Periodic-physical-information measuring apparatus

Surgery – Diagnostic testing – Via monitoring a plurality of physiological data – e.g.,...

Reexamination Certificate

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C600S481000, C600S529000

Reexamination Certificate

active

06616608

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an apparatus for iteratively measuring a value of a periodic physical information including a periodically changing component and removing one or more abnormal values from the iteratively measured values of the periodic physical information.
2. Discussion of Related Art
When a sort of physical information is obtained or measured from a patient, for the purpose of diagnosing a disease of the patient or monitoring a physical condition of the patient, the physical information is often measured continuously to improve the accuracy of measurement or find any significant change of the information during the measurement.
For example, a degree of arteriosclerosis may be diagnosed based on a pulse-wave propagation velocity at which a pulse wave propagates through an artery of a patient. The measurement of pulse-wave propagation velocity needs to measure a pulse-wave propagation time needed for the pulse wave to propagate from a first portion, to a second portion, of the artery. To this end, a rising or start point of a second heart sound, II, detected by a heart-sound sensor from the heart of the patient may be used as a first or upstream-side point to measure the pulse-wave propagation time. Here, the accuracy of detection of the start point of the second heart sound II may be improved by detecting respective start points of a plurality of second heart sounds II and calculating an average of the detected start points. More specifically described, first, respective time durations from respective reference waves to respective start points of a plurality of second heart sounds II are measured, and then an average of those time durations is calculated. For example, the reference waves may be respective R waves of an electrocardiogram (ECG) whose waveform can be clearly detected. That is, respective time durations, R-II, from respective R waves of ECG waveform to respective start points of second heart sounds II are measured, and then an average of those time durations R-II is calculated. Thus, the measurement of pulse-wave propagation velocity may need to iteratively measure, in advance, the time durations R-II as a sort of physical information of the patient.
However, the second heart sounds II detected by the heart-sound sensor are easily mixed with noise. Therefore, the time durations R-II measured as described above may include one or more aberrant or abnormal values produced by the noise. In addition, not only the second heart sound II but also other sorts of physical information obtained from a living subject are easily mixed with noise. Thus, the measured values of each sort of physical information may include one or more abnormal values resulting from the occurrence of one or more errors during the measurement. In addition, there is a need to finish the measurement in a short time to reduce the burden exerted to the patient. To this end, the total number of measured values of the physical information should be as small as possible. However, if the small number of measured values include one abnormal value, it may adversely influence a diagnosis to be made for the patient.
Here, it is possible to make a graph showing a distribution of the measured values of physical information, judge one or more values largely deviated from the distribution, as being abnormal, and remove the values judged as abnormal.
However, there is known a periodic physical information having a periodically changing component. Even if the measured values of periodic physical information may include one or more abnormal values resulting from erroneous measurement, the abnormal value or values may not be largely deviated from the distribution of measured values and may not be Judged as being abnormal, or removed.
FIGS. 10A and 10B
show abnormal values which cannot be discriminated or removed. More specifically described,
FIG. 10A
shows a graph representing respective values of periodic physical information that are iteratively measured as time elapses. An axis of abscissa is indicative of the time, and an axis of ordinate is indicative of the magnitude or value of periodic physical information. Circles
80
indicate correctly measured values of periodic physical information, a cross
82
indicates an abnormal value resulting from erroneous measurement. A periodic curve, C, represents a waveform of the periodically changing component of the periodic physical information.
FIG. 10B
shows a histogram representing the respective measured values of periodic physical information. The abnormal value indicated by the cross
82
in
FIG. 10A
is located at an outermost end of the distribution shown in
FIG. 10B
, but is not clearly deviated from the other measured values. Thus, it is difficult to find and discard the abnormal value
82
. In addition, in
FIG. 10A
, a triangle
84
also indicates an abnormal value which, however, falls within the periodic change of the physical information. Since this abnormal value is mixed with the normal celio values in the histogram shown in
FIG. 10B
, it cannot be found or discarded. Thus, it has been difficult to discard one or more abnormal values from the measured values of any sort of periodic physical information.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a periodic-physical-information measuring apparatus which iteratively measures a value of periodic physical information and which can easily remove one or move abnormal values from the iteratively measured values of periodic physical information.
The present invention provides a periodic-physical-information measuring apparatus which has one or more of the following technical features that are described below in respective paragraphs given parenthesized sequential numbers (1) to (6). Any technical feature that includes another technical feature shall do so by referring, at the beginning, to the parenthesized sequential number given to the latter feature.
However, the following technical features and the appropriate combinations thereof are just examples to which the present invention is by no means limited.
(1) According to a first feature of the present invention, there is provided an apparatus for measuring a periodic physical information of a living subject, comprising a measuring device which iteratively measures, from the subject, a value of the periodic physical information comprising a periodically changing component; a waveform determining means for determining a changing-component waveform representing the periodically changing component of the periodic physical information; a difference determining means for determining at least one difference between at least one first value of the periodic physical information measured by the measuring device at at least one time and at least one second value of the changing-component waveform at the at least one time; and a removing means for judging, based on the at least one difference determined by the difference determining means, whether the at least one first value is abnormal, and removing the at least one first value judged as being abnormal.
In the present periodic-physical-information measuring apparatus, the measuring device measures values of the periodic physical information, the waveform determining means determines the changing-component waveform representing the periodically changing component of the periodic physical information measured by the measuring device, the difference determining means determines a difference between a first value of the periodic physical information measured by the measuring device at a time and a second value of the changing-component waveform at that time, and the removing means judges, based on the determined difference, whether the first value is abnormal, and removes the first value of the periodic physical information that is judged as being abnormal. Thus, the present apparatus can easily remove one or more abnormal values from the iteratively measured values of periodic physical information.
(2)

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