76 results about "Peripheral resistance" patented technology

The present invention provides methods and apparatus for determining a dynamical property of the systemic or pulmonary arterial tree using long time scale information, i.e., information obtained from measurements over time scales greater than a single cardiac cycle. In one aspect, the invention provides a method and apparatus for monitoring cardiac output (CO) from a single blood pressure signal measurement obtained at any site in the systemic or pulmonary arterial tree or from any related measurement including, for example, fingertip photoplethysmography.According to the method the time constant of the arterial tree, defined to be the product of the total peripheral resistance (TPR) and the nearly constant arterial compliance, is determined by analyzing the long time scale variations (greater than a single cardiac cycle) in any of these blood pressure signals. Then, according to Ohm's law, a value proportional to CO may be determined from the ratio of the blood pressure signal to the estimated time constant. The proportional CO values derived from this method may be calibrated to absolute CO, if desired, with a single, absolute measure of CO (e.g., thermodilution). The present invention may be applied to invasive radial arterial blood pressure or pulmonary arterial blood pressure signals which are routinely measured in intensive care units and surgical suites or to noninvasively measured peripheral arterial blood pressure signals or related noninvasively measured signals in order to facilitate the clinical monitoring of CO as well as TPR.

Systems and methods using a database of physiological information for the design, development, testing and use of therapeutics. In one aspect, the physiological information can include at least one of: hemodynamic monitoring information, pulmonary arterial pressure, cardiac output, heart rate, respiratory rate, peripheral vascular resistance, total peripheral resistance or dicrotic notch information. Optionally, the cardiovascular physiology information can include ambulatory physiological information.

Provided is a mounting table structure (60) on which an object (W) to be treated is mounted in order to be heat-treated in a treatment container and which heats the mounted object to be treated. Outermost peripheral feed lines (L1-L4) are connected to a plurality of positions different in the circumferential direction of an outermost peripheral resistance heating heater (100) for heating an outermost peripheral heating zone (96) of a mounting table body (62), thereby dividing the outermost peripheral resistance heating heater (100) into a plurality of heater sections (100A-100D). A heater control unit (92) can individually control electrical states (for example, voltage application states, zero potential states, and floating states) of the respective outermost peripheral feed lines. The power supply state of each of the heater sections can be changed by a simple configuration.

A cardiovascular parameter such as cardiac output is estimated from a current pressure waveform data set without needing to directly measure blood flow or arterial compliance. The general shape of an input flow waveform over one beat-to-beat cycle is assumed (or computed), and then the parameters of a flow-to-pressure model, if not pre-determined, are determined using system identification techniques. In one embodiment, the parameters thus determined are used to estimate a current peripheral resistance, which is used not only to compute an estimate of the cardiovascular parameter, but also to adjust the shape of the input flow waveform assumed during at least one subsequent beat-to-beat cycle. Another embodiment does not require computation of the peripheral resistance and still another embodiment computes a flow estimate from an optimized identification of the parameters defining the assumed input flow waveform.

The methods and systems for estimating cardiac output and total peripheral resistance include observing arterial blood pressure waveforms to determine intra-beat and inter-beat variability in arterial blood pressure and estimating from the variability a time constant for a lumped parameter beat-to-beat averaged Windkessel model of the arterial tree. Uncalibrated cardiac output and uncalibrated total peripheral resistance may then be calculated from the time constant. Calibrated cardiac output and calibrated total peripheral resistance may be computed using calibration data, assuming an arterial compliance that is either constant or dependent on mean arterial blood pressure. The parameters of the arterial compliance may be estimated in a least-squares manner.

Systems and methods for prediction and detection of circulatory shock using estimates or measurements of arterial blood pressure, heart rate, stroke volume, cardiac output, total peripheral resistance, cardiac ejection fraction, cardiac contractility and ventricular end-diastolic volume are provided. These estimates and measurements are used to determine a type of circulatory shock. In some embodiments, the type of circulatory shock is determined to be one of septic shock, hypovolemic shock, anaphylactic shock, hemorrhagic shock, and cardiogenic shock.

The methods and systems for estimating cardiac output and total peripheral resistance include observing arterial blood pressure waveforms to determine intra-beat and inter-beat variability in arterial blood pressure and estimating from the variability a time constant for a lumped parameter beat-to-beat averaged Windkessel model of the arterial tree. Uncalibrated cardiac output and uncalibrated total peripheral resistance may then be calculated from the time constant. Calibrated cardiac output and calibrated total peripheral resistance may be computed using calibration data, assuming an arterial compliance that is either constant or dependent on mean arterial blood pressure. The parameters of the arterial compliance may be estimated in a least-squares manner.

A hydraulic model of the cardiovascular system for illustrating a plurality of physiological concepts and relationships including arterial compliance, venous compliance, and peripheral resistance, said model comprising: a.) a cardiac subsystem for moving a fluid in a singular direction in a closed hydraulic system; b.) an arterial subsystem for modeling arterial compliance, the arterial subsystem fluidically coupled with the cardiac subsystem to receive the fluid discharged from the cardiac subsystem; c.) a peripheral resistance subsystem for modeling peripheral resistance, the peripheral resistance subsystem fluidically coupled with the arterial subsystem to receive the fluid discharged from arterial subsystem; d.) a peripheral venous (PV) subsystem for modeling peripheral venous compliance and for modeling a peripheral venous pump (PVP), the peripheral venous subsystem fluidically coupled with the peripheral resistance subsystem to receive the fluid discharged from the at least one downstream conduit; and e.) a central venous (CV) subsystem for modeling central venous compliance and for modeling a thoracic pump (TP), the CV subsystem fluidically coupled with the PV subsystem to receive the fluid discharged from the PV subsystem and to pass the fluid to the cardiac subsystem to complete the cardiovascular cycle.