Surgery – Diagnostic testing – Cardiovascular
Reexamination Certificate
1999-06-08
2001-05-01
Hindenburg, Max (Department: 3736)
Surgery
Diagnostic testing
Cardiovascular
C600S493000, C600S485000
Reexamination Certificate
active
06224559
ABSTRACT:
FIELD OF THE INVENTION
The present invention pertains to a device for noninvasive blood pressure measurement, the device including a cuff and a control and evaluating circuit.
BACKGROUND OF THE INVENTION
Noninvasive blood pressure measurements are performed by means of corresponding devices and processes and have been known in many variants. For example, EP 0 029 166 B1 describes an electronic blood pressure-measuring device that has a circuit for processing the measured signals.
The prior-art processes and devices are based on the separation of a quasi static signal from a superimposed dynamic signal by means of analog electronic components in suitable evaluating circuits.
In the idealized case, the quasi static signal is a step function decreasing especially over time, which reproduces the currently present pressure preset in the inflatable cuff. The medical measured value that is actually of interest can be determined only from the superimposed dynamic signal.
The separation of the two signals is usually performed in prior-art measuring and evaluating devices via analog filter elements, which have an operational amplifier connected as a high-pass filter with a downstream analog-digital converter.
One essential drawback of the prior-art devices is the dead times of up to 150 msec occurring during measurement in the case of a reduction of the pressure in the cuff by one pressure stage each.
SUMMARY AND OBJECTS OF THE INVENTION
Correspondingly, the primary object of the present invention is to provide an improved device for noninvasive blood pressure measurement, which has a higher time resolution and measuring sensitivity with respect to the evaluation of the measured values.
According to the invention, a device is provided for noninvasive blood pressure measurement. The device includes a cuff and a control and evaluating circuit. The cuff is connected, on the one hand, to a downstream amplifier via a pressure sensor with a pressure transducer. An analog-digital converter is arranged directly downstream of the amplifier with the computing and control unit. On the other hand, the computing and control unit is connected to the cuff via an electronically driven pressure transducer.
One essential advantage of the device according to the present invention is that a marked improvement is achieved in noninvasive blood pressure measurement and evaluation in medical engineering by means of available electronic components that are known per se based on the arrangement described.
The analog-digital converter may have a resolution of at least 16 bits and a scanning rate of at least 50 Hz.
The electrically driven pressure transducer may be designed as a pump that can be driven electronically with an associated valve that can be driven electronically. In this way, the pressure preset by the computing and control unit is set and changed in the cuff in a time-dependent manner. The cuff may be pneumatically connected to the pressure transducer.
The computing and control unit preferably has one or more microprocessors. The process steps determining the pressure control, the measurement evaluation and the output of the measured values are preferably stored in a, permanently writable memory associated with the computing and control unit. The process steps determining the pressure control and the filter process may be synchronously coupled in the computing and control unit, which has at least one microprocessor.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawing and descriptive matter in which a preferred embodiment of the invention is illustrated.
REFERENCES:
patent: 4703760 (1987-11-01), Miyawaki et al.
patent: 4880013 (1989-11-01), Chio
Carter Ryan
Drager Medizintechnik GmbH
Hindenburg Max
McGlew and Tuttle , P.C.
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