Method and apparatus for estimating physiological parameters using model-based adaptive filtering

A method for reducing noise effects in a system for measuring a physiological parameter comprising the steps of:

• generating a plurality of measurements corresponding to a series of cardiac pulses;
• comparing each selected measurement with at least one expected measurement characteristic;
• assigning one of a plurality of variable weights to each selected measurement based on the comparing step, thereby generating a plurality of weighted measurements;
• averaging the plurality of weighted measurements from successive pulses to obtain a filtered measurement, each weighted measurement corresponding to a particular filtered measurement being similarly situated in a corresponding one of the successive pulses;
• and
• selectively adjusting at least one step in the averaging and assigning steps, the adjusting step based on knowledge, derived independently of the plurality of measurements in the generating step, of at least one characteristics of cardiac pulses.

An apparatus for reducing noise effects in a system for measuring a physiological parameter, comprising:

• means for generating a plurality of measurements corresponding to a series of cardiac pulses;
• means for comparing each selected measurement with at least one expected measurement characteristic;
• means for assigning one of a plurality of variable weights to each measurement based on the comparing step, thereby generating a plurality of weighted measurements;
• means for averaging the plurality of weighted measurements from successive pulses to obtain a filtered measurement, each weighted measurement corresponding to a particular filtered measurement being similarly situated in a corresponding one of the successive pulses;
• and
• means for selectively adjusting at least one means in the averaging and assigning means, the adjusting means being based on knowledge, derived independently of the plurality of measurements in the generating means, of at least one characteristics of cardiac pulses.

A method for reducing noise effects in a system for measuring a physiological parameter comprising the steps of:

• generating a plurality of measurements derived from at least one wavelength of electromagnetic energy transmitted through living tissue;
• comparing selected measurements with at least one expected measurement characteristic;
• assigning one of a plurality of variable weights to each selected measurement based on the comparing step, thereby generating a plurality of weighted measurements;
• averaging the plurality of weighted measurements to obtain a filtered measurement;
• and
• selectively adjusting, in a non-linear manner, at least one step in the averaging and assigning steps based on characteristics of the physiological parameter.

A method for reducing noise effects in a system for measuring a physiological parameter comprising the steps of:

• generating a plurality of time-based measurements which are not event driven, the time-based measurements being derived from at least one wavelength of electromagnetic energy transmitted through living tissue;
• comparing selected time-based measurements with at least one expected measurement characteristic;
• assigning one of a plurality of variable weights to each selected time-based measurement based on the comparing step, thereby generating a plurality of weighted time-based measurements;
• averaging the plurality of weighted time-based measurements to obtain a filtered time-based measurement;
• and
• selectively adjusting at least one step in the averaging and assigning steps, the adjusting step based on knowledge, derived independently of the plurality of time-based measurements in the generating step, of at least one characteristics of the physiological parameter.

An apparatus for reducing noise effects in a system for measuring a physiological parameter, comprising:

• means for generating a plurality of time-based measurements which are not event driven, the time-based measurements being derived from at least one wavelength of electromagnetic energy transmitted through living tissue;
• means for comparing selected time-based measurements with at least one expected measurement characteristic;
• means for assigning one of a plurality of variable weights to each selected time-based measurement based on the comparing step, thereby generating a plurality of weighted time-based measurements;
• means for averaging the plurality of the weighted time-based measurements to obtain a filtered time-based measurement;
• and
• means for selectively adjusting at least one means in the averaging and assigning means, the adjusting means being based on knowledge, derived independently of the plurality of time-based measurements in the generating means, of at least one characteristics of the physiological parameter.

An apparatus for reducing noise effects in a system for measuring a physiological parameter, comprising:

• means for generating a plurality of measurements derived from at least one wavelength of electromagnetic energy transmitted through living tissue;
• means for providing a signal indicative of the at least one wavelength of electromagnetic energy;
• means for comparing selected measurements with at least one expected measurement characteristic;
• means for assigning one of a plurality of variable weights to each selected measurement based on the comparing step thereby generating a plurality of differently weighted measurements for each wavelength, the variable weights being assigned, in part, in response to a similarity between each selected measurement and a corresponding previous measurement, the variable weights comprising a plurality of different non-zero numbers;
• means for averaging a plurality of the differently weighted measurements to obtain a filtered measurement for use in estimating the physiological parameter;
• and
• means for calibrating the system to measure the physiological parameter in response to the signal indicative of the at least one wavelength of electromagnetic energy.