383 results about "Blood velocity" patented technology

Methods and systems for long term monitoring of one or more physiological parameters such as respiration, heart rate, body temperature, electrical heart activity, blood oxygenation, blood flow velocity, blood pressure, intracranial pressure, the presence of emboli in the blood stream and electrical brain activity are provided. Data is acquired non-invasively using ambulatory data acquisition techniques.

New devices and methods are provided for noninvasive and noncontact real-time measurements of tissue blood velocity. The invention uses a digital imaging device such as a detector array that allows independent intensity measurements at each pixel to capture images of laser speckle patterns on any surfaces, such as tissue surfaces. The laser speckle is generated by illuminating the surface of interest with an expanded beam from a laser source such as a laser diode or a HeNe laser as long as the detector can detect that particular laser radiation. Digitized speckle images are analyzed using new algorithms for tissue optics and blood optics employing multiple scattering analysis and laser Doppler velocimetry analysis. The resultant two-dimensional images can be displayed on a color monitor and superimposed on images of the tissues.

A method and apparatus for determining the mean arterial blood pressure (MAP) of a subject during tonometric conditions. In one embodiment, the apparatus comprises one or more pressure and ultrasound transducers placed over the radial artery of a human subject's wrist, the latter transmitting and receiving acoustic energy so as to permit the measurement of blood velocity during periods of variable compression of the artery. In another aspect of the invention, a wrist brace useful for measuring blood pressure using the aforementioned apparatus is disclosed. In yet another aspect of the invention, backscattered acoustic energy is used to identify the location of the blood vessel of interest, and optionally control the position of measurement or treatment equipment with respect thereto.

A method, system and device for measurement of a blood constituent level, including a light source, a light detector proximate an organ surface, adjustable gain amplifiers, and a processor / controller connected within a processing unit operative to separate AC and DC signal components. The device may determine the level of blood constituent, may use this level for monitoring and / or to activate an alarm when the level falls outside a predetermined range, may be applied to monitoring conditions of apnea, respiratory stress, and reduced blood flow in organ regions, heart rate, jaundice, and blood flow velocity, and may be incorporated within a monitoring system.

Provided herein is a method for use in medical applications that permits (1) affordable three-dimensional imaging of blood flow using a low-profile easily-attached transducer pad, (2) real-time blood-flow vector velocity, and (3) long-term unattended Doppler-ultrasound monitoring in spite of motion of the patient or pad. The pad and associated processor collects and Doppler processes ultrasound blood velocity data in a three dimensional region through the use of a planar phased array of piezoelectric elements. The invention locks onto and tracks the points in three-dimensional space that produce the locally maximum blood velocity signals. The integrated coordinates of points acquired by the accurate tracking process is used to form a three-dimensional map of blood vessels and provide a display that can be used to select multiple points of interest for expanded data collection and for long term continuous and unattended blood flow monitoring. The three dimensional map allows for the calculation of vector velocity from measured radial Doppler.A thinned array (greater than half-wavelength element spacing of the transducer array) is used to make a device of the present invention inexpensive and allow the pad to have a low profile (fewer connecting cables for a given spatial resolution). The full aperture is used for transmit and receive so that there is no loss of sensitivity (signal-to-noise ratio) or dynamic range. Utilizing more elements (extending the physical array) without increasing the number of active elements increases the angular field of view. A further increase is obtained by utilizing a convex non-planar surface.

The present invention provides a method for monitoring long-term potentiation and long-term depression, comprising placing a subject in head down rest position and monitoring in real-time cerebral mean blood flow velocity using a transcranial Doppler device during psychophysiologic tasks. The method involves using Fourier analysis of mean blood flow velocity data to derive spectral density peaks of cortical and subcortical processes. The effect of head-down rest at different time intervals is seen as accentuation of the cortical peaks in long-term potentiation and attenuation of subcortical peaks in long-term depression. The effect of different interventions could be evaluated for research, diagnosis, rehabilitation and therapeutic use.

Provided herein is a method for use in medical applications that permits affordable three-dimensional imaging of blood flow using a low-profile easily-attached transducer pad, real-time blood-flow vector velocity, and long-term unattended Doppler-ultrasound monitoring in spite of motion of the patient or pad. The pad and associated processor collects and Doppler processes ultrasound blood velocity data in a three dimensional region through the use of a planar phased array of piezoelectric elements. The invention locks onto and tracks the points in three-dimensional space that produce the locally maximum blood velocity signals. The integrated coordinates of points acquired by the accurate tracking process is used to form a three-dimensional map of blood vessels and provide a display that can be used to select multiple points of interest for expanded data collection and for long term continuous and unattended blood flow monitoring. The three dimensional map allows for the calculation of vector velocity from measured radial Doppler.

The invention relates to clinical cardiology and cardiovascular surgery. The method for forming a blood flow in research stands and in surgically reconstructed segments of the blood circulation system comprises diagnosing the individual condition of a patient's blood circulation system; measuring the blood flow velocity field in the heart chambers and great vessels; comparing the parameters measured against the physiological norm; determining parameters forming a swirled blood flow; and modeling an individual swirled blood current in the blood circulation system being diagnosed, the streamlined surfaces and guide elements of flow channels of the blood circulation system reconstructed being given shapes conforming to the flow lines of the restored normally swirled blood flow in accordance with formulas:Q(t)=[z+Z0(t)]2(1.1)ϕ=ϕ0+k(t)z(1.2)k(t)=Γ0(t) / 4πQ(t)C0(t)Vz=2C0(t)zVr=-C0(t)rVϕ=Γ0(t)2πr{1-exp[-C0(t)r22v]}(1.3)wherein: Vr, Vz, and Vφ are the radial, longitudinal, and tangential velocities of the swirled current; v is the kinematic viscosity of the medium; φ0 is the initial swirling angle in relation to the flow axis normal; φ, z and r are current values of the angular, longitudinal, and radial coordinates along the flow line; and Q(t), Z0(t), k(t), Γ0(t), and C0(t) are parameters of the swirled blood flow variable over time because of the non-stationary current and corresponding to the individual normal indicators for a physiologically swirled blood flow. The normal indicators are established by routine examination of a representative sample of patients having no changes in the cardiovascular system. A vessel prosthesis comprises a tube having an internal surface in contact with the blood flow provided with a pattern to swirl the blood flow in accordance with formulas (1.1 to 1.3) conforming to a specific localization of the segment being reconstructed. A cannula for para-corporeal perfusion devices comprises a flow channel having an internal surface that is provided with a longitudinal pattern to swirl the blood flow, the shape of the pattern being determined from formulas (1.1 to 1.3), relative to the specific localization of the point where the cannula is inserted into the vessel channel. A heart valve prosthesis comprises one or more shutoff elements arranged symmetrically in the center of a body of round and / or oval cross-section, the streamlined surfaces of the valve being provided with a pattern in accordance with formulas (1.1 to 1.3). A blood pump comprises a flow swirling unit, a flow channel, and valves at the inlet and outlet of the channel, the surface washed over by blood being provided with a relief variable over time in accordance with formulas (1.1 to 1.3). A swirling device comprises an end piece having a streamlined surface provided with guides in the form of ribs, grooves, or blades of a shape defined by formulas (1.1 to 1.3), the swirling angle of the guides relative to the flow axis being varied optionally an operator or by a special-purpose device for modeling different current conditions.

The present invention provides an apparatus and methods for continuous intravascular measurement of whole blood concentration, blood pressure, and pulse pressure. The intravascular catheter incorporates a sensor to measure whole blood sound velocity, attenuation, backscatter amplitude, and blood flow velocity and also incorporates existing technologies for multiple physiologic measurements of whole blood. Pulse wave velocity and wave intensity are derived mathematically for purposes of estimating degree of local vascular tone.

In the apparatus and method for monitoring a vascular access (6) of an extracorporeal circuit (5; 10) of a patient, a control and calculation unit (17) varies a flow rate of a blood pump (9) predisposed to cause blood to circulate in the extracorporeal circuit. The control and calculation unit receives-the pressure values in the blood withdrawal line (5) and the blood return line (10) from two pressure sensors (8, 12); the pressure values are a series of different values of the blood flow rate. The control and calculation unit processes the data gathered by means of a mathematical model which describes the variation of pressure in the vascular access as a function of the flow rate, in order to determine the blood flow rate in the vascular access. The invention detects the presence and location of a stenosis at the vascular access of a patient subjected to a hemodialysis treatment.

The invention provides analysis algorithms for quantitative assessment of microvasculatory video sequences that provide vessel thickness, vessel length and blood velocity per vessel segment. It further provides a method of for calculating the functional microvasculatory density and blood velocity as distributed over vessels with different thickness, in the field of view.

Apparatus for helmeting with carotid collars works in conjunction with a transcranial Doppler, phased array photoacoustic device to transmit a first energy to a region of interest at an internal site of a subject to produce an image and blood flow velocities of a region of interest by outputting an optical excitation energy to said region of interest and heating said region, causing a transient thermoelastic expansion and produce a wideband ultrasonic emission. Systems integrate and register the signals for use in, for example, acute stroke care.

A pulse Doppler ultrasound system and associated methods are described for monitoring blood flow. A graphical information display includes simultaneously displayed depth-mode and spectrogram displays. The depth-mode display indicates the various positions along the ultrasound beam axis at which blood flow is detected. These positions are indicated as one or more colored regions, with the color indicating direction of blood flow and varying in intensity as a function of detected Doppler ultrasound signal amplitude or detected blood flow velocity. The depth-mode display also includes a pointer whose position may be selected by a user. The spectrogram displayed corresponds to the location identified by the pointer. Embolus detection and characterization are also provided.

A blood pump including a ultrasonic sensor mounted in or on a blood contacting surface of said blood pump. The ultrasonic sensor measures blood velocity and reports information to a blood pump controller and wherein the ultrasonic sensor is directed to measure blood velocity in an inflow cannula connected to the blood pump.

Methods and compositions are disclosed to quantitatively measure in vivo blood vessel diameter, blood velocity, and other flow dynamics. Such methods and compositions can optimize therapeutic interventions designed to prevent or reduce the risk of cardiovascular and blood disorders. In one aspect, the methods and apparatus involve calculating blood vessel characteristics from a two dimensional image of a blood vessel in the conjunctiva of a subject's eye. In another aspect, a series of temporal images of a blood vessel are obtained to determine blood flow properties. The apparatus can include, for example, a biomicroscope, an illuminating light source and a high speed camera to acquire the series of temporal images with the data then analyzed by a programmed processor.

What is disclosed is a system and method for determining an arterial pulse transit time of a subject of interest in a remote sensing environment. A video imaging system is used to capture a time varying source images of a proximal and distal region of a subject intended to be analyzed for arterial pulse transit time. A time series signal for each of the proximal and distal regions is extracted from the source images and a phase of each of the extracted time series signals is computed. A difference is then computed between these phases. This phase difference is a monotonic function of frequencies in the signals. From the monotonic function, an arterial pulse transit time of the subject is extracted. The subject's arterial pulse transit time is then communicated to a computer system. The computer system determines blood pressure, blood vessel blockage, blood flow velocity, or a peripheral neuropathy.

In embodiments of the invention, there is provided a dialyzer or filter comprising hollow fibers, in which blood flows on the exterior of the hollow fibers, and dialysate or filtrate may flow on the inside. The external surfaces of the hollow fibers may have properties of smoothness and hemocompatibility. The fiber bundle may have appropriate packing fraction and may have wavy fibers. Optimum shear rates and blood velocities are identified. Geometric features of the cartridge, such as pertaining to flow distribution of the blood, may be different for different ends of the cartridge. Air bleed and emboli traps may be provided. Lengthened service life may be achieved by combinations of these features, which may permit additional therapies and applications or better economics.

A high-definition imaging method for the craniocerebral blood flow includes such steps as irradiating the near infrared collimated laser beam onto an object to be tested, continuously taking several frames of reflected laser speckle image at intervals, calculating the time contrast of light intensity variation with time for each pixel, calculating the speed of its cerebral blood flow, and using it as grayscale to configure the 2D speed distribution chart of cerebral blood flow. Its apparatus is composed of laser device, two polarizers, bench, photoelectric imaging system and computer.

Hemodynamic monitoring systems and methods are disclosed including a device comprising a first sensor configured to measure a velocity of blood flow in an adjacently-located portion of a superior vena cava of a mammalian patient using ultrasound waves; a second sensor configured to measure respiratory cycle data of the mammalian patient; and a computer configured to process the measured velocity of blood flow and the measured respiratory cycle data to provide hemodynamic parameters corresponding to the mammalian patient.

A method and apparatus for obtaining the absolute value of intracranial pressure in a non-invasive manner is described by using an ultrasonic Doppler measuring device which detects the intracranial and extracranial blood flow velocities of the intracranial and extracranial segments of the ophthalmic artery. The eye in which the blood flow is monitored is subjected to an external pressure, sufficient to equalize the intracranial and extracranial angle-independent blood flow factors calculated from the intracranial velocity signal and extracranial velocity signal. The absolute value of the intracranial pressure is identified as that external pressure at which such equalization occurs.