Abstract:
The invention is a method for calculating from the contours of the pressure pulses in the brachial, carotid and radial arteries the absolute systolic pressure, the degree of augmentation, and the contour of the pressure pulse wave in the ascending aorta. The pressure in the ascending aorta is related to a combination of a primary pressure pulse and a secondary pressure wave which is a reflection of the primary pressure pulse from the periphery of the body. The maximum central arterial pressure can be determined from an analysis of the contour of the pressure pulses in the peripheral arteries, and the relationship between the peaks in the pulses relating to the maximum primary pressure and the maximum secondary wave pressure. The inventive system determines the positions of the two peaks and then analyses their amplitudes to ascertain the maximum systolic pressure in the central arteries and the amount of augmentation. Transfer functions relating the measured peripheral artery pressure pulses to the ascending aorta pressure pulses developed from an analysis of the pressure pulse waves of a number of individuals using Fourier transform techniques are used to determine the contour of the ascending aorta pressure pulse based on the measured peripheral pulses.
Abstract:
A system and method obtains physiologic parameter information of an animal or human, such as respiratory rate, from a blood pressure signal from an implanted blood pressure sensor (11) in the animal or human (10, 12, 14). Specifically, the blood pressure signal is externally signal processed to develop an amplitude versus time waveform. A sequence of selected blood pressure features derived from individual cardiac cycles of the amplitude versus time waveform over a selected time interval are extracted from the developed amplitude versus time waveform. A mathematical model is fitted to the extracted sequence of selected blood pressure features to yield a fitted mathematical model. The physiologic parameter information is computed from the fitted mathematical model.
Abstract:
Disclosed is an improved arrangement for allowing more accurate automatic calibration for a system in which blood pressure pulses are derived for remote sites from a calibrated measurement and a waveform measurement, when these are made at different sites. Where a calibrated measurement is made, say, at the brachial artery (11), and a waveform recorded at the radial artery (12), a waveform is derived for the calibrated site using a known transfer function, this drived waveform is then calibrated by the measurements already made, and the calibrated waveform for any remote site, for example the ascending aorta (14), can be derived using a known transfer function.
Abstract:
A sensor (180) having a sensing surface (100) for sensing blood pressure within an underlying artery of a patient includes a transducer (96), a sidewall (184), a flexible diaphragm (186) and a fluid coupling medium (188). The sidewall (184) is distinct from transducer (96) and supports the transducer (96) above the underlying artery. The fluid coupling medium (188) is coupled between the sensing surface (100) of transducer (96) and the flexible diaphragm (186) and transmits blood pressure pulses within the underlying artery from the flexible diaphragm (186) to the sensing surface (100) of transducer (96). In one embodiment, the fluid coupling medium (188) is isolated from sidewall (184).
Abstract:
A novel pressure transducer apparatus (10) for medical pressure monitoring apparatus having a housing (14, 28) with a calibration port or well (38). The patient side of the transducer (60) senses fluid pressures to be monitored. The non-patient side of the transducer (60) is hermetically sealed in the housing (14, 28) of the apparatus (10). The housing (14, 28) has a female calibration well (38) communicating, via a pinhole (42), with the non-patient side of the transducer (60). The non-patient side of the transducer (60) can thus alternatively be vented to atmospheric pressure or be exposed to a vacuum calibration pressure.
Abstract:
The blood pressure measuring device (10) has a bowl-shaped casing (11) in which is arranged a pressure measuring system with measuring scale (13) and indicator. The casing (1) is closed at its upper edge by a transparent cover plate (25). This primary casing (11) is surrounded at a given distance on the outside by a protective housing (15), whereby the base (18) of the protective housing (15) is combined in one piece with the base (16) of the primary casing (11). The compressed air line is connected either through a hole (22) in the base (16) of the casing (11) or through the casing walls. In the latter case, there is a material bridge in the space between the wall of the primary casing (11) and of the protective housing (15).
Abstract:
A method for diagnosing, treating and monitoring hypertension uses the parameter C2 (i.e. distal vascular compliance) of the modified Windkessel model as an indication of the hypertensive disease condition. Apparatus for determining the parameter C2 of the modified Windkessel model includes means for obtaining a pressure pulse contour and a cardiac output value and for determining the model parameters.