Abstract: As placement of a physiological monitoring sensor is typically at a sensor site located at an extremity of the body, the state of microcirculation, such as whether vessels are blocked or open, can have a significant effect on the readings at the sensor site. It is therefore desirable to provide a patient monitor and/or physiological monitoring sensor capable of distinguishing the microcirculation state of blood vessels. In some embodiments, the patient monitor and/or sensor provide a warning and/or compensates a measurement based on the microcirculation state. In some embodiments, a microcirculation determination process implementable by the patient monitor and/or sensor is used to determine the state of microcirculation of the patient.

Abstract: Methods are provided for detecting lipid cores underneath thin fibrous caps (LCTC) and thin-cap fibroatheromas (TCFA) in a subject in need of diagnosis for having a vulnerable plaque, a plaque at risk of disruption or thrombosis, or risk of an acute coronary syndrome, and for screening compounds for modulators of this process.

Abstract: Methods and apparatuses are described to obtain cardiac data, which includes acquiring vibrational field cardiac data from a transducer wherein the transducer measures vibration over a surface of a human's body. An unwanted coronary event is separated from vibrational cardiac data. A transient event is extracted from the vibrational cardiac heart cycle data. The transient event occurs during a diastolic interval within a heart cycle. The transient event is evaluated for a condition of coronary artery blood flow turbulence and a condition of health of a coronary artery is assessed from a feature in the vibrational frequency power spectrum estimate.

Abstract: A system is provided including a thoracic bio-impedance or bio-reactance (TBIR) analysis module, a photoplethysmograph (PPG) analysis module, and a cardiac output module. The TBIR module is configured to obtain TBIR information from a TBIR detector, and the PPG analysis module is configured to obtain PPG information from a PPG detector. The cardiac output module is configured to determine the cardiac output of a patient using the TBIR information and the PPG information.

Abstract: Embodiments of the present invention relate to a system and method for monitoring intracranial pressure. Embodiments of the present invention include emitting an electromagnetic wavelength into forehead tissue of a patient and detecting characteristics of the electromagnetic wavelength after the electromagnetic wavelength has been scattered by the tissue. The characteristics may include variations in the electromagnetic wavelength corresponding to a pulse. Further, embodiments of the present invention include analyzing the variations to identify venous pulsations, and determining whether intracranial pressure is elevated in the patient based on a correlation between the venous pulsations and levels of intracranial pressure.

Abstract: A biological information detector includes a light-emitting part subjected to emit a first light directed at a detection site of a test subject and a second light directed in a direction other than a direction of the detection site, a first reflecting part subjected to reflect the second light and directing the second light towards the detection site, a light-receiving part subjected to receive light having biological information, where the light produced by the first light and the second light is reflected at the detection site, and a second reflecting part subjected to reflect the light having biological information from the detection site and directing the light having biological information towards the light-receiving part.

Abstract: A monitoring device includes a band capable of encircling a portion of the body of a subject, and an optical emitter and detector attached to the band. The band includes comprises light transmissive material in optical communication with the optical emitter and optical detector and is configured to deliver light from the optical emitter to one or more locations of the body of the subject and to collect light from one or more locations of the body of the subject and deliver the collected light to the optical detector. The monitoring device may include a signal processor configured to receive and process signals produced by the optical detector, a transmitter configured to transmit signals processed by the signal processor to a remote device, and/or an optical filter.

Abstract: Methods and systems for determining a physiological parameter of a subject through interrogation of an eye of the subject with an optical signal are described. Interrogation is performed unobtrusively. The system includes a gaze attractor for attracting the gaze of the subject to cause an eye of the subject to move into alignment with regard to an interrogation signal source and/or response signal sensor to facilitate detection of a signal from the eye of the subject.

Abstract: Embodiments provide methods and systems for quantitative imaging of blood perfusion in living tissue. A method provides for obtaining an optical microangiography (OMAG) image of a sample, wherein the image has an OMAG background sample; digitally reconstructing a homogeneous ideal static background tissue; replacing the OMAG background sample with the digitally reconstructed homogeneous ideal static background tissue; correlating two or more neighboring A-lines with the digitally reconstructed homogeneous ideal static background tissue; and measuring a phase difference between the two or more neighboring A-lines to quantify blood perfusion in the sample. Methods using digital reconstruction to reduce random phase noise in phase-resolved Doppler OCT are also provided.

Abstract: The present invention is a Miniature Vein Enhancer that includes a Miniature Projection Head. The Miniature Projection Head may be operated in one of three modes, AFM, DBM, and RTM. The Miniature Projection Head of the present invention projects an image of the veins of a patient, which aids the practitioner in pinpointing a vein for an intravenous drip, blood test, and the like. The Miniature projection head may have a cavity for a power source or it may have a power source located in a body portion of the Miniature Vein Enhancer. The Miniature Vein Enhancer may be attached to one of several improved needle protectors, or the Miniature Vein Enhancer may be attached to a body similar to a flashlight for hand held use. The Miniature Vein Enhancer of the present invention may also be attached to a magnifying glass, a flat panel display, and the like.

Abstract: An apparatus and method for non-invasive determination of hydration, hydration state, total body water, or water concentration by quantitative spectroscopy. The system includes subsystems optimized to contend with the complexities of the tissue spectroscopy, high signal-to-noise ratio and photometric accuracy requirements, tissue sampling errors, calibration maintenance, and calibration transfer. The subsystems include an illumination subsystem, a tissue sampling subsystem, a spectrometer subsystem, a data acquisition subsystem, a computing subsystem, and a calibration subsystem. The system can include a plurality of measurement devices, configured to communicate with each other and with a remote receiver or centralized server. The invention contemplates novel ways to arrange various subsystems and to provide operability and communication among them.

Abstract: Apparatus is provided, including a sensor, adapted to generate a sensor signal indicative of biorhythmic activity of a user of the apparatus, the sensor signal having a first characteristic, indicative of a voluntary action of the user, and a second characteristic, indicative of a benefit-related variable of the user. The apparatus also includes a control unit, adapted to receive the sensor signal, and, responsive to the second characteristics generate an output signal which directs the user to modify a parameter of the voluntary action indicated by the first characteristic.

Abstract: An endoscopic system can include an endoscope shaft having a proximal end and a distal end, and an electrically active sensor system including at least one sensor mounted proximate the distal end and positioned to sense at least one characteristic of an environment in which the distal end is located. The capacitance of the sensor system relative to earth ground maintains current leakage to a level that meets a cardiac float rating.

Abstract: A device for obtaining vital sign information of a living being comprises a detection unit that receives light in at least one wavelength interval reflected from at least a region of interest of a living being and that generates an input signal from the received light. A processing unit processes the input signal and derives vital sign information of said living being from said input signal by use of remote photoplethysmography. An illumination unit illuminates at least said region of interest with light, and a control unit controls said illumination unit based on said input signal and/or said derived vital sign information.

Abstract: An optical measurement apparatus, to which a base end portion of a measurement probe introduced into a subject is connected so that scattering light from the subject through the measurement probe can be measured, includes: calibration member serving as an irradiation target of illumination light when a calibration process is performed for the measurement probe using the illumination light from the measurement probe; an insertion portion where a leading end of the measurement probe can be inserted; a housing portion that communicates with the insertion portion and accommodates the calibration member movably along a penetration direction of the insertion portion; a detection unit that detects insertion of the measurement probe when the calibration member reaches a predetermined position in the housing portion by the insertion of the measurement probe through the insertion portion; and a control unit that performs control for initiating the calibration process when the detection unit detects the insertion of the

Abstract: A system for integrating heart rate measurement and identity recognition is provided. The system includes a storage unit, an image sensor, an identity recognition unit and a frequency extractor. The storage unit stores a user information database. The image sensor captures a plurality of skin images of a user during a time period. The identity recognition unit receives a physiological feature from the user and recognizes the user by comparing the physiological feature with the user information database in the storage unit. The frequency extractor obtains a frequency signal by extracting a motion signal from the skin images according to the brightness change of the different color lights in the skin images during a time period. The frequency signal represents a frequency in a specific frequency interval, and it represents heart rate information of the user. A method for use in the above-mentioned system is also disclosed.

Abstract: Characteristics of a user's heart are detected. In accordance with an example embodiment, a ballistocardiogram (BCG) sensor is used to detect heart characteristics of a user, and provide a BCG output indicative of the detected heart characteristics. The BCG output is further processed using data from one or more additional sensors, such as to reduce noise and/or otherwise process the BCG signal to characterize the user's heart function.

Abstract: A biometric monitoring device measuring various biometric information is provided that allows the person to take and/or display a heart rate reading by a simple user interaction with the device, e.g., by simply touching a heart rate sensor surface area or moving the device in a defined motion pattern. Some embodiments of this disclosure provide biometric monitoring devices that allow a person to get a quick heart rate reading without removing the device or interrupting their other activities. Some embodiments provide heart rate monitoring with other desirable features such as feedback on data acquisition status.

Abstract: A biometric monitoring device measuring various biometric information is provided that allows the person to take and/or display a heart rate reading by a simple user interaction with the device, e.g., by simply touching a heart rate sensor surface area or moving the device in a defined motion pattern. Some embodiments of this disclosure provide biometric monitoring devices that allow a person to get a quick heart rate reading without removing the device or interrupting their other activities. Some embodiments provide heart rate monitoring with other desirable features such as feedback on data acquisition status.

Abstract: A sleep apnea diagnostic system includes a housing that is configured to be attached to near the nose of a patient's face to sense physiological information of a patient. The housing includes sensors to sense the physiological information. The physiological information may be, for example, air flow through the nose or the mouth or both. The physiological information further may be, for example, blood volume. The sleep apnea diagnostic system includes at least one processor in the housing or external to the housing or both to analyze the physiological information to determine whether the patient has experienced irregular or abnormal respiratory activity and to detect respiratory effort. The analysis may be real time or delayed.

Abstract: The invention pertains to the establishment, implementation and management of a personalized information system pertinent to a user's general health, wellness and/or sport performance. Disclosed is a system capable of transcutaneous measurement of a subject including at least one light source, at least one light detector, and at least one component for generating or storing at least one value of VC02 or at least one value of V02 from the detected signal. Further, disclosed is a portable device for analyzing the composition of the respired gasses of a subject including at least one air flow conduit through which the subject can inspire or expire air through the body of the device, at least one sampling portal, an oxygen sensor, and at least one flow sensor. A dual-battery system is also provided by which an uninterrupted power supply can be provided for electronic components.

Abstract: The present subject matter relates to in vivo volumetric bidirectional blood flow imaging using single-pass flow imaging spectral domain optical coherence tomography. This technique uses a modified Hilbert transform algorithm to separate moving and non-moving scatterers within a depth. The resulting reconstructed image maps the components of moving scatterers flowing into and out of the imaging axis onto opposite image halfplanes, enabling volumetric bidirectional flow mapping without manual segmentation.

Abstract: An illumination source may be configured to illuminate the skin of the user. An illumination detector may detect electromagnetic radiation reflected of the skin of the user. A compensation module may be configured to determine the position of the skin of the user relative to the illumination detector. A processor may be configured to determine a heart rate of the user by analyzing information corresponding to an amount of the electromagnetic radiation detected by the illumination detector. The processor may also determine the heart rate of the user by compensating for the position of the skin of the user as determined by the compensation module.

Abstract: A personal information system is provided. The system may include a portable information device having a housing including a top surface defined at least partially by a display, a bottom surface configured with a central region in which an optical sensor, electrical connector, and data connector are positioned, the housing enclosing an internal volume in which a processor is provided, the top surface and bottom surface being coupled by a perimeter side edge extending therebetween, and a mounting structure formed at least partially around the perimeter side edge of the housing. The system may further include a frame, which may be connected to a band, the frame surrounding a void and configured to receive the mounting structure, the frame and mounting structure being releasably securable via a tongue and groove connection. The system may further comprise a dock to which the information device may be connected.

Abstract: Embodiments of the present application relate generally to electrical and electronic hardware, computer software, wired and wireless network communications, wearable, hand held, portable computing devices for facilitating communication of information, and the fields of healthcare and personal health. More specifically the present application relates generally to the field of personal health, and more specifically to new and useful systems and methods for monitoring the health of a user as applied to the field of healthcare and personal health. A system optically detects facial features of a user and analyzes the features along with weight information about the user to make one or more recommendations to the user that are related to the user's health. The weight information may be wirelessly transmitted to the system by a wirelessly-enabled scale (e.g., a bath scale), data capable strap band, wristband, wristwatch, digital watch, or wireless activity monitoring and reporting device.

Abstract: A magnetic-flap optical sensor has an emitter activated so as to transmit light into a fingertip inserted between an emitter pad and a detector pad. The sensor has a detector responsive to the transmitted light after attenuation by pulsatile blood flow within fingertip so as to generate a detector signal. Flaps extend from the emitter pad and along the sides of a detector shell housing the detector pad. Flap magnets are disposed on the flap ends and shell magnets are disposed on the detector shell sides. A spring urges the emitter shell and detector shell together, so as to squeeze the fingertip between its fingernail and its finger pad. The flap magnets have opposite north and south orientations from the shell magnets, urging the flaps to the detector shell sides and squeezing the fingertip sides. These spring and magnet squeezing forces occlude the fingertip blood flow and accentuate a detector signal responsive to an active pulsing of the fingertip.

Abstract: Method and apparatus for diagnosing heart failure are disclosed. They include monitoring a subject's pulsatile blood flow with a non-invasive probe during a Valsalva maneuver (VM), processing data therefrom to calculate fall in flow, hear rate changes, Rebound, and heart stroke volume during the VM. Monitored and calculated results are compared to defined thresholds and interpreted and reported. The apparatus takes the form of a pulsatile blood flow probe on a finger or toe or in a mouthpiece facilitating the VM, the mouthpiece optionally including a pressure transducer or digital monometer to ensure that the subject is performing the VM within required pressure and time ranges. The method and apparatus include a controller or digital processor for processing and reporting the results of the monitoring, calculations, comparisons, interpretation, and reporting of the diagnostic results.

Abstract: A wearable apparatus including a waveguide configured to act as a conduit for light emitted from an illumination source to a photodetector via an interaction portion of the waveguide, the interaction portion configured to channel the light out of the waveguide to enable interaction of the light with a wearer's body and back into the waveguide to enable detection of the interacted light by the photodetector.

Abstract: The present inventions, in one aspect, are directed to portable biometric monitoring device including a housing having a physical size and shape that is adapted to couple to the user's body, at least one band to secure the monitoring device to the user, a physiological sensor, disposed in the housing, to generate data which is representative of a physiological condition of the user data. The physiological sensor may include a light source to generate and output light having at least a first wavelength, and a photodetector to detect scattered light (e.g., from the user). A light pipe is disposed in the housing and optically coupled to the light source directs/transmits light therefrom along a predetermined path to an outer surface of the housing. Processing circuitry calculates a heart rate of the user using data which is representative of the scattered light.

Abstract: Systems, methods and devices for reducing noise in cardiac monitoring including wearable monitoring devices having at least one electrode for cardiac monitoring; in some implementations, the wearable device using a composite adhesive having at least one conductive portion applied adjacent the electrode; and, in some implementations, including circuitry adaptations for the at least one electrode to act as a proxy driven right leg electrode.

Abstract: Direct optical imaging of anatomical features and structures from within a biological organ in a dynamic environment (where the tissue being imaged is in motion due to cardiac rhythms, respiration, etc) presents certain image stability issues due (and/or related) to the motion of the target structure and may limit the ability of the user to visually interpret the image for the purposes of diagnostics and therapeutics. Systems and mechanisms for the purpose of actively stabilizing the image or for compiling and re-displaying the image information in a manner that is more suitable to interpretation by the user are disclosed.

Abstract: A light emitter and a light receiver are provided at a side surface of a lever. When a user grips the lever with his hand, the light emitter and the light receiver are positioned close to bases of the middle finger, a ring finger, and a little finger, as a measurement portion of a palm. A blood-flow blockage reducing component protrudes to contact a portion between the index finger and the middle finger, and a thumb, as a contact portion of the palm.

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 system for monitoring a body includes a surgical implant configured for implantation within a body, a sensory module coupled to the surgical implant and configured for implantation into the body in conjunction with the surgical implant, and a communication module coupled to the surgical implant and configured for implantation into a body in conjunction with the surgical implant. The sensory module is configured to monitor characteristics of the surgical implant, surrounding tissue and/or adjacent tissue. The communication module is electrically coupled to the sensory module and is configured to communicate a signal derived from said characteristics to an external entity.

Abstract: A pulse data detecting apparatus, pulse data detecting method and pulse data detection program are provided capable of suppressing an influence of the condition of the body surface to be measured and obtaining an appropriate measurement result under a wide range of conditions. In the present invention, light-emitting elements irradiate a skin surface with light. A light-emission driving section controls lighting-up and the light emission amount of the plurality of light-emitting elements under the control of a CPU. Light-receiving elements each receive reflected light when the skin surface is irradiated by the light-emitting elements, and output a signal. The CPU determines an appropriate combination of light-emitting elements and a light-receiving element(s) based on the output signal from each of the light-receiving elements. A pulse rate calculating section calculates a pulse rate based on the signal outputted from any of the light-receiving elements in the appropriate combination.

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 determine a first metric value indicative of a physiological classification based on the physiological signal. An algorithm setting may be determined based on the physiological classification. The system may determine a second metric value indicative of a different physiological classification based on the physiological signal. A different algorithm may be determined based on the different physiological classification. 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, 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 window of data, and determine physiological information based on the window of data. The generated window of data may include one or more samples of physiological data, from the physiological signal, and one or more initialization values. The initialization values may include random numbers, noise values, sample values, scaled values thereof, or a combination thereof.

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 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: Apparatus, method and computer accessible medium can be provided for determining presence of individual scattering objects in at least one blood vessel. For example, with at least one detector arrangement, it is possible to detect interferometric radiation from at least one portion of the blood vessel(s), and provide data associated therewith. The interferometric radiation can be based on a first radiation provided from the portion at a second radiation provided from a reference. Further, with a computer arrangement, it is possible to determine the presence of the individual scattering objects in the portion of the blood vessel(s) based on the data. It is also possible to identify individual passage of the scattering objects and/or measure at least one characteristic of the passage.

Abstract: Techniques for mobile cardiac health monitoring are disclosed. In some embodiments, a system for mobile cardiac health monitoring includes a mobile device that includes a processor configured to receive a first set of data from an optical sensor; receive a second set of data from an electrical sensor; and perform a plurality of cardiac health measurements using the first set of data from the optical sensor and the second set of data from the electrical sensor.

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 PPG system for determining a stroke volume of a patient includes a PPG sensor configured to be secured to an anatomical portion of the patient. The PPG sensor is configured to sense a physiological characteristic of the patient. The PPG system may include a monitor operatively connected to the PPG sensor. The monitor receives a PPG signal from the PPG sensor. The monitor includes a pulse trending module determining a slope transit time of an upslope of a primary peak of the PPG signal. The pulse trending module determines a stroke volume of the patient as a function of the slope transit time.

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.