Abstract: Methods and systems are provided for using time-frequency warping to analyze a physiological signal. One embodiment includes applying a warping operator to the physiological signal based on the energy density of the signal. The warped physiological signal may be analyzed to determine whether non-physiological signal components are present. Further, the same warping operator may be applied to signal quality indicators, and the warped physiological signal may be analyzed based on the warped signal quality indicators. Non-physiological signal components, or types of non-physiological noise sources, may be identified based on a comparison of the physiological signal with the signal quality indicators. Non-physiological signal components may also be identified based on a neural network of known noise functions. In some embodiments, the non-physiological signal components may be removed to increase accuracy in estimating physiological parameters.

Abstract: A process and apparatus for determining the arterial and venous oxygenation of blood in vivo with improved precision. The optical properties of tissue are measured by determination of differential and total attenuations of light at a set of wavelengths. By choosing distinct wavelengths and using the measured attenuations, the influence of variables such as light scattering, absorption and other optical tissue properties is canceled out or minimized.

Abstract: Methods and systems for determining a physiological parameter in the presence of correlated artifact are provided. One method includes receiving two waveforms corresponding to two different wavelengths of light from a patient. Each of the two waveforms includes a correlated artifact. The method also includes combining the two waveforms to form a plurality of weighted difference waveforms, wherein the plurality of weighted difference waveforms vary from one another by a value of a multiplier. The method further includes identifying one of the weighted difference waveforms from the plurality of weighted difference waveforms using a characteristic of one or more of the plurality of weighted difference waveforms and determining a characteristic of the correlated artifact based at least in part on the identified weighted difference waveform.

Abstract: Embodiments disclosed herein may describe systems and methods for reducing nuisance alarms using probability and/or accuracy of a measured physiological parameter, such as the pulse rate or SpO2 measurement generated by a pulse oximeter. Embodiments may include methods for adjusting a predetermined alarm threshold based on the probability distribution of the estimated pulse rate and/or oxygen saturation of a patient's blood.

Abstract: A method and an apparatus for separating a composite signal into a plurality of signals is described. A signal processor receives a composite signal and separates a composite signal in to separate output signals. Pre-demodulation signal values are used to adjust the demodulation scheme.

Abstract: Optical coherence tomography (herein “OCT”) based analyte monitoring systems are disclosed. In one aspect, techniques are disclosed that can identify fluid flow in vivo (e.g., blood flow), which can act as a metric for gauging the extent of blood perfusion in tissue. For instance, if OCT is to be used to estimate the level of an analyte (e.g., glucose) in tissue, a measure of the extent of blood flow can potentially indicate the presence of an analyte correlating region, which would be suitable for analyte level estimation with OCT. Another aspect is related to systems and methods for scanning multiple regions. An optical beam is moved across the surface of the tissue in two distinct manners. The first can be a coarse scan, moving the beam to provide distinct scanning positions on the skin. The second can be a fine scan where the beam is applied for more detailed analysis.

Abstract: According to embodiments, techniques for using continuous wavelet transforms and spectral transforms to determine oxygen saturation from photoplethysmographic (PPG) signals are disclosed. According to embodiments, a first oxygen saturation may be determined from wavelet transformed PPG signals and a second oxygen saturation may be determined from spectral transformed PPG signals. An optimal oxygen saturation may be determined by selecting one of the first and the second oxygen saturation or by combining the first and the second oxygen saturation. According to embodiments, a spectral transform of PPG signals may be performed to identify a frequency region associated with a pulse rate of the PPG signal. A continuous wavelet transform of the PPG signals at a scale corresponding to the identified frequency region may be performed to determine oxygen saturation from the wavelet transformed signal.

Abstract: The present disclosure describes a method and an apparatus for analyzing measured signals using various processing techniques. In certain embodiments, the measured signals are physiological signals. In certain embodiments, the measurements relate to blood constituent measurements including blood oxygen saturation.

Abstract: To make the peak value of the driving current of light source smaller than the conventional one and to make the peak value of the light receiving level of light-sensitive elements smaller than the conventional one in order to save power consumption of the device and to improve the precision of measurement, codes of which the bits of the Hadamard codes are shifted by the same bit for each code series having the same bit cycle, or codes of which the bits of a PN code are shifted are used as different codes.

Abstract: A technique is provided for processing a physiological signal to compensate for artifacts. The technique includes identifying artifacts within the physiological signal. The technique also includes performing one or more multi-resolution decompositions, such as wavelet transformations, on the physiological signal and compensating for the identified artifacts in some or all of the respective decomposition components. The modified decomposition components may be reconstructed to generate an artifact-compensated signal which may be provided to a monitor or other device which is otherwise not configured to compensate for signal artifacts.

Abstract: A method and an apparatus measure blood oxygenation in a subject. A light source is activated to cause a first emission at a first wavelength and a second emission at a second wavelength. A detector detects a composite signal indicative of an attenuation of the first and second wavelengths by tissue of a patient. The composite signal is demodulated into a first intensity signal and a second intensity signal. Blood oxygenation in the subject is determined from the first and second intensity signals.

Abstract: A physiological sensor having reduced sensitivity to interference includes a light source, a light detector in optical communication with the light source, and a sensor pad at least partially housing the light source and the light detector. The sensor pad is configured to be capacitively isolated from a patient. Moreover, the physiological sensor may be electrically connected to an amplifier having a signal ground and a monitor.

Abstract: Embodiments of the present invention relate to a system and method for in vivo measurement of blood parameters by processing analog electrical signals from a plurality of photodetectors. In some embodiments, it is possible to determine one or more blood parameters according to (i) a first electrical signal from a first detector and (ii) a second electrical signal from a second photodetector. A difference analog electrical signal is generated, indicative of a difference between the light response signal at the first location and light response signal at the second location, is generated. One or more blood parameters may be detected according to the difference analog electrical signal.

Abstract: A method and an apparatus for separating a composite signal into a plurality of signals is described. A signal processor receives a composite signal and separates a composite signal in to separate output signals. Feedback from one or more of the output signals is provided to a configuration module that configures the signal processor to improve a quality of the output signals. In one embodiment, the signal processor separates the composite signal by applying a first demodulation scheme to the composite signal to generate a first output signal. In one embodiment, the signal processor also applies a second demodulation scheme to the composite signal to generate a second output signal. In one embodiment, the composite signal is obtained from a detector in a system for measuring one or more blood constituents.

Abstract: Apparatus for reducing an interference portion in a time-discrete signal further including a useful portion, including a first provider for providing the time-discrete signal including the interference portion and the useful portion; a second provider for providing a first time-discrete reference signal including a first interference portion, and a second time-discrete reference signal including a second interference portion, the second interference portion being shifted in phase relative to the first interference portion. The apparatus further includes a subtractor for generating a differential signal from the two reference signals, the differential signal including a frequency component caused by the first and second interference portions; and a manipulator for manipulating the time-discrete signal on the basis of the differential signal such that in a manipulated time-discrete signal the frequency component is reduced.

Abstract: A pulse oximetry sensor adapted to emit light from an emitter proximate to a patient's tissue and detect a portion of the emitted light on a detector proximate to the tissue. The pulse oximetry system is adapted to acquire position data for the emitter and for the detector with one or more position indicators. The pulse oximetry system is adapted to process the position data to obtain a change in position of the emitter and the detector; and to process pulse oximetry measurements using the change in position to obtain a motion-corrected pulse oximetry data.

Abstract: The present invention involves a method and an apparatus for analyzing measured signals, including the determination of a measurement of oxygen saturation and respiration rate in the measured signals during a calculation of a physiological parameter of a monitored patient. Use of this invention is described in particular detail with respect to oximetry-based measurements but extends to other types of measurements.

Abstract: A system includes a light source, a photodetector in optical communication with the light source, and a processor in communication with said photodetector and configured to output a signal representing oxygen saturation independent of an interfering signal from an interfering source. The system may further include an analog-to-digital converter in communication with the processor that is configured to digitize a signal from the photodetector by oversampling and output oversampling data to the processor. The processor may include an averaging filter that averages the oversampling data received from said analog-to-digital converter prior to decimation to generate an oversampling number.

Abstract: The disclosure includes pulse oximetry systems and methods for determining point-by-point saturation values by encoding photoplethysmographs in the complex domain and processing the complex signals. The systems filter motion artifacts and other noise using a variety of techniques, including statistical analysis such as correlation, or phase filtering.

Abstract: Methods and systems are provided that allow for the simultaneous calculation of pulse and regional blood oxygen saturation. An oximeter system that includes a sensor with a plurality of emitters and detectors may be used to calculate a pulse and/or regional blood oxygen saturation. A plurality of light signals may be emitted from light emitters. A first light signal may be received at a first light detector and a second light signal may be received at a second light detector. A pulse and/or regional blood oxygen saturation value may be calculated based on the received first and/or second light signals. The pulse and regional blood oxygen saturation values may be calculated substantially simultaneously. The calculated pulse and regional blood oxygen saturation values as well as other blood oxygen saturation values may be displayed simultaneously in a preconfigured portion of a display.

Abstract: The present invention involves method and apparatus for analyzing two measured signals that are modeled as containing primary and secondary portions. Coefficients relate the two signals according to a model defined in accordance with the present invention. In one embodiment, the present invention involves utilizing a transformation which evaluates a plurality of possible signal coefficients find appropriate coefficients. Alternatively, the present invention involves using statistical functions or Fourier transform and windowing techniques to determine the coefficients relating to two measured signals. Use of this invention is described in particular detail with respect to blood oximetry measurements.

Abstract: A pulse oximeter system is presently disclosed. The pulse oximeter system includes a processor and circuitry. The processor and circuitry are configured to receive light waveforms from a sensor, determine at least one signal quality metric for the light waveforms, calculate at least one weight using a continuously variable weighting function based on the at least one signal quality metric, and ensemble average the light waveforms using the at least one calculated weight.

Abstract: A pulse oximetry includes: irradiating living tissue with a plurality of light beams of different wavelengths; receiving the light beams transmitted through or reflected from the living tissue and converting the received light beams to electric signals which correspond to the different wavelengths; time-segmenting time series data of the electric signals; calculating, with respect to each of the segmented time series data of the electric signals, a slope value of a regression line between each two of the electric signals; calculating SaO2 based on the slope value of each of the segmented time series data of the electric signals; constructing a histogram of SaO2 for each predetermined number of time segments; and obtaining a mode value from the histogram as SpO2 to be output of the pulse oximetry.

Abstract: A processor provides signal quality based limits to a signal strength operating region of a pulse oximeter. These limits are superimposed on the typical gain dependent signal strength limits. If a sensor signal appears physiologically generated, the pulse oximeter is allowed to operate with minimal signal strength, maximizing low perfusion performance. If a sensor signal is potentially due to a signal induced by a dislodged sensor, signal strength requirements are raised. Thus, signal quality limitations enhance probe off detection without significantly impacting low perfusion performance. One signal quality measure used is pulse rate density, which defines the percentage of time physiologically acceptable pulses are occurring. If the detected signal contains a significant percentage of unacceptable pulses, the minimum required signal strength is raised proportionately.

Abstract: A physiological sensor includes an emitter configured to transmit light and a detector configured to receive the transmitted light. The sensor also includes a first accelerometer disposed on a first portion of the sensor and a second accelerometer disposed on a second portion of the sensor, the second portion opposing the first portion. The first and second accelerometers are configured to measure a change in motion that corresponds to a change in distance between the detector and the emitter.

Abstract: Methods and systems for determining a physiological parameter in the presence of correlated artifact are provided. One method includes receiving two waveforms corresponding to two different wavelengths of light from a patient. Each of the two waveforms includes a correlated artifact. The method also includes combining the two waveforms to form a plurality of weighted difference waveforms, wherein the plurality of weighted difference waveforms vary from one another by a value of a multiplier. The method further includes identifying one of the weighted difference waveforms from the plurality of weighted difference waveforms using a characteristic of one or more of the plurality of weighted difference waveforms and determining a characteristic of the correlated artifact based at least in part on the identified weighted difference waveform.

Abstract: A system includes a light source, a photodetector in optical communication with the light source, and a processor in communication with said photodetector and configured to output a signal representing oxygen saturation independent of an interfering signal from an interfering source. The system may further include an analog-to-digital converter in communication with the processor that is configured to digitize a signal from the photodetector by oversampling and output oversampling data to the processor. The processor may include an averaging filter that averages the oversampling data received from said analog-to-digital converter prior to decimation to generate an oversampling number.

Abstract: A variable indication estimator which determines an output value representative of a set of input data. For example, the estimator can reduce input data to estimates of a desired signal, select a time, and determine an output value from the estimates and the time. In one embodiment, the time is selected using one or more adjustable signal confidence parameters determine where along the estimates the output value will be computed. By varying the parameters, the characteristics of the output value are variable. For example, when input signal confidence is low, the parameters are adjusted so that the output value is a smoothed representation of the input signal. When input signal confidence is high, the parameters are adjusted so that the output value has a faster and more accurate response to the input signal.

Abstract: According to embodiments, a pulse band region is identified in a wavelet scalogram of a physiological signal (e.g., a plethysmograph or photoplethysmograph signal). Components of the scalogram at scales larger than the identified pulse band region are then used to determine a baseline signal in wavelet space. The baseline signal may then be used to normalize the physiological signal. Physiological information may be determined from the normalized signal. For example, oxygen saturation may be determined using a ratio of ratios or any other suitable technique.

Abstract: The present invention involves a method and an apparatus for analyzing measured signals, including the determination of a measurement of oxygen saturation and respiration rate in the measured signals during a calculation of a physiological parameter of a monitored patient. Use of this invention is described in particular detail with respect to oximetry-based measurements but extends to other types of measurements.

Abstract: The disclosure includes pulse oximetry systems and methods for determining point-by-point saturation values by encoding photoplethysmographs in the complex domain and processing the complex signals. The systems filter motion artifacts and other noise using a variety of techniques, including statistical analysis such as correlation, or phase filtering.

Abstract: There is disclosed a system and methods to estimate physiological parameters. In accordance with embodiments a method is disclosed which includes generating distribution data for a plurality of signals. The method may also include deconvolving one of the plurality of signals from the other plurality of signals to produce clean signals. The clean signals may then be used to calculate physiological parameters.

Abstract: The invention provides a body-worn system that continuously measures pulse oximetry and blood pressure, along with motion, posture, and activity level, from an ambulatory patient. The system features an oximetry probe that comfortably clips to the base of the patient's thumb, thereby freeing up their fingers for conventional activities in a hospital, such as reading and eating. The probe secures to the thumb and measures time-dependent signals corresponding to LEDs operating near 660 and 905 nm. Analog versions of these signals pass through a low-profile cable to a wrist-worn transceiver that encloses a processing unit. Also within the wrist-worn transceiver is an accelerometer, a wireless system that sends information through a network to a remote receiver, e.g. a computer located in a central nursing station.

Abstract: A spectrophotometric sensor assembly for non-invasive monitoring of a blood metabolite within a subject's body tissue is provided that includes a pad, a light source, and a light detector The light source is operative to emit light signals of a plurality of different wavelengths. The light detector is operative to detect light emitted by the light source and passed through the subject's body tissue. The light detector is at least partially enclosed in EMI shielding. In some embodiments, the light detector and EMI shielding are disposed in a detector housing that encloses the light detector and shielding. The housing is aligned with a detector aperture disposed in the pad.

Abstract: A pulse oximetry includes: irradiating living tissue with a plurality of light beams of different wavelengths; receiving the light beams transmitted through or reflected from the living tissue and converting the received light beams to electric signals which correspond to the different wavelengths; time-segmenting time series data of the electric signals; calculating, with respect to each of the segmented time series data of the electric signals, a slope value of a regression line between each two of the electric signals; calculating SaO2 based on the slope value of each of the segmented time series data of the electric signals; constructing a histogram of SaO2 for each predetermined number of time segments; and obtaining a mode value from the histogram as SpO2 to be output of the pulse oximetry.

Abstract: A method for determining a physiological parameter in the presence of correlated artifact, including obtaining two digital waveforms, x and y, the waveforms being representative of the absorption of two wavelengths of electromagnetic energy received from a blood-perfused tissue, and where each of the waveforms has a component corresponding to a plethysmographic waveform and a component corresponding to the correlated artifact; calculating several weighted difference waveforms of the form x?R*y, where R is a multiplier, by varying R over a range; evaluating the several weighted difference waveforms using a shape characteristic of the weighted difference waveform; identifying a weighted difference waveform most closely representative of and one most different from the plethysmographic waveform; determining a pleth-based physiological parameter using the waveform most closely representative of the plethysmographic waveform; determining at least one artifact-based physiological parameter using the waveform most d

Abstract: Methods and systems are discussed for determining venous oxygen saturation by calculating a ratio of ratios from respiration-induced baseline modulations. A calculated venous ratio of ratios may be compared with a look-up table value to estimate venous oxygen saturation. A calculated venous ratio of ratios is compared with an arterial ratio of ratios to determine whether baseline modulations are the result of a subject's respiration or movement. Such a determination is also made by deriving a venous ratio of ratios using a transform technique, such as a continuous wavelet transform. Derived venous and arterial saturation values are used to non-invasively determine a cardiac output of the subject.

Abstract: The present disclosure is directed towards embodiments of systems and methods for discriminating (e.g., masking out) scale bands that are determined to be not of interest from a scalogram derived from a continuous wavelet transform of a signal. Techniques for determining whether a scale band is not of interest include, for example, determining whether a scale band's amplitude is being modulated by one or more other bands in the scalogram. Another technique involves determining whether a scale band is located between two other bands and has energy less than that of its neighboring bands. Another technique involves determining whether a scale band is located at about half the scale of another, more dominant (i.e., higher energy) band.

Abstract: The present invention involves a method and an apparatus for analyzing measured signals, including the determination of a measurement of oxygen saturation and respiration rate in the measured signals during a calculation of a physiological parameter of a monitored patient. Use of this invention is described in particular detail with respect to oximetry-based measurements.

Abstract: According to embodiments, estimated values for a signal transform may be generated using estimated values for the signal. Signal parameters may then be determined based on the estimated signal transform. A first portion of a signal may be obtained. A second portion of the signal may be estimated. The second portion of the signal may correspond to a portion of the that is unknown, that is not yet available and/or that is obscured by noise and/or artifacts. A transform (e.g., a continuous wavelet transform) of both of the signal portions may be performed. One or more parameters corresponding to the signal may then be determined from transformed signal.

Abstract: The present invention involves a method and an apparatus for analyzing measured signals, including the determination of a measurement of oxygen saturation and respiration rate in the measured signals during a calculation of a physiological parameter of a monitored patient. Use of this invention is described in particular detail with respect to oximetry-based measurements but extends to other types of measurements.

Abstract: A medical device system and associated method are used for monitoring tissue oxygenation. An optical sensor produces a signal corresponding to tissue light attenuation. A processor receives the optical sensor signal and computes a first measure of light attenuation at a first light wavelength and a second measure of light attenuation at a second light wavelength. In one embodiment, noise cancellation circuitry receives the first measure and the second measure and generates a guessed ratio of the first and second measures. Using the first measure, the second measure and the guessed ratio, the noise cancellation circuitry provides a peak output power when the guessed ratio corresponds to an actual ratio of the first and second measures.

Abstract: According to embodiments, techniques for estimating scalogram energy values in a wedge region of a scalogram are disclosed. A pulse oximetry system including a sensor or probe may be used to receive a photoplethysmograph (PPG) signal from a patient or subject. A scalogram, corresponding to the obtained PPG signal, may be determined. In an arrangement, energy values in the wedge region of the scalogram may be estimated by calculating a set of estimation locations in the wedge region and estimating scalogram energy values at each location. In an arrangement, scalogram energy values may be estimated based on an estimation scheme and by combining scalogram values in a vicinity region. In an arrangement, the vicinity region may include energy values in a resolved region of the scalogram and previously estimated energy values in the wedge region of the scalogram. In an arrangement, one or more signal parameters may be determined based on the resolved and estimated values of the scalogram.

Abstract: A signal acquisition circuit detects a wanted signal in a composite signal containing the wanted signal and an unwanted signal, where the highest frequency in the unwanted signal is higher than the highest frequency in the wanted signal. A sensor captures the composite signal and an analog-to-digital converter samples and converts the composite signal to digital format, and a filter subtracts the unwanted signal from the composite signal. The sampled signal contains a first component containing the sum of the wanted signal and the unwanted signal sampled at a first rate at least equal to the Nyquist rate for the wanted signal but less than a second rate that is at least equal to the Nyquist rate for the unwanted signal, and a second component containing the unwanted signal sampled at the second rate.

Abstract: A pulse oximeter method and apparatus which provides (1) a notch filter at a distance between a modulation frequency and a common multiple of commonly used power line frequencies (50, 60, 100 and 120) and also (2) a demodulation frequency greater than a highest pulse rate of a person and lower than any harmonic of 50, 60, 100 or 120 Hz, to filter ambient light interference, while choosing an optimum demodulation frequency that avoids interference from the notch filter or from harmonics of the line interference. Also, ambient light for any low frequency interference, such as power line interference, is measured both before and after each of the light emitter wavelengths and the average of the ambient light is then subtracted from the detected signal.

Abstract: Several techniques are disclosed for isolating either heart or breath rate data from a photoplethysmograph, which is a time domain signal such as from a pulse oximeter. The techniques involve the use of filtering in the frequency domain, after a Fast Fourier Transform (FFT) has been conducted on a given photoplethysmograph also references as a given set of discrete time-domain data. The filtering may be applied to an identified fundamental frequency and one or more harmonics for heart related parameters. The filter may be truncated to the frequency data set and further applied multiple times to improve roll off. After filtering, an Inverse FFT (IFFT) is used to reconstruct the time-domain signal, except with undesirable frequency content eliminated or reduced. Calculation or measurement of parameters is then conducted on this reconstructed time-domain signal.

Abstract: A sensor is disclosed having one or more light sources, and one or more light detectors. At least one of the detectors produces an output in response to received light. Also, electrical circuitry in response to the output generates a pulse waveform proportional to the arterial and venous pulse of a human body, wherein the pulse waveform is used to synchronize an arterial-pulse measurement of the absorption or reflectance of one or more coherent light sources.

Abstract: A variable indication estimator which determines an output value representative of a set of input data. For example, the estimator can reduce input data to estimates of a desired signal, select a time, and determine an output value from the estimates and the time. In one embodiment, the time is selected using one or more adjustable signal confidence parameters determine where along the estimates the output value will be computed. By varying the parameters, the characteristics of the output value are variable. For example, when input signal confidence is low, the parameters are adjusted so that the output value is a smoothed representation of the input signal. When input signal confidence is high, the parameters are adjusted so that the output value has a faster and more accurate response to the input signal.

Abstract: A patient monitor has multiple sensors adapted to attach to tissue sites of a living subject. The sensors generate sensor signals that are responsive to at least two wavelengths of optical radiation after attenuation by pulsatile blood within the tissue sites. A patient monitor uses the plurality of signals to reduce the effects of noise.

Abstract: A method and apparatus for spectrophotometric in vivo monitoring of blood metabolites such as hemoglobin oxygen concentration at a plurality of different areas or regions on the same organ or test site on an ongoing basis, by applying a plurality of spectrophotometric sensors to a test subject at each of a corresponding plurality of testing sites and coupling each such sensor to a control and processing station, operating each of said sensors to spectrophotometrically irradiate a particular region within the test subject; detecting and receiving the light energy resulting from said spectrophotometric irradiation for each such region and conveying corresponding signals to said control and processing station, analyzing said conveyed signals to determine preselected blood metabolite data, and visually displaying the data so determined for each of a plurality of said areas or regions in a comparative manner. REEXAMINATION RESULTS The questions raised in reexamination proceeding No. 90/010,128, filed Mar.