Abstract: A method for ventilating a patient with a ventilator includes receiving a target pressure input for a breathing phase, receiving at least one oscillation parameter, imposing an oscillatory waveform on the target pressure, the oscillatory waveform having characteristics defined by the at least one oscillation parameter and configured to oscillate substantially about the target pressure for at least a portion of the breathing phase, and delivering an amount of flow sufficient to achieve an oscillatory target pressure based on the imposed oscillatory waveform.

Abstract: Embodiments of the present disclosure relate to a system and method for determining a risk, onset, or presence of hypovolemia based on one or more features of a plethysmographic waveform during a patient breathing cycle. For example, a hypovolemic patient may exhibit characteristic changes in pulse amplitude or stroke volume during inhalation and exhalation relative to a healthy patient. Further, a trend or pattern of such features may be used to assess the patient's fluid condition.

Abstract: According to various embodiments, a regional oximetry sensor may include a light emitting element configured to emit light, a light detector configured to receive the light, and a memory device configured to store a baseline. The baseline stored by the memory device enables a regional oximetry monitor to display the baseline on a display of the regional oximetry monitor.

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, systems and methods for non-invasive blood pressure monitoring are disclosed. An exciter may induce perturbations in a subject, and a sensor or probe may be used to obtain a detected signal from the subject. The detected signal may then be used to measure one or more physiological parameters of the patient. For example if the perturbations are based on a known signal, any differences between the known signal and the input signal may be attributable to the patient's physiological parameters. A phase drift between the perturbation signal and the detected signal may be determined from a comparison of the scalograms of the exciter location and the sensor or probe location. From the scalogram comparison, more accurate and reliable physiological parameters may be determined.

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: This disclosure describes systems and methods for configuring a ventilator to estimate the carinal pressure to minimize the work of breathing due to a breathing tube. A patient's carina is a cartilaginous ridge located at the site of the tracheal bifurcation between the two primary bronchi. According to embodiments, an estimated carinal pressure may be determined and used as feedback control for the carinal pressure. An estimated carinal pressure refers to a pressure estimated to exist at the patient carina. According to embodiments, the estimated carinal pressure may be compared to the carinal pressure command to determine an error. The carinal pressure command may be positive end expiratory pressure (PEEP) or some other suitable target pressure. The error between the estimated carinal pressure and the carinal pressure command may then be used as feedback control to achieve the carinal pressure command and thereby to minimize the work of breathing due to the breathing tube.

Abstract: A physiological monitoring system may use photoacoustic sensing to determine one or more physiological parameters of a subject. A photoacoustic signal generated in response to a photonic signal may include multiple peaks as a result of multiple blood vessels and other structures below the surface of the skin of a subject. A photoacoustic system may identify a first and second peak in the photoacoustic signal and determine values from the peaks indicative of physiological parameters. Physiological parameters, such as venous oxygen saturation and arterial oxygen saturation, may be determined based on the values.

Abstract: A body-mounted photoacoustic sensor unit may use photoacoustic sensing to determine one or more physiological parameters of a subject. The body-mounted photoacoustic sensor unit may fixably locate a light source and photoacoustic detector relative to a target area. The photoacoustic detector may detect an acoustic pressure response generated by the application and absorption of light from the light source.

Abstract: An oral cavity mounted photoacoustic sensing unit is disclosed. The sensing unit may include a light source, a photoacoustic detector, and a support assembly. The support assembly may be configured such that the light source and the photoacoustic detector are fixably located relative to the buccal or sublingual tissue of a subject.

Abstract: According to embodiments, systems, devices, and methods for ridge selection in scalograms are disclosed. Ridges or ridge components are features within a scalogram which may be computed from a signal such as a physiological (e.g., photoplethysmographic) signal. Ridges may be identified from one or more scalograms of the signal. Parameters characterizing these ridges may be determined. Based at least in part on these parameters, a ridge density distribution function is determined. A ridge is selected from analyzing this ridge density distribution function. In some embodiments, the selected ridge is used to determine a physiological parameter such as respiration rate.

Abstract: A patient monitoring system may receive a physiological signal such as a photoplethysmograph (PPG) signal that exhibits frequency and amplitude modulation based on respiration. A phase locked loop may generate a frequency demodulated signal and an amplitude demodulated signal from the PPG signal. An autocorrelation sequence may be generated for each of the frequency demodulated signal and the amplitude demodulated signal. The autocorrelation sequences may be combined and respiration information may be determined based on the combined autocorrelation sequence.

Abstract: This disclosure describes systems and methods for providing adaptive base flow scheduling during ventilation of a patient to optimize patient-machine synchrony and accuracy of estimated exhaled as well as inhaled tidal volumes. Further, this disclosure describes systems and methods for providing adaptive inspiratory trigger threshold scheduling during the adaptive base flow scheduling. Further still, this disclosure describes systems and methods for determining an estimated leak flow and adjusting the adaptive base flow scheduling and the adaptive inspiratory trigger threshold scheduling based on the estimated leak flow. Moreover, this disclosure describes systems and methods for determining a change in the estimated leak flow and adjusting the adaptive base flow scheduling and the adaptive inspiratory trigger threshold scheduling based on the change in the estimated leak flow.

Abstract: A patient monitoring system may receive a physiological signal having gap portions in the received data. The gap portions may be identified and a plurality of morphology metric signals may be modified based on the identified gap portions. The morphology metric signals may be modified based on the identified gaps, and a combined autocorrelation sequence may be generated based on the modified morphology metric signals. The combined autocorrelation sequence may be used to determine physiological information.

Abstract: This disclosure describes systems and methods for piloting a pneumatic valve using one or more piezoelectric blowers. According to embodiments, the one or more piezoelectric blowers may be coupled to the pneumatic valve to form a small, light-weight pneumatic valve that may be placed proximal to a ventilated patient, e.g., at the patient wye or the patient interface. Due to the close coupling of the one or more piezoelectric blowers, the pneumatic valve has a substantially shorter response time than traditional pneumatically piloted valves. Moreover, when piezoelectric blowers are coupled to the pneumatic valve in parallel, response time may be further decreased. Additionally or alternatively, when piezoelectric blowers are coupled to the pneumatic valve in series, pilot pressure may be increased as a function of the number of piezoelectric blowers in the series.

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: 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: Systems and methods for measuring a physiological parameter of tissue in a patient are provided herein, such as a system to optically analyze tissue of a patient. An example system includes a tissue interface assembly configured to emit an input optical signal into the tissue, receive a reference optical signal and a measurement optical signal from the tissue, and transfer the reference optical signal and the measurement optical signal to the optical link. The optical link is configured to transfer the reference optical signal and the measurement optical signal. The transceiver is configured to receive and convert the optical signals into digital signals.

Abstract: Medical sensors configured to provide enhanced patient comfort when worn over a period of time are provided. The medical sensors may include a first padding layer and a second padding layer disposed on either side of an emitter and a detector for measuring a physiological parameter of a patient. The medical sensors may also include an island padding layer secured to a patient-facing side of the second padding layer for reducing localized pressure points that may be caused by protrusions of the sensor. Additionally or alternatively, certain edges of the sensors may be rounded and/or stepped to reduce marking on the patient's tissue and to reduce strain and shear forces produced on the patient's tissue. Still further, certain embodiments provide enhanced light transmission between the emitter and detector of the sensors.

Abstract: Systems and methods for measuring a physiological parameter of tissue in a patient are provided herein. In a first example, tissue interface pad for applying optical signals to tissue of a patient is provided. The tissue interface pad includes a first surface configured to interface with the tissue of the patient and further includes a first guide channel disposed generally parallel to a second guide channel. The first guide channel is configured to route an input optical fiber to a first location and optically couple an end of the input optical fiber to the tissue at the first location. The second guide channel is configured to route an output optical fiber to a second location and optically couple an end of the output optical fiber to the tissue at the second location.