Effect of psychological stress on gastric motility assessed by electrical bio-impedance

AIM:To evaluate gastric motility using electrical bioimpedance(EBI) and gastric changes as a result of stress induced by psychological tests.METHODS:A group of 57 healthy women,aged 40-60 years,was recruited,and a clinical history and physical examination were performed.The women were free from severe anxiety,chronic or acute stress,severe depression,mental diseases and conditions that affect gastric activity.The women were evaluated under fasting conditions,and using a four-electrode configuration,the gastric signals were obtained through a BIOPAC MP-150 system.The volunteers were evaluated using the following paradigm:basal state,recording during the Stroop Test,intermediate resting period,recording during the Raven Test,and a final resting period.We analyzed the relative areas of the frequency spectrum:A1(1-2 cpm),A2(2-4 cpm),A3(4-8 cpm),and A4(8-12 cpm),as well as the median of area A2 + A3.The data were analyzed by an autoregressive method using a Butterworth filter with MatLab and Origin.Analysis of variance(ANOVA) and Friedman ANOVA(for nonparametric variables) were performed;in addition,pairs of groups were compared using the T dependent and Wilcoxon T tests.RESULTS:The results of the main values of area A2 were not significantly different comparing the five steps of the experimental paradigm.Nevertheless,there was a tendency of this A2 region to decrease during the stress tests,with recuperation at the final resting step.When an extended gastric region was considered(1-4 cpm),significant differences with the psychological stress tests were present(F = 3.85,P = 0.005).The A3 region also showed significant changes when the stress psychological tests were administered(F = 7.25,P < 0.001).These differences were influenced by the changes in the adjacent gastric region of A2.The parameter that we proposed in previous studies for the evaluation of gastric motility by electrical bio-impedance(EBI) was the median of the area under the region from 2 to 8 cpm(A2 + A3).The mean values of these frequencies(median of the A2 + A3 area) with the stress test showed significant changes(F = 5.5,P < 0.001).The results of the WilcoxonT test for the A4 area parameter,which is influenced by the breathing response,changed significantly during the Raven stress test(P < 0.05).CONCLUSION:We confirm that the gastric response to acute psychological stress can be evaluated by short-term EBI.

Effects of metoclopramide on gastric motility measured by short-term bio-impedance

AIM:To analyze the accuracy of short-term bio-impedance as a means of measuring gastric motility.METHODS: We evaluated differences in the short-term electrical bio-impedance signal from the gastric region in the following conditions: (1) fasting state, (2) after the administration of metoclopramide (a drug that induces an increase in gastric motility) and (3) after food ingestion in 23 healthy volunteers. We record-ed the real component of the electrical impedance signal from the gastric region for 1000 s. We performed a Fast Fourier Transform (FFT) on this data and then compared the signal among the fasting, medicated, and postprandial conditions using the median of the area under the curve, the relative area under the curve and the main peak activity.RESULTS: The median of the area under the curve of the frequency range in the region between 2-8 cycles per minute (cpm) decreased from 4.7 cpm in the fasting condition to 4.0 cpm in the medicated state (t=3.32, P=0.004). This concurred with the decrease seen in the relative area under the FFT curve in the region from 4 to 8 cpm from 38.3% to 26.6% (t=2.81, P=0.012) and the increase in area in the region from 2 to 4 cpm from 22.4% to 27.7%, respectively (t=-2.5, P=0.022). Finally the main peak position also decreased in the region from 2 to 8 cpm. Main peak activity in the fasting state was 4.72 cpm and declined to 3.45 cpm in the medicated state (t=2.47, P=0.025). There was a decrease from the fasting state to the postprandial state at 3.02 cpm (t=4.0, P=0.0013). CONCLUSION: Short-term electrical bio-impedance can assess gastric motility changes in individuals experiencing gastric stress by analyzing the area medians and relative areas under the FFT curve.

Concordance between bio-impedance analysis and clinical score in fluid-status assessment of maintenance haemodialysis patients: A single centre experience

BACKGROUND The burden of chronic kidney disease(CKD)is rising rapidly globally.Fluid overload(FO),an independent predictor of mortality in CKD,should be accurately assessed to guide estimation of the volume of fluid to be removed during haemodialysis(HD).Clinical score(CS)and bio-impedance analysis(BIA)have been utilized in assessment of FO and BIA has demonstrated reproducibility and accuracy in determination of fluid status in patients on HD.There is need to determine the performance of locally-developed CSs in fluid status assessment when evaluated against BIA.AIM To assess the hydration status of patients on maintenance HD using BIA and a CS,as well as to evaluate the performance of that CS against BIA in fluid status assessment.METHODS This was a single-centre,hospital-based cross-sectional study which recruited adult patients with CKD who were on maintenance HD at Kenyatta National Hospital.The patients were aged 18 years and above and had been on maintenance HD for at least 3 mo.Those with pacemakers,metallic implants,or bilateral limbs amputations were excluded.Data on the patients’clinical history,physical examination,and chest radiograph findings were collected.BIA was performed on each of the study participants using the Quantum®II bio-impedance analyser manufactured by RJL Systems together with the BC 4®software.In evaluating the performance of the CS,BIA was considered as the gold standard test.A 2-by-2 table of the participants’fluid status at each of the CS values obtained compared to their paired BIA results was constructed(either++,+-,--or-+for FO using the CS and BIA,respectively).The results from this 2-by-2 table were used to compute the sensitivity and specificity of the CS at the various reference points and subsequently plot a receiver operating characteristic(ROC)curve that was used to determine the best cut-off point.Those above and below the best CS cut-off point as determined by the ROC were classified as being positive and negative for FO,respectively.The proportions of participants diagnosed with FO by the CS and BIA,respectively,were computed and summarized in a 2-by-2 contingency table for comparison.McNemar’s chi-squared test was used to assess any statistically significant difference in proportions of patients diagnosed as having FO by CS and BIA.Logistic regression analysis was conducted to assess whether the variables for the duration of dialysis,the number of missed dialysis sessions,advisement by health care professional on fluid or salt intake,actual fluid intake,the number of anti-hypertensives used,or body mass index were associated with a patient’s odds of having FO as diagnosed by BIA.RESULTS From 100 patients on maintenance HD screened for eligibility,80 were recruited into this study.Seventy-one(88.75%)patients were fluid overloaded when evaluated using BIA with mean extracellular volume of 3.02±1.79 L as opposed to the forty-seven(58.25%)patients who had FO when evaluated using the CS.The difference was significant,with a P value of<0.0001(95%confidence interval:0.1758-0.4242).Using CS,values above 4 were indicative of FO while values less than or equal to 4 denoted the best cut-off for no FO.The sensitivity and specificity for the CS were 63%and 78%respectively.None of the factors evaluated for association with FO showed statistical significance on the multivariable logistic regression model.CONCLUSION FO is very prevalent in patients on chronic HD at the Kenyatta National Hospital.CS detects FO less frequently when compared with BIA.The sensitivity and specificity for the CS were 63%and 78%respectively.None of the factors evaluated for association with FO showed statistical significance on the multivariable logistic regression model.

Design of a Noninvasive Bladder Urinary Volume Monitoring System Based on Bio-Impedance

For the needs of bladder urinary volume noninvasive monitoring in clinical, we present a noninvasive bladder urinary volume monitoring system based on bio-impedance. The system uses a four-electrode structure,which is composed of a pair of excitation electrodes and a pair of measurement electrodes. The Direct Digital Frequency Synthesis (DDS) is applied to generate a 50 kHz sine current excitation source. The impedance information extracted from phase sensibility demodulation technology is transferred to a computer through Zigbee wireless technology for real-time monitoring. Two experiments are taken to verify the accuracy and feasibility of the system. The experiments results show that the system can accurately measure the corresponding electrical impedance change of the bladder. The system provides a new way to continuously and noninvasively monitor the bladder urinary volume of patients with bladder dysfunction.

Towards Bio-impedance Based Labs： A Review

In this article, some of the main contributions to BI （Bio-Impedance） parameter-based systems for medical, biological and industrial fields, oriented to develop micro laboratory systems are summarized. These small systems are enabled by the development of new measurement techniques and systems （labs）, based on the impedance as biomarker. The electrical properties of the life mater allow the straightforward, low cost and usually non-invasive measurement methods to define its status or value, with the possibility to know its time evolution. This work proposes a review of bio-impedance based methods being employed to develop new LoC （Lab-on-a-Chips） systems, and some open problems identified as main research challenges, such as, the accuracy limits of measurements techniques, the role of the microelectrode-biological impedance modeling in measurements and system portability specifications demanded for many applications.

Hematocrit level correlates with lungs resistivity in elderly patients with cardiogenic pulmonary edema

Regular monitoring of pulmonary congestion in car-diogenic pulmonary edema (CPE) patients is neces-sary for its adequate management via pharmaceuti-cal treatment. It is well known that the development of CPE is accompanied with an increase in hema-tocrit, plasma protein concentration and colloid os-motic pressure due to the decrease in the plasma volume. In the present study the mean left and right lung resistivity values taken pre- and post treatment with diuretics using a hybrid bio-impedance electri-cal impedance tomography system were correlate to the measured changes in hematocrit level. A marginal significant correlation was found between the abso-lute mean lung resistivity and hematocrit levels (Pearson’s correlation coefficient of R = 0.4, p-value = 0.057). When the change in the mean lung resistivity of a patient was plotted vs. the change in hematocrit readout, a significant linear correlation was found (R = 0.7, p-value = 0.02). These results support the validity of the resistivity measurements using bio-impedance system in monitoring changes of pulmonary edema in CPE patients.

Acute heart failure (suspected or confirmed): Initial diagnosis and subsequent evaluation with traditional and novel technologies

Acute or worsening heart failure is a common reason for hospitalization which carries a high mortality. Prompt diagnosis or exclusion of HF and its cause and precipitating factors can improve the quality and efficiency of care, shorten hospital stay, reduce readmission and improve prognosis. While the clinician remains central to reaching a clinical diagnosis of heart failure, the use of traditional and novel diagnostic technologies will improve the specificity and sensitivity of the diagnosis of heart failure diagnosis and provide insights into its pathophysiogical profile and help tailor therapy to individual patient need. Chest X-rays and electrocardiograms are generally available;echocardiograms less so. Novel technologies include both invasive and non-invasive methods to detect increases in intrathoracic fluid, pulmonary congestion, left ventricular filling pressures, cardiac output and vascular function. However, few of these technologies have been subjected to randomised controlled trials investigating their ability to improve patient management.

Determinants of Regional Obesity (Visceral and Subcutaneous Obesity) within Cardiovascular Risk Factors in the Cardiology Department of the University Clinics of Kinshasa

Objective: This study aimed to determine searching for the determinants of regional obesity (visceral and subcutaneous obesity) within the cardiovascular risk factors (CVRF) in patients followed in cardiology at the University Clinics of Kinshasa (UCK) in the Democratic Republic of Congo (DRC). Material and Methods: Cross-sectional and analytical study had sought the determinants of regional obesity (visceral and subcutaneous obesity) by bio-impedance inside the CVRF during the period from July 1 to September 31, 2014. The multivariate analysis (logistic regression) has established the levels of association between regional obesity and CVRF. The statistical significance threshold was set at p Results: A total of 642 patients participated in the present study. The frequencies of visceral and subcutaneous obesity were respectively 45.5% (without significant distinction between the two sexes: Men 48% n = 92/188 vs. Women 44.1 n = 200/454;p = 0.148) and 60.7% with a predominance in women (36.2 n = 68/188 vs. 70.9% n = 322/454;p that alongside regional obesity was: advanced age, tobacco use, alcohol use, physical inactivity, high blood pressure (HBP), diabetes mellitus (DM) and Chronic renal failure (CRF) in the respective proportions of 50.8%, 13.4%, 44.2%, 86.3%, 10.7%, 13.4% and 0.3%. The determinants of regional obesity were advanced age, smoking and obesity on body mass index (BMI) for visceral obesity;advanced age, female gender, alcohol intake and obesity on BMI and waist circumference (WC) as well as hypertriglyceridemia for subcutaneous obesity. Conclusion: This study showed a significant frequency of regional obesity with the following determinants: advanced age, female gender, smoking, alcohol, BMI/WC obesity and hypertriglyceridemia.

Total body water percentage and 3rd space water are novel risk factors for training-related lower extremity muscle injuries in young males

Purpose:To identify the risk factors for training-related lower extremity muscle injuries in young males by a non-invasive method of body composition analysis.Methods:A total of 282 healthy young male volunteers aged 18-20 years participated in this cohort study.Injury location,degree,and injury rate were adjusted by a questionnaire based on the overuse injury assessment methods used in epidemiological studies of sports injuries.The occurrence of training injuries is monitored and diagnosed by physicians and treated accordingly.The body composition was measured using the BodyStat QuadScan 4000 multifrequency Bio-impedance system at 5,50,100 and 200 kHz to obtain 4 impedance values.The Shapiro-Wilk test was used to check whether the data conformed to a normal distribution.Data of normal distribution were shown as mean±SD and analyzed by t-test,while those of non-normal distribution were shown as median(Q1,Q3)and analyzed by Wilcoxon rank sum test.The receiver operator characteristic curve and logistic regression analysis were performed to investigate risk factors for developing training-related lower extremity injuries and accuracy.Results:Among the 282 subjects,78(27.7%)developed training injuries.Lower extremity training injuries revealed the highest incidence,accounting for 23.4%(66 cases).These patients showed higher percentages of lean body mass(p=0.001),total body water(TBW,p=0.006),extracellular water(p=0.020)and intracellular water(p=0.010)as well as a larger ratio of basal metabolic rate/total weight(p=0.006),compared with those without lower extremity muscle injuries.On the contrary,the percentage of body fat(p=0.001)and body fat mass index(p=0.002)were lower.Logistic regression analysis showed that TBW percentage>65.35%(p=0.050,odds ratio=3.114)and 3rd space water>0.95%(p=0.045,odds ratio=2.342)were independent risk factors for lower extremity muscle injuries.Conclusion:TBW percentage and 3rd space water measured with bio-impedance method are potential risk factors for predicting the incidence of lower extremity muscle injuries in young males following training.