| abstract |
A measuring instrument for the intracardial acquistion of the blood oxygen saturation of a patient for use in controlling a heart pacemaker implanted in the patient has a measuring probe with a measuring current path which includes a light transmitter and a light receiver which receives light emitted by the light transmitter and reflected by the blood. The measuring probe is connected to an evaluation circuit via two lines. A useful signal measurement and a reference measurement, independent of the blood reflection, are made and the blood oxygen saturation is identified by comparing the two signals. A separate evaluation of the useful signal measurement and the reference signal measurement is enabled by making the useful signal measurement chronologically offset with respect to the reference measurement in one embodiment, or by using the amplitude of the current from the light receiver to make one measurement, and using the voltage amplitude to make the other measurement in another embodiment. |