Abstract: Devices and methods for multi-parameter hemodynamic monitoring are provided. Determining a cardiac output of a patient using a cuff device includes measuring a cuff pressure waveform of a subject during inflation and/or deflation of the cuff device, computing systolic and diastolic blood pressure from the cuff pressure waveform using the cuff device, constructing a blood pressure waveform from the systolic and diastolic blood pressure and cuff pressure waveform using the cuff device, computing brachial artery compliance from the cuff pressure waveform, and computing the cardiac output from the blood pressure waveform and/or brachial artery compliance using the cuff device.

Abstract: Devices and methods for determining blood pressures are provided. In one example, a device for determining blood pressure of a subject includes a camera configured to measure a finger photo-plethysmography (PPG) waveform, an accelerometer configured to measure a vertical height of the device relative to a heart of a subject, an output device configured to guide the subject to raise a hand to vary the transmural pressure of an artery while maintaining a finger pressure on the camera, and a processor configured to compute pulse pressure of the subject from the finger PPG waveform and the vertical height, and display the pulse pressure on the screen.

Abstract: Current oscillometric devices for monitoring central blood pressure (BP) maintain the cuff pressure at a constant level to acquire a pulse volume plethysmography (PVP) waveform and calibrate it to brachial BP levels estimated with population average methods. A physiologic method was developed to further advance central BP measurement. A patient-specific method was applied to estimate brachial BP levels from a cuff pressure waveform obtained during conventional deflation via a nonlinear arterial compliance model. A physiologically-inspired method was then employed to extract the PVP waveform from the same waveform via ensemble averaging and calibrate it to the brachial BP levels. A method based on a wave reflection model was thereafter employed to define a variable transfer function, which was applied to the calibrated waveform to derive central BP.

Abstract: An aortic aneurysm carries increasing risk of rupture with growing aneurysm diameter. This condition is typically asymptomatic, so screening and surveillance are essential. Ultrasound and other imaging methods are employed for such monitoring at high accuracy. However, these methods require an expert and are expensive. Aortic aneurysms are considerably under-detected at present and may become even more under-detected in the future as the disease prevalence increases with societal aging. This disclosure present devices that are convenient in use and cost for aortic aneurysm screening and surveillance.

Abstract: A system and method is presented for cuff-less blood pressure measurement in a mobile device. A key aspect of this disclosure is the discovery of a new location for blood pressure measurement at the fingertip of a subject and that reflectance-mode photoplethysmography can be used to help make this measurement. Through experiments in human subjects, it was discovered that it is indeed possible to measure systemic blood pressure by having a subject press the fingertip against a reflectance-mode photo-plethysmography-force sensor unit under visual guidance and then compute blood pressure from the resulting variable-amplitude blood volume oscillations and applied pressure via an oscillometric algorithm.

Abstract: A method and apparatus for monitoring arterial properties, including systolic and diastolic pressure levels, of a subject is provided, in which a hardware processor receives and analyzes ballistocardiogram (BCG) data of the subject. A non-transient computer readable medium, accessible by the hardware processor, contains instructions that, when executed by the hardware processor, identify features of the BCG waveform and determine the arterial properties therefrom. For example, a diastolic pressure level may be determined from a time interval between the ‘I’ and ‘J’ peaks of the waveform and a systolic pressure level determined from the amplitude difference between the ‘J’ and ‘K’ peaks of the waveform in combination with the ‘I-J’ time interval or amplitude difference. A physical mechanism for the BCG data is disclosed that enables other arterial properties of the subject to be determined from the BCG data alone or from the BCG data in combination with other measurements.

Abstract: Most automatic cuff blood pressure (BP) measurement devices are based on oscillometry. These devices estimate BP from the envelopes of the cuff pressure oscillations using fixed ratios. The values of the fixed ratios represent population averages, so the devices may be accurate only in subjects with normal BP levels. A patient-specific oscillometric BP measurement method was developed. The idea was to represent the cuff pressure oscillation envelopes with a physiologic model and then estimate the patient-specific parameters of the model, which includes BP levels, by optimally fitting it to the envelopes.

Abstract: A system and method is presented for cuff-less blood pressure measurement in a mobile device. A key aspect of this disclosure is the discovery of a new location for blood pressure measurement at the fingertip of a subject and that reflectance-mode photoplethysmography can be used to help make this measurement. Through experiments in human subjects, it was discovered that it is indeed possible to measure systemic blood pressure by having a subject press the fingertip against a reflectance-mode photo-plethysmography-force sensor unit under visual guidance and then compute blood pressure from the resulting variable-amplitude blood volume oscillations and applied pressure via an oscillometric algorithm.

Abstract: A system and method is presented for cuff-less blood pressure measurement in a mobile device. A key aspect of this disclosure is the discovery of a new location for blood pressure measurement at the fingertip of a subject and that reflectance-mode photoplethysmography can be used to help make this measurement. Through experiments in human subjects, it was discovered that it is indeed possible to measure systemic blood pressure by having a subject press the fingertip against a reflectance-mode photo-plethysmography-force sensor unit under visual guidance and then compute blood pressure from the resulting variable-amplitude blood volume oscillations and applied pressure via an oscillometric algorithm.

Abstract: Various systems, techniques, and embodiments are disclosed for implementing a blood-pressure measurement method that does not require specialized equipment (such as inflatable blood pressure cuffs). The measurement can be taken from arterial locations within a user's finger, via the standard equipment and features of many widely-available consumer mobile devices. Such devices can be programmed to accurately and easily guide a user to press her finger on the screen of a device at a precise location, so that an accurate measurement can be taken. For example, guidance visualizations on a screen (such as finger silhouettes and animations) can be employed on the same screen on which a user presses her finger. Pressure sensitivity and optical camera readings are then used to calculate blood pressure for the user.

Abstract: A method is presented for predicting onset of pulmonary congestion symptoms. The overall idea is to track rising left ventricular filling pressure (LVFP) in heart failure patients by exploiting significant changes in a pulsatile arterial waveform obtained with a mobile device and thereby avert hospitalizations. The stimulus for the changes may be metronomic deep breathing performed by the patient or a natural occurring arrhythmia such as atrial fibrillation or premature beats. For either stimulus, the extent of the amplitude variations depends on where the patient is on the Starling curve. If the patient is on the steep part of the curve, the variations will be large and LVFP will be low. If the patient is on the flatter part of the curve, the variations will be smaller and LFVP will be higher. These variations can be normalized in various ways to arrive at a congestion prediction index (CPI).

Abstract: Current oscillometric devices for monitoring central blood pressure (BP) maintain the cuff pressure at a constant level to acquire a pulse volume plethysmography (PVP) waveform and calibrate it to brachial BP levels estimated with population average methods. A physiologic method was developed to further advance central BP measurement. A patient-specific method was applied to estimate brachial BP levels from a cuff pressure waveform obtained during conventional deflation via a nonlinear arterial compliance model. A physiologically-inspired method was then employed to extract the PVP waveform from the same waveform via ensemble averaging and calibrate it to the brachial BP levels. A method based on a wave reflection model was thereafter employed to define a variable transfer function, which was applied to the calibrated waveform to derive central BP.

Abstract: A system and method is presented for cuff-less blood pressure measurement in a mobile device. A key aspect of this disclosure is the discovery of a new location for blood pressure measurement at the fingertip of a subject and that reflectance-mode photoplethysmography can be used to help make this measurement. Through experiments in human subjects, it was discovered that it is indeed possible to measure systemic blood pressure by having a subject press the fingertip against a reflectance-mode photo-plethysmography-force sensor unit under visual guidance and then compute blood pressure from the resulting variable-amplitude blood volume oscillations and applied pressure via an oscillometric algorithm.

Abstract: Generalized transfer functions are available to mathematically derive the more relevant central blood pressure waveform from a more easily measured radial blood pressure waveform. However, these transfer functions are population averages and therefore may not adapt well to variations in pulse pressure amplification (ratio of radial to central pulse pressure). An adaptive transfer function was developed. First, the transfer function is represented in terms of the wave travel time and wave reflection coefficient parameters of an arterial model. Then, the model parameters are estimated from only the radial blood pressure waveform by exploiting the frequent observation that central blood pressure waveforms exhibit exponential diastolic decays.

Abstract: A method is provided for determining pulse transit time of a subject as a function of blood pressure. The method includes: measuring a proximal waveform indicative of the arterial pulse at a proximal site of the subject; measuring a distal waveform indicative of the arterial pulse at a distal site of the subject; defining a relationship between the proximal waveform and the distal waveform in terms of unknown parameters of a nonlinear model; determining the unknown parameters of the nonlinear model from the measured proximal waveform and the measured distal waveform; and determining pulse transit time for the subject as a function of blood pressure from the parameters of the nonlinear model. The nonlinear model can account for arterial compliance and peripheral wave reflection, where the arterial compliance depends on blood pressure.

Abstract: A system and method is presented for cuff-less blood pressure measurement in a mobile device. A key aspect of this disclosure is the discovery of a new location for blood pressure measurement at the fingertip of a subject and that reflectance-mode photoplethysmography can be used to help make this measurement. Through experiments in human subjects, it was discovered that it is indeed possible to measure systemic blood pressure by having a subject press the fingertip against a reflectance-mode photo-plethysmography-force sensor unit under visual guidance and then compute blood pressure from the resulting variable-amplitude blood volume oscillations and applied pressure via an oscillometric algorithm.

Abstract: Methods are presented for determining pulse transit time (PTT) and/or pulse wave velocity (PWV) of a subject by application of parametric system identification to proximal and distal arterial waveforms. The two waveforms are measured from the subject. A system is defined that relates the proximal arterial waveform to the distal arterial waveform (or vice versa) in terms of the unknown parameters of a parametric mathematical model. The model parameters are determined from the measured waveforms using system identification. PTT between the proximal and distal arterial sites is then determined from the system model. PWV may also be determined by dividing the distance between measurement sites (D) by PTT.

Abstract: A method is provided for determining a central aortic pressure (AP) wave-form for a subject. The method includes measuring a peripheral artery pressure (PAP) waveform from the subject, employing a distributed model to define a pressure-to-pressure transfer function relating PAP to AP and a pressure-to-flow transfer function relating PAP to a central arterial flow in terms of the same unknown parameters, estimating the unknown parameters by finding the pressure-to-flow transfer function, which when applied to the measured PAP waveform, minimizes the magnitude of the central arterial flow waveform during diastole, and applying the pressure-to-pressure transfer function with the estimated parameters to determine an AP waveform for the subject.

Abstract: A method is provided for determining blood pressure for a subject using a sphygmomanometer. The method includes: measuring an oscillometric cuff pressure waveform of the subject using the sphygmomanometer; representing the measured waveform with a physical model accounting for mechanics of the cuff, an artery and coupling between the cuff and the artery; determining the model unknowns from the measured waveform; and determining blood pressure for the subject using the determined model.

Abstract: A system and method is presented for cuff-less blood pressure measurement in a mobile device. A key aspect of this disclosure is the discovery of a new location for blood pressure measurement at the fingertip of a subject and that reflectance-mode photoplethysmography can be used to help make this measurement. Through experiments in human subjects, it was discovered that it is indeed possible to measure systemic blood pressure by having a subject press the fingertip against a reflectance-mode photo-plethysmography-force sensor unit under visual guidance and then compute blood pressure from the resulting variable-amplitude blood volume oscillations and applied pressure via an oscillometric algorithm.