Surgery – Diagnostic testing – Cardiovascular
Reexamination Certificate
1999-09-15
2001-03-06
O'Connor, Cary (Department: 3736)
Surgery
Diagnostic testing
Cardiovascular
C600S485000, C600S494000, C600S500000
Reexamination Certificate
active
06196974
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a blood-pressure monitoring apparatus which monitors a blood pressure of a living subject based on information which changes in relation to the change of blood pressure of the subject.
2. Related Art Statement
As information relating to a pulse wave which propagates through an arterial vessel of a living subject, there are known a pulse-wave-propagation time DT and a pulse-wave-propagation velocity V
M
(m/s). The pulse-wave-propagation time DT is a time which is needed by the pulse wave to propagate between two different positions of the arterial vessel. Additionally, it is known that the above pulse-wave-propagation-relating information is, within a predetermined range, substantially proportional to the blood pressure (“BP”, mmHg) of the living subject. Hence, there has been proposed a BP monitoring apparatus which determines, in advance, coefficients &agr;, &bgr; in the following expression: EBP=&agr;(DT)+&bgr; (where a is a negative constant and &bgr; is a positive constant), or EBP=&agr;(V
M
)+&bgr; (where &agr; and &bgr; are positive constants), based on two measured BP values of the subject and two measured pulse-wave-propagation time values (DT) or two measured pulse-wave-propagation velocity values (V
M
), iteratively determines an estimated BP value EBP of the subject, based on each piece of subsequently obtained pulse-wave-propagation-relating information, according to the above-indicated first or second expression, and starts a BP measurement using an inflatable cuff when an estimated BP value EBP has changed by not less than a predetermined amount or proportion from a prior value EBP determined at the time of the last BP measuring operation.
A relationship between pulse-wave-propagation-relating information and estimated BP value BP, represented by the above-indicated first or second expression, changes depending upon the condition of a central organ of the living subject (e.g., the condition of cardiac muscle) and/or the condition of a peripheral organ of the subject (e.g., the hardness of peripheral blood vessels, or the resistance of those vessels to the blood flow). Thus, there has been proposed a BP monitoring apparatus which obtains hertbeat-relating information (e.g., heart rate or pulse period) as central-organ-relating information, and peripheral-pulse-wave-area-relating information as peripheral-organ-relating information and which starts a BP measurement using an inflatable cuff when the pulse-wave-propagation-relating information (or the estimated BP value EBP calculated based on the pulse-wave-propagation-relating information) has changed by not less than a predetermined amount or proportion from the time of the last BP measuring operation and simultaneously when at least one of the hertbeat-relating information and the peripheral-pulse-wave-area-relating information has changed by not less than a predetermined amount or proportion from the time of the last BP measuring operation. An example of this BP monitoring apparatus is disclosed in U.S. Pat. No. 5,752,920.
However, the prior BP monitoring apparatuses as described above display only a digital value indicative of each piece of BP-relating information which is used in judging whether or not to start a BP measurement using the cuff, or a trend graph representing a timewise change of a plurality of pieces of BP-relating information. From only those items, however, the subject or a medical person who attends to the subject cannot judge whether the BP of the subject is near to, or is changing toward, a state in which a BP measurement using the cuff is started. Accordingly, the medical person can not give any treatments to the subject before a BP measurement using the cuff is actually started.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a blood-pressure monitoring apparatus which monitors the blood pressure of a living subject based on information which changes in relation to the change of blood pressure of the subject and which enables a user to judge whether the blood pressure of the subject is near to the state in which a blood-pressure measurement using an inflatable cuff is started.
The present invention provides a blood-pressure monitoring apparatus which has one or more of the technical features that are described below in respective paragraphs given parenthesized sequential numbers (1) to (18). Any technical feature which includes another technical feature shall do so by referring, at the beginning, to the parenthesized sequential number given to that technical feature.
(1) According to a first feature of the present invention, there is provided a blood-pressure monitoring apparatus comprising a measuring device which includes an inflatable cuff adapted to apply a pressing pressure to a first body portion of a living subject and which measures a blood-pressure value of the living subject by changing the pressing pressure of the inflatable cuff, a blood-pressure-relating-information obtaining device which iteratively obtains a piece of blood-pressure-relating information which changes in relation to a change of the blood pressure of the living subject, starting means for starting, when the obtained blood-pressure-relating information satisfies a predetermined condition with respect to at least one reference value, a blood-pressure measurement of the measuring device, and a display device which displays a first graphical representation of the obtained blood-pressure-relating information, and a second graphical representation of the reference value, so that the first graphical representation is comparable with the second graphical representation. A user such as the living subject or a person who attends to the subject can judge or recognize, from a positional relationship between the first graphical represetation of the obtained blood-pressure-relating information, and the second graphical representation of the reference value, on the display device, whether or not the blood pressure of the subject is near to the state in which the starting means starts a blood-pressure measurement of the measuring device using the inflatable cuff.
(2) According to a second feature of the present invention that includes the first feature (1), the blood-pressure-relating-information obtaining device comprises means for iteratively calculating a blood-pressure-relating value which changes in relation to a change of the blood pressure of the living subject, and the starting means comprises means for starting the blood-pressure measurement of the measuring device, when a value based on the calculated blood-pressure-relating value satisfies the predetermined condition with respect to two reference values that the value based on the calculated blood-pressure-relating value does not fall within an alarm range having an upper limit value defined by one of the two reference values and a lower limit value defined by the other of the two reference values. The alarm range may be replaced with a single alarm value according to the fourth or sixth feature (4) or (6) described below.
(3) According to a third feature of the present invention that includes the second feature (2), the display device comprises means for displaying, with the first and second graphical representations, a third graphical representation of an alert range which is contained in the alarm range and is narrower than the alarm range, so that the first graphical representation is comparable with the second and third graphical representations. The fact that the value based on the calculated blood-pressure-relating value falls within the alarm range but does not fall within the alert range, indicates that the blood pressure of the subject needs alerting of the subject or the person who attends to the subject. Thus, the user can more easily judge, from the first to third representations displayed on the display device, whether or not the blood pressure of the subject is near to the state in which the starting
Carter Ryan
Colin Corporation
O'Connor Cary
Oliff & Berridg,e PLC
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