Surgery – Diagnostic testing – Detecting muscle electrical signal
Reexamination Certificate
1999-06-10
2001-06-19
Jastrzab, Jeffrey R. (Department: 3737)
Surgery
Diagnostic testing
Detecting muscle electrical signal
Reexamination Certificate
active
06249697
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an electrogastrograph and a method for analyzing data obtained by the electrogastrograph, wherein the electrogastrograph is an apparatus for measuring an electric signal (hereinafter referred to as the stomach signal) produced in the stomach when the stomach goes into action.
2. Description of the Related Art
Heretofore, it has been known to use a method for measuring such stomach signal derived from the stomach's action, in which method, only frequency bands containing the stomach signal are obtained through combination of low-pass filters with high-pass filters, wherein the low-pass filters are used to remove essentially breath signals, and the high-pass filters are used to remove essentially the influence of the body action, so that only the frequency bands containing the stomach signal thus obtained are recorded in a suitable storage medium. In this case, the stomach's action produces
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slow wave signal that occurs approximately three times a minute, and is very small in variation in its cycle. Consequently, in order to find out or extract the cycle of the stomach signal thus measured, peak frequencies resulted from the Fourier transform such as FFT and like transforms of the thus measured stomach signal are used.
Now, problems to be solved by the present invention will be described.
In general, in order to evaluate the stomach's action, 0.1 cpm (i.e., cycle/minute) resolution is required. In order to achieve this resolution, it is necessary for the conventional Fourier transform to use the amount of data obtained over a period of 10 minutes. Furthermore, the thus obtained result shows an average value of the data obtained over the period of 10 minutes. However, in general, the stomach's action varies drastically in two or three minutes. Consequently, it is not possible for the conventional Fourier transform to process such drastic variations in the stomach's action.
The stomach signal taken out of an electrode attached to a human body surface is feeble, and, therefore always suffers from a relatively high level noise even when the high-pass filters are used to remove the influence which the body action exercises on the stomach signal. When the stomach signal mixed with such noise is subjected to the Fourier transform, its noise components become dominant over all the others to hidden the stomach signal therein, which means that it is impossible to analyze the stomach signal over an extended period of time, for example such as twenty minutes in total before and after noise mixture occurs. However, in a real life, it is substantially impossible to prevent such a noise derived from the body action from entering the stomach signal over such an extended period of time, for example, over twenty minutes in total. Consequently, in the conventional method, it is substantially impossible to analyze the stomach signal occurring in the real life.
SUMMARY OF THE INVENTION
Under such circumstances, the present invention was made to solve the problems inherent in the related art described above. Consequently, it is an object of the present invention to provide an electrogastrograph and a method for analyzing data obtained by this electrogastrograph, wherein the electrogastrograph of the present invention is capable of: catching the stomach's action which varies drastically in a brief space of time, for example, in two or three minutes; and, clearly identifying the body action, which enables a user of the electrogastrograph of the present invention to analyze the stomach signal in daily life without fail, wherein the stomach signal is an electric signal derived from the stomach's action in daily life.
According to a first aspect of the present invention, the above object of the present invention is accomplished by providing:
An electrogastrograph which is an apparatus for measuring an electric signal derived from the stomach's action, the electrogastrograph being characterized in that:
the electric signal derived from the stomach's action is decomposed into its frequency components by means of a series of filters constructed of a plurality of band pass filters.
In the electrogastrograph as set forth in the first aspect of the present invention, preferably, the electric signal having been decomposed into the frequency components thereof is capable of being stored in a suitable storage medium.
According to a second aspect of the present invention, the above object of the present invention is accomplished by providing:
A method for analyzing data obtained by an electrogastrograph, comprising the steps of:
decomposing an electric signal into its frequency components by means of a series of filters constructed of a plurality of band pass filters, the electric signal having been derived from the stomach's action and measured; and,
evaluating the stomach in its action on the basis of variations in amplitude of the frequency components.
Namely, in the present invention having the above construction, there are provided a plurality of band pass filters the number of which is equal to the number of frequency bands being analyzed, wherein the band pass filters have their cut-off frequencies staggered on their passing band widths, so that the stomach signal is: directly; or, after removal of the influences of the body action and the breath action, i.e., indirectly; analyzed by these band pass filters into the individual frequency components of the stomach signal. More specifically, a signal extracted by one of the band pass filters produces an amplitude proportional to the magnitude of the frequency component extracted by the band pass filter. This amplitude is analogous to the amplitude of the frequency component in the Fourier transform.
Resolution in time of the band pass filter is largely depending on the delay properties of the filter. In this connection, as for the band pass filer having a passing band width of 0.1 cpm, it is possible to obtain approximately 1 minute of resolution, which makes it possible to catch, without fail, the stomach's action varying on a minute-to-minute basis.
Further, since the response time of the band pass filter is on a minute-to-minute basis, the influence of the noise caused by the body action goes out in one or two minutes. Further, since the noise contains a wide range of frequency components, it is possible to clearly distinguish the stomach signal from the noise through spectrum analysis of amplitude.
REFERENCES:
patent: 5795304 (1998-08-01), Sun et al.
patent: 5995872 (1999-11-01), Bourgeois
Browdy & Neimark
Jastrzab Jeffrey R.
Nipro Corporation
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