Surgery – Diagnostic testing – Cardiovascular
Reexamination Certificate
2002-06-25
2004-03-30
Hindenburg, Max F. (Department: 3736)
Surgery
Diagnostic testing
Cardiovascular
C600S485000, C600S595000
Reexamination Certificate
active
06712769
ABSTRACT:
This invention relates to a blood pressure monitoring device according to the prior-art portion of claim
1
.
Blood pressure monitoring devices of this type include integrated in a housing a display device for indicating the blood pressure measurement values, a control device for controlling the individual components of the blood pressure monitoring device, a power source, a pumping device, and a valve for controlled air inflation and deflation in the bladder of a cuff, a pressure sensor for detecting a pressure signal, an evaluating device for evaluating the pressure signal, and an inclination detecting device preferably arranged in the interior of a housing of the blood pressure monitoring device for detecting the inclination of the blood pressure monitoring device relative to the horizontal and for delivering an electrical inclination signal indicative of the inclination, and, disposed on the housing, an applicator unit for applying the pressure sensor against a subject's limb in the wrist area of his or her lower arm.
Blood pressure monitoring at a subject's wrist or finger frequently suffer from lack of measurement accuracy and insufficient repeatability. For one part, this may be attributable to the high sensitivity of the measurements to variations in the measuring position, that is, the individual position of the wrist or finger relative to the position of the heart. In the event of a measuring position deviating from heart level, the measurement result is corrupted by about 0.8 mm Hg/mm due to the hydrostatic pressure differential between the heart and the measuring position. An improper position during a measurement cycle hence produces a systematic measurement error.
Various proposals have been made in the past to obtain improved blood pressure readings in the light of these problems. In particular, proposals have been made to detect the inclination of the lower arm relative to the horizontal because this inclination, given a predetermined position of the elbow as, for example, a position in which it rests against the upper part of the body, is a measure of the level of the wrist and hence of the hydrostatic component of the blood pressure in the wrist area.
An inclination-sensing blood pressure monitoring device is described, for example, in DE 296 12 412 U1. Arranged in the interior of the housing of the blood pressure monitoring device is a disk-shaped pendulum whose circumference visible through a window in the housing is color-marked. This marking indicates an inclination range within which the blood pressure measurement values can be considered as sufficiently correct because the arm is held so that the wrist is positioned roughly at the level of the heart. Similar simple mechanical solutions are also described in Japanese Offenlegungsschrift JP-8-580 (Application Serial No. 6-145168) or in Japanese publication 09038055 A (Application Serial No. 07196590). The requirement for direct observability of the pendulum through the window disposed adjacent to the blood pressure value indicating device results in considerable overall sizes of such blood pressure monitoring devices. Furthermore, handling is rendered difficult because of the need for the pendulum to settle first before reliable readings can be obtained.
The art knows of blood pressure monitoring devices equipped with inclination detecting devices which are in a position to produce an electrical inclination signal which, also for reasons of greater ease of the further processing of electrical signals, is advantageous. Such a blood pressure monitoring device is disclosed, for example, in U.S. Pat. No. 5,778,879 which does not however provide any specifics as to the mode of operation of the inclination detecting device. Japanese Offenlegungsschrift 7-143970 (Application Serial No. 5-295062) describes a blood pressure monitoring device which uses as inclination sensor an electrolyte sensor, not described in greater detail, whose output voltage is varied in response to the inclination by variation of the resistance value. Such sensors require elaborate sealing and should operate on A.C. voltage to avoid changes in the composition of the electrolyte, which again necessitates a substantial control effort.
From U.S. Pat. No. 5,042,505 an electronic sensing device is known in which the change of an angular position relative to a first angular position of the human spinal column can be measured. To this effect, provision is made for an optical encoder with a movable pendulum unit whose degree of rotation up to 360° is determinable in a digital electrical signal in the form of electrical pulses per angular degree of rotation of the pendulum. This known inclination detecting device thus comprises a movable positioning element and an inclination sensing device cooperating with the positioning element, which includes at least one sensing element movable with the positioning element and at least one further sensing element, said sensing elements being configured such that the electrical inclination signal is derivable from the relative position of the relatively movable sensing elements.
From SU 1825091 an inclination sensor for measuring rails is known. The inclination measurement supplies a relative signal formed by the position of a pendulum with inductive measuring unit.
From U.S. Pat. No. 5,574,442 an inclination sensor with a movable electrode engaging between two fixed electrodes is known. The movable electrode produces an electrical capacitance between the two other electrodes which varies with the angle of inclination.
A blood pressure monitoring device of the type initially referred to is known from DE 197 57 974 A1.
It is an object of the present invention to provide a blood pressure monitoring device of the type indicated in the prior art portion, which is equipped with an inclination detecting device for delivering an electrical inclination signal, said detecting device being of straightforward construction and operating accurately and reliably.
To accomplish this object, the present invention proposes a blood pressure monitoring device incorporating the features of claim
1
.
In blood pressure monitoring devices of the invention, the inclination detecting device comprises at least one movable positioning element and an inclination sensing device cooperating with the positioning element and including at least one first sensing element movable with the positioning element and at least one second sensing element movable relative to the first sensing element, said sensing elements being configured such that the electrical inclination signal is derivable from the relative position of the relatively movable sensing elements. In this arrangement, the positioning element is understood to be a movable member which, in relation to the gravity vector, that is, in relation to the vertical, attempts to occupy invariably the same position of equilibrium, with the inclination of the blood pressure monitoring device being a measure of the inclination of the lower arm. The positioning element may be formed, for example, of a liquid surface or a body floating on a liquid, whose alignment is dictated by the alignment of the liquid surface. The possibility also exists to configure the positioning element as a pendulum movable in one or several axes, that is, as a mass which is, for example, fixedly mounted on a housing outside its center of gravity. Positioning elements rolling off along curved surfaces or operating according to the gyroscopic principle may also be contemplated. The use of the relative movability of the sensing elements and the unambiguous relationship between inclination angle and equilibrium rest position afford the possibility of employing a plurality of preferably physical effects for generation of the inclination signal, utilizing in particular electric, electromagnetic and/or magnetic fields and/or electromagnetic and/or acoustic waves, as well as changes in capacitance resulting from position changes of capacitor surfaces.
The sensing element movable with the positioning unit can be coupled
Freund Dirk
Giersiepen Martin
Harttmann Brigitte
Heck Ulrich
Hollinger Stefan
Braun GmbH
Fish & Richardson PC
Hindenburg Max F.
Natnithithadha Navin
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