Surgery – Diagnostic testing – Cardiovascular
Reexamination Certificate
2000-04-28
2002-04-30
Lacyk, John P. (Department: 3736)
Surgery
Diagnostic testing
Cardiovascular
C600S492000, C600S485000, C600S494000
Reexamination Certificate
active
06379309
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an apparatus for measuring a superior-and-inferior-limb blood-pressure index of a living subject (e.g., a ratio of an inferior-limb blood pressure to a superior-limb blood pressure, or a ratio of a superior-limb blood pressure to an inferior-limb blood pressure), and to an apparatus for measuring a blood pressure of an inferior limb of a living subject, the latter apparatus being advantageously employed by the former apparatus.
2. Related Art Statement
For a person who suffers arterial obstruction or arteriostenosis, his or her inferior-limb blood pressure (“BP”) value is lower than his or her corresponding superior-limb BP value (for example, a systolic superior-limb BP value corresponds to a systolic inferior-limb BP value). Meanwhile, if an inferior-limb BP value of a person is higher than his or her corresponding superior-limb BP value by a prescribed value, he or she may suffer aortic incompetence or aortitis syndrome limited to aortic arch. It has been practiced to utilize this for diagnosing arterial disease based on the ratio of inferior-limb BP value to superior-limb BP value or the ratio of superior-limb BP value to inferior-limb BP value, that is, a superior-and-inferior-limb BP index.
Since the superior-and-inferior-limb BP index is simply obtained as the ratio of inferior-limb BP value to superior-limb BP value or the ratio of superior-limb BP value to inferior-limb BP value, it is required to measure accurately the inferior-limb BP value. However, if one or more blood vessels running in a portion of an inferior limb from which the inferior-limb BP value is measured suffer advanced calcification, that is, sclerosis of tunica media as the middle one of three layers of tunica vasculosa, the inferior-limb BP value is raised because of the hardness of the blood vessels. In addition, since an inferior limb is thicker than a superior limb and has a generally conical shape, it is hard to wind an inflatable cuff around it. Moreover, since arterial vessels running in an inferior limb are present deep in adipose tissues and muscles, it is naturally harder to measure an inferior-limb BP value than measure a superior-limb BP value. In the case where blood vessels running in a portion of an inferior limb from which an inferior-limb BP value is measured suffer highly advanced calcification, those blood vessels cannot be fully occluded by the pressing of an inflatable cuff and accordingly an excessively high inferior-limb BP value may be measured. Therefore, if a person who suffers arterial obstruction or arteriostenosis also suffers advanced calcification of his or her inferior-limb blood vessels, a normal superior-and-inferior-limb BP index value may be measured from the person. In this case, arterial obstruction or arterio-stenosis cannot be accurately diagnoses based on the superior-and-inferior-limb BP index.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide an apparatus which can measure a highly reliable superior-and-inferior-limb blood-pressure index of a living subject even if he or she may suffer the calcification of his or her inferior-limb blood vessels.
It is another object of the present invention to provide an apparatus which measures a superior-and-inferior-limb blood-pressure index of a living subject while judging whether the measurement of an inferior-limb blood pressure is abnormal.
It is another object of the present invention to provide an apparatus which measures an inferior-limb blood-pressure of a living subject while judging whether the subject suffers the calcification of his or her inferior-limb blood vessel.
(1) According to a first feature of the present invention, there is provided an apparatus for measuring a superior-and-inferior-limb blood-pressure index of a living subject, comprising a first blood-pressure measuring device which measures a first blood pressure of a right inferior limb of the subject; a second blood-pressure measuring device which measures a second blood pressure of a left inferior limb of the subject; a third blood-pressure measuring device which measures a third blood pressure of a superior limb of the subject; a first information obtaining device which obtains first information relating to a first velocity of propagation of a first pulse wave which propagates through a first route a portion of which runs in the right inferior limb; a second information obtaining device which obtains second information relating to a second velocity of propagation of a second pulse wave which propagates through a second route a portion of which runs in the left inferior limb; selecting means for selecting one of the measured first and second blood pressures that corresponds to one of the first and second information that relates to a lower one of the first and second velocities; and index determining means for determining the superior-and-inferior-limb blood-pressure index, based on the selected one of the first and second blood pressures, and the measured third blood pressure.
According to this feature, the first information obtaining device obtains first information relating to a first velocity of propagation of a first pulse wave which propagates through a first route a portion of which runs in the right inferior limb, the second information obtaining device obtains second information relating to a second velocity of propagation of a second pulse wave which propagates through a second route a portion of which runs in the left inferior limb, the selecting means selects one of the measured first and second BP values that corresponds to one of the first and second information that relates to a lower one of the first and second velocities, and the index determining means determines the superior-and-inferior-limb BP index, based on the selected one of the first and second BP values, and the measured third BP value. The higher the degree of calcification of blood vessel is, the higher the velocity of propagation of pulse wave through the blood vessel is. Therefore, the selected one of the measured first and second BP values that corresponds to the lower one of the first and second velocities, means the inferior-limb BP value measured from the less calcified inferior limb. Since this inferior-limb BP value, selected by the selecting means, is used in determining the superior-and-inferior-limb BP index, a highly reliably superior-and-inferior-limb BP index value can be obtained.
(2) According to a second feature of the present invention that includes the first feature (1), the index determining means comprises means for determining, as the superior-and-inferior-limb blood-pressure index, a ratio of the selected one of the first and second blood pressures to the third blood pressure, or a ratio OF the third blood pressure to the selected one of the first and second blood pressures.
(3) According to a third feature of the present invention that includes the first or second feature (1) or (2), the first information obtaining device comprises two first pulse-wave sensors which are worn on two different first portions of the living subject, respectively, and each of which detects the first pulse wave at a corresponding one of the two first portions, at least one of the two first portions belonging to the right inferior limb, and the second information obtaining device comprises two second pulse-wave sensors which are worn on two different second portions of the subject, respectively, and each of which detects the second pulse wave at a corresponding one of the two second portions, at least one of the two second portions belonging to the left inferior limb.
(4) According to a fourth feature of the present invention that includes the third feature (3), the first information obtaining device comprises first time determining means for determining, based on respective times when the two first pulse-wave sensors detect the first pulse wave, a first propagation time needed for the first pulse wave to propagate between the two different f
Nunome Tomohiro
Ogura Toshihiko
Suzuki Hidenori
Colin Corporation
Lacyk John P.
Natnithithadha Navin
LandOfFree
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