Electrical bioimpedance gastric motility measurement based on an electrical-mechanical composite mechanism

AIM： To introduce a bioimpedance gastric motility mea- surement method based on an electrical-mechanical composite concept and a preliminary clinical application. METHODS： A noninvasive gastric motility measure- ment method combining electrogastrograrn （EGG） and impedance gastric motility （IGM） test was used. Prelim- inary clinical application studies of patients with func- tional dyspepsia （FD） and gastritis, as well as healthy controls, were carried out. Twenty-eight FD patients （mean age 40.9±9.7 years） and 40 healthy volun- teers （mean age 30.9±7.9 years） were involved. IGM spectrum was measured for both the healthy subjects and FD patients, and outcomes were compared in the FD patients before treatment and 1 wk and 3 wk after treatment. IGM parameters were obtained from 30 erosive gastritis patients （mean age 50.5±13.0 years） and 40 healthy adults, and IGM and EGG results were compared in the gastritis patients before treatment and 1 wk after treatment.RESULTS： There were significant differences in the IGM parameters between the FD patients and healthy subjects, and FD patients had a poorer gastric motility [percentage of normal frequency （PNF） 70.8±25.5 in healthy subjects and 28.3 =t= 16.9 in FD patients, P 〈 0.01]. After 1 wk administration of domperidone 10 mg, tid, the gastric motility of FD patients was not im- proved, although the EGG of the patients had returned to normal. After 3 wk of treatment, the IGM rhythm of the FD patients became normal. There was a significant difference in IGM parameters between the two groups （PNF 70.4：1：25.5 for healthy subjects and 36.1 4- 21.8 for gastritis patients, P 〈 0.05）. The EGG rhythm of the gastritis patients returned to normal （frequency insta- bility coefficient 2.22±0.43 before treatment and 1.77 ：t： 0.19 one wk after treatment, P 〈 0.05） after 1 wk of treatment with sodium rabeprazole tablets, 10 mg, qd, po, qm, while some IGM parameters showed a tenden- cy toward improvement but had not reached statistical significance. CONCLUSION： The electrical-mechanical composite measurement method showed an attractive clinical appli- cation prospect in gastric motility research and evaluation.

Frequency Domain Adaptive Learning Algorithm for Thoracic Electrical Bioimpedance Enhancement

The Thoracic Electrical Bioimpedance(TEB)helps to determine the stroke volume during cardiac arrest.While measuring cardiac signal it is contaminated with artifacts.The commonly encountered artifacts are Baseline wander(BW)and Muscle artifact(MA),these are physiological and nonstationary.As the nature of these artifacts is random,adaptive filtering is needed than conventional fixed coefficient filtering techniques.To address this,a new block based adaptive learning scheme is proposed to remove artifacts from TEB signals in clinical scenario.The proposed block least mean square(BLMS)algorithm is mathematically normalized with reference to data and error.This normalization leads,block normalized LMS(BNLMS)and block error normalized LMS(BENLMS)algorithms.Various adaptive artifact cancellers are developed in both time and frequency domains and applied on real TEB quantities contaminated with physiological signals.The ability of these techniques is measured by calculating signal to noise ratio improvement(SNRI),Excess Mean Square Error(EMSE),and Misadjustment(Mad).Among the considered algorithms,the frequency domain version of BENLMS algorithm removes the physiological artifacts effectively then the other counter parts.Hence,this adaptive artifact canceller is suitable for real time applications like wearable,remove health care monitoring units.

Gastric motility functional study based on electrical bioimpedance measurements and simultaneous electrogastrography

For some time now,the research on gastric motility and function has fallen behind in the amount of research on gastric endocrine,exocrine secretion,and gastric morphology.In this paper,a noninvasive method to study gastric motility was developed,taking bioimpedance measurements over the gastric area simultaneously with the electrogastrography(EGG).This is based on the concept of observing and analyzing simultaneously the intrinsic electrical gastric activity(basic electric rhythm) and the mechanical gastric activity.Additionally,preliminary clinical studies of healthy subjects and subjects with functional dyspepsia(FD) and gastritis were carried out.The impedance gastric motility(IGM) measurements of the healthy and FD subjects were compared,along with the studies of the FD subjects before treatment and after one week and three weeks of treatment.We also compared IGM measurements of healthy subjects and subjects with erosive gastritis,along with the studies of the subjects with erosive gastritis before treatment and after one week of treatment.Results show that FD subjects have poor gastric motility(P<0.01).After a week of treatment,the gastric motility of FD subjects was not yet improved although the EGG had returned to normal by this time.By three weeks of treatment,the regular IGM rhythm returned in FD subjects.There was a significant difference of IGM parameters between the gastritis and healthy subjects(P<0.05).The EGG rhythm of the gastritis subjects returned to normal at one week post-treatment,while IGM parameters showed a trend to improvement(P>0.05),These results suggest the possibility of clinic application of the proposed method.

Bioelectrical impedance vector analysis evaluates cellularity and hydration in cirrhotic patients

BACKGROUND Malnutrition in cirrhotic patients is correlated with mortality and a better response to liver transplantation.However,recovery of the nutritional status in these patients is a challenge due to the difficulty in establishing a reliable nutritional diagnosis.The bioelectrical impedance vector analysis(BIVA)method appears as a feasible tool in clinical practice to define the physiological state of cirrhotic patients by assessing hydration and body cellularity.AIM To evaluate body composition in cirrhotic patients using BIVA.METHODS This retrospective cross-sectional study was carried out by following cirrhotic outpatients at a hospital in Porto Alegre,Brazil.A tetrapolar bioelectrical impedance analysis device was used to evaluate cellularity and hydration and to perform the BIVA.The BIVA graphic was elaborated by software and for statistical analysis a significance level of 5%(P≤0.05)was considered.RESULTS One hundred and ninety patients,61.1%males,with a mean age of 56.6±11.0 years,were evaluated.Of these,56.3%had Child-Turcotte-Pugh(CTP)A score,and the prevalent etiology was hepatitis C virus(47.4%).The patients were classified according to cellularity and hydration by the quadrants and ellipses of the BIVA method,quadrant 1(47.9%);quadrant 2(18.9%);quadrant 3(14.2%);and quadrant 4(18.9%).Those classified in quadrant 1 and 2 had a higher phase angle compared to those in quadrants 3 and 4(P<0.001).Quadrant 2 patients had a lower average age than the other groups.The association with CTP score showed that patients in quadrant 2 had a higher proportion of CTP A,and those in quadrant 4 had a higher proportion of CTP C(P<0.052).CONCLUSION The BIVA method allows identification of the cellularity and hydration status of cirrhotic patients,and its association with clinical factors determines the disease severity,age and prognostic index.

Characterization of Short-Term Stress Applied to the Root System by Electrical Impedance Measurement in the First Leaf of Corn(Zea mays L.)and Pumpkin(Cucurbita maxima L.)

We applied electrical spectroscopic impedance measurements (ESI) to the first leaf of intact plants of corn and pumpkin. The electric capacity (C) and resistance (Rp) were determined at the characteristic frequency (FC). We observed that the electrical parameters of the ESI change in relation to the nutrition and the addition to the root medium of KCN, N,N'-dicyclohexylcar-bodiimide (DCCD), CH3COOH, H2SO4, polyethylene glycol 200 (PEG 200) and NaCl. The amplitude of the curves of bioimpedance spectrometry decreased when plant roots were stressed comparatively to their controls. An increase of the electrical capacity with a reduction of the electrical resistance characterizes a stress. The increase of stress intensity provokes decreases of Rp and curve amplitudes and an increase of C. We conclude that electrical parameters studied can be widely used for stress characterization.

Role of the phase angle in the prognosis of the cirrhotic patient:15 years of follow-up

BACKGROUND In 2019,cirrhosis accounted for 2.4%of global deaths.The projection for 2030 is an increase in this index.In recent years,hospitalization costs have escalated by 36%for compensated cirrhosis and 24%for decompensated cirrhosis.Therefore,it is necessary to identify a tool capable of predicting the mortality of these patients according to their clinical condition and consequently extending their survival time.Different studies have shown that the phase angle(PA)can be a feasible method in clinical practice,with the potential to guide assertive patient management in the therapeutic of chronic liver disease.AIM To evaluate the prognostic role of PA in cirrhotic patients over a 15-year followup period.METHODS Retrospective cohort study with 129 cirrhotic patients of both sexes over 18 years old.Diagnosis of cirrhosis by liver biopsy.The first year of data collection was 2007,and data regarding outcomes was collected in 2023.Data were gathered from medical records,such as esophageal varices(EV),EV bleeding,ascites,spontaneous bacterial peritonitis(SBP),encephalopathy,laboratory findings and PA.The cut-off value for the PA was 5.4°,a value described in 2012 by Fernandes et al for 129 patients evaluated in this study and the cut-off points for the Brazilian population presented in percentiles(P),as described by Mattiello et al.The mortality was assessed using the PA percentile through Kaplan-Meier curves and multivariate binary logistic regression models.RESULTS Patients were divided into two groups according to the PA 5.4th(PA>5.4°,n=40;PA≤5.4°,n=89)PA percentile(<P50,n=56;≥P50 n=73).The percentile classification was more accurate in identifying long-term deaths than the 5.4ºPA.Patients with<P50 had a higher number of relevant complications such as ascites,SBP,liver encephalopathy and HCC.PA is strongly correlated with serum albumin(P<0.001),International Normalized Ratio(P=0.01),total bilirubin(P=0.02)and direct bilirubin(P=0.003).PA is correlated with survival time(P<0.001)and length of stay(P=0.02).Logistic regression analysis shows that an increase of 1°in PA enlarges the cirrhotic patient's chance of survival by 17.7%.CONCLUSION PA is a good predictor of morbidity and mortality for cirrhotic patients.The PA by percentile showed greater sensitivity in predicting mortality compared to the cut-off point of 5.4º.