130 results about "Vascular resistance" patented technology

A long-term implantable arterio-venous shunt device or creation of a fistula is provided that can be used as a therapeutic method for treating chronic obstructive pulmonary disease (COPD). The shunt device is implanted between an artery and a vein, preferably between a peripheral artery and the inferior vena cava. The shunt device and method of creating a fistula increases cardiac output and decreases the systemic vascular resistance and allows a blood flow rate through the shunt device of at least 5 ml / min after the implantation. Based on the effects of the method and device to the respiratory, cardiac and circulatory system, the method and device are beneficial as a therapy to patients with problems or conditions related to these systems.

One or more cardiovascular parameters is estimated as a function of the arterial pressure waveform, in particular, using at least one statistical moment of pressure waveform having an order greater than one. Arterial compliance, the exponential pressure decay constant, vascular resistance, cardiac output, and stroke volume are examples of cardiovascular parameters that can be estimated using various aspects of the invention. In one embodiment of the invention, not only are the first four moments (mean, standard deviation, skewness, and kurtosis) of the pressure waveform used to estimate the cardiovascular parameter(s) of interest, but also heart rate, statistical moments of a set of pressure-weighted time values, and certain anthropometric patient measurements such as age, sex, body surface area, etc.

A non-invasive device for evaluating circulatory state parameters, and specifically, a pulsewave analysis device capable of evaluation by separating blood vessel compliance and blood vessel resistance into central and peripheral components of the arterial system is provided. Microcomputer 4 detects the waveform at a test subject's radius artery via pulsewave detector 1, and uptakes the stroke volume in the test subject which is measured by a stroke-volume measurer. Next, based on the measured stroke volume, microcomputer 4 adjusts the values of each element in a lumped five parameter model made up of an electrical circuit which models the arterial system from the center to the periphery of the body, so that the response waveform obtained when an electric signal corresponding to the pressure waveform at the proximal portion of the aorta in a test subject is provided to the electric circuit coincides with the waveform at the radius artery. Microcomputer 4 then outputs the thus-obtained values of each element as circulatory state parameters. In addition, microcomputer 4 calculates the diastolic pressure value, systolic pressure value and pulse waveform at the proximal portion of the aorta from the values of each element, and outputs the calculated result to output device 6.

A method for determining haemodynamic performance in a human or animal subject comprises receiving at a processor data representing haemodynamic variables measured from the subject over time. The haemodynamic variables comprise at least two of Systemic Perfusion Pressure (SPP), Systemic Vascular Resistance (SVR), Cardiac Output (CO), Heart Rate (HR) and Stroke Volume (SV). The data are processed to produce a display signal for causing a display device to present a visual mapping relating the haemodynamic variables according to the relationship SPP=CO H SVR and the visual mapping is displayed on a display device. The visual mapping may be corrected Heart Rate (HR) or include a second mapping which facilitates an adjustment to take account of HR.

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.

Method and apparatus are introduced for determining proportional cardiac output (CO), absolute left atrial pressure (LAP), and / or other important hemodynamic variables from a contour of a circulatory pressure waveform or related signal. Certain embodiments of the invention provided herein include the mathematical analysis of a pulmonary artery pressure (PAP) waveform or a right ventricular pressure (RVP) waveform in order to determine beat-to-beat or time-averaged proportional CO, proportional pulmonary vascular resistance (PVR), and / or LAP. The invention permits continuous and automatic monitoring of critical hemodynamic variables with a level of invasiveness suitable for routine clinical application. The invention may be utilized, for example, to continuously monitor critically ill patients with pulmonary artery catheters installed and chronically monitor heart failure patients instrumented with implanted devices for measuring RVP.

A method and apparatus of automatically locating in an image of a blood vessel the lumen boundary at a position in the vessel and from that measuring the diameter of the vessel. From the diameter of the vessel and estimate blood flow rate, a number of clinically significant physiological parameters are then determine and various user displays of interest generated. One use of these images and parameters is to aid the clinician in the placement of a stent. The system, in one embodiment, uses these measurements to allow the clinician to simulate the placement of a stent and to determine the effect of the placement. In addition, from these patient parameters various patient treatments are then performed.

An arterially measured pressure signal is continuously read in and temporarily stored in the working memory (RAM). The function p(t) is processed by the central processing unit (CPU), to calculate the heart / time volume PCCO and other hemodynamic parameters. The calculation comprises the following steps: The systemic vascular resistance SVRk is calculated for the current pulse period. The stroke volume SVk is numerically determined from the pressure values of a pulse period, according to the following equation:SVk∝∑(pi⁡(t)SVRk+Ck⁡(pi)⁢ⅆpiⅆt)with the compliance C(p)=(MAP−CVP)k / [SVR·<dp / dt>k]·ƒ(p). The difference between the mean arterial pressure MAP and the central venous pressure CVP, and the mean incline of the pressure curve in the diastole <dp / dt>, are re-determined for the current pulse period. The heart / time volume calculated in the current pulse period results from PCCOk=SVk·HR. Therefore, continuous recalibration of the systemic vascular resistance and of the compliance takes place, from the continuously determined pressure measurement data.

The invention relates to a method for determining a cardiovascular performance reserve for each individual patient, comprising the steps of: a) receiving input physiological data from the patient for obtaining a parameter Z which is or approximates the product of the Stroke Volume (SV) by the Systemic Vascular Resistance (SVR); b) providing a value representing the Respiratory Rate (RR) of said patient, wherein the Respiratory Rate (RR) value is provided by measurements using dedicated device(s), calculations from the input physiological data or manually by using best estimate; c) providing anthropometric data of said patient for calculating the Body Surface Area (BSA) of said individual, wherein the anthropometric data includes at least body dimensions (such as height and weight) of said patient; d) calculating the Cardiovascular Reserve (CVR) by using said Z parameter and said RR according to following formula: CVR=(Z / RR); e) calculating a Cardiovascular Reserve Index (CVRI) by standardizing said CVR (by said BSA) and normalizing it to a scale of 1 according to the following formula: CVRI=CVR / (BSA*4); and outputting said Cardiovascular Reserve Index.