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: 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: 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: 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.

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.

Abstract: One or more respiratory characteristics of a patient are measured by coupling patient monitor apparatus (e.g., a photoplethysmograph (“PPG”)) to the patient in order to produce a patient monitor signal that includes signal indicia indicative of effort the patient is exerting to breathe. A breathing or respiratory effort signal for the patient is extracted from the patient monitor signal. A respiratory characteristic signal is extracted (at least in part) from the effort signal. This may be done, for example, on the basis of an amplitude feature of the effort signal and a relative time of occurrence of that amplitude feature. Alternatively, the respiratory characteristic signal may be based on a relationship between two amplitude features of the effort signal, with or without regard for specifics of the times of occurrence of those amplitude features. A breath air flow meter may also be coupled to the patient, if desired, in order to produce a flow signal.

Abstract: Methods and systems are provided for deriving and analyzing shape metrics, including skewness metrics, from physiological signals and their derivatives to determine measurement quality, patient status and operating conditions of a physiological measurement device. Such determinations may be used for any number of functions, including indicating to a patient or care provider that the measurement quality is low or unacceptable, alerting a patient or care provider to a change in patient status, triggering or delaying a recalibration of a monitoring device, and adjusting the operating parameters of a monitoring system.

Abstract: A method and system for detecting effort events is disclosed. Effort may be determined through feature analysis of the signal as transformed by a continuous wavelet transform, which may be compared against a reference effort measure to trigger an effort event flag that signals the onset and/or severity of an effort event. For example, a respiratory effort measure may be determined based at least in part on a wavelet transform of a photoplethysmograph (PP G) signal and features of the transformed signal. A respiratory reference effort measure may be based at least in part on past values of the respiratory effort measure, and a threshold test may be used to trigger an effort event flag, which may indicate a marked change in respiratory effort exerted by a patient.

Abstract: Breathing effort of a patient, as determined (for example) from a photoplethysmograph (“PPG”) signal from the patient, can be used in conjunction with signals from a spirometer being used by the patient to provide additional information about various characteristics of the patient's breathing. For example, such additional information may include the relationship between the patient's breathing effort and breath volume. As another example, the additional information may include the relationship between the patient's breathing effort and rate of breath flow. Still other such additional information may be derived from various combinations of spirometer and PPG output signals.

Abstract: The present disclosure relates to monitoring a characteristic physiological parameter of a patient during a suitable time period that either precedes or follows a triggering event, such as a clinician/patient interaction, that 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, tracking the physiological parameter 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 physiological parameter. The patient signal used to derive a patient's physiological parameter 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, techniques for extracting a signal parameter from a selected region of a generally repetitive signal are disclosed. A pulse oximetry system including a sensor or probe may be used to obtain an original photoplethysmograph (PPG) signal from a subject. A filter transformation may be applied to the original PPG signal to produce a baseline PPG signal. The baseline PPG signal may contain artifacts and/or noise, and a region of the baseline PPG signal suitable for extracting the signal parameter may be selected. A suitable region of the baseline PPG signal may be selected by applying one or more thresholds to the baseline PPG signal, where the values of the thresholds may be set based on derivative values, amplitude-based percentiles, and/or local minima and maxima of the baseline PPG signal. A portion of the original PPG signal corresponding to the selected region may be processed, and the signal parameter may be extracted from the processed region.

Abstract: The present disclosure relates to systems and methods for monitoring pain management using measurements of physiological parameters based on a PPG signal. A reference physiological parameter may be compared against a later measurement to identify a change in condition that may indicate a pain management problem.

Abstract: The present disclosure relates to systems and methods for monitoring pain management using measurements of physiological parameters based on a PPG signal. A reference physiological parameter may be compared against a later measurement to identify a change in condition that may indicate a pain management problem.

Abstract: The present disclosure relates to systems and methods for monitoring pain management using measurements of physiological parameters based on a PPG signal. A reference physiological parameter may be compared against a later measurement to identify a change in condition that may indicate a pain management problem.

Abstract: The present disclosure relates to systems and methods for monitoring pain management using measurements of physiological parameters based on a PPG signal. A reference physiological parameter may be compared against a later measurement to identify a change in condition that may indicate a pain management problem.

Abstract: According to embodiments, techniques for selecting a consistent part of a signal, including a photoplethysmograph (PPG) signal, are disclosed. A pulse oximetry system including a sensor or probe may be used to obtain a PPG signal from a subject. Signal peaks may be identified in the PPG signal. Characteristics of the signal peaks, including the amplitude levels of the signal peaks and/or the time-distance between the signal peaks may be used to determine if the PPG signal is consistent. In an embodiment, signal peaks are processed based on a consistency metric, and the processed signal peaks are compared to the consistency metric to determine if the PPG signal is consistent. If the PPG signal is determined to be consistent, the PPG signal may be further analyzed to determine an underlying signal parameter, including, for example, a patient respiration rate.