Computer analysis of bowel sounds

An automatic method of analysis of bowel sound recordings has been developed. A PDP8/I computer, equipped with DECtape and interfaced with a TR48 analog computer was used for the analysis. It was found that the probability of a sound occurring followed a law similar to that of Poisson's phenomenon. Mean energy, sound duration and silence duration in the postmeal situation were respectively, 0·1589 V R.M.S., 4·5 msec, and 31·7 msec. No frequency exceeded 3000 Hz. This method of analysis was applied to experimental situations to study the importance of various parameters influencing the genesis of bowel sounds.     

Computerised method for acquisition and display of gastrointestinal motility data

A computerised system is developed for the acquisition and display of gastrointestinal motility data which utilises a purpose developed software program called ‘PC-motil’, running on an IBM compatible microcomputer. ‘PC-motil’ displays data during collection, writes data to disk file and compresses all data at the end of a study on to a single monitor screen for convenient overview. Any area of interest, in single or multiple channels, may be selected and expanded for detailed examination. This system is tested by the recording of gastric and jejunal motility patterns of 11 healthy volunteers in fasting and fed states. All antral and jejunal migrating motor complexes (MMCs) in fasting studies, as well as all fed motility patterns were recognisable in both ‘compressed’ and ‘expanded’ form. The reproduction of motility patterns by the computer based system was indistinguishable from that of a conventional analogue chart recorder. This computerised system provides a convenient and cost-effective means of acquisition, storage and display of motility data in digital form.     

Computer-supported analysis of continuous ambulatory manometric recordings in the human small bowel

An algorithm has been developed for the offline analysis of prolonged manometric recordings in the upper small intestine of humans. Sample data are acquired in the human duodenum and jejunum using six solid-state strain-gauge transducers mounted on a silicon catheter that is connected to a portable digital recording device. The data are sampled at 4 Hz and filtered. For accurate calculations, the filtered signals are converted to cubic B-spline functions of order four. Based on an exponential weighted moving average, a base-line is calculated from the signal. Contractions are recognised on the basis of thresholds for minimum amplitude and duration. The developed algorithm calculates properties of these contractions, such as amplitude, duration, area and a motility index. In addition, the program automatically recognises normal motor patterns of the fasted human small intestine, such as the migrating motor complex, and aids in the identification of the postprandial motor pattern. Motor patterns are defined in terms of properties such as contraction frequency and propagation. In a validation procedure using conventional manual analysis, the program correctly identifies the number of individual contractions with a 98% confidence interval and also correctly recognises 96% of phase 3 motor activity.     

Long-term signal detection, segmentation and summarization using wavelets and fractal dimension: a bioacoustics application in gastrointestinal-motility monitoring

The current paper describes a wavelet-based method for long-term processing and analysis of gastrointestinal sounds (GIS). Windowing techniques are used to select sequential blocks of the prolonged multi-channel recordings and proceed to various wavelet-domain processing stages. De-noising, significant-activity detection, automated segmentation and extraction of summary curves are applied in an integrated mode, allowing for enhanced content manipulation and analysis. The proposed analysis scheme combines flexible long-term graphical representation tools, while maintaining the ability of quick browsing via visualization and auralization of the detected short-term events. This work is part of a project aiming to implement non-invasive diagnosis over gastrointestinal-motility (GIM) physiology. However, the proposed techniques might be applied to any study of long-term bioacoustics time series.     

Design and application of sensor for recording sounds over human eye and nose

The recording of sounds over the oribt of the eye has been found to be useful in the detection of intracranial aneurysms. A hydrophone for auscultation over the eye has been developed and is tested under controlled conditions. The tests consist of measurement over the eyes in three healthy volunteers at rest, during voluntary breathing, during eyeball movements and during sustained orbicular muscular contractions. Furthermore, measurements are performed at the side of the nose. Major features of the hydrophonic transducer are high sensitivity to physiological sounds and a high degree of insensitivity to environmental sounds propagated through the air. It can be concluded that the hydrophone may be useful for the early detection of intracranial aneurysms and also for apnoea detection.     

Detection of epileptic events in electroencephalograms using wavelet analysis

This study deals with the problem of identification of epileptic events in electroencephalograms using multiresolution wavelet analysis. The following problems are analyzed: time localization and characterization of epileptiform events, and computational efficiency of the method. The algorithm presented is based on a polynomial spline wavelet transform. The multiresolution representation obtained from this wavelet transform and the corresponding digital filters derived allows time localization of epileptiform activity. The proposed detector is based on the multiresolution energy function. Electroencephalogram records from epileptic patients were analyzed, and results obtained are shown. Some comparisons with other methods are given.     

Evaluation of small bowel measurement in alive patients

Introduction  Based on the importance of bowel length in massive bowel resection, the aim of this study is to evaluate the small bowel length in patients who had laparotomy. Methods  In this study, 100 consecutive adults (age ≥ 20 years old) who underwent laparotomy were studied. Patients with peritonitis, intra-abdominal infection, bowel obstruction and ascitis were excluded. For comparison we used 30 cadavers as control group after case control matching. Under general anesthesia and after opening of abdomen, bowel length was measured by an umbilical tape from Treitz’ ligament to ileocecal valve, antimesentrically. Data such as age, sex, height, weight and bowel length were measured and analyzed. Results  Between May 2007 and December 2007, 100 patients (54 males and 46 females) aged 20–43 years were studied. The small bowel length was 459.6 ± 78.47 cm in patients and 632.5 ± 88.9 cm in cadavers (P < 0.01). Small bowel length was 452.2 ± 79.36 cm in males and 468.2 ± 80.44 cm in females (P = NS). Jejunum length was 140.2 ± 45.4 cm in males and 138.6 ± 40.2 cm in females (P = NS). Ileum length was 286.3 ± 34.7 cm in males and 289.9 ± 37.8 cm in females (P = NS). Conclusion  In this study, we report a measurement of the length of small bowel more accurate than the estimation given by the classical anatomic books. In our study, there was no correlation between bowel length and age, gender, height and weight.     

The effectiveness of the wavelet transforms method in the heart sounds analysis

Heart sounds can be used more efficiently by medical doctors when they are displayed visually, rather through a conventional stethoscope. Heart sounds provide clinicians with valuable diagnostic and prognostic information. Although heart sound analysis by auscultation is convenient as a clinical tool, heart sound signals are so complex and non-stationary that they are very difficult to analyse in time or frequency domains. We have studied the extraction of features from heart sounds in the time-frequency domain for recognition of heart sounds through time-frequency analysis. The application of wavelet transform for the heart sounds is thus described. The performance of continuous wavelet transform, discrete wavelet transform and packet wavelet transform is discussed in this paper. After these transformations, we can compare normal and abnormal heart sounds to verify clinical usefulness of our extraction methods for recognition of heart sounds.     

Detection of contractions in adaptive transit time of the small bowel from wireless capsule endoscopy videos

Recognizing intestinal contractions from wireless capsule endoscopy (WCE) image sequences provides a non-invasive method of measurement, and suggests a solution to the problems of traditional techniques for assessing intestinal motility. Based on the characteristics of contractile patterns and information on their frequencies, the contractions can be investigated using essential image features extracted from WCE videos. In this study, we proposed a coherent three-stage procedure using temporal and spatial features. The possible contractions are recognized by changes in the edge structure of the intestinal folds in Stage 1 and evaluating similarity features in consecutive frames in Stage 2. In order to take account of the properties of contraction frequency, we consider that the possible contractions are located within windows including consecutive frames. The size of these contraction windows is adjusted according to the passage of the WCE. These procedures aim to exclude as many non-contractions as possible. True contractions are determined through spatial analysis of directional information in Stage 3. Using the proposed method, 81% of true contractions are detected with a 37% false alarm rate for evaluations in the experiments. The overall performance of this method is better than that of previous methods, in terms of both the quality and quantity indices. The results suggest feasible data for further clinical applications.     

Spectral analysis and acoustic transmission of mitral and aortic valve closure sounds in dogs

A surgical protocol was designed to implant, in seven dogs, a programmable sequential atrioventricular pacemaker after destruction of the bundle of His to produce a chronic heart block. The heart rate and P-R interval were then varied independently and their influence on the spectra and acoustic transmission of the mitral M1 and aortic A2 valve closure sounds was studied. Results indicate that the major effects of varying the P-R interval are a strong change in the intensity of M1 and modifications of its acoustic transmission across the heart/thorax acoustic system. No similar influence is observed on the intensity and acoustic transmission of A2. Varying the heart rate has a small effect of the intensity of M1 but none on the intensity of A2. In addition, changes in either the P-R interval or the heart rate do not seem to modify the spectral profile of the intracardiac and thoracic M1 and A2 components.     

机械瓣心音频谱分析与基于改进LDB算法的识别

听诊是通过听取心脏所发出的声音来帮助诊断各种心脏疾病的一种有效手段。鉴于目前机械瓣的使用非常普遍,研究简单有效的机械瓣病变判别方法对于临床诊断来讲具有很大的意义。针对五种不同的机械瓣心音进行的分析表明,运用频谱仅能鉴别瓣周漏这一种机械瓣病变。虽然直接利用信号的时频成分进行机械瓣心音分类是可能的,但识别率只有84.0%。利用改进的局部最优基(LDB)算法来提取特征对机械瓣心音分类有着非常大的帮助,识别率达到了97.3%。与原始的LDB算法相比,实验表明改进后的LDB算法对提高识别率和降低计算复杂性都有着明显的优势。     

Spectral analysis and acoustic transmission of mitral and aortic valve closure sounds in dogs

A system model based on the simultaneous recording and analysis of the intracardiac and thoracic phonocardiograms to estimate the time-varying properties of the heart/thorax acoustic system of the dog is described. The presence of instrumental noise in the recording of intracardiac phonocardiograms is characterised, and it is demonstrated that its effect on the estimate of the transfer and coherence functions of the system can be quantified and corrected. Application of the model to study the spectral characteristics and the acoustic transmission properties of the mitral component M1 of the first heart sound and of the aortic component A2 of the second heart sound in the dog shows that the heart/thorax acoustic system acts like a bandpass filter having a higher attenuation for A2 than for M1. Between 20 and 100 Hz, the mean attenuation of M1 is 30 dB while that of A2 is 46 dB. Above 100 Hz, the attenuation slope is—12 dB per octave for M1 and—6 dB per octave for A2.     

Effects of Feedback in a Forced-Choice GSR Detection Task

Previous studies of the detection of internal events have failed to assess adequately the effects of external feedback on detection and identification of internal events. The purpose of the present study was to make use of a signal detection paradigm in an evaluation of feedback effects on the detection and identification of galvanic skin responses (GSRs). GSR detection was measured by the absolute difference between the areas above and below the receiver operating characteristic (ROC) curve, and reflected the extent to which subjects were able to differentiate between GSR and no-GSR trials. GSR identification was measured by the area below the ROC curve and reflected the labeling strategy (accurate or reversed) chosen by the subjects. It was found that external feedback as to the presence or absence and relative magnitude of GSRs was not necessary for differentiation of GSR and no-GSR trials, and that such feedback was detrimental to increased differentiation over sessions. External feedback may, however, have been useful in directing the attachment of identifying responses to the differentiated internal events. The similarity of these findings to findings reported in the schematic concept formation (SCF) literature was discussed. It was concluded that internal event detection tasks such as that used in the present study may be seen as examples of SCF involving internal stimulus events.     

Lifelong variations in heart rates in SPF Sprague Dawley rats of both sexes

In unanesthetized Sprague Dawleys, SPF, of both sexes, housed indl _12:12 (110 lux), at a temperature of 18–23°C and a hygrometry of 60–75%, the measurements of heart frequencies during most part of their life point out a continuous decrease with age and an always higher (40–20 c. min^–1) heart rate in females than in males. Significant correlations between rate and body weight can account for these heart which corresponds to the growth period, a linear relationship was established between Log heart rate (y;c. min^–1) and Log body weight (x; gram); for males: Logy=–0.122 Logx+Log 938 and for females: Logy=–0.166 Logx+Log 1217. After the age of 600 days, which corresponds to senescence, decreases in heart rate as well as in body weight were observed in both sexes.We acknowledge the technical assistance of Serge Hazout, Christian Lemercerre and Micheline Duriez     

A review of signal processing techniques for heart sound analysis in clinical diagnosis

This paper presents an overview of approaches to analysis of heart sound signals. The paper reviews the milestones in the development of phonocardiogram (PCG) signal analysis. It describes the various stages involved in the analysis of heart sounds and discrete wavelet transform as a preferred method for bio-signal processing. In addition, the gaps that still exist between contemporary methods of signal analysis of heart sounds and their applications for clinical diagnosis is reviewed. A lot of progress has been made but crucial gaps still exist. The findings of this review paper are as follows: there is a lack of consensus in research outputs; inter-patient adaptability of signal processing algorithm is still problematic; the process of clinical validation of analysis techniques was not sufficiently rigorous in most of the reviewed literature; and as such data integrity and measurement are still in doubt, which most of the time led to inaccurate interpretation of results. In addition, the existing diagnostic systems are too complex and expensive. The paper concluded that the ability to correctly acquire, analyse and interpret heart sound signals for improved clinical diagnostic processes has become a priority.     

Use of the fast Fourier transform in the frequency analysis of the second heart sound in normal man

The second heart sounds of 26 normal, young males, recorded at the aortic and pulmonary areas, were analysed for their frequency content by means of the fast Fourier transform. For both locations of measurement, peaks were observed in the frequency spectra in the lowfrequency range (10–80 Hz), the medium-frequency range (80–220 Hz), and the high-frequency range (220–400 Hz). In both the aortic and pulmonary areas, 25 of the 26 subjects had at least two peaks in the 80–400 Hz range, and a majority had one peak in the low-frequency range. A correlation coefficient of 0·75 was obtained between the medium frequency peaks in the aortic and pulmonary areas. The average frequency spectrum obtained for the entire study at each area indicates that the attenuation characteristics are nonlinear in the region of 10–160 Hz. For 160–400 Hz the attenuation in the pulmonary area is about 18 dB per octave and in the aortic area about 23 dB per octave. The observed peaks are probably related to the fluid-dynamic events causing the second heart sound. Thus important diagnostic information can probably be obtained from frequency analysis studies of cardiovascular sounds, and these studies will help in understanding the basic mechanisms which produce the sounds.     

Differential expression of HLA-D gene products in the normal and coeliac small bowel

Monoclonal antibodies to monomorphic determinants of the MHC class II region products, HLA-DR, DP and DQ were used to investigate their expression on cells of the normal and coeliac (both treated and untreated) small bowel. HLA-DR antigens showed a characteristic distribution in the normal small bowel: epithelial cells in the apical portions of the villi stained heavily, and this staining decreased in intensity towards the villous base. The crypt epithelial cells were clearly unstained. Stellate cells within the lamina propria were also HLA-DR positive. HLA-DP antigens showed a similar distribution, although the intensity of staining was less than that seen with HLA-DR. HLA-DQ antigens were absent from epithelial cells and were confined solely to cells within the lamina propria. In untreated coeliac disease, the intensities of both HLA-DR and HLA-DP were increased, and in addition a more extensive distribution of these antigens was observed. In addition to occurring on the surface epithelial cells, DR and DP antigens were now present on crypt epithelial cells. Despite this change in expression of DR and DP antigens, the distribution of HLA-DQ was essentially unaltered from that of the normal small bowel. The findings in treated coeliac disease were intermediate between those in the normal and untreated coeliac small bowel. The differential expression of class II antigens by normal and diseased small bowel epithelium which has been demonstrated may have implications for interactions of these cells with cells of the immune system.     

体表心电Mapping系统中心电信号的处理与峰值定位检测

体表心电Mapping是又一个新的心脏疾病诊断技术。作者考虑了体表心电噪声强、各导联之间心电差异性较大的特点,提出了性能较好的心电处理算法。其中包括:50Hz陷波、零相位低通滤波及宽范围抛物线拟合去除基线漂移的算法等。在此基础上,将心电信号的一阶差分、二阶差分及时域幅值相结合以形成阈值,通过在主峰值左、右作反复搜索的方法对Q、R、S及其它子波作精确定位。通过对28名临床病例的检验,定位准确率为97.7％。