Fluid Shift and Fluid Resuscitation in Burn Patients with the use of Bio-Electrical Impedance Spectroscopy to Monitor Fluid Levels

The purpose of this research is to explore the current methods of fluid resuscitation and other possible methods of measuring the body fluid levels of burn patients in order to fully understand the fluid increase patterns in the torso area. This will be done primarily by focusing on the concept of bio-electrical impedance spectroscopy to measure the fluid levels only in the human torso area. Three similar tests were carried out by measuring the resistance values after ingesting 500ml of water. This was repeated until a total of 1500ml of water was ingested. It was found that the resistance in the extracellular fluid (R0) appear to not be significantly affected by the increase in fluid intake but the resistance in the intracellular fluid (R∞) show a greater difference. This can be due to a variety of conditions including the path flow of the ingested water content. The resistance measurements from the back of the torso posed to be more accurate than that of the front of the torso. This can also be connected to the water path flow. In order to further study the chosen electrode placements and understand the cause of the difference between the front and back torso results, more focused tests will be carried out in the future

Evaluating Calf Bioimpedance Measurements For Fluid Overload Management In A Controlled Environment

Objective: To evaluate the relationship between calf bioimpedance measurements and fluid removal in a controlled environment (hemodialysis) as a first step toward using these measurements for remote congestive heart failure (CHF) monitoring. Approach: Calf bioimpedance measurements were recorded in 17 patients undergoing hemodialysis (9/17 (53%) CHF, 5/17 (30%) female). Measurements were performed before and after hemodialysis. Additional parameters related to hemodialysis and patient fluid status such as estimated dry weight were also recorded. Main results: Calf bioimpedance changes depended on calf fluid status as assessed by calf normalized resistivity (CNR). Patients with lower calf fluid overload (as assessed by CNR greater than 0.1017 Ω m3 kg-1) had larger decreases in calf fluid than patients with higher calf fluid overload. High CNR patients had fluid changes within the calf that depended on the ultrafiltration rate, with patients with lower ultrafiltration rates experiencing fluid shifts from extracellular to intracellular fluid. Additionally, there were correlations between changes in calf extra-, intra- and total- water and the ultrafiltration volume removed for high CNR patients (R² = 0.44, 0.42, 0.56, respectively, all p-values \u3c 0.05). Significance: These results suggest that while the relationship between calf fluid status and total fluid status is complex, changes in calf volumes comparable to those expected in an ambulatory setting are measurable and relate to changes in total volume. This suggests that calf bioimpedance measurements for CHF remote monitoring warrant future investigation, as remote fluid status management could reduce fluid overload related hospitalizations in CHF patients

Monitoring intracellular, interstitial, and intravascular volume changes during fluid management procedures

The bioimpedance spectroscopic (BIS) analytical algorithm described in this report allows for the non-invasive measurement of intravascular, interstitial, and intracellular volume changes during various fluid management procedures. The purpose of this study was to test clinical use feasibility and to demonstrate the validity of the BIS algorithm in computing compartmental volume shifts in human subjects undergoing fluid management treatment. Validation was performed using volume changes recorded from 20 end stage renal disease (ESRD) patients. The validation procedure involved mathematically deriving post hoc hematocrit profiles from the BIS data-generated fluid redistribution time profiles. These derived hematocrit profiles were then compared to serial hematocrit values measured simultaneously by a CritLine® monitor during 60 routine hemodialysis (HD) sessions. Regression and Bland Altman analyses confirm that the BIS algorithm can be used to reliably derive the continuous and real time rates of change of the compartmental fluid volumes. Regression results yielded a R(2) > 0.99 between the two measures of hematocrit at different times during dialysis. The slopes of the regression equations at the different times were nearly identical, demonstrating an almost one to one correspondence between the BIS and CritLine® hematocrits. Bland Altman analyses show that the BIS algorithm can be used interchangeably with the CritLine® monitor for the measurement of hematocrit. The present study demonstrates for the first time that BIS can provide real-time continuous measurements of compartmental intravascular, interstitial and intracellular fluid volume changes during fluid management procedures when used in conjunction with this new algorithm

Bioimpedance spectroscopy - can it be used as a tool for monitoring fluid shifts in burns?

Large fluid shifts and oedema are features of burn injuries. Oedema hampers burn wound healing and is directly related to the size and depth of the burn. The degree of oedema in burns covers a broad spectrum: Minor burns cause localised or peripheral oedema, whilst major burns may result in a systemic inflammatory response which can be life threatening and necessitates formal fluid resuscitation. Acute burn fluid resuscitation is paramount in decreasing patient morbidity and mortality but can contribute to already large amounts of oedema. There is currently no single clinically applicable, non-invasive and accurate outcome measure to titrate fluid volumes in acute burns or monitor the effect of treatments on oedema (in minor and major burns). Bioimpedance spectroscopy (BIS) has emerged as a possible solution to these challenges. It can measure body fluid compartments and thus fluid volume changes over time providing a sensitive non-invasive device to estimate resuscitation requirements and oedema change and is emerging as a measure of wound healing. This series of studies therefore aimed to 1) address the potential barriers to use of BIS in the burns population, 2) determine if BIS provides an accurate measure of whole body/systemic fluid volume change and 3) localised burn wound oedema changes, as applied across the spectrum of burn severity, and 4) determine if BIS can monitor wound healing in minor burns. The studies therefore investigated novel whole body and localised electrode positions in the presence of open and dressed wounds, using repeated measures over time in minor and major burns. The key novel findings arising from the research series include: 1) alternate electrode placements are interchangeable with standardised placement for the measurement of whole body resistance, extracellular and total body fluid volumes in specified dressing conditions. Therefore BIS can be utilised to monitor changes in fluid shifts when wounds preclude the manufacturer’s standard placement of electrodes in the presence of burn wounds, 2) BIS is a reliable method of monitoring fluid in any dressing condition and electrode position with no systematic bias indicated in both major and minor burns, 3) In both minor and major burns, BIS is a valid indicator of net fluid shifts and oedema change, if dressing condition is adjusted for using the developed algorithms or calculator and 4) BIS resistance variables, R0 and Rinf, can be used to monitor wound healing in minor limb burns as an adjunct to standard practice

Bioimpedance as a predictor of survival in renal failure and associated comorbidities.

Background: Renal failure requiring dialysis is associated with a high mortality. One of the contributing causes is overhydration. Overhydration can be assessed by bioimpedance analysis (BIA)– the non-invasive electrical measure of small current through the tissues that estimates the proportion of fluid that is intracellular water (ICW, typically muscle which is healthy) and extracellular (ECW, which in excess causes tissue oedema and is potentially dangerous). Several studies indicate that a extracellular water to total body water (TBW) ratio is associated with increased risk of death in dialysis patients but it is not clear if this is independent of other risk factors for death, namely comorbidity. Aims and objectives: To establish the prognostic value of BIA in the prediction of survival on dialysis in the context of other known predictors of survival or hospitalisation. With further analysis of the applicability of the same scenario to heart failure patients. Methodology: To conduct a systematic review using a standardised approach including a prespecified research question, search terms and criteria for study inclusion. With independent selection for inclusion in the study and quality appraisal by multiple authors with different backgrounds and experience. Results: 2701 studies identified by literature search, plus an additional 4 through reference checking. 38 papers included in final analysis, 4 of which were regarding heart failure cohorts. Analysis of the research shows that BIA is an independent predictor of mortality. Conclusion: BIA shown to be an independent predictor of mortality in dialysis patients, further research needed to extrapolate to heart failure (HF) populations