portion of the directed radiation comprising a second quantity of radiation at the chosen radiation wavelength; (d) energy-detecting means for detecting energy from the flowing blood within the blood conduit and for measuring the time rate of change of blood volume, the energy-detecting means being situated within the blood conduit receiver, the energy defining a transduced energy comprising a quantity of energy which when detected from the flowing blood within the blood conduit, has a value that varies with the normalized change of the pulsatile blood; and (e) operating means for operating exclusively on the second quantity of the radiation and the transduced energy to determine the desired biologic constituent concentration.