Protocol Systems, Inc.

Hemonix, Inc.

Other

Charles L Davis

John R Marshall

Thomas J Dorsett

Patrick D Harrison

Paul V Long

Craig H Nelson

John E Bronson

Apparatus and methods for noninvasively measuring blood density and hematocrit in a human subject can include an appliance for applying pressure around a segment of a subject's limb or appendage that includes a pressure sensing means and encloses an array of impedance sensing devices applied to the subject's skin for independent fluid volume measurements. While applying pressure to the limb segment by the pressure appliance, measurements of blood pressure, blood pulse wave velocity, and limb segment impedance are recorded. The measurements are subsequently processed to yield changes of arterial blood volume during pulse wave passage. Then pressure, wave velocity, and derived volume data are combined to yield the density of the blood. Blood density is converted to hematocrit by means of a linear relationship between the two. Independent of the blood hematocrit, such apparatus and means may also be used to measure the density of enclosed fluid in other pulsed flow non-rigid wall vessel systems.

Noninvasive method of measuring blood density and hematocrit

The present invention provides means and methods for noninvasively identifying the blood pressure characteristics in each of the seven types of vessels in the circulatory system, including the central venous pressure (CVP) through a single monitoring system using fluid depletion plethysmography. Known pressure is applied to a body region in increasing amounts to force blood volume from the body region in step-wise fashion through each vessel type. Blood volume depletion for each vessel type is measured by the increasing electrical impedance of the body part during depletion and is plotted against the increasing pressure data. The resulting series of slope changes within the plotted curve reveals the blood pressure for each vessel type. The data obtained may further be used to determine vessel wall compliance/tension as well as standard measurements such as pulse and large artery systolic and diastolic pressure. Release of the applied pressure may then yield similar data by measuring blood volume replenishment against the decreasingly applied pressure during the same diagnostic operation. The method is not dependent on oscillometric or pulsatile measurement methods. The electrical leads of the impedance/volume sensor and the means for applying pressure to the body part are coextensive to ensure accurate indication of blood volume depletion and replenishment in the body region under pressure and may be incorporated into a single integrated structure.

Noninvasive method of measuring physiologic parameters

Noninvasive-blood-pressure (NIBP) monitoring apparatus is disclosed which is usable to perform either oscillometric or auscultatory NIBP. The apparatus includes relatively adjustable, noninflatable, pressure-information-providing (PIP) structure usable to apply NIBP-useful pressure to such limb adjacent such vessel. Also included is pressure-changer structure associated with the PIP structure, and operable to adjust the same to a beginning NIBP-useful pressure, and to subsequent NIBP-useful pressures, with such adjustment effecting the availability of pressure information that can be sensed by such sensor structure. The apparatus is preferably constructed for oscillometric NIBP monitoring and includes a reaction band removably fittable on and circumscribingly about the limb of such living subject. The preferred construction is for portable, self-contained, ambulatory usage. Other embodiments include providing an output communicator for sending NIBP-data signals in various outputs including electrical, wireless and optical, and visually perceptible ones.

Noninvasive-blood-pressure(NIBP) monitoring apparatus with

A patient monitoring system which includes a portable device and a central station. The portable device includes an ECG and a photo-plethysmograph connected to the patient; arrhythmia analysis apparatus; an expert system for determining if a pre-established critical parameter set has been exceeded; and a wireless wide area communication device for automatically contacting the central station via a public cellular phone network when the critical parameter set has been exceeded. When the central station is contacted, the patient's ECG waveforms, measurements, and trends, are sent to the central monitoring station and a two way voice channel between the patient and the central station is automatically opened. The central station includes a computerized facility which has a station from which a clinician can observe the real time data being sent from the patient, the patients historical records and from which the clinician can talk to the patient and activate therapeutic devices attached to the patient such as an external defibrillator, a pacer or an automatic drug infusion device.

Real time ambulatory patient monitor

Noninvasive-blood-pressure (NIBP) monitoring apparatus with

For use in performing non-invasive blood-pressure measurement (NIBP), an artifact rejection method for predicting expected data values from acquired data, and for adjusting previously acquired data based on the relationship of actually measured data values to their corresponding predicted values. The method is practiced in a system comprising an inflatable, occluding cuff, a pump and a valve coupled to the cuff, and monitoring apparatus coupled to the cuff adapted to measure cuff pressure and recurring blood-pressure pulsations occurring in the cuff that are caused by each heart contraction occurring in a measurement cycle. Cuff pressure is raised to a level above the patient's systolic pressure, and progressively reduced in a stepwise fashion to an ending cuff pressure. A fixed number of pulsations are measured and processed at a first and second cuff-pressure step, and a generally lesser number of pulsations are measured and processed at a third and subsequent cuff-pressure steps. The method includes, at the second cuff-pressure step, generating a prediction curve for predicting a next, expected-to-be-stored pulsation data value for a next, lower cuff-pressure step. The method also includes repeatedly smoothing the prediction curve based on the difference between a pulsations's calculated data value and its respective predicted data value. A final, smoothed curve is generated reflecting a final pulsation data value for each cuff-pressure step. From the final curve, the desired blood pressure parameters are derived and displayed in the form of arabic numerals by means of an LCD read-out.

Method of artifact rejection for noninvasive blood-pressure measurement

A microprocessor-controlled, oscillometric method for determining a patient's systolic, diastolic, and mean arterial pressure, practiced in a system comprising an inflatable, occluding cuff, a pump and a valve coupled to the cuff, and monitoring apparatus coupled to the cuff adapted to measure cuff pressure and recurring blood-pressure pulsations occurring in the cuff that are caused by each heart contraction occurring in a measurement cycle. Cuff pressure is raised to a level above the patinet's systolic pressure, and progressively reduced in a stepwise fashion to an ending cuff pressure. A fixed number of pulsations are measured and processed at a first and second cuff-pressure step, and a generally lesser number of oscillations are measured and processed at a third and subsequent cuff-pressure steps. The method includes a first artifact rejection technique used to check for false data relative to the formation of each blood-pressure pulsation. Further, the method includes calculating, for each blood-pressure pulsation, the impulse of a force that is exerted upon the patinet's blood from, and during, each heart contraction that occurs in the measurement cycle. An impulse value is stored relative to each pulsation. A second artifact rejection technique is used, beginning at the second cuff-pressure step, to generate a prediction curve for predicting a next, expected-to-be-stored pulsation impulse value for a next, lower cuff-pressure step. The second artifact rejection technique is also used to repeatedly smooth the prediction curve based on the difference between a pulsation's calculated impulse value and its respective predicted impulse value. A final, smoothed curve is generated reflecting a final impulse value for each cuff-pressure step. From the final curve, the desired blood pressure parameters are derived and displayed in the form of arabic numerals by means of an LCD readout.

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Beaverton, OR, United States of America

Charles L Davis