Method for synchronizing biological signals from different monitoring devices

Inventors

Ruchti, Timothy • EHRENBERG, Joshua Andrew • LIN, Abel

Assignees

Nihon Kohden Digital Health Solutions LLC

Abstract

A method for time-synchronizing waveforms from different patient monitors that does not require devices to have high-precision synchronized clocks or to be coupled to a triggering synchronization signal generator. Comparable signals may be obtained from different devices either by placing selected sensors from the devices in the same locations, or by filtering signals from one device to obtain a signal comparable to signals from another device. Filtering may for example transform waveforms into independent components and identify a component that matches a signal from another device. The comparable signals may then be transformed into frequency variation curves, such as time intervals between peak values, to facilitate detection of the time shift between the signals. Cross correlation of the frequency variation curves may be used to locate the precise time shift between the signals. Use of frequency variation curves may be more robust than directly comparing and correlating the original signals.

Core Innovation

The invention relates to a method for synchronizing biological signals from different monitoring devices coupled to a patient. The method obtains one or more first device signals from a first device and one or more second device signals from a second device, generates a first comparable signal and a second comparable signal from the respective device signals, and calculates a first frequency variation signal and a second frequency variation signal from the comparable signals. Synchronized device signals are derived by applying a time shift to one set of device signals.

The invention addresses synchronization when biological signals originate from independently operating monitoring devices over a network with variable latency and without a high-precision shared clock or common trigger. The method time-aligns physiological signals by determining a time shift that aligns the first frequency variation signal with the second frequency variation signal, while maintaining the second device signals unchanged.

In a described physiological embodiment, the first device comprises a heart monitor and the second device comprises a brain monitor. The comparable heart activity signal is used to compute frequency-variation signals, where the frequency-variation signal comprises RR-interval signal time differences between peaks of R-waves of the heart activity signal, and the second device signals are transformed into comparable signals using independent components or matched filtering using a reference signal.

Claims Coverage

The provided content contains two independent claims. Each independent claim covers generating comparable signals from first and second device signals, calculating frequency-variation signals from those comparable signals, determining a time shift to align the frequency-variation signals, and outputting synchronized device signals including the first device signals shifted by the time shift; one independent claim additionally specifies cross-correlation over a series of time offsets.

Across the independent claims, synchronization is achieved by generating comparable signals from signals of a first device and a second device, converting each comparable signal into a frequency-variation signal, computing a time shift that aligns the two frequency-variation signals, and outputting synchronized device signals by shifting the first device signals. The second independent claim further limits the alignment computation to cross-correlation evaluated over a series of time offsets with selection of the offset corresponding to a maximum cross-correlation value.

Stated Advantages

Documented Applications