Abstract: An improved method and apparatus for non-invasively assessing one or more hemodynamic parameters associated with the circulatory system of a living organism. In one aspect, the invention comprises a method of measuring a hemodynamic parameter by measuring a non-calibrated value of the parameter non-invasively, and inducing a stress of the circulatory system while measuring a second parameter. The response of the circulatory system to the stress is determined directly from the subject, and a calibration function is derived from the response and applied to the non-calibrated measured value to produce a calibrated measure of the actual value of the hemodynamic parameter. Methods of using backscattered acoustic energy for determination of hemodynamic markers are also disclosed.

Abstract: 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.

Abstract: An improved method and apparatus for non-invasively assessing one or more hemodynamic parameters associated with the circulatory system of a living organism. In one aspect, the invention comprises a method of measuring a hemodynamic parameter by measuring a non-calibrated value of the parameter non-invasively, and inducing a stress of the circulatory system while measuring a second parameter. The response of the circulatory system to the stress is determined directly from the subject, and a calibration function is derived from the response and applied to the non-calibrated measured value to produce a calibrated measure of the actual value of the hemodynamic parameter. Methods of using backscattered acoustic energy for determination of hemodynamic markers are also disclosed.

Abstract: An improved method and apparatus for non-invasively assessing one or more hemodynamic parameters associated with the circulatory system of a living organism. In one aspect, the invention comprises a method of measuring a hemodynamic parameter by measuring a non-calibrated value of the parameter non-invasively, and inducing a stress of the circulatory system while measuring a second parameter. The response of the circulatory system to the stress is determined directly from the subject, and a calibration function is derived from the response and applied to the non-calibrated measured value to produce a calibrated measure of the actual value of the hemodynamic parameter. Methods of using backscattered acoustic energy for determination of hemodynamic markers are also disclosed.

Abstract: Techniques are provided for obtaining selected instantaneous area measurements for a dynamic orifice through which blood is flowing in at least one direction, for obtaining instantaneous flow rates of blood passing through such a dynamic orifice and for obtaining flow volume for blood passing through a dynamic orifice. All of these techniques involve ensonifying a thin sample volume of blood flow exiting at the orifice, which volume is in a region of flow which is substantially laminar, such region normally being the vena contracta for the orifice, with an ultrasonic pulsed Doppler signal, receiving backscattered signal from blood within the sample volume and forming a power-velocity spectrum from the received backscattered signal. Techniques are disclosed for assuring that only laminar flow is looked at in forming the power-velocity spectrum.

Abstract: Techniques are provided for obtaining selected instantaneous area measurements for a dynamic orifice through which blood is flowing in at least one direction, for obtaining instantaneous flow rates of blood passing through such a dynamic orifice and for obtaining flow volume for blood passing through a dynamic orifice. All of these techniques involve ensonifying a thin sample volume of blood flow exiting at the orifice, which volume is in a region of flow which is substantially laminar, such region normally being the vena contracta for the orifice, with an ultrasonic pulsed Doppler signal, receiving backscattered signal from blood within the sample volume and forming a power-velocity spectrum from the received backscattered signal. Techniques are disclosed for assuring that only laminar flow is looked at in forming the power-velocity spectrum.

Abstract: Techniques are provided for obtaining selected instantaneous area measurements for a dynamic orifice through which blood is flowing in at least one direction, for obtaining instantaneous flow rates of blood passing through such a dynamic orifice and for obtaining flow volume for blood passing through a dynamic orifice. All of these techniques involve ensonifying a thin sample volume of blood flow exiting at the orifice, which volume is in a region of flow which is substantially laminar, such region normally being the vena contracta for the orifice, with an ultrasonic pulsed Doppler signal, receiving backscattered signal from blood within the sample volume and forming a power-velocity spectrum from the received backscattered signal. Techniques are disclosed for assuring that only laminar flow is looked at in forming the power-velocity spectrum.

Abstract: The invention implements a method for adaptively using raw image data (before compression) to produce pixel display values in an ultrasound system in accord with variations in signal-to-noise ratio. Initially, for each subject pixel of an image, a first regional value is derived by taking into account values of a neighborhood of pixels that includes the subject pixel. The first regional value is then compared to a threshold value related to noise and each subject pixel is assigned a classification as a tentative signal pixel if the regional value equals or exceeds the threshold value. Any pixel value not so classified is considered a tentative noise pixel. A second regional value is then derived for each subject pixel by taking into account first regional classifications of a second neighborhood of pixels that includes the subject pixel. If the number of signals classified as signal in the second neighborhood is less than a second threshold, the subject pixel is classified as noise.

Abstract: An improved method and apparatus for non-invasively assessing one or more hemodynamic parameters associated with the circulatory system of a living organism. In one aspect, the invention comprises a method of measuring a hemodynamic parameter by measuring a non-calibrated value of the parameter non-invasively, and inducing a stress of the circulatory system while measuring a second parameter. The response of the circulatory system to the stress is determined directly from the subject, and a calibration function is derived from the response and applied to the non-calibrated measured value to produce a calibrated measure of the actual value of the hemodynamic parameter. Methods of using backscattered acoustic energy for determination of hemodynamic markers are also disclosed.

Abstract: 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.

Abstract: The present invention provides a method and apparatus for processing acoustic information obtained with an ultrasound device to generate cardiac information, such as, for example, a patient's heart rate. In accordance with the present invention, an ultrasound system is utilized to image a patient's heart to obtain acoustic information relating to the patient's heart. The acoustic information is converted into electrical information, which is then processed to extract a particular feature of interest therefrom, such as, for example, the patient's heart rate. In accordance with the preferred embodiment of the present invention, processing of the electrical signals comprises the steps of generating a time-series from a series of image frames and then performing a spectral analysis on the time-series. The features of interest are then easily extracted from the results of the spectral analysis.

Abstract: In the present invention, a control system uses acoustic data produced by an ultrasound system to assess whether the acoustic environment presented to the ultrasound system's transducer is an imaging environment, such as patient's body, or a nonimaging environment, such as air. Various operating parameters of the ultrasound system may be controlled based on the assessment. In the nonimaging environment, the control system reduces the amplitude of a drive signal applied to the transducer, substantially reducing power dissipation in the transducer. The control system detects a transition to the imaging environment and returns the drive signal to the amplitude used in the previous imaging environment. If the nonimaging environment persists for greater than a predetermined time period, the control system initiates a standby mode which substantially reduces power consumption by the ultrasound system. The control system is readily integrated into the imaging stream of an ultrasound system.

Abstract: A beamformer for an array of sonar transducers, or electromagnetic radiating elements, includes mixers for translating the signals received by the transducers to a lower frequency. The beamformer incorporates delay lines operating at a clock rate which is reduced in proportion to the decrease in frequency. Each delay line provides delays to the signals of corresponding ones of the transducers in accordance with the time of arrival of a wavefront of radiation upon the respective transducers. Phase shifters coupled between the mixers and the delay lines impart phase shifts to the transducer signals proportional to the respective delays to compensate for the lowering of the frequency.

Abstract: A beamformer forms a beam from a set of samples of signals from an array of elements such as sonar transducers. Sequences of signal samples from each transducer are delayed relative to each other by fractional amounts of the intersample interval. The sequences of the signal samples with the predetermined delays therebetween are applied to a common beamforming filter having a pass band of sufficient width to accommodate the signals. The impulse response time of the filter is longer than the intersample interval in any one of the sample sequences for providing a beam equal to the sum of regenerated transducer signals. The radiation pattern of the beam is independent of the sampling rate.