531 results about "Normal blood volume" patented technology

A blood glucose monitoring system is disclosed which provides for inducing an active pulse in the blood volume of a patient. The induction of an active pulse results in a cyclic, and periodic change in the flow of blood through a fleshy medium under test. By actively inducing a change of the blood volume, modulation of the volume of blood can be obtained to provide a greater signal to noise ratio. This allows for the detection of constituents in blood at concentration levels below those previously detectable in a non-invasive system. Radiation which passes through the fleshy medium is detected by a detector which generates a signal indicative of the intensity of the detected radiation. Signal processing is performed on the electrical signal to isolate those optical characteristics of the electrical signal due to the optical characteristics of the blood.

A mapping catheter is positioned in a heart chamber, and active electrode sites are activated to impose an electric field within the chamber. The blood volume and wall motion modulates the electric field, which is detected by passive electrode sites on the preferred catheter. Electrophysiology measurements, as well as geometry measurements, are taken from the passive electrodes and used to display a map of intrinsic heart activity.

A plethysmographic respiration processor is responsive to respiratory effects appearing on a blood volume waveform and the corresponding detected intensity waveform measured with an optical sensor at a blood perfused peripheral tissue site so as to provide a measurement of respiration rate. A preprocessor identifies a windowed pleth corresponding to a physiologically acceptable series of plethysmograph waveform pulses. Multiple processors derive different parameters responsive to particular respiratory effects on the windowed pleth. Decision logic determines a respiration rate based upon at least a portion of these parameters.

A method and apparatus are disclosed for using photoplethysmography to obtain physiological parameter information related to respiration rate, heart rate, heart rate variability, blood volume variability and/or the autonomic nervous system. In one implementation, the process involves obtaining (2502) a pleth, filtering (2504) the pleth to remove unwanted components, identifying (2506) a signal component of interest, monitoring (2508) blood pressure changes, monitoring (2510) heart rate, and performing (2512) an analysis of the blood pressure signal to the heart rate signal to identify a relationship associated with the component of interest. Based on this relationship, the component of interest may be identified (2514) as relating to the respiration or Mayer Wave. If it is related to the respiration wave (2516), a respiratory parameter such as breathing rate may be determined (2520). Otherwise, a Mayer Wave analysis (2518) may be performed to obtain parameter information related to the autonomic nervous system.

The present invention generally provides methods and devices that allow more efficient delivery of a stimulus, such as optical radiation, to the skin. In many embodiments, negative and/or positive pressure is applied to one or more skin regions in order to maintain a skin target under tension so as to redistribute blood volume between the skin target and other skin segments. In many cases, such tension can cause a depletion of the volumetric blood content in the skin target (that is, in the blood vessels beneath a surface of the skin target), thereby facilitating delivery of radiation to the skin target.

The present disclosure relates, in some embodiments, to devices, systems, and/or methods for collecting, processing, and/or displaying stroke volume and/or cardiac output data. For example, a device for assessing changes in cardiac output and/or stroke volume of a subject receiving airway support may comprise a processor; an airway sensor in communication with the processor, wherein the airway sensor is configured and arranged to sense pressure in the subject's airway, lungs, and/or intrapleural space over time; a blood volume sensor in communication with the processor, wherein the blood volume sensor is configured and arranged to sense pulsatile volume of blood in a tissue of the subject over time; and a display configured and arranged to display a representative of an airway pressure, a pulsatile blood volume, a photoplethysmogram, a photoplethysmogram ratio, the determined cardiac output and/or stroke volume, or combinations thereof. A method of assessing changes in cardiac output or stroke volume of a subject receiving airway support from a breathing assistance system may comprise sensing pressure in the subject's airway as a function of time, sensing pulsatile volume of blood in a tissue of the subject as a function of time, producing a photoplethysmogram from the sensed pulsatile volume, determining the ratio of the amplitude of the photoplethysmogram during inhalation to the amplitude of the photoplethysmogram during exhalation, and determining the change in cardiac output or stroke volume of the subject using the determined ratio.

The invention comprises a patient information server device (10) which automatically accumulates together with time information:

• • biological information detected by a bedside monitoring device (1) of a patient or a biological-measuring device;
  • biological information and device information detected by a blood purification device (2, 3) which treats a blood sample taken from the patient; and
  • blood information detected by a circulating blood volume measuring device (4) that detects blood information about a circulating blood sample taken from the patient. A client device simultaneously and chronologically displays or records the patient information stored in the patient information server device (10). Through this arrangement, it is possible to obtain on a real time basis the biological information of a human body such as a patient's body, and the device information, for example, of a blood treating device.

A method of estimating blood flow in the brain, comprising: a) causing currents to flow inside the head by producing electric fields inside the head; b) measuring at least changes in the electric fields and the currents; and c) estimating changes in the blood volume of the head, using the measurements of the electric fields and the currents.

A method and system for assessing blood volume within a subject includes generating a cardiovascular waveform representing physiological characteristics of a subject and determining blood volume of the subject by analyzing the cardiovascular waveform. The step of analyzing includes generating a first trace of the per heart-beat maximums of the cardiovascular waveform, which is representative of the systolic pressure upon the cardiovascular signal, generating a second trace of the per heart-beat minimums of the cardiovascular waveform, which is representative of the diastolic pressure upon the cardiovascular signal, and comparing the respective first trace and the second trace to generate an estimate of relative blood volume within the subject. In accordance with an alternate method of analyzing harmonic analysis is applied to the cardiovascular waveform, extracting a frequency signal created by ventilation and applying the extracted frequency signal in determining blood volume of the subject.

A respiratory monitoring apparatus that detects changes in physiological parameters relevant to respiration, including blood oxygen and blood volume, using near infrared spectroscopy. Methods for diagnosing respiratory-related events including hypoxia index, hypopnea, arousal, tissue oxygen debt, and respiratory muscle events or distinguishing central from obstructive sleep apnea are also disclosed.

An arterial blood pressure apparatus and methods for using the apparatus are disclosed. The apparatus has a force transfer element for applying unidirectional force to a body part of the subject and a pressure sensor for generating a signal based on the unidirectional force. Multiple degrees of force may be applied simultaneously or serially. The apparatus also has a second sensor for generating a signal associated with blood volume within a blood vessel of the body part and a processor for inferring arterial blood pressure from the force sensor signal and the second sensor. The apparatus may take the form of a glove or a wand.

Apparatus for monitoring a plurality of tissue viability parameters of a tissue layer element, in which two different illumination sources are used via a common illumination element in contact with the tissue. One illumination source is used for monitoring blood flow rate and optionally flavoprotein concentration, and collection fibers are provided to receive the appropriate radiation from the tissue. The other illuminating radiation is used for monitoring any one of and preferably all of NADH, blood volume and blood oxygenation state of the tissue element, and collection fibers are provided to receive the appropriate radiation from the tissue. In one embodiment, the wavelengths of the two illumination sources are similar, and common collection fibers for the two illuminating radiations are used. In another embodiment, the respective collection fibers are distanced from the illumination point at different distances correlated to the ratio of the first and second illuminating wavelengths.

Ultrasound is used to provide input data for a blood pressure estimation scheme. The use of transcutaneous ultrasound provides arterial lumen area and pulse wave velocity information. In addition, ultrasound measurements are taken in such a way that all the data describes a single, uniform arterial segment. Therefore a computed area relates only to the arterial blood volume present. Also, the measured pulse wave velocity is directly related to the mechanical properties of the segment of elastic tube (artery) for which the blood volume is being measured. In a patient monitoring application, the operator of the ultrasound device is eliminated through the use of software that automatically locates the artery in the ultrasound data, e.g., using known edge detection techniques. Autonomous operation of the ultrasound system allows it to report blood pressure and blood flow traces to the clinical users without those users having to interpret an ultrasound image or operate an ultrasound imaging device.

A hemodialysis treatment apparatus includes a circulating blood volume variation rate detecting device, a vital sign detecting device and a display. The circulating blood volume variation rate detecting device detects a circulating blood volume variation rate of a patient in a time-course of a hemodialysis treatment. The vital sign detecting device detects a vital sign value of the patient in the time-course of the hemodialysis treatment. The display has a screen and displays both the circulating blood volume variation rate and the vital sign value on the screen along a time scale. The hemodialysis treatment apparatus dialyzes and ultrafiltrates extracorporeally circulating blood of the patient to perform the hemodialysis treatment.

A method and apparatus for monitoring fluid balance status of a subject are disclosed. A hemoglobin measure indicative of hemoglobin concentration in the blood of a subject and at least one physiological parameter responsive to blood volume changes in the subject are determined and concurrent behavior of the hemoglobin measure and the at least one physiological parameter is indicated to a user, thereby to give an indication of fluid balance status of the subject. The cause and/or reliability of the fluid balance status may also be indicated.

Microwave apparatus for measuring the blood flow rate in a patient's blood vessel includes an intravascular catheter having proximal and distal ends and containing an inner coaxial cable forming a first antenna and an outer cable coaxial with the inner cable and forming a second antenna, the first antenna extending axially beyond the second antenna a selected distance. The apparatus also includes a control unit including a microwave transmitter, a microwave receiver and a processor controlling the transmitter and receiver. A diplexer is connected between the first and second antenna and the control unit to couple signals from the transmitter to the second antenna but not to the receiver and to couple signals from the first antenna to the receiver but not to the transmitter. The transmitter transmits microwave pulses to the first antenna which heat blood around that antenna. When the heated blood volume flows to the second antenna this is detected at the receiver which produces a detect signal. The processor measures the time interval between each pulse a subsequent detect signal and divides that time interval into the axial distance between the two antennas to compute the flow rate.

A method for determining a physiologic characteristic associated with cardiac function in a subject comprising the steps of providing at least one electromagnetic radiation absorption measurement, providing demographic information reflecting the subject's physical condition, determining a temporal plethysmographic value from the electromagnetic radiation absorption measurement, and determining at least one physiologic characteristic from the temporal plethysmographic value and demographic information by using a predetermined phenomenological model that is adapted to provide an estimate of a blood volume-time relationship proximate the heart and compute at least one physiologic characteristic associated with cardiac function based on the estimated blood volume-time relationship.

Methods and systems for graphically creating a representation of an anatomical structure, such as a heart, is provided. The distal end of an elongated probe is moved within the anatomical structure, and geometric shapes are defined within a coordinate system. By defining geometric shapes, such as spheres or circles, as the distal probe end is moved within the anatomical structure, the cavity within the anatomical structure can be represented. A representation of at least a portion of the anatomical structure can be graphically generated based on the geometric shapes, e.g., by determining a union of the geometric shapes and conforming the graphical representation around the union of the shapes. In the case of a heart, the union of the shapes will generally represent the blood volume within the heart, so that the graphical anatomical representation (which in this case will be a graphical representation of the endocardial surface of the heart) can be accurately conformed around the representative blood volume.

An apparatus for determining cardiac performance in the patient involving a conductance catheter (12) for measuring conductance and blood volume in a heart chamber of the patient. The apparatus includes a processor (14) for determining instantaneous volume of the ventricle by applying a non-linear relationship between the measured conductance and the volume of blood in the heart chamber to identify mechanical strength of the chamber. The processor (14) is in communication with the conductance catheter (12).