为胃的倒空和活动性评估的电的 bioimpedance 和另外的技术

The aim of this article is to identify non-invasive, inexpensive, highly sensitive and accurate techniques for evaluating and diagnosing gastric diseases. In the case of the stomach, there are highly sensitive and specific methods for assessing gastric motility and emptying (GME). However, these methods are invasive, expensive and/or not technically feasible for all clinicians and patients. We present a summary of the most relevant international information on non-invasive methods and techniques for clinically evaluating GME. We particularly emphasize the potential of gastric electrical bioimpedance (EBI). EBI was initially used mainly in gastric emptying studies and was essentially abandoned in favor of techniques such as electrogastrography and the gold standard, scintigraphy. The current research evaluating the utility of gastric EBI either combines this technique with other frequently used techniques or uses new methods for gastric EBI signal analysis. In this context, we discuss our results and those of other researchers who have worked with gastric EBI. In this review article, we present the following topics: (1) a description of the oldest methods and procedures for evaluating GME; (2) an explanation of the methods currently used to evaluate gastric activity; and (3) a perspective on the newest trends and techniques in clinical and research GME methods. We conclude that gastric EBI is a highly effective non-invasive, easy to use and inexpensive technique for assessing GME.

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.

Multi-frequency bioimpedance measurements of rabbit shanks with stress fracture

Purpose: The objective of this research is to investigate whether bioimpedance is useful to indicate a shank’s physical condition during training. Methods: Bioimpedance was applied to monitor the condition of 8 rabbits’ shanks in 3 weeks, during which the rabbits were trained for regular excessive jump daily. Nine tibias in 16 developed stress fracture after the 3-week training. Results: According to the analysis of the bioimpedance data, we found that changing pattern of bioimpedance properties of shanks which were more liable to suffer from SF was different from that of shanks which were not during training. Conclusions: This suggests that bioimpedance may be used to monitor the physical condition of a limb, imply its liability to develop stress fracture, and indicate stress fracture during training.

The Development of an Instrument for Multi-frequency Bioimpedance Measurement

In order to study the bioimpedance method for evaluating body fluid equilibrium in hemodialysis patients, an instrument based on multi frequency bioimpedance measurement was developed. The hardware and software design of the instrument was introduced in this paper. The instrument is of safety and good duplicity.

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.

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.

Can non-invasive measurements aid clinical assessment of volume in patients with cirrhosis?

AIM:To evaluate the non-invasive assessments of volume status in patients with cirrhosis.METHODS:Echocardiography and multifrequency bioimpedance analysis measurements and short synacthen tests were made in 20 stable and 25 acutely decompensated patients with cirrhosis.RESULTS:Both groups had similar clinical assessments,cortisol response and total body water(TBW),however the ratio of extracellular water(ECW)/TBW was significantly greater in the trunk(0.420±0.004 vs0.404±0.005),and limbs(R leg 0.41±0.003 vs 0.398±0.003,P<0.05,and L leg 0.412±0.003 vs 0.399±0.003)with decompensated cirrhosis compared to stable cirrhotics,P<0.05).Echocardiogram derived right atrial and ventricular filling and end diastolic pressures and presence of increased left ventricular end diastolic volume and diastolic dysfunction were similar in both groups.The decompensated group had lower systemic blood pressure,mean systolic 101.8±4.3 vs122.4±5.3 and diastolic 58.4±4.1 mmHg vs 68.8±3.1 mmHg respectively,P<0.01,and serum albumin30(27-33)vs 32(31-40.5)g/L,P<0.01.CONCLUSION:Decompensated cirrhotics had greater leg and truncal ECW expansion with lower serum albumin levels consistent with intravascular volume depletion and increased vascular permeability.

Comparison of Cardiac Output Measurement by Noninvasive Method with Electrical Cardiometry and Invasive Method with Thermodilution Technique in Patients Undergoing Coronary Artery Bypass Grafting

Objective: This study was conducted to compare the cardiac output by using Electrical Cardiometry (EC), a noninvasive method of continuous cardiac output monitoring during cardiac surgery with pulmonary artery catheter (PAC) derived cardiac output. Design: Prospective observational clinical study. Setting: Cardiac surgery operating room of a tertiary care cardiac center. Participants: Twenty five patients undergoing coronary artery bypass surgery with cardiopulmonary bypass. Measurements and Main Results: A total of 150 double data of cardiac output were compared with Thermodilution Cardiac Output (TDCO) and Thoracic Electrical Bioimpedance (TEBCO). The TDCO value ranges from 1.8-6.9 litre·min-1 with a mean of 4.39 ± 1.16 litre·min-1 and TEBCO ranges from 1.8-7.1 litre·min-1 with a mean of 4.21 ± 1.16 litre·min-1. The averaged Bland-Altman analysis for TDCO and TEBCO revealed that a mean bias was 0.18 and limit of agreement was -1.25 - 0.89 litre·min-1 and the percentage error (PE) ranged from 22%-32%. The precision for the TDCO was measured to be ±16.2% and the precision for TEBCO was ±19.6%. Receiver Operating Characteristic (ROC) curve analysis between TDCO and TEBCO with a cutoff of 15% shows a sensitivity of 84% and specificity of 63 and area under ROC curve of 0.80. Mountain plot between TDCO and TEBCO shows that a median percentile is 0.25 and value of 97.5 percentile is 1.525. Conclusions: The present study indicates that the electric cardiometry device yields numerically comparable results to cardiac outputs derived from the PAC during the cardiac surgery. Therefore, electrical cardiometry can be used to evaluate haemodynamic variables with clinically acceptable accuracy, when invasive methods are to be avoided or not available.

High Accurate Howland Current Source: Output Constraints Analysis

Howland circuits have been widely used as powerful source for exciting tissue over a wide frequency range. When a Howland source is designed, the components are chosen so that the designed source has the desired characteristics. However, the operational amplifier limitations and resistor tolerances cause undesired behaviors. This work proposes to take into account the influence of the random distribution of the resistors in the modified Howland circuit over the frequency range of 10 Hz to 10 MHz. Both output current and impedance of the circuit are deduced either considering or the operational amplifiers parameters. The probability density function due to small changes in the resistors of the circuit was calculated by using the analytical modeling. Results showed that both output current and impedance are very sensitive to the resistors variations. In order to get higher output impedances, high operational amplifier gains are required. The operational amplifier open-loop gain increases as increasing the sensitivity of the output impedance. The analysis done in this work can be used as a powerful co-adjuvant tool when projecting this type of circuit in Spice simulators. This might improve the implementations of practical current sources used in electrical bioimpedance.

Microcontroller-Based Sinusoidal Voltage Generation for Electrical Bio-Impedance Spectroscopy Applications

A sinusoidal voltage wave generator is proposed based on the use of micro-processor digital signals with programmable duty-cycles, with application to real-time Electrical Cell-substrate Impedance Spectroscopy (ECIS) assays in cell cultures. The working principle relies on the time convolution of the programmed microcontroller (μC) digital signals. The expected frequency is easily tuned on the bio-impedance spectroscopy range [100 Hz, 1 MHz] thanks to the μC clock frequency selection. This system has been simulated and tested on the 8 bits μC ArduinoTM Uno with ATmega328 version. Results obtained prove that only three digital signals are required to fit the general specification in ECIS experiments, below 1% THD accuracy, and show the appropriateness of the system for the real-time monitoring of this type of biological experiments.

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.

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.

Ratio of Capacitance/BMI Reflects Deficit in Nutritional Concentration While CH2 Reflects Total Nutritional Deficit in CAPD Patients and General Population

Traditionally phase angle was the best predictor in BIA for nutrition and survival in dialysis population. We recently showed that normalized bioimpedance indices are a better risk discriminator for dialysis patients and the general popu-lation. We hereby aimed to explore discriminating factors behind them. Methods: We assessed the body capacitive index (BCI = Capacitance × Height2/Weight);body resistive index (BRI = Resistance × Weight/Height2);and also, CH2 (= Capacitance × Height2) which represents total body capacitive volume in physics. We initially performed BIA for 206 female, 116 male healthy volunteers, followed by, prospective study for 128 CAPD patients (47 diabetes mellitus (DM), 81 non-DM;59 male, 69 female) for >2 years. Results: Moderately good negative correlation of albumin and BCI (r = -0.533, p X2 = 165.6), followed by CH2 (X2 = 140), phase angle (X2 = 59.3) and BRI (X2 = 52.2). Thirty five (27.3%) patients died during the study period (Fatal cause: infection (54%), cardiovascular (26%)). In Cox regression, CH2 ( X24 = 32.4) was the best predictor for all-cause mortality, followed by BCI (X24 = 27.7) and phase angle ( X24 = 19.3). Conclusion: The phase angle was a compound parameter of the body capacity index (BCI) and body resistive index (BRI). BCI has a mod-erately good negative correlation with albumin and this supports its role in reflecting the severity of malnutrition in CAPD patients. CH2 represents total nutrition deficit and thus the major risk indicator for the survival of CAPD pa-tients.

A New Method for Cardiac Diseases Diagnosis

The objective of this work is to perform automatic diagnosis using a non invasive method which consists on the bioimpedance signal processing. Bioimpedance signal (BIS) represents the aorta impedance variation during the heart cycle activity. BIS is detected by mean of two electrodes located at the level of the ascendant aorta. Automatic diagnosis method consists on preparing, first, a data base with a set of cepstral parameters of different BIS according to normal case and different cardiac diseases. This data base is composed from n classes Yk corresponding to n diseases. The classification of anonymous individuals is based on the determination of Fisher distance between anonymous disease and class Yk using Fischer formula. Our method permits to calculate seven relevant cepstral parameters. The application of Fisher method has allowed us to perform the diagnosis of five anonymous cases. The major interest of this method is its especially useful for the exploration of cardiovascular system anomalies for emergency cases, children, elderly and pregnant women who can’t support surgical operations especially at the level of the heart.

Feasibility of bioelectric impedance as a measure of muscle mass in mechanically ventilated ICU patients

Background: Critically ill patients receiving prolonged mechanical ventilatory support are at risk for loss of muscle mass and muscle strength from immobility. Feasible, non-invasive methods are needed to accurately obtain data on markers of muscle mass to design effective interventions and monitor patient progress during recovery from critical illness. Bioelectric impedance has been used in other settings to obtain data on body composition and muscle mass. Purpose: The aims of this study were to determine the feasibility of bioelectric impedance as a marker of muscle mass in a sample of mechanically ventilated patients and to assess data trends in these obtained values. Methods: A descriptive design was used to obtain standard bioelectric impedance parameters (total body resistance, legs resistance, and percent lean body mass) over 4 days from eligible patients already enrolled in a randomized clinical trial. Results: Bioimpedance parameters were readily obtained over 4 days in a sample of 43 patients (age 59 + 15.7 years, 56% male) receiving prolonged ventilatory support (mean 9.4 + 10.4 days) due to respiratory failure. Reasons for not obtaining impedance measures included skin impairment, monitoring devices, or presence of implantable cardiac defibrillator or pacemaker. Average total body impedance was 464.3 + 117.1 ohms, while average impedance of legs was 479.1 + 146.4 ohms. Lean body mass was 68.4% (+10.8). Conclusions/Implications for Practice: With carefully trained staff and a standardized measurement protocol, bioimpedance is a feasible method to obtain body composition data reflective of muscle mass in mechanically ventilated patients. Further research will determine the utility of bioimpedance to monitor recovery and effectiveness of interventions to restore function after prolonged periods of ventilatory support and immobility in mechanically ventilated patients.

Treatment of Edematofibrosclerotic Panniculitis (Cellulite) and of Localised Adiposity with Extracts of Birch, Melilotus, Orthosiphon, Bromelin and Red Vine Leukocyanidine: Results from a Single-Centre Observational Prospective Study

The Edematofibrosclerotic Panniculitis (EFP) and the Localised Adiposity (LA) have controversial pathogenesis and therapy. A single-centre observational study has been performed to assess the potential efficacy, the limitations and the side effects of the medical treatment of EFP and AL by means of a multicomponent nutraceutical product. Fifty female subjects have been enrolled, mean age and BMI of the patients were 46 years and 24.18 respectively. The subjects have been submitted to a two-month treatment with two tablets of a nutraceutical based on extracts of Birch (100 mg), Orthosiphon (100 mg), Red Vine Leukocyanidines (100 mg), Melilotus (5 mg) and Bromelin (150 mg). The patients have been investigated before the treatment and during the treatment (at 30 and 60 days) by means of: a) volumetry of the lower limbs with tape measurement;b) visual analogue scale assessment (VAS) of symptoms such as pain paresthesia/dysesthesia, heaviness, and of the daily diuresis;c) duplex ultrasound evaluation of the thickness of the adipose tissue at the peri-trochanteric level;d) multifrequency segmental bioimpedance (MSB) analysis for the tissue liquid component. Forty-five of the 50 enrolled subjects have completed the study and five patients have discontinued the treatment, four of which due to unexpected personal problems or health problems not related to the treatment itself and one for reporting gastrointestinal disorders (such as constipation/diarrhea) with the nutraceutical intake. At the end of the therapeutical cycle, volumetry of the limbs decreased of 7% (right) and of 6% (left). Pre/post treatment VAS assessment of symptoms showed the following mean figures: heaviness from 5.10 to 0.88;paresthesia/dysesthesia from 0.90 to 0.00;pain from 2.03 to 0.12. Diuresis increased of 31%. Duplex-ultrasound assessment of the subcutaneous adipose layers at the trochanteric level showed a reduction of slightly more than 20% at the end of the treatment in both limbs. L-Dex bioimpedance values have been as follows: 3.97 at the enrolment;1.17 at the end of the treatment (reduction of the subcutaneous tissue fluid content). The present single-centre observational study proved that the tested nutraceutical multicomponent is effective and free of relevant side effects in the treatment of EFP and AL of the lower limbs. Larger cohort studies may possibly confirm the results of this preliminary experience.