Abstract: A physiological monitoring system may use photonic signals to determine physiological parameters. The system may vary parameters of a light drive signal used to generate the photonic signal from a light source such that power consumption is reduced or optimized. Parameters may include light intensity, firing rate, duty cycle, other suitable parameters, or any combination thereof. In some embodiments, the system may use information from a first light source to generate a light drive signal for a second light source. In some embodiments, the system may vary parameters in a way substantially synchronous with physiological pulses, for example, cardiac pulses. In some embodiments, the system may vary parameters in response to an external trigger.

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: This disclosure describes systems and methods for displaying information that describes the accuracy of estimated values of physiological parameters. As part of the process of estimating a physiological parameter, the data used for the estimation are further analyzed to determine one or more statistical parameters indicative of the accuracy of the estimate. These statistical parameters are then displayed to the caregiver in order to provide the caregiver additional information concerning the estimated value. In the systems and methods described herein, one or more probability analyses are performed on the data used to generate the estimate of the physiological parameter. The analyses may include calculating the accuracy, confidence interval or some other statistical parameter representative of the accuracy of the estimate of the physiological parameter from the variations in the data An indication of the accuracy and/or an indication of the calculated probability may then be displayed to a caregiver or user.

Abstract: Adjusting a pulse qualification criterion includes receiving a signal representing a plurality of pulses, where the signal is generated in response to detecting light scattered from blood perfused tissue. A characteristic is determined. A pulse qualification criterion used for qualifying a pulse is adjusted in accordance with the characteristic. The pulses are evaluated according to the pulse qualification criterion.

Abstract: Adjusting a pulse qualification criterion includes receiving a signal representing a plurality of pulses, where the signal is generated in response to detecting light scattered from blood perfused tissue. A characteristic is determined. A pulse qualification criterion used for qualifying a pulse is adjusted in accordance with the characteristic. The pulses are evaluated according to the pulse qualification criterion.

Abstract: Embodiments disclosed herein may include systems and methods for determining a patient's respiratory effort and blood oxygen saturation based on data acquired from a pulse oximetry sensor and analyzing the parameters in conjunction with each other. For example, the respiratory effort may be determined based on a photo-plethysmographic waveform generated from light attenuation detected by the sensor, and the blood oxygen saturation may be a pulse-based estimate of arterial blood oxygen saturation determined from the detected attenuation. Analysis of the parameters may enable detection and classification of apnea (e.g., obstructive or central) or another underlying cause for respiratory instability. Furthermore, the measured respiratory effort may be compared to respiratory effort supplied by a ventilator to ensure proper sensor placement before enabling automatic adjustment of ventilator settings.

Abstract: Systems and methods for measuring a physiological parameter of tissue in a patient are provided herein. In a first example, a method of measuring a physiological parameter of blood in a patient is provided. The method includes emitting at least two optical signals for propagation through tissue of the patient, detecting the optical signals after propagation, identifying propagation pathlengths of the optical signals, and identifying detected intensities of the optical signals. The method also includes processing at least the propagation pathlengths to scale the detected intensities for determination of a value of the physiological parameter.

Abstract: Methods and systems are presented for determining whether a regional oximetry sensor is properly positioned on a subject. First and second metric values may be determined based on respective first and second light signals. The first and second metric values and a relationship between the first and second metrics are used to determine whether the sensor is properly positioned on the subject. The first and second metrics may form a pair of metrics, and whether the sensor is properly positioned on the subject may be determined based on whether the pair of metrics falls within a sensor-on region. In some embodiments, a plurality of metrics may be determined based on a plurality of received physiological signals. The plurality of metrics may be combined, using, for example, a neural network, to determine whether the regional oximetry sensor is properly positioned on a subject.

Abstract: A physiological monitoring system may use photonic signals to determine physiological parameters. The system may vary parameters of a light drive signal used to generate the photonic signal from a light source such that power consumption is reduced or optimized. Parameters may include light intensity, firing rate, duty cycle, other suitable parameters, or any combination thereof. In some embodiments, the system may use information from a first light source to generate a light drive signal for a second light source. In some embodiments, the system may vary parameters in a way substantially synchronous with physiological pulses, for example, cardiac pulses. In some embodiments, the system may vary parameters in response to an external trigger.

Abstract: Systems and methods for measuring a physiological parameter of tissue in a patient are provided herein. In a first example, a method of measuring a physiological parameter of blood in a patient is provided. The method includes emitting at least two optical signals for propagation through tissue of the patient, detecting the optical signals after propagation, identifying propagation pathlengths of the optical signals, and identifying detected intensities of the optical signals. The method also includes processing at least the propagation pathlengths to scale the detected intensities for determination of a value of the physiological parameter.

Abstract: Embodiments disclosed herein may include systems and methods for determining a patient's respiratory effort and blood oxygen saturation based on data acquired from a pulse oximetry sensor and analyzing the parameters in conjunction with each other. For example, the respiratory effort may be determined based on a photo-plethysmographic waveform generated from light attenuation detected by the sensor, and the blood oxygen saturation may be a pulse-based estimate of arterial blood oxygen saturation determined from the detected attenuation. Analysis of the parameters may enable detection and classification of apnea (e.g., obstructive or central) or another underlying cause for respiratory instability. Furthermore, the measured respiratory effort may be compared to respiratory effort supplied by a ventilator to ensure proper sensor placement before enabling automatic adjustment of ventilator settings.

Abstract: Methods and systems are presented for triggering physiological measurements in a physiological monitor. Metrics are computed for a received physiological signal (e.g., a PPG signal), or a determined physiological parameter associated with the physiological signal (e.g., blood pressure). A change parameter is determined based on one or more of the metrics, and a variable change threshold is determined. The variable change threshold may be determined over time based on a time measure, a frequency measure, or both. The change parameter is compared to the variable change threshold, and a physiological measurement is triggered based on the comparison. The variable change threshold technique may allow measurements to be taken frequently enough to catch clinically significant changes in a physiological parameter of a subject but not so often as to interfere with the subject's comfort or the function of other medical monitors.

Abstract: A sensor for pulse oximetry or other applications utilizing spectrophotometry may be adapted to reduce motion artifacts by fixing the optical distance between an emitter and detector. A flexible sensor is provided with a stiffening member to hold the emitter and detector of the sensor in a relatively fixed position when applied to a patient. Further, an annular or partially annular sensor is adapted to hold an emitter and detector of the sensor in a relatively fixed position when applied to a patient. A clip-style sensor is provided with a spacer that controls the distance between the emitter and detector.

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 of the present invention relate to a method for analyzing pulse data. In one embodiment, the method comprises receiving a signal containing data representing a plurality of pulses, the signal generated in response to detecting light scattered from blood perfused tissue. Further, one embodiment includes performing a pulse identification or qualification algorithm on at least a portion of the data, the pulse identification or qualification algorithm comprising at least one constant, and modifying the at least one constant based on results obtained from performing the pulse identification or qualification algorithm, wherein the results indicate that a designated number of rejected pulses has been reached.

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: The present disclosure relates, according to some embodiments, to devices, systems, and methods for estimating a physiological parameter in the presence of noise. For example, the disclosure relates, in some embodiments, to devices, systems, and methods for assessing (e.g., estimating, measuring, calculating) oxygen saturation (SpO2). Methods of assessing SpO2 may include assessing a noise metric associated with motion artifact. In some embodiments, a percentage (e.g., an empirically determined percentage) of a noise metric may be simply added to the SpO2 estimate to produce a corrected SpO2 estimate. An oximetry algorithm may include, according to some embodiments, combining multiple internal SpO2 estimates and associated noise and/or signal quality metrics (e.g., using a radial basis neural network) to produce a modified (e.g., corrected) SpO2 estimate (e.g., rather than merely selecting the estimate from a finite number of candidates). A modified SpO2 estimate may include little or no movement-based error.

Abstract: In an embodiment, a sensor may be adapted to provide information related to its position on a patient's tissue. The sensor may include tissue contact sensors which may relay a signal related to the proper placement of the sensor relative to the tissue of a patient. Such a sensor may be useful for providing information to a clinician regarding the location of the sensor in relation to the skin of a patient in order to provide improved measurements.

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 of the present disclosure relate to a system and method for determining a likelihood of successful ventilator weaning for a patient undergoing mechanical or assisted ventilation. Specifically, embodiments provided herein include methods and systems for determining or predicting weaning readiness in a patient based on physiological parameters determined via photoplethysmography.