Methods for improving response time, robustness and user comfort in continuous estimation of biophysiological rates

A method for determining a biophysiological feature, the method comprising:

• measuring a quasiperiodic function with a biophysiological sensor that is configured for application to a patient and operable for detecting signals in the patient associated with the quasiperiodic function;
• receiving, at a sensor signal receiver, a quasiperiodic data stream for the measured quasiperiodic function from the biophysiological sensor;
• removing, with a processor comprising a signal offset remover coupled to the sensor signal receiver and comprising a bandpass filter, at least a portion of an offset from the quasiperiodic data stream to provide a smoothed data stream by filtering the quasiperiodic data stream through the bandpass filter and phase compensating the filtered quasiperiodic data stream;
• with a rate estimator of the processor coupled to the signal offset remover:
• transforming the smoothed data stream into an analytic data stream using a Hilbert transform approximation;
• calculating a time derivative associated with a phase angle of the analytic data stream;
• and providing, to a user via an input/output device, an output data stream derived from a frequency, wherein the frequency is the time derivative of the quasiperiodic data stream and wherein the output data stream comprises the biophysiological feature;
• and
• masking, with an excursion fault detector coupled to the rate estimator, the output data stream while a sensor motion fault is detected.

An apparatus for signal processing, the apparatus comprising:

• a memory having machine instructions stored therein;
• a processor coupled to the memory;
• and
• a biophysiological sensor coupled to the processor and operable for sensing a heartbeat of a patient;
• wherein the processor executes the machine instructions to:
• receive a signal comprising a quasiperiodic data stream for the sensed heartbeat from the biophysiological sensor,
• remove at least a portion of an offset from the signal to center the signal at a target voltage and provide a smoothed data stream by filtering the signal through a bandpass filter and phase compensating the filtered quasiperiodic data stream,
• transform the smoothed data stream into an analytic data stream using a Hilbert transform approximation,
• calculate a time derivative associated with a phase angle of the analytic data stream,
• provide, to a user via an input/output device, an output data stream derived from a frequency, wherein the frequency is the time derivative of the quasiperiodic data stream and wherein the output data stream comprises at least one of a heartbeat rate and a heart interbeat interval, and
• mask the output data stream during a sensor motion fault.