239 results about "Pressure waveform" patented technology

A method and apparatus for continuous measurement of blood pressure, based on pulse transit time, which does not require any external calibration. This technique, referred to herein as the ‘composite technique’, is carried out with a body-won sensor that measures blood pressure and other vital signs, and wirelessly transmits them to a remote monitor. A network of disposable sensors, typically placed on the patient's right arm and chest, connect to the body sensor and measure a time-dependent electrical waveform, optical waveform, and pressure waveform. The disposable sensors typically include an armband that features an inflatable bladder coupled to a pressure sensor, at least 3 electrical sensors (e.g. electrodes), and an optical sensor (e.g., a light source and photodiode) attached to a wrist-worn band.

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 method and apparatus for determining the fluid permeability of an earth formation is described. An instrument comprising an acoustic source and acoustic and electrokinetic sensors is located in a borehole at a site of interest. The acoustic source is fired and the resulting variations in pressure and electric field generated are measured and recorded. The Biot equation, and an equation for the streaming potential coupled to fluid displacement terms, is solved using finite element analysis to give an expected pressure waveform and electrokinetic waveform based on estimated earth formation properties. By comparison of the measured waveforms and those calculated from the equations, the actual permeability of the earth formation can be deduced.

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.

An improved ventilator which delivers ventilatory support that is synchronized with the phase of the patients respiratory efforts and guarantees a targeted minimum ventilation. Improved synchronization is achieved through an instantaneous respiratory phase determination process based upon measured respiratory airflow as well as measured respiratory effort using an effort sensor accessory, preferably a suprasternal notch sensor. The ventilator processes a respiratory airflow signal, a respiratory effort signal and their respective rates of change to determine a phase using standard fuzzy logic methods. A calculated pressure amplitude is adjusted based upon the calculated phase and a smooth pressure waveform template to deliver synchronized ventilation.

Systems and methods are provided for monitoring changes in blood volume using waveforms in the peripheral vasculature. In particular, the systems and methods relate to detecting ventilation-induced variation (VIV) of waveforms in the peripheral vasculature. Advantageously, the systems and methods may relate to analyzing VIV in peripheral venous pressure (PVP). Thus, the VIV of PVP may be measured, wherein decreased VIV is indicative of decreased blood volume In exemplary embodiments, such as involving spontaneous breathing, it may be necessary to account for changes in respiratory signal strength. Thus systems and methods are also provided for assessing coherence between ventilation and VIV for a flow or pressure waveform. Specifically, coherence is evaluated by comparing the waveform to a detected respiratory signal. Finally, systems and method are provided for distinguishing the impact of respiration on the PG signal during hypervolemia as compared to hypovolemia. Such systems and methods may advantageously be utilized to monitor fluid status during fluid replacement.

The invention relates to a brain vascular blood circulation dynamic analysis method and the apparatus thereof. According to the cerebral circulation vascular bed anatomical model, an equivalent network model which comprises 12 pipeline units simulating the brain circulation blood dynamics is built, and the relevant parameter calculation formulas are confirmed, by utilizing the formulas, the flow rate waveform and the value inside the cartid artery, the pressure waveform, the blood pressure of the body, the diameter of the blood vessel, the flow rate waveform and the valve of the vertebral artery and the front, the middle and the rear parts on two sides inside the skull, and the characteristic and the parameter of the cartid artery and each blood vessel section inside the skull can be determined, the apparatus designed by the invention can be performed, the detecting system comprises the vessel diameter detecting of the cartid artery outside the skull, the blood pressure detecting, theblood flow rate detecting of the cartid artery outside the skull, the pressure waveform detecting of the cartid artery outside the skull, and the blood flow rate detecting on the artery inside the skull; the control system comprises a control module and a power supply module; the calculation and analysis system comprises a host computer, a peripheral equipment, and an analog-digital converter, the invention can fully analyze the brain circulation dynamic characteristic, thereby having notable effect on the early stage and the ultra early stage diagnosis and therapy of the brain vascular illness.

A neuromuscular monitoring system comprises at least one neurostimulator to apply muscle-activating stimulation signals to a patient's body via at least one electrode, and at least one pressure waveform sensor to detect pressure waveform signals produced by a patient's muscle in response to the applied stimulation signals. The detected pressure waveform signals are processed and data related to these detected pressure waveform signals are displayed. A method for neuromuscular monitoring using pressure waveform sensors is also described.

A fuel injection device includes a fuel injection valve for injecting fuel, which is distributed from a pressure-accumulation vessel. A pressure sensor is located in a fuel passage, which extends from the pressure-accumulation vessel to a nozzle hole, and configured to detect pressure of the fuel. The pressure sensor is located closer to the nozzle hole than the pressure-accumulation vessel. A storage unit stores individual difference information, which indicates an injection characteristic of the fuel injection valve, the injection characteristic being obtained by an examination. The individual difference information is related to a fluctuation pattern of a portion of the fluctuation in detected pressure waveform of the pressure sensor. The fluctuation is attributed to one fuel injection through the nozzle hole. The portion of the fluctuation is subsequent to an end of the fuel injection.

A method is provided for detecting filter clogging which are able to keep track of the filter clogging with precision and in detail. At least one pressure selected from the group consisting of a pressure Pa in a blood inflow portion (32a), a pressure Pv in a blood outflow portion (32b), a pressure Pf1 in a filtrate inflow portion (32c), and a pressure Pf2 in a filtrate outflow portion (32d) is measured continuously, then a variation (pressure waveform) of the pressure is analyzed, a clogging of a filter (32) is detected using the analyzed result. Thereby a clogging of a filter is detected early. As a result, it is possible to prevent from developing of the filter clogging by controlling a dosage amount of anti-coagulant properly and changing a flow rate of blood. The variation of the pressure wave may be analyzed by subjecting the variable to Fast Fourier Transform.

The methods and systems for estimating cardiac ejection fraction, cardiac contractility, and ventricular end-diastolic volume on a beat-by-beat basis include observing arterial blood pressure waveforms to determine ventricular compliances for a pressure-volume loop in the ventricle. Uncalibrated or calibrated cardiac ejection fraction may be calculated from estimates of stroke volume and the ventricular compliances. Cardiac contractility may be calculated from estimates of a ventricular compliance. Uncalibrated or calibrated ventricular end-diastolic volume may also be calculated from estimates of stroke volume and the ventricular compliances. A set of calibration parameters for calibrating cardiac ejection fraction or ventricular end-diastolic volume may be estimated in a least-squares manner.

A technique is provided for computing or monitoring blood viscosity. The technique includes measuring a cross sectional area of a arterial segment and a volumetric flow rate of blood flowing through the arterial segment at two or more locations, estimating a compliance transfer function from blood measurements to scale the arterial cross sectional area into a pressure waveform, deriving a transmission line model of the arterial segment based on the cross sectional area, as scaled by the compliance transfer function, of the arterial segment at the two or more locations and the volumetric flow rate of blood at the two or more locations. The technique also includes computing the blood viscosity based on the transmission line model.

A pump supplies pressurized air to inflate compression garments, mattresses, cushions, or similar at the desired times and to desired pressures appropriate to the therapy. The garments are each identified by small steps generated in the pressure waveform during inflation, with the identifying means including a flat sheet valve in the connector chamber having vents to atmosphere and being situated along the flow path from the pump to the garment(s). As the air flows through the connection tubing and through the connector a pressure wave is generated by the valve and fed back upstream to a pressure sensor in the pump. The shape of the pressure waveform identifies a particular compression garment, the pump supplying the appropriate inflation regime upon detection of this pressure waveform.