Acquisition and Analysis of Electrogastrogram for Human Stomach Disorders – A Statistical Approach

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patient stomach disorder

Article:

Acquisition and Analysis of Electrogastrogram for Human Stomach Disorders - A Statistical Approach

G. Gopu, Research Scholar, Dept. of  EEE. PSG College of  Technology, Coimbatore- 04

R. Neelaveni, Assistant Professor, Dept. of  EEE. PSG College of  Technology, Coimbatore- 04

K. Porkumaran, Professor & Head, Dept. of BME, Sri Ramakrishna Engineering College, Coimbatore-22

Abstract

The aim of this investigation is to determine the universal remedy for human beings at fair amount of accuracy for the digestive system disorders. Presently, Endoscopy procedure is used to investigate the stomach disorders, which is very tedious, expensive and invasive. Electrogastrogram [EGG] is a non-invasive, cheap and painless method is performed on patients to investigate the stomach disorders. Approximately 150 people have participated in the EGG procedure. EGG has been recorded for the human being in the preprandial and postprandial condition. The biosignal is detected from the patient's coutaneous from the stomach. This signal is amplified using the instrumentation amplifier and it is acquired for further analysis using statistical analysis using LabVIEW. The diagnosis is made based on the comparison of the statistical parameters such as Mean, RMS, Kurtosis, Mode, Median, Amplitude, Variance, Frequency and Power with the normal individual to the Patients to fare amount of accuracy. The stomach disorders such as Dyspepsia, Nausea, Stomach Ulcer, gastritis, etc can be determined from the comparisons of statistical parameters. 1 The normal individual`s EGG frequency value is about 3 cycle per minute.

Keywords: Electrogastrogram, preprandial, postprandial, statistical parameters, Dyspepsia, Nausea, Stomach Ulcer, gastritis.

Introduction

Electrogastrography is a noninvasive method for the recording of gastric myoelectrical activity that controls gastric motility [1, 2]. Although the first measurement of the EGG was reported 70 years ago, the progress in this field has been very slow , especially compared with other cutaneous electrophysiological measurements, such us the Electrogastrography because of its difficulty in data acquisition, lack of understanding ,etc. . Due to the advancement in quantitative analysis of the EGG, more and more physicians and biomedical researchers have been interested in this field. The abnormality arises due to recurrent nausea, vomiting, Dyspepsia, Stomach ulcer, Cyclic vomiting syndrome, etc which signals that the stomach is not emptying food normally. If the EGG is abnormal, it confirms that the problem probably is with the stomach's muscles or the nerves that control the muscles. In our previous research paper, we have identified the digestive system disorders with a recording setup designed with a Microcontroller and Virtins sound card software. Here the output is found to be noisy with a variation in frequency. Then the same setup is interfaced with LabVIEW software via serial port to acquire the EGG signal at a fair amount of accuracy. This paper deals with the novel approach of recording of the electrical signals that travel through the muscles of the stomach and control the muscle's contraction and analysis with the statistical parameters such as mean, rms, kurtosis, mode, median, amplitude, variance, frequency and power. The EGG can be considered as an experimental procedure since its exact role in the diagnosis of digestive disorders of the stomach has not been defined yet.

The paper is organised as follows: Section 1,introduction about the EGG analysis with an statistical parameters. Section 2, present about the EGG. Section 3, Illustrate the proposed EGG recording setup with a block diagram. Section 4, briefly explain about the anatomy of the stomach. Section 5, illustrate the electrode positioning for recording EGG signals. Section 6, Presents information about the material and methodology adopted for recording statistical parameters for digestive system disorder patients. Here the statistical parameters are compared particularly for a normal Individual and dyspepsia patients. Section 7, includes algorithm and flow diagram for EGG recording setup. Section 8, Illustrate the results of the recorded EGG by observing the changes in the frequency and power for the both preprantial and postprantial condition for the diagnosis of a digestive system disorder. Section 9, includes the summary of the research work and futher expansion method to detect the disorder at fair amount of accuracy. Section 10, includes the acknowledgement to the experts. Section 11, includes the reference papers for this research paper.

Electrogastrogram

An EGG is similar to an electrocardiogram of the heart. It is a recording of the electrical signals that travel through the muscles of the stomach and control the muscle's contraction [12, 13]. EGG used when there is a suspicion that the muscles of the stomach or the nerves controlling the muscles are not working normally. EGG done by placing the electrode cutaneously over the stomach and the electrical signals coming from the stomach's muscles are sensed by the electrode and recorded on a computer for analysis by lying patient quietly. In normal individuals the EGG is a regular electrical rhythm generated by the muscles of the stomach and the power (voltage) of the electrical current increases after the meal. In patients with abnormalities of the muscles or nerves of the stomach, the rhythm often is irregular or there is no post-meal increase in electric power. EGG will not have any side effects and it is painless study. The normal individual EGG frequency value is found to be approximately 3 cycles per minute. The EGG wave pattern before and after denoising is shown in figure 1.

Figure 1 - A and B are EGG waveform before filtering and after filtering respectively

Proposed EGG Recording Setup

The sensors used in this recording setup are Ag/Agcl electrodes [4, 3, 5]. The electrodes are used to tap the electrical signals directly surface of the stomach. The electrical signals generated are usually of very low amplitude ranging from 0.01 to 0.5 mV. This is given as a input to an instrumentation amplifier which has a gain of 1000 to 10,000. The amplified signal is then connected to the Data Acquisition Card [DAQ]. DAQ is an instrument for LabVIEW software. The key function of the DAQ is to act as an interface between the external signal and the subject after the amplification is sent to the DAQ. The DAQ digitizes this signal and makes it edible for further processing. DAQ assistant is a module in the LabVIEW flow diagram which has set of parameters that should be selected to acquire the signal from the DAQ. There are various other noises that will be obtained during the during signal acquisition process namely respiratory effects, disturbances due to bowel movements,etc., in order to reject these signals and select the EGG we will have to filter out there noises. Butterworth low pass filter of tenth order is used for this purpose. The cut off frequency is set to 3 Hz which implies that all those frequency components above 3 Hz will be rejected. This leaves the EGG Signal alone to the Statistical analysis, from these parameters the abnormal patients are identified by comparing it with the statistical parameters for the normal individual as shown in figure 2.

Figure 2 - General block diagram for recording EGG

The Anatomy of the stomach

The main function of the stomach is to process and transport food [2]. After feeding, the contractile activity of the stomach helps to mix, grind and eventually evacuate small portions of chyme into the small bowel, while the rest of the chyme is mixed and ground. Anatomically, the stomach can be divided into three major regions: fundus (the most proximal), corpus and antrum. Histologically, the fundus and corpus are hardly separable. In the antral area, the density of the smooth muscle cells increases. The area in the corpus around the greater curvature, where the split of the longitudinal layers takes place, is considered to be anatomically correlated with the origin of gastric electrical activity. The stomach wall, like the wall of most other parts of the digestive canal, consists of three layers: the mucosal (the innermost), the muscularis and the serosal (the outermost). The mucosal layer itself can be divided into three layers: the mucosa (the epithelial lining of the gastric cavity), the muscularis mucosae (low density smooth muscle cells) and the submucosal layer (consisting of connective tissue interlaced with plexi of the enteric nervous system). The second gastric layer, the muscularis, can also be divided into three layers: the longitudinal (the most superficial), the circular and the oblique. The longitudinal layer of the muscularis can be separated into two different categories: a longitudinal layer that is common with the esophagus and ends in the corpus, and a longitudinal layer that originates in the corpus and spreads into the duodenum as shown in figure 3.

Figure 3 - The Anatomy of the Stomach

Electrodes Positioning

The electrical signals are generally produced in the mid-corpus of the stomach where the electrical activity takes place. The positioning of the Ag/ Agcl electrodes for tapping of these signals is as follows as shown figure 4: Two electrodes A and B are placed in the fundus and the mid corpus of the stomach. The third electrode C is placed as ground at the end of the stomach region for patient safety [3, 4, 5].

Figure 4 - Electrode Positioning for Recording EGG

Materials and Methods

EGG has been conducted to the patients suffered from stomach disorders at gastroenterology department of a reputed hospital. Approximately 150 nos. includes patients, normal individual in both male and female category of different age groups are participated in this recording [8]. Table 1 lists the statistical parameters of the dyspepsia patient. These parameters are compared to portray the difference in magnitude of the signals. Readings were taken before and after food intake to shows the difference in the signal amplitude, frequency and power values. The signals were obtained from the patients with the stomach disorders such as Dyspepsia, Nausea, Stomach Ulcer, gastritis, etc. It is very apparent from the values in the table that the kurtosis and variance values vary to a large extent when compared to the other parameters. Higher kurtosis means more of the variance is due to infrequent extreme deviations, as opposed to frequent modestly-sized deviations. The kurtosis value of the patients decreases in the postprandial condition due to the changes in the occurrence of the peaks and fat tails [6, 7].

Table 1 - Statistical Parameters For Dyspepsia Patients

The variance parameter as defined before shows the difference in the values throughout the distribution the variation in the kurtosis and variance values implies the difference in the gastric emptying and stomach contractions in these subjects owing to the different diseases. The parameters recorded from normal individual are shown in Table 2. From this table it clearly understood that power increase in postprandial condition indicates that is normal individual.

Table 2 - Statistical parameters for normal individual

Figure 5 - A and B are recorded EGG from Dyspepsia, Normal Individual respectively

The EGG signals statistical parameter such as mean, rms, kurtosis, mode, median, amplitude, variance, frequency and power are recorded for further analysis of stomach disorders as shown in figure.5. Here A represent EGG waveform and all the statistical parameter for normal individual and B represents the same for dyspepsia patients respectively.

Algorithm and Flowchart

1. Lightly abrade the skin with abrasive pads, and put a spot of gel on the electrode contact area.

2. Two electrodes are placed on the Fundus and the mid-corpus and a reference electrode is placed on the right side of the abdomen.

3. The output of the electrodes is given to the Instrumentation amplifier (INA 129).

4. The amplified output signal is given to the virtual instrument setup via DAQ instrument

5. From DAQ Assistant (NI-DAQmx) device analog voltage is selected and the same is filtered using tenth order Low pass Butterworth filter.

6. The output of the filter is given to the statistical and spectral analysis sub VI.

7. The statistical parameters such us mean, rms, kurtosis, mode, median, amplitude, variance, frequency and power are recorded.

8. These data are displayed on the PC using LabVIEW software and the statistical parameters are recorded for preprandial and postprandial conditions.

9. The threshold for detection of various disorders was fixed based on the observations and in consultation with the physician as 4-5 cpm and 1-2.8 cpm for dyspepsia in preprandial condition and postprandial condition respectively, where as for a normal individual is about 3-3.5 cpm.

The pictorial representation of the above algorithm is shown in figure.6

Figure 6 - Flowchart of EGG Acquisition System for statistical analysis

Results and Discussion

The effectiveness of the proposed methodology is illustrated in figure. 7, which shows the range of frequencies and amplitudes for the abnormalities at preprandial and postprandial condition as observed from the recording setup in consultation of physician. The Variation in the frequency and power values are observed between preprandial and postprandial condition. The frequency, power variation for a dyspepsia patient is found to be around 0.135 Hz, 0.007 respectively for preprantial condition. The frequency, power variation for a dyspepsia patient is found to be around 1.9 Hz, 0.0039respectively for postprantial condition. It is observed from the above said, the value of power for postprandial condition is fall below the value of power occurs at preprantial condition. The change in the frequency value is observed for the dyspepsia patient is increased in the postprantial condition with respect to preprantial condition.

In this study, we have used the EGG to record myoelectrical activity for the patients suffering from Dyspepsia, Stomach ulcer and Nausea. The statistical parameters for the EGG signals are obtained with the help of LabVIEW software and its accessories for the both preprantial condition and postprantial condition and the same is plotted between normal individual and stomach disorder patients (Dyspepsia) [7,9].The deviation in the frequency and the power from the plot indicate stomach disorder at the fair amount of accuracy as shown in figure 7. The treatment of dyspepsia should be aimed at correcting physiological abnormalities [8]. A normal or abnormal EGG will not only help distinguish patient heterogeneity in clinical studies but might also provide a useful objective marker of treatment effect [11]. Further studies of wavelet transform tool in MATLAB software may improve the accuracy of the stomach disorders diagnosis. The EGG pattern recorded for a normal individual and the patients with digestive system disorders is shown in figure 8.

Figure 7 - Graphical representation between Normal Individual and dyspepsia patient with Statistical Parameter. Frequency variation plot Plot A & B) for preprantial and postprantial condition respectively. Power variation plot (Plot C & D) for preprantial and postprantial condition respectively. Bar graph representation Power variation in dyspepsia patient and Normal Individual (Plot E &F)

Figure 8 - Waveforms for different disease patterns. Normal patient Waveform with 3 cycles per minute as frequency (recording A). A dyspepsia patient wave pattern (recording B). A Nausea patient wave pattern (recording C). A Vomiting patient wave pattern (recording D). An Ulcer patient wave pattern (recording E)

Conclusion

In this paper, we have made an attempt and have succeeded in acquiring the EGG from normal individual and abnormal patients who are suffering from different stomach disorders under the monitor and guidance of the gastroenterologist from the reputed hospital. The signal analysis is performed using LabVIEW 8.0 statistical analysis sub VI for the recorded EGG before and after food for both normal individual and abnormal patients. The statistical parameters of the EGG are compared and it is observed that the power of the signal increased is confirmed in the postprantial condition. This fact very much support the previous research work done in the field. The kurtosis and variance values vary differently for different people owing to the kind of disease they are afflicted with. The snapshots showing the signals acquired from patients have been produced and the tables for statistical parameters are shown. The future work in this project would be to acquire EGG from patients suffering from different diseases. The signal analysis can be extended further using spectral analysis to a greater extent to study the intricate behaviour of the EGG signals which would help diagnose the diseases more efficiently and precisely. A database for each disease is desired to be created so that sufficient data will be available to diagnose a disease.

Acknowledgements

The authors acknowledge their indebtedness to the following medical experts Dr L Venkatakrishnan, M.D., D.M.,D.N.B., Head of Gastroenterology Dept., Dr.J.Krishnaveni, M.D.,D.N.B., Gastroenterologist from PSG Hospitals, Coimbatore and Dr M G Shekar, M.S., D.N.B., M.R.C.S., Laparoscopic surgeon Stanley Medical College and Hospital, Chennai for their support and for permitting us to use the facilities at the hospitals for live testing of the recording setup and sharing valuable patient database with us.

References

1. W.C.Alvarez. “The Electrogastrogram and what it shows”. JAMA, vol 78, pp.1116-1118, 1922.

2. A.J.P.M. Smout, E.J. Van Der Schee, J.L.Grashuis, “What is measured in electrogastrography?” Digestive Diseases and Sciences, pp.253, 1980.

3. T.L.Abell, J.R.Malagelada, “Electrogastrography: Current assessment and future perspectives”. Digestive Diseases and Sciences, vol 33, pp. 982-992, 1988.

4. J. Chen, R.W. McCallum, “Electrogastrography: measurement, analysis and prospective applications”. Medical &Biological Engineering & Computing, vol 29, pp.339-350, 1991.

5. G.Riezzo, F.Pezzolla, J. Thouvenot, et al, “Reproducibility of cutaneous recordings of electrogasography in the fasting state in man. Pathology Biology, vol 40, pp.889-894, 1992.

6. M.P. Mintchev, Y.J. Kingma, K.L. Bowes, “Accuracy of coutaneous recordings of gastric electrical activity”. Gastroenterology, vol 104, pp.1273-1280, 1993.

7. J. Chen, R.W. McCallum, “Gastric slow wave abnormalities in patients with gastroparesis”. Am J Gastroenterology, vol 87, pp.477-482, 1992.

8. B.Pfaffenban, R.J.Adamek, K.kuhn, et al. “Electrogastrography in healthy subjects. Evalation of normal values influences of age and gender”. Digestive Diseases and Sciences, vol 40, pp.445-450, 1995.

9. J.D.Z.Chen, Z.Lin, I.Pan, et al. “Abnormal gastric myoelectrical activity and delayed gastric emptying in patients with symptoms suggestive of gastroparesis”. Digestive Diseases and Sciences, vol 41, pp.15381545, 1996.

10. J.D.Z. Chen, “Non_invasive Measurement of gastric Myoelectrical Activity and its Analysis and Applications,” Annual International Conference of the IEEE Engineering in Medicine and Biology Society, Vol.20, No.6, pp.2802-2807, 1998.

11. A.Leahy, K.Besherdas, C.Clayman, I.Mason, O.Epstein., “Abnormalities of the electrogastrogram in functional dyspepsia”. American Journal of Gastroenterology, vol 94(4), pp.1023-1028, 1999.

12. J.D.Z. Chen, Zhiyue Lin, “Electrogastrogram-Encyclopedia of Medical Devices and Instrumentation”, Second Edition, edited by John G. Webster, John Wiley & Sons, Inc.2006.

13. G.Gopu, R.Neelaveni, K.Porkumaran, “Investigation of Digestive System Disorders using Electrogastrogram”, Proceeding International conference on Computer and Communication Engineering (ICCCE '08), Vol.2, pp.201-205, 13-15 May 2008, Kuala Lumpur, MALAYSIA.

14. G.Gopu, R.Neelaveni, K.Porkumaran, “Acquisition and Analysis of Electrogastrogram for Human Stomach Disorders”, Proceeding International conference on Recent Trends in Computational Science (ICRTCS'08), Vol.1,pp.162-169, 11-13 June 2008, Ernakulam, Kerala, INDIA.

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