A medical device system and associated method to control a laser Doppler unit to emit light from a coherent laser light source and collect a photodetector signal produced by the laser Doppler unit by a signal processor comprising a bandpass filter. The bandpass filter is applied to the photodetector signal to determine a tissue perfusion measurement from the filtered signal. A monitoring unit is enabled to receive the tissue perfusion measurement to detect a physiological condition of the patient in response to the tissue perfusion measurement.
