Southwest Research Institute

Colin Electronics Co., Ltd.

Omron Healthcare Company Ltd.

Nippon Colin Co., Ltd.

Kevin S Honeyager

Dean C Winter

Larry D Canady

Dennis J Wenzel

Jerome A Helffrich

Stephen Anthony Cerwin

Keith Alan Bartels

Armando De Los Santos

Ralph E Harris

Terrie L McDaniel

Larry D Canady, Jr

David A Tong

Christopher B Catterson

Susan W Zogbi

Methods and systems for determining cardiovascular parameters of a patient. In an exemplary embodiment, the method includes placing a phonocardiogram sensor on a patient's body at a first distal location to the heart, and a blood-pressure waveform sensor at a second distal location to the heart. Then, a first set and a second set of waveforms is obtained from the phonocardiogram sensor and the blood-pressure waveform sensor, respectively. A signal processing or conditioning operation may optionally be performed using the first and second sets of waveforms. Then, a time delay between a dicrotic notch signal and an S2 signal is determined. A blood pressure pulse transit time value is calculated by adding S2D, representing a time delay between a patient's heart valve closure time and an arrival time of the S2 signal at the first distal location, to the time delay between a dicrotic notch signal and an S2 signal. Cardiovascular parameters are then determined using the determined blood pressure pulse transit time and at least one physical parameter representative of a arterial distance between a location of the aortic valve and a location of the blood-pressure waveform sensor.

Methods and systems for distal recording of phonocardiographic signals

A system that remotely measures displacement between two objects. A passive sensor is affixed between the objects. The internal sensor uses magnetic coupling between two sensor elements to measure their relative displacement. The sensors are either a) a permeable rod and a complimentary coil in parallel with a tuning capacitor; or b) two permeable rods, each having its own surrounding coil and a tuning capacitor. One of the sensor elements is affixed to each object which is to be monitored. When an interrogating device is placed near the sensors, a resonance can be measured whose frequency characteristics change in a reproducible manner with the relative displacement of the sensors. The resulting resonance characteristics can be calibrated in such a way as to enable the displacement of the objects to be determined.

Passive and wireless displacement measuring device

A method and system for physiological monitoring using a microprocessor-enhanced magnetic field sensor to measure the mechanical effects of body motion is described. The measurements may be used for a variety of applications, such as detection of respiration, cardiac rhythms, and blood pressure. The source or detector may be made sufficiently small so as to be implantable. The system is sufficiently sensitive to provide output data for very small movements.

Motion detection for physiological applications

A hand-held monitor (10) for monitoring environmental or physiological conditions affecting the user. The monitor (10) has a main housing (10a) and a sensor module (10b). The sensor module (10b) has a plurality of sensors (33-36) extending from it. The sensor module (10b) is generally cylindrical in shape and rests in a curved cradle (14c) of the main housing (10a). This permits the sensor module (10b) to rotate between a position in which the sensors are deployed and extend outwardly from the main housing (10a), and a position in which the sensors rest in the main housing (10a). The main housing (10a) contains processor-based electronics circuitry (50) for processing the data acquired by the sensors. The sensor module (10b) contains sensor electronics circuitry (60), including all circuitry unique to the sensors, and is easily detachable from the main housing (10a). This permits sensor modules having the same or different sensors to be easily interchanged.

Hand-held environmental monitor

A high frequency oscillatory ventilator for infants and adults using feedback control to maintain either the desired tidal volume or pressure delivered to the subject. The inspiratory to expiratory time ratio of the ventilator is variable. The ventilator corrects the measured pressure for arbitrarily-sized endotracheal tubes and calculates the actual pressure or tidal volume delivered to the subject. The ventilator also separates the source of the tidal volume oscillations from the patient circuit with a flexible membrane or diaphragm, allowing transmission of oscillating tidal volumes while blocking mean airway pressures. The patient circuit is flexible, but fabricated from low-compliance material to minimize the loss of tidal volume. The ventilator uses feedback control of the exhaust flow to maintain mean airway pressure in the presence of an independently controlled bias flow. Further, a respiratory impedance measurement system is built into or connected to the patient circuit which monitors changes in lung mechanics while the patient is connected to the high frequency ventilator without changing mean airway pressure or removing the patient from the ventilator.

High frequency oscillatory ventilator and respiratory measurement system

A method and apparatus is provided for detecting motion artifacts in data obtained from a blood pressure monitoring transducer and for preventing erroneous data related to such artifacts from interfering with the accuracy of the blood pressure measurement. Operation includes the steps of monitoring the amplitude of a pulse waveform from a first pulse to a next successive pulse and determining if the output signal changes by more than a predetermined percentage, thus indicating a motion condition.

Motion artifact detection for continuous blood pressure monitor

A method for detecting motion artifacts in data obtained from a blood pressure monitoring transducer is provided which prevents erroneous data related to such artifacts from interfering with the accuracy of the blood pressure measurement by way of continuously monitoring the pressure control source which maintains the transducer hold down pressure, and temporarily delaying data acquisition in the event the hold down pressure changes in excess of a predetermined limit.

A method for monitoring a transducer array of individual pressure or force sensitive elements and for selecting the element within the array which most tracks the actual pulse waveform in an underlying artery, thus providing the most accurate measurement of the patient's blood pressure. The outputs of all of the transducer elements are employed in locating the particular element which is centrally located over the artery. A limited number of elements exhibiting local minima of diastolic pressure is first chosen. Then, pulse amplitude outputs from the limited number of transducer elements are employed in selecting that element within the limited-number group which is to be used for obtaining blood pressure measurements. The method provided by the present invention selects from the limited-number group of elements that element about which is centered the greatest spatially weighted average of a predetermined number of pulse amplitude values.

Active element selection for continuous blood pressure monitor transducer

A method for computing optimal hold down pressure for a transducer comprising an array of pressure sensing elements for generation of electrical waveforms indicative of blood pressure in an artery. Using the selected pressure sensing element that is determined to be positioned substantially over the center of the underlying artery, a set of data corresponding to the diastolic pressure and the pulse amplitude pressure is collected and stored. The diastolic pressures and pulse amplitude pressures are taken as a function of hold down pressure over a range of hold down pressures between the pressure at which the artery is unflattened and the pressure at which the artery is occluded. First and second polynomials are fitted to the diastolic pressure data set and the pulse amplitude data set, respectively. The hold-down pressure at the point of minimum slope of the first polynomial fitted to the diastolic versus hold-down pressures values provides one estimate of the correct hold-down pressure. Another estimate of the correct hold-down pressure using the pulse amplitude measurements is provided by locating the point where the slope of the second polynomial is zero. In another embodiment of the method of the present invention, the two above described estimates are combined into a single estimate.

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San Antonio, TX, United States of America

Kevin S Honeyager