Impedance ratio: a novel marker and a powerful predictor of mortality in hemodialysis patients

Phase angle and impedance ratio as meta-inflammation biomarkers after a colon cleansing protocol in a group of overweight young women

Objective. Blood C-reactive protein (CRP) and the electrical bioimpedance spectroscopy (EBIS) variables phase angle (PhA) and impedance ratio (IR) have been proposed as biomarkers of metainflammation in overweight/obesity. CRP involves taking blood samples, while PhA and IR imply a less-than-2-minute-non-invasive procedure. In this study, values for these variables and percent body fat mass (PBFM) were obtained and compared before and immediately after a colon cleansing protocol (CCP), aimed at modulating intestinal microbiota and reducing metainflammation, as dysbiosis and the latter are intrinsically related, as well as along a period of 8 weeks after it.Approach. 20 female volunteers (20.9-24.9 years old) participated: 12 in an overweight group (OG), and 8 in a lean group (LG). TheOGwas divided in two subgroups (n= 6, each): control (CSG) and experimental (ESG). TheESGunderwent a 6-day CCP at week 2, while 5 volunteers in theCSGunderwent it at week 9.Main results.Pre/post-CCP mean values for the variables in theOGwere: PBFM (34.3/31.3%), CRP (3.7/0.6 mg dl-1), PhA (6.9/7.5°) and IR*10 (0.78/0.77). CalculatedR2correlation factors among these variables are all above 0.89. The favourable changes first seen in theESGwere still present 8 weeks after the CCP.Significance.(a) the CCP drastically lowers meta-inflammation, (b) EBIS can be used to measure metainflammation, before and after treatment, (c) for microbiota modulation, CCP could be a good alternative to more drastic procedures like faecal microbiota transplantation; (d) reestablishing eubiosis by CCP could be an effective coadjutant in the treatment of overweight young adult women.

SOFA Score Plus Impedance Ratio Predicts Mortality in Critically Ill Patients Admitted to the Emergency Department: Retrospective Observational Study

Background: The Sequential Organ Failure Assessment (SOFA) is a scoring system used for the evaluation of disease severity and prognosis of critically ill patients. The impedance ratio (Imp-R) is a novel mortality predictor. Aims: This study aimed to evaluate the combination of the SOFA + Imp-R in the prediction of mortality in critically ill patients admitted to the Emergency Department (ED). Methods: A retrospective cohort study was performed in adult patients with acute illness admitted to the ED of a tertiary-care referral center. Baseline SOFA score and bioelectrical impedance analysis to obtain the Imp-R were performed within the first 24 h after admission to the ED. A Cox regression analysis was performed to evaluate the mortality risk of the initial SOFA score plus the Imp-R. Harrell’s C-statistic and decision curve analyses (DCA) were performed. Results: Out of 325 patients, 240 were included for analysis. Overall mortality was 31.3%. Only 21.3% of non-surviving patients died after hospital discharge, and 78.4% died during their hospital stay. Of the latter, 40.6% died in the ED. The SOFA and Imp-R values were higher in non-survivors and were significantly associated with mortality in all models. The combination of the SOFA + Imp-R significantly predicted 30-day mortality, in-hospital mortality, and ED mortality with an area under the curve (AUC) of 0.80 (95% CI: 74–0.86), 0.79 (95% CI: 0.74–0.86) and 0.75 (95% CI: 0.66–0.84), respectively. The DCA showed that combining the SOFA + Imp-R improved the prediction of mortality through the lower risk thresholds. Conclusions: The addition of the Imp-R to the baseline SOFA score on admission to the ED improves mortality prediction in severely acutely ill patients admitted to the ED.

The impact of hydration status and fluid distribution on pulmonary function in COPD patients

Chronic Obstructive Pulmonary Disease (COPD) patients have alterations in body composition. Bioelectrical impedance analysis (BIA) evaluates body composition, hydration status, and fluid distribution. Subjects with fluid disturbances have been found to have lower FEV1, respiratory muscle strength, and poor prognosis. We aimed to evaluate the effect of hydration status and fluid distribution on pulmonary function in COPD patients. A cross-sectional study, 180 patients with a confirmed diagnosis of COPD were included. Patients with asthma, advanced renal or liver disease, acute HF, exacerbation of COPD, or pacemakers were excluded. Hydration status variables (TBW, ECW, ICW) and disturbance of fluid distribution [impedance ratio (IR) > 0.84 and phase angle (PhA)] were evaluated by BIA. Pulmonary function was assessed by spirometry. The mean population age was 71.55 ± 8.94 years; 55% were men. Subjects were divided into two groups according to the IR ≥ 0.84 or < 0.84. The group with higher IR ≥ 0.84 had lower FEV1, FVC, FEV1/FVC, DLCO and, PhA compared to those with IR < 0.84. After adjusting for confounding variables TBW, ECW, IR ≥ 0.84, PhA, and resistance/height increase were associated with decreased FEV1. In the same way, with IR ≥ 0.84, edema index ≥ 0.48, trunk and abdominal IR were negatively associated with FVC, and PhA had a positive association with FVC. Fluid distribution, especially IR and PhA, could be a useful parameter for predicting pulmonary function in COPD patients.

Effect of bioimpedance-defined overhydration parameters on mortality and cardiovascular events in patients undergoing dialysis: a systematic review and meta-analysis

OBJECTIVE

To evaluate the role of bioimpedance-defined overhydration (BI-OH) parameters in predicting the risk of mortality and cardiovascular (CV) events in patients undergoing dialysis.

METHODS

We searched multiple electronic databases for studies investigating BI-OH indicators in the prediction of mortality and CV events through 23 May 2020. We assessed the effect of BI-OH indexes using unadjusted hazard ratios (HRs) and 95% confidence intervals (CIs). Sensitivity analysis was used for each outcome.

RESULTS

We included 55 studies with 104,758 patients in the meta-analysis. Extracellular water/total body water (ECW/TBW) >0.4 (HR 5.912, 95% CI: 2.016-17.342), ECW/intracellular water (ICW) for every 0.01 increase (HR 1.041, 95% CI: 1.031-1.051), and OH/ECW >15% (HR 2.722, 95% CI: 2.005-3.439) increased the risk of mortality in patients receiving dialysis. ECW/TBW >0.4 (HR 2.679, 95% CI: 1.345-5.339) and ECW/ICW per increment of 10% (HR 1.032, 95% CI: 1.017-1.047) were associated with an increased risk of CV events in patients undergoing dialysis. A 1-degree increase in phase angle was a protective factor for both mortality (HR 0.676, 95% CI: 0.474-0.879) and CV events (HR 0.736, 95% CI: 0.589-0.920).

CONCLUSIONS

BI-OH parameters might be independent predictors for mortality and CV events in patients undergoing dialysis.

Association of impedance ratio with corrected Geriatric Nutritional Risk Index in older patients with nondialysis chronic kidney disease stage 5

BACKGROUND

The usual calculation of body mass index (BMI) can be misleading in patients with advanced chronic kidney disease (CKD) because their altered fluid balances may not be reflected. We obtained corrected BMI (cBMI) and corrected Geriatric Nutritional Risk Index (cGNRI) values and investigated whether the impedance ratio (IR) of 200/5 kHz, measured using bioimpedance spectroscopy, was associated with cGNRI in older patients with nondialysis CKD stage 5 (CKD5-ND).

METHODS

Patients over 65 years old (n = 118) were divided into groups by cGNRI tertiles. The differences between the correlations were tested using Steiger's z-test. The IR and cBMI were used as both continuous and categorical variables in the regression analyses to determine the factors that were independently associated with the cGNRI.

RESULTS

Patients in the third cGNRI tertile had a significantly lower mean IR than those in the other 2 tertiles (P < .001). Across the 3 cGNRI tertile groups, the IR was incrementally lower in the higher cGNRI tertiles (P for trend < .001). The Steiger's z-test showed that the IR had a significantly stronger correlation with cGNRI than cBMI had with cGNRI. In the multivariable linear regression analyses, the IR was independently associated with the cGNRI, after adjusting for various confounders.

CONCLUSION

The current results revealed that the IR was a more sensitive indicator of nutrition risk than BMI and was independently associated with cGNRI in older patients with CKD5-ND. Our study suggests that the IR is an appropriate tool for nutrition risk screening.

Comparison of Bioelectrical Impedance Analysis Parameters for the Detection of Fluid Overload in the Prediction of Mortality in Patients Admitted at the Emergency Department

BACKGROUND

Fluid overload (FO) in critically ill patients is associated with increased adverse events. This study aims to compare different bioelectrical impedance analysis (BIA) parameters that demonstrate FO and their association with 30-day mortality in critical patients admitted to the emergency department (ED).

METHODS

Five components of the BIA were obtained by multifrequency device-total body water (TBW), extracellular water (ECW), intracellular water (ICW), resistance (R), and reactance (Xc)-to calculate parameters (impedance vectors, impedance ratio, and the ratios of ECW to TBW, ECW to ICW, ECW to body surface area, TBW to height² , ICW to height² , Xc to height, and R to height) that have been used for the detection of FO. A concordance analysis (κ) was performed comparing every parameter with each other. Furthermore, different regression models (Cox regression) were created associating the FO for each parameter with 30-day mortality, adjusted for age, body mass index, sex, Sequential Organ Failure Assessment score, and serum albumin level.

RESULTS

A total of 142 patients were included in the study. Only FO by impedance vector analysis (relative risk [RR] = 6.4; 95% CI, 1.5-27.9; P = .01), impedance ratio (RR = 2.7; 95% CI, 1.1-7.1; P = .04), and R (RR = 2.6; 95% CI, 1.2-5.5; P = .02) increased the probability of 30-day mortality.

CONCLUSIONS

Different parameters that determine FO by BIA were associated with the mortality of patients admitted to the ED, but the impedance vector analysis was superior to any other parameter of the BIA.

Smart Bioimpedance Spectroscopy Device for Body Composition Estimation

The purpose of this work is to describe a first approach to a smart bioimpedance spectroscopy device for its application to the estimation of body composition. The proposed device is capable of carrying out bioimpedance measurements in multiple configurable frequencies, processing the data to obtain the modulus and the bioimpedance phase in each of the frequencies, and transmitting the processed information wirelessly. Another novelty of this work is a new algorithm for the identification of Cole model parameters, which is the basis of body composition estimation through bioimpedance spectroscopy analysis. Against other proposals, the main advantages of the proposed method are its robustness against parasitic effects by employing an extended version of Cole model with phase delay and three dispersions, its simplicity and low computational load. The results obtained in a validation study with respiratory patients show the accuracy and feasibility of the proposed technology for bioimpedance measurements. The precision and validity of the algorithm was also proven in a validation study with peritoneal dialysis patients. The proposed method was the most accurate compared with other existing algorithms. Moreover, in those cases affected by parasitic effects the proposed algorithm provided better approximations to the bioimpedance values than a reference device.

An evaluation of phase angle, bioelectrical impedance vector analysis and impedance ratio for the assessment of disease status in children with nephrotic syndrome

Background

Oedema, characterized by accumulation of extracellular water (ECW), is one of the major clinical manifestations in children suffering from nephrotic syndrome (NS).

The lack of a simple, inexpensive and harmless method for assessing ECW may be solved by the use of the bioelectrical impedance analysis (BIA) technique.

The aims of this study were to examine whether phase angle (PA), bioelectrical impedance vector analysis (BIVA) and the impedance ratio (IR) reflect change in disease status in children with NS.

Methods

Eight children (age range: 2–10 years) with active NS (ANS group) were enrolled. In five of these (ANS* subgroup), impedance was also measured at remission (NSR group). Thirty-eight healthy children (age range: 2–10 years) were included as healthy controls (HC group). Whole-body impedance was measured with a bioimpedance spectroscopy device (Xitron 4200) with surface electrodes placed on the wrist and ankle.

Results

Values of PA, BIVA and IR were found to be significantly lower (p-value range < 0.001 to < 0.01) in the ANS patients compared to the HC and NSR groups. No significant differences were observed between the NSR and HC groups.

Conclusion

The studied parameters can be used to assess change in disease status in NS patients. Data were consistent with NS being associated with expansion of ECW.

Electronic supplementary material

The online version of this article (10.1186/s12882-019-1511-y) contains supplementary material, which is available to authorized users.

The effect of "xanthan gum-based fluid thickener" on hydration, swallowing functions and nutritional status in total maxillectomy patients

PURPOSE

Swallowing functions are affected after total maxillectomy operations and adjuvant chemoradiotherapy. The purpose of our study is to assess the role of xanthan gum based thickening agents on swallowing and hydration of maxillectomy patients on a randomized controlled fashion.

METHODS

12 of the 22 patients diagnosed with maxillary carcinoma and planned to undergo total maxillectomy was identified as study group and 10 of them were identified as control group. The study group used "xantham based liquid thickener" for liquid foods up to 3 months postoperatively and the control group did not use. Dysphagia-related quality of life, bioimpedance analysis, EAT-10 scores, swallowing functions were evaluated both preoperative and postoperative period.

RESULTS

The mean age of the study group was 56 ± 9.87, and 41.6% were women. The mean age of control group was 60 ± 15.63, and 50% were women. Postoperative EAT-10 scores were statistically significant higher than preoperative scores in both groups (p < 0.05). In both of the study and control groups, a statistically significant reduction in dysphagia related quality of life was detected postoperatively (p < 0.05). Intracellular water, extracellular water and total body water detected statistically significant higher in study group at postoperative month three.

CONCLUSION

Swallowing functions are affected due to total maxillectomy and radiotherapy. With this study, it has been shown that, total maxillectomy and radiotherapy reduce dysphagia-related quality of life. Swallowing dysfunction and dehydration has been shown to affect total maxillectomy patients. Using of 'xanthan gum-based fluid thickener' helps to maintain intracellular water, extracellular water, and total body water.

Bioimpedance-defined overhydration predicts survival in end stage kidney failure (ESKF): systematic review and subgroup meta-analysis

Both overhydration and comorbidity predict mortality in end-stage kidney failure (ESKF) but it is not clear whether these are independent of one another. We undertook a systematic review of studies reporting outcomes in adult dialysis patients in which comorbidity and overhydration, quantified by whole body bioimpedance (BI), were reported. PubMed, EMBASE, PsychInfo and the Cochrane trial database were searched (1990-2017). Independent reviewers appraised studies including methodological quality (assessed using QUIPS). Primary outcome was mortality, with secondary outcomes including hospitalisation and cardiovascular events. Of 4028 citations identified, 46 matched inclusion criteria (42 cohorts; 60790 patients; 8187 deaths; 95% haemodialysis/5% peritoneal dialysis). BI measures included phase angle/BI vector (41%), overhydration index (39%) and extra:intracellular water ratio (20%). 38 of 42 cohorts had multivariable survival analyses (MVSA) adjusting for age (92%), gender (66%), diabetes (63%), albumin (58%), inflammation (CRP/IL6-37%), non-BI nutritional markers (24%) and echocardiographic data (8%). BI-defined overhydration (BI-OH) independently predicted mortality in 32 observational cohorts. Meta-analysis revealed overhydration >15% (HR 2.28, 95% CI 1.56-3.34, P < 0.001) and a 1-degree decrease in phase angle (HR 1.74, 95% CI 1.37-2.21, P < 0.001) predicted mortality. BI-OH predicts mortality in dialysis patients independent of the influence of comorbidity.

Prediction of hemodialysis vascular access failure using segmental bioimpedance analysis parameters

PURPOSE

Segmental bioimpedance analysis (BIA) can identify fluid volume changes in the arms of patients on hemodialysis (HD) after vascular access surgery. We investigated whether the difference in fluid volumes between the arms of the patients using segmental BIA is associated with vascular access outcome.

METHODS

Body composition measurements were taken for 127 patients on HD with segmental, multi-frequency BIA equipment (InBody 1.0, Biospace Co. Ltd, Seoul, Korea). The difference in fluid volume between the arms of the patients was calculated from the fluid volume of the arm with the vascular access minus that of the other. The primary outcome was the loss of vascular access patency within 3 months of BIA measurement.

RESULTS

The median absolute and relative inter-arm fluid volume differences were 150 ml [interquartile range (IQR) 90-250 ml] and 9.6% (IQR 4.9-14.4%), respectively. Within 3 months of BIA measurement, 38 patients (30.0%) experienced vascular access failure. When the patients were divided into three groups based on the tertiles of relative inter-arm fluid volume differences (lowest tertile: < 6.8%; middle tertile: 6.8-12.7%; highest tertile: > 12.7%), greater difference in relative inter-arm fluid volume differences was associated with higher vascular access failure rates (14 vs. 28 vs. 48%, p value for trend across tertiles = 0.003).

CONCLUSIONS

We conclude that segmental BIA may be used as a tool that can predict vascular access failure in patients on HD by calculating the relative difference in fluid volume between the arms of the patients with and without vascular access.