Method and apparatus for hemodynamic assessment including fiducial point detection

A method of assessing a hemodynamic parameter within a living subject, comprising:

• disposing a plurality of electrodes relative to said subject;
• measuring at least one impedance waveform from said subject using at least one of said plurality of electrodes;
• processing said at least one impedance waveform using at least one wavelet transform to identify one or more fiducial points within said at least one impedance waveform;
• and
• assessing said hemodynamic parameter based at least in part on the one or more of said fiducial points.

A method of detecting events within the electrocardiogram (ECG) of a living subject, comprising:

• disposing at least one electrode relative to the thoracic cavity of said subject;
• measuring at least one ECG waveform using said at least one electrode;
• and
• processing said at least one ECG waveform using discrete wavelet transforms to identify one or more events within said ECG waveform.

An information storage device, comprising;

• a data storage medium;
• a plurality of data stored on said medium, said plurality of data comprising a computer program adapted to run on a data processor, said computer program being configured for determining at least one value of a first hemodynamic parameter of a living subject based on first input data and second input data, said first input data being representative of an impedance waveform, said second input data being representative of a an electrocardiographic (ECG) waveform, the act of determining said at least one value of said first hemodynamic parameter comprising:
• processing said at least one impedance waveform using wavelet transforms to identify at least one fiducial point therein;
• processing said at least one ECG waveform using wavelet transforms to identify at least one fiducial point therein;
• and
• determining said at least one value of said first hemodynamic parameter based at least in part on said at least one fiducial points from said impedance and ECG waveforms, respectively.

Apparatus for assessing at least one hemodynamic parameter associated with a living subject comprising;

• a plurality of electrodes adapted to be disposed in proximity to the thoracic cavity of the subject;
• a current source adapted to provide an electrical current through at least a portion of said thoracic cavity via at least a first of said plurality of electrodes, and produce an impedance waveform relating thereto on at least a second of said plurality of electrodes;
• and
• a signal processing apparatus, operatively coupled to said at least second of said plurality of electrodes, said signal processing apparatus adapted to analyze said impedance waveform using wavelet transforms to assess said at least one hemodynamic parameter.

A method of providing treatment to a living subject, comprising:

• disposing a plurality of electrodes with respect to the thoracic cavity of said subject;
• measuring at least one impedance waveform via at least one of said plurality of electrodes;
• measuring at least one ECG waveform via at least one of said plurality of electrodes;
• determining the stroke volume of the subject's heart using at least one discrete wavelet transform;
• and
• providing treatment to the subject based on the determined cardiac stroke volume.

A method of assessing cardiac output within a living subject, comprising the steps of:

• disposing a plurality of electrodes disposed relative to the thoracic cavity of said subject for detecting electrical signals therefrom;
• passing an electrical current through at least a portion of said thoracic cavity to permit measurement of at least one impedance waveform associated therewith;
• measuring said at least one impedance waveform;
• processing said at least one impedance waveform using discrete wavelet transforms for identification one or more fiducial points within said at least one impedance waveform;
• and
• determining cardiac output based at least in part on said one or more fiducial points.

A method of filtering a cardiac impedance (Z) waveform having a plurality of cardiac beats, comprising:

• selecting a beat average;
• calculating a first value of at least one parameter associated with said impedance waveform;
• buffering said first value in at least one median filter, said at least one median filter being adapted to permit shifting with each successive one of said plurality of beats;
• calculating a second value of at least one parameter associated with said impedance waveform;
• buffering said second value in said at least one median filter;
• and
• calculating a median value for said at least one parameter based at least in part on said first and second values and said beat average.

Apparatus useful for assessing at least one hemodynamic parameter associated with a living subject comprising;

• at least one electrical pathway adapted for signal communication with a monitoring system, said monitoring system comprising;
• a plurality of electrodes adapted for use proximate the thoracic cavity of said living subject;
• and
• a current source adapted to provide an electrical current through at least a portion of said thoracic cavity via at least a first of said plurality of electrodes, and produce an impedance waveform relating thereto on at least a second of said plurality of electrodes, wherein said at least second electrode of said plurality is in signal communication with said at least one electrical pathway;
• and
• a signal processing apparatus, operatively coupled to said at least one electrical pathway, said signal processing apparatus adapted to analyze said impedance waveform using wavelet transforms to assess said at least one hemodynamic parameter.