Abstract: A sensor system is provided for determining a pulse transit time measurement of a patient. The sensor system includes a carotid sensor device configured to be positioned on a neck of the patient over a carotid artery of the patient. The carotid sensor device is configured to detect a plethysmograph waveform from the carotid artery. The sensor system includes a temporal sensor device that is operatively connected to the carotid sensor device. The temporal sensor device is configured to be positioned on the patient over a temporal artery of the patient. The temporal sensor device is configured to detect a plethysmograph waveform from the temporal artery.

Abstract: A PPG system for determining cardiac stability of a patient includes a PPG sensor configured to be secured to an anatomical portion of the patient, wherein the PPG sensor is configured to sense a physiological characteristic of the patient. The PPG system includes a monitor operatively connected to the PPG sensor. The monitor receives a PPG signal from the PPG sensor. The monitor includes a cardiac stability analysis module configured to determine an amplitude variance of the PPG signal over a predetermined time period and configured to determine a pulse period variance of the PPG signal over the time period. The cardiac stability analysis module is configured to determine cardiac stability as a function of the amplitude variance and the pulse period variance.

Abstract: A physiological monitoring system may process a physiological signal such a photoplethysmograph signal from a subject. The system may determine physiological information, such as a physiological rate, from the physiological signal. The system may use search techniques and qualification techniques to determine one or more initialization parameters. The initialization parameters may be used to calculate and qualify a physiological rate. The system may use signal conditioning to reduce noise in the physiological signal and to improve the determination of physiological information. The system may use qualification techniques to confirm determined physiological parameters. The system may also use autocorrelation techniques, cross-correlation techniques, fast start techniques, and/or reference waveforms when processing the physiological signal.

Abstract: A system includes a controller that receives a physiological signal representing a non-invasive measure of a physiological parameter. The controller applies a compliance metric to the physiological signal and generates an autoregulation status signal that indicates a status of cerebral autoregulation in the patient. The autoregulation status signal is based at least in part on the compliance metric applied to the physiological signal.

Abstract: A physiological monitoring system may determine physiological information, such as physiological rate information, from physiological data. The system may condition the physiological data to assist in the determination of the physiological information. The system may calculate differences based on the physiological data and identify differences that exceed a threshold. The calculated differences may, for example, be a derivative signal. The system may modify the physiological data based on the identified differences. The modification may include reducing, or otherwise limiting, some differences between adjacent values in the physiological data.

Abstract: A physiological monitoring system may determine physiological information, such as physiological rate information, and other information, such as noise information, from a physiological signal. The system may generate a first difference signal based on a first segment of the physiological signal and sort the first difference signal to generate a first sorted difference signal. The system may generate a second difference signal based on a second segment of the physiological signal and sort the second difference signal to generate a second sorted difference signal. The first and second sorted difference signals may be analyzed and a value indicative of noise may be determined based on the analysis.

Abstract: A physiological monitoring system may process a physiological signal such a photoplethysmograph signal from a subject. The system may determine physiological information, such as a physiological rate, from the physiological signal. The system may use search techniques and qualification techniques to determine one or more initialization parameters. The initialization parameters may be used to calculate and qualify a physiological rate. The system may use signal conditioning to reduce noise in the physiological signal and to improve the determination of physiological information. The system may use qualification techniques to confirm determined physiological parameters. The system may also use autocorrelation techniques, cross-correlation techniques, fast start techniques, and/or reference waveforms when processing the physiological signal.

Abstract: A physiological monitoring system may determine physiological information, such as physiological rate information, from a physiological signal. The system may generate a first difference signal based on the physiological signal. The system may sort the first difference signal to generate a sorted difference signal. The system may generate a second difference signal based on the sorted difference signal. The system may determine an algorithm setting based on the second difference signal. The algorithm setting may, for example, affect the amount of filtering applied to the physiological signal.

Abstract: A physiological monitoring system may determine physiological information, such as physiological rate information, and other information, such as signal-to-noise information, from a physiological signal. The system may generate at least one difference signal based on the physiological signal and sort the at least one difference signal to generate at least one sorted difference signal. The system may analyze the at least one sorted difference signal to determine at least two values indicative of noise. The system may determine a value indicative of a signal-to-noise ratio based on the two or more values indicative of noise.

Abstract: A physiological monitoring system may process a physiological signal such a photoplethysmograph signal from a subject. The system may determine physiological information, such as a physiological rate, from the physiological signal. The system may use search techniques and qualification techniques to determine one or more initialization parameters. The initialization parameters may be used to calculate and qualify a physiological rate. The system may use signal conditioning to reduce noise in the physiological signal and to improve the determination of physiological information. The system may use qualification techniques to confirm determined physiological parameters. The system may also use autocorrelation techniques, cross-correlation techniques, fast start techniques, and/or reference waveforms when processing the physiological signal.

Abstract: A physiological monitoring system may determine physiological information, such as physiological rate information, from a physiological signal. The system may filter the physiological signal based on an adjustable filter to generate a filtered physiological signal. The system may perform calculations over time based on the filtered physiological signal to determine values indicative of a physiological parameter. The adjustable filter may be adjusted based on the values indicative of the physiological parameter. Some of the calculations are qualified and some of the calculations are disqualified. The system may determine a metric based on the physiological signal that is used to determine whether to output a value based on one or more previously calculated values when a current calculation is disqualified. The system may output a value based on one or more previously calculated values when a current calculation is disqualified and when a criterion based on the metric is satisfied.

Abstract: A physiological monitoring system may determine physiological information, such as physiological rate information, from a physiological signal. The system may generate a correlation sequence between two segments of the physiological signal at multiple correlation lag values. The system may compare the correlation sequence to a predetermined threshold, which may vary as a function of lag. Based on the comparison, the system may determine whether the correlation sequence value exceeds the threshold, and whether the correlation sequence value corresponds to a peak. The system may identify a lag value when the correlation sequence corresponding to the lag value exceeds the threshold and corresponds to a peak. The system may determine physiological rate information based on the identified lag value.

Abstract: A physiological monitoring system may process a physiological signal such a photoplethysmograph signal from a subject. The system may determine physiological information, such as a physiological rate, from the physiological signal. The system may use search techniques and qualification techniques to determine one or more initialization parameters. The initialization parameters may be used to calculate and qualify a physiological rate. The system may use signal conditioning to reduce noise in the physiological signal and to improve the determination of physiological information. The system may use qualification techniques to confirm determined physiological parameters. The system may also use autocorrelation techniques, cross-correlation techniques, fast start techniques, and/or reference waveforms when processing the physiological signal.

Abstract: A physiological monitoring system may process a physiological signal such a photoplethysmograph signal from a subject. The system may determine physiological information, such as a physiological rate, from the physiological signal. The system may use search techniques and qualification techniques to determine one or more initialization parameters. The initialization parameters may be used to calculate and qualify a physiological rate. The system may use signal conditioning to reduce noise in the physiological signal and to improve the determination of physiological information. The system may use qualification techniques to confirm determined physiological parameters. The system may also use autocorrelation techniques, cross-correlation techniques, fast start techniques, and/or reference waveforms when processing the physiological signal.

Abstract: A physiological monitoring system may process a physiological signal such a photoplethysmograph signal from a subject. The system may determine physiological information, such as a physiological rate, from the physiological signal. The system may use search techniques and qualification techniques to determine one or more initialization parameters. The initialization parameters may be used to calculate and qualify a physiological rate. The system may use signal conditioning to reduce noise in the physiological signal and to improve the determination of physiological information. The system may use qualification techniques to confirm determined physiological parameters. The system may also use autocorrelation techniques, cross-correlation techniques, fast start techniques, and/or reference waveforms when processing the physiological signal.

Abstract: A physiological monitoring system may determine physiological information, such as physiological rate information, from a physiological signal. The system may condition the physiological signal to assist in the determination of the physiological information. The system may generate a difference signal based on the physiological signal and sort the difference signal. The system may identify values in the sorted difference signal that exceed a threshold, and modify the physiological signal based on the identified values. The modification may include reducing, or otherwise limiting, some differences between adjacent values in the physiological signal.

Abstract: A physiological monitoring system may process a physiological signal such a photoplethysmograph signal from a subject. The system may determine physiological information, such as a physiological rate, from the physiological signal. The system may use search techniques and qualification techniques to determine one or more initialization parameters. The initialization parameters may be used to calculate and qualify a physiological rate. The system may use signal conditioning to reduce noise in the physiological signal and to improve the determination of physiological information. The system may use qualification techniques to confirm determined physiological parameters. The system may also use autocorrelation techniques, cross-correlation techniques, fast start techniques, and/or reference waveforms when processing the physiological signal.

Abstract: A sensor fixture is provided for operatively attaching a photoacoustic (PA) sensor to a patient. The sensor fixture includes an acoustic coupling agent that is configured to allow the transmission of both acoustic energy and light therethrough. The sensor fixture includes a bracket configured to be affixed to skin of the patient. The bracket includes a cavity, a patient side, and a sensor side. The acoustic coupling agent is held within the cavity. The patient side includes a patient opening that is configured to expose the acoustic coupling agent along the patient side. The sensor side includes a sensor opening that is configured to expose the acoustic coupling agent along the sensor side. The sensor side includes a sensor cradle that is configured to hold the PA sensor such that the PA sensor is operatively attached to the acoustic coupling agent for receiving an acoustic response from the patient.

Abstract: A system includes a controller that receives a blood pressure signal and an oxygen saturation signal. The blood pressure signal represents a non-invasive measure of blood pressure. The oxygen saturation signal represents a non-invasive measure of oxygen saturation. The controller generates an autoregulation status signal representing a status of cerebral autoregulation. The autoregulation status signal is based, at least in part, on a relationship between the measured blood pressure and the measured oxygen saturation. An exemplary method may include receiving the blood pressure signal and the oxygen saturation signal, defining a relationship between the measured blood pressure and the measured oxygen saturation, determining an autoregulation status based at least in part on the defined relationship, and generating an autoregulation status signal representing the determined autoregulation status.

Abstract: A physiological monitoring system may determine physiological information, such as physiological rate information, from a physiological signal. The system may receive a calculated value indicative of a physiological rate. The system may generate value pairs from a first collection of values of the physiological signal and another collection of corresponding value of the physiological signal spaced from the first collection based on the calculated value. The system may determine a best fit linear relationship based on the value pairs and determine at least one statistical metric based on the linear relationship and the value pairs. The system may qualify or disqualify the calculated value based on the at least one statistical metric.