An system for calculating blood pressure may include a sensor system and a control system. The control system may be capable of controlling one or more sensors of the sensor system to take at least two measurements, the at least two measurements including at least one measurement taken at each of two or more different measurement elevations of a subject's limb. In some examples, the control system may be capable of determining a blood flow difference based on the at least two measurements, of determining a hydrostatic pressure difference based on the two or more different elevations of the at least two measurements and of estimating a blood pressure based on one or more values of blood flow, the hydrostatic pressure difference and the blood flow difference.

Disclosed are devices and methods for estimating blood pressure, which implement a pulse-transit-time-based blood pressure model that can be calibrated. Some implementations provide reliable and user friendly means for calibrating the blood pressure model using blood pressure perturbation methods and multiple sensors.

Embodiments of the present invention address the limitations of current central venous pressure monitoring by providing a noninvasive, non-implanted, and self-administered test for the determination of central venous pressure. Some embodiments use alterations in transmural pressure, optical measurements of venous volume, and anatomical measurements to determine central venous pressure. The system can provide an absolute measurement of central pressure and can be used to monitor relative changes in central venous pressure over time. Changes in transmural pressure are used to create detectable changes in peripheral venous vascular volume for central venous pressure measurement.

Disclosed are devices and methods for estimating blood pressure, which implement a pulse-transit-time-based blood pressure model that can be calibrated. Some implementations provide reliable and user friendly means for calibrating the blood pressure model using blood pressure perturbation methods and multiple sensors.

The invention provides a system and method for measuring vital signs and motion from a patient. The system features: (i) first and second sensors configured to independently generate time-dependent waveforms indicative of one or more contractile properties of the patient's heart; and (ii) at least three motion-detecting sensors positioned on the forearm, upper arm, and a body location other than the forearm or upper arm of the patient. Each motion-detecting sensor generates at least one time-dependent motion waveform indicative of motion of the location on the patient's body to which it is affixed. A processing component, typically worn on the patient's body and featuring a microprocessor, receives the time-dependent waveforms generated by the different sensors and processes them to determine: (i) a pulse transit time calculated using a time difference between features in two separate time-dependent waveforms, (ii) a blood pressure value calculated from the time difference, and (iii) a motion parameter calculated from at least one motion waveform.

Systems and methods for correcting sensed hemodynamic data are provided. Sensed hemodynamic data can be affected by hydrostatic forces and thus a correction is applied based on vertical position of where the site of sensing is being performed. The correction can be a computationally determined.

One embodiment provides an offset calibration circuitry configured to compensate an offset voltage of a resistive bridge sensor. The offset calibration circuitry includes a first current digital to analog converter (IDAC) coupled to a first successive approximation register (SAR), a second IDAC coupled to a second SAR and an SAR controller circuitry. The first IDAC is configured to couple to a negative voltage port of a resistive bridge sensor. The first SAR is configured to store a first digital value. The second IDAC is configured to couple to a positive voltage port of the resistive bridge sensor. The second SAR is configured to store a second digital value. The SAR controller circuitry is configured to adjust each bit of the first SAR and each bit of the second SAR based, at least in part, on an output of a comparator. The comparator is configured to compare a voltage on the negative voltage port or a voltage on the positive voltage port to a common mode voltage.

The present disclosure relates to a method and corresponding system for a non-invasive determination of a physiological parameter, the method (400) comprising: applying (410) a first pressure cuff (150) to a limb of a living subject, in particular of a human being; applying (420) a second pressure cuff (104) distally to the first pressure cuff (150) to the limb of the subject; inflating (430) the first pressure cuff (150) to a pressure value exceeding a first threshold value; monitoring (440) a pressure signal of the second pressure cuff (104) after the step of inflating the first pressure cuff (150); deriving (450) a measure indicative of mean systemic filling pressure, MSFP, from the monitored pressure signal of the second pressure cuff (104).