Abstract: Breathing effort of a patient, as determined (for example) from a photoplethysmograph (“PPG”) signal from the patient, can be calibrated in relation to air pressure in the patient's respiratory system. This calibration can be done by subjecting the patient to varying amounts of breathing resistance; and for each such amount, concurrently measuring (1) air pressure in the respiratory system (e.g., in the oral/nasal cavity) and (2) breathing effort (from the PPG signal). Use can be made of this calibration, e.g., during a sleep study of the patient. During such a study, breathing effort, again determined from the PPG signal and occurring, for example, during an apneic event of the patient, can be used to infer air pressure in the respiratory system by using the above calibration.

Abstract: Techniques and structures are disclosed for using photoplethysmograph (PPG) and electrocardiographic (EKG)-based readings of a subject to determine one or more physiological characteristics of the subject. In an arrangement, a combined PPG-EKG sensor unit may be used to detect both PPG and EKG signals of the subject. The sensor unit may include a PPG sensor, an EKG sensor, and a support structure for connecting or fastening the sensor unit to the subject. The detected readings may be provided to an electronic monitor. In an arrangement, a PPG-EKG monitoring system, including the electronic monitor, may be used to determine the physiological parameters of the subject. The monitoring system may first determine an auxiliary parameter based at least in part on the EKG signal, and then compute the one or more physiological characteristics of the subject based at least in part on both the PPG signal and the auxiliary parameter.

Abstract: Methods and systems are provided for generating Lissajous figures based on monitored signals and identifying features of Lissajous figures. Features may include similarity metrics, shape change metrics and noise metrics, and may be used to determine information about the monitored signal. Features may also be used in monitoring operations, such as measurement quality assessment and recalibration.

Abstract: Systems and methods are disclosed herein for measuring the electromechanical delay of the heart of a patient. An electrocardiogram (EKG) signal may be used to detect heart electrical activity. Photoplethysmograph (PPG) signals may be used to detect heart mechanical activity. The electromechanical delay may be calculated based at least in part on the timing of an EKG signal and at least two PPG signals.

Abstract: A combined physiological sensor and methods for detecting one or more physiological characteristics of a subject are provided. The combined sensor (e.g., a forehead sensor) may be used to detect and/or calculate at least one of a pulse blood oxygen saturation level, a regional blood oxygen saturation level, a respiration rate, blood pressure, an electrical physiological signal (EPS), a pulse transit time (PTT), body temperature associated with the subject, a depth of consciousness (DOC) measurement, any other suitable physiological parameter, and any suitable combination thereof. The combined sensor may include a variety of individual sensors, such as electrodes, optical detectors, optical emitters, temperature sensors, and/or other suitable sensors. The sensors may be advantageously positioned in accordance with a number of different geometries.

Abstract: Techniques for the display of a signal with a wavelet transform of that signal in a wavelet transform viewer are disclosed, according to embodiments. According to embodiments, the wavelet transform viewer can display a plot of physiological signals such as a photoplethysmograph (PPG) signal. A portion of the plot of the signal can be selected. A wavelet transform the selected portion of the signal can be calculated and a wavelet plot of the tranformed signal can be displayed simultaneously with that signal. A plot of the selected portion of the signal can also be simultaneously displayed with both the plot of the signal and the wavelet plot.

Abstract: Systems and methods for determining physiological parameters of a subject using a sensor array. In an embodiment, a sensor array may contain sensor elements for determining multiple physiological parameters. A combination of sensor elements and the physiological parameters determined may be selected based on signals obtained from the sensor elements of the sensor array. A sensor array may be connected to a monitoring device that may select an optimal sensor element or combination of sensor elements and one or more physiological parameters to be determined. The monitoring device may then determine physiological parameters using the selected combination of sensor elements and display information associated with the parameters on a monitor for use, for example, in monitoring a medical patient.

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: Systems and methods are provided for monitoring the physiological state of a subject. One or more physiological parameters of a subject may be determined from a photoplethysmograph (PPG) signal or signals obtained using at least one PPG sensor. In some embodiments, an electrical physiological signal (EPS) sensor may be located in or near a PPG sensor. A sensor configuration including both PPG sensors and EPS sensors may be advantageously used to detect a PPG signal or signals in combination with one or more EPS signal or signals. To reduce potential interference between an EPS sensor and a PPG sensor, fiber-optic input and output lines may be used to transmit optical signals from light generating circuitry and light detecting circuitry. In some embodiments, the generating and detecting circuitry may be located remotely from one another and may further be located remotely from the EPS sensor, PPG sensor, or both.

Abstract: A method and system for automatically gating an imaging device is disclosed. Physiological process information of a patient may be derived from a plethysmographic signal, for example, by analyzing the plethysmographic signal transformed by a continuous wavelet transform. Other techniques for deriving physiological process information of a patient include, for example, analyzing a scalogram derived from the continuous wavelet transform. The physiological process information may be used to automatically gate imaging data acquired from an imaging device in order to synchronize the imaging data with the physiological process information.

Abstract: According to embodiments, non-corrupted signal segments are detected by a data modeling processor implementing an artificial neural network. The neural network may be trained to detect artifact in the signal (e.g., a PPG signal or some wavelet representation of a PPG signal) and gate valid signal segments for use in determining physiological parameters, such as, for example, pulse rate, oxygen saturation, pulse rate, respiration rate, and respiratory effort. When an artifact is detected, previously received known-good signal segments may be buffered and replace the signal segment or segments containing artifact. A regression analysis may also be performed in order to extrapolate new data from previously received known-good signal segments. In this way, more accurate and reliable physiological parameters may be determined.

Abstract: According to embodiments, systems and methods for high-pass filtering a plethysmograph or photoplethysmograph (PPG) signal are disclosed. A sensor or probe may be used to obtain a plethysmograph or PPG signal from a subject. The sensor may be placed at any suitable location on the body, e.g., the forehead, finger, or toe. The PPG signal generated by the sensor may be high-pass filtered to disambiguate certain features of the PPG signal, including one or more characteristic points. The cut-off frequency for the high-pass filter may be greater than 0.75 Hz and less than 15 Hz. The cut-off frequency for the high-pass filter may be selected to be greater than the subject's computed pulse rate. These characteristic points on the filtered PPG signal may be used to compute non-invasive blood pressure measurements continuously or on a periodic basis. For example, the time difference between two or more characteristic points in a high-pass filtered version of the generated PPG signal may be computed.

Abstract: The present disclosure relates to systems and methods for analyzing and normalizing signals, such as PPG signals, for use in patent monitoring. The PPG signal may be detected using a continuous non-invasive blood pressure monitoring system and the normalized signals may be used to determine whether a recalibration of the system should be performed.

Abstract: The present disclosure relates to monitoring a characteristic respiration rate of a patient based at least in part on a suitable time period that either precedes or follows a triggering event, such as a clinician/patient interaction, where the triggering event may negatively impact the physiological parameter. In some embodiments, physiological parameter values falling between one or more pre-set thresholds may be used to derive the characteristic physiological parameter. In some embodiments, monitoring the respiration rate may provide additional information about the patient's status. In some embodiments, confidence measures may be associated with, or may be used to analyze features of the patient signal to derive information about, the characteristic respiration rate. The patient signal used to derive a patient's respiration rate may be of an oscillatory nature or may include oscillatory features that may be analyzed to derive a characteristic respiration rate.

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: One or more physiological conditions of a patient can be observed by obtaining a photoplethysmograph (“PPG”) signal from the patient and by only lightly filtering that signal. The light filtering of the PPG may be such as to only remove (for example) high frequency noise from that signal, while leaving in the signal most or all frequency components that are due to physiological events in the patient. In this way, such physiological events can be observed via a visual display of the lightly filtered PPG signal and/or via other signal processing of the lightly filtered PPG signal to automatically extract certain physiological parameters or characteristics from that signal.

Abstract: According to an embodiment, 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 approach, energy values in the wedge region of the scalogram may be estimated by performing convolution-based or convolution-like operations on the obtained PPG signal, or a transformed version thereof, and the scalogram may be updated according to the estimated values. In an approach, a deskewing technique may be used to align data prior to adding the data to the scalogram. In an approach, one or more signal parameters may be determined based on the resolved and estimated values of the scalogram.

Abstract: Methods and systems for determining blood pressure from a pressure signal are disclosed. A patient's blood pressure may be determined by analyzing features of a wavelet transformation of a pressure signal obtained during an occlusion procedure. Ridges in a scalogram of the transformed signal may be identified and used to determine an envelope of a pressure oscillation signal, to which oscillometric blood pressure determination techniques may be applied.

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: According to embodiments, techniques for determining respiratory parameters are disclosed. More suitable probe locations for determining respiratory parameters, such as respiration rate and respiratory effort, may be identified. The most suitable probe location may be selected for probe placement. A scalogram may be generated from the detected signal at the more suitable location, resulting in an enhanced breathing band for determining respiratory parameters. Flexible probes that allow for a patient's natural movement due to respiration may also be used to enhance the breathing components of the detected signal. From the enhanced signal, more accurate and reliable respiratory parameters may be determined.