Time-division multiplexing in a multi-wavelength photon density wave system

摘要

Multi-wavelength photon density wave medical systems, methods, and devices are provided. In one embodiment, a multi-wavelength system may include a sensor, a sensor cable, and a patient monitor. The sensor may have an emitter output and a detector input configured to pass a multi-wavelength photon density wave input signal into a patient and receive a resulting multi-wavelength photon density wave output signal. The sensor cable may couple to the sensor using two optical cables for transmitting and receiving the multi-wavelength photon density wave signals. The patient monitor may couple to the sensor cable and generate several time-division multiplexed single-wavelength input signals by modulating one or more light sources at a frequency sufficient to produce resolvable photon density waves. By combining the several time-division multiplexed single-wavelength input signals into one of the optical cables of the sensor cable, the patient monitor may generate the multi-wavelength photon density wave input signal.

主权项

1. A system comprising:
a patient monitor configured to generate a multi-wavelength photon density wave input signal from two or more single-wavelength photon density wave signals generated by a driving circuit configured to modulate one or more light sources at one or more modulation frequencies that exceed the product of a mean absorption coefficient of the pulsatile tissue of the patient multiplied by the speed of light and are sufficient to produce resolvable photon density waves in the pulsatile tissue of the patient, in which each of the single-wavelength photon density wave signals is alternatingly the sole wavelength active in the multi-wavelength photon density wave input signal for periods of time brief enough to enable each of the single-wavelength photon density wave signals to pass through pulsatile tissue of a patient such that there is no perceptible change in the pulsatile tissue of the patient between the start of each of the multi-wavelength photon density wave input signals and the start of each subsequent multi-wavelength photon density wave input signal, wherein the patient monitor is configured to receive a multi-wavelength photon density wave output signal resulting after the multi-wavelength photon density wave input signal is passed through the pulsatile tissue of the patient, and wherein the patient monitor comprises data processing circuitry configured to determine a scattering property and an absorption property of the pulsatile tissue of the patient based at least in part on a comparison between the multi-wavelength photon density wave output signal and the multi-wavelength photon density wave input signal, wherein the mean absorption coefficient is determined based on the absorption property of the pulsatile tissue of the patient; a sensor having an emitter output and a detector input, wherein the emitter output is configured to pass the multi-wavelength photon density wave input signal into the pulsatile tissue of the patient, and wherein the detector input is configured to receive the multi-wavelength photon density wave output signal from the pulsatile tissue of the patient; and a sensor cable coupled to the sensor and to the patient monitor and having a first optical cable configured to transmit the multi-wavelength photon density wave input signal from the patient monitor to the sensor and having a second optical cable configured to transmit the multi-wavelength photon density wave output signal from the sensor to the patient monitor.