Pulse oximetry system

Inventors

Mazar, Scott Thomas • Ricci, Carlos A. • Kovtun, Vladimir V.

Assignees

Murata Vios Inc

Abstract

In one aspect, a computer-implemented method includes receiving signals corresponding to wavelengths of light detected by an optical sensor placed in proximity to a patient's body, and for each received signal: separating the signal into an AC signal and a DC signal; separating the AC signal into component signals; analyzing the component signals through a fractional phase transformation to identify a desired component signal and harmonic signals associated with the desired component signal; smoothing the desired component signal, the harmonic signals, and the DC signal; and combining the smoothed desired component signal, the smoothed harmonic signals, and the smoothed DC signal to generate a modulation signal. A modulation ratio signal is generated based on the modulation signals derived from the signals, and a peripheral oxygen saturation (SpO2) of the patient's body is determined based on the modulation ratio signal.

Core Innovation

The invention is directed to pulse oximetry based on photoplethysmogram (PPG) signals at a first wavelength of light and a second wavelength of light detected by an optical sensor placed in proximity to a patient's body. For each received signal, the signal is separated into an AC signal and a DC signal, and the AC signal is further separated into component signals, where each component signal represents a frequency-limited band.

The component signals are analyzed through a fractional phase transformation to identify a desired component signal and harmonic signals associated with the desired component signal. A smoothing operation is applied to the desired component signal, the harmonic signals, and the DC signal, and the smoothed desired component signal, the smoothed harmonic signals, and the smoothed DC signal are combined to generate a modulation signal.

A modulation ratio signal is generated based on the modulation signal derived from the first wavelength and the modulation signal derived from the second wavelength. Peripheral oxygen saturation (SpO2) of the patient's body is determined based on the modulation ratio signal, and pulse-rate-related information is derived based on harmonic periodicity, with instantaneous pulse interval/atomic period-related measures, output smoothing, and signal-quality qualification.

Claims Coverage

The provided excerpts include three independent claims: a non-transitory computer readable storage medium, a computer-implemented method, and a system including an optical sensor and a display apparatus. Across these independent claims, the main inventive features comprise fractional phase transformation-based harmonic identification, smoothing and combining AC/DC and harmonic components into a modulation signal, modulation ratio generation from two wavelengths, and SpO2 determination from the modulation ratio, with system-level display of the SpO2 value.

The independent claims are centered on separating each received wavelength signal into AC and DC components, decomposing the AC into frequency-limited component signals, applying a fractional phase transformation to identify a desired component and associated harmonics, smoothing and combining these components into a modulation signal, generating a modulation ratio from the two wavelengths’ modulation signals, and determining peripheral oxygen saturation (SpO2) from that modulation ratio. The system claim additionally requires displaying the determined SpO2 value via a display apparatus.

Stated Advantages

Documented Applications