Addressing the Barriers to Bioimpedance Spectroscopy Use in Major Burns: Alternate Electrode Placement

Does exercise influence burn-induced inflammation: A cross-over randomised controlled feasibility trial

Background

Burn injuries trigger a greater and more persistent inflammatory response than other trauma cases. Exercise has been shown to positively influence inflammation in healthy and diseased populations, however little is known about the latent effect of exercise on chronic inflammation in burn injured patients. The aims of the pilot study were to assess the feasibility of implementing a long duration exercise training program, in burn injured individuals including learnings associated with conducting a clinical trial in COVID-19 pandemic.

Methods

Fifteen participants with a burn injury between 5–20% total body surface area acquired greater than a year ago were randomised in a within-subject designed study, into one of two conditions, exercise–control or control–exercise. The exercise condition consisted of six weeks of resistance and cardiovascular exercises, completed remotely or supervised in a hospital gym. A comprehensive outcome measurement was completed at the initial, mid and end point of each exercise and control condition. To determine the success of implementation, the feasibility indicator for the data completeness across the comprehensive outcome battery was set at 80%.

Results

Half (49%) of eligible participants in the timeframe, were recruited and commenced the study. Six participants withdrew prior to completion and a total of 15 participants completed the study. Eight participants were randomised to the exercise-control and seven to the control exercise group. Five participants trained remotely and seven did supervised training. Three participants completed a mix of both supervised and remote training initiated due to COVID restrictions. Outcome measures were completed on 97% of protocolised occasions and 100% of participants completed the exercise training.

Conclusions

Conducting a long duration exercise training study on burn injured individuals is feasible using the described methods. The knowledge gained helps improve the methodology in larger-scale projects. Insights into the impact of COVID-19 on this clinical trial and success enhancing adaptations for the researcher, research practice and the participant, are presented.

Comparison of silver-plated nylon (Ag/PA66) e-textile and Ag/AgCl electrodes for bioelectrical impedance analysis (BIA)

Recently, researchers have adapted Bioelectrical Impedance Analysis (BIA) as a new approach to objectively monitor wounds. They have indicated various BIA parameters associated to specific wound types can be linked to wound healing through trend analysis relative to time. However, these studies are conducted using wet electrodes which have been identified as possessing several shortcomings, such as unstable measurements. Thus, the adaption of e-textile electrodes has become an area of interest in measuring biosignals. E-textile electrodes are known to possess a significantly large polarization impedance (Z_p) that potentially influences these biosignal measurements. In this study we aim to identify the suitability of e-textile electrodes to monitor wounds using BIA methodologies. By adapting suggested methodologies conducted in-vivo from previous studies, we used an ex-vivo model to observe the behaviour of e-textile electrodes relative to time. This was compared to common clinical wet electrodes, specifically Ag/AgCl. The objective of this study was to identify the BIA parameters that can be used to monitor wounds with e-textile electrodes. By analysing the BIA parameters relative to time, we observed the influence ofZ_pon these parameters.

Bioimpedance Spectroscopy Is a Valid and Reliable Measure of Edema Following Hand Burn Injury (Part 1-Method Validation)

The assessment of swelling following burn injury is complicated by the presence of wounds and dressings and due to patients experiencing significant pain and impaired movement. There remains a lack of sensitive objective measures for edema in patients presenting with hand burn injury. Bioimpedance spectroscopy (BIS) is a measure of body composition that has been demonstrated by our group to be reliable for measuring whole body and limb edema during resuscitation and to be sensitive to edema changes within healing wounds. The aim of this study was to determine the reliability and validity of BIS as a measure of edema following hand burn injury specifically. One hundred patients presenting with burn injury including a portion of a hand were recruited to this trial. Repeated measures of the hand were recorded using a novel application of BIS and in parallel with water displacement volumetry (WDV). The results were analyzed using mixed-effects regressions. Paired repeated measures were obtained for 195 hands, using four electrode configurations. BIS demonstrated high reliability in measuring hand BIS-Intraclass Correlation Coefficient 0.995 to 0.999 (95% CI 0.992-1.000) and sensitivity-Minimum Detectable Difference 0.74 to 3.86 Ω (0.09-0.48 Ω/cm). A strong correlation was shown with WDV, Pearson's r = -0.831 to -0.798 (P < .001). BIS is a sensitive and reliable measure of edema following acute hand burn injury.

An objective measure for the assessment and management of fluid shifts in acute major burns

BACKGROUND

Major burns are life threatening. Fluid resuscitation is required for survival to maintain intravascular volumes and prevent hypovolemic shock. Bioimpedance spectroscopy (BIS) has been recognised as a potential method of monitoring fluid shifts after burn and in other disease states. The aims of this study were to examine the reliability of BIS across different dressing conditions and electrode positions, establish the influence of Acticoat™ on BIS variable measures and determine the validity of whole-body BIS to assess net fluid shift in the presence of moderate to major burns.

METHODS

An observational longitudinal cohort study was conducted from December 2014 to February 2016. Patients with over 15% total body surface area (TBSA) burns and injury less than 48 h were enrolled in the study. BIS triplicate measures were collected in an open wound and with an ActicoatTM dressing (at 5 half hour intervals). Standard and alternate electrode placements were utilised for the reliability analysis and standard placement only for determining the validity of BIS in moderate to major burns. The ImpediMde SFB7 was used to collect whole-body and segmental BIS measures. Stata statistical software, release 14 was utilised to analyse all results. Descriptive analyses were performed and were reported using the means and standard deviations (SD).

RESULTS

BIS-repeated measures established BIS raw resistance (R), and predicted volume variables were reliable in any condition (intra-class correlation coefficient (ICC) 0.996-0.999, 95% confidence intervals (CI) 0.996-0.999) without a systematic difference. Acticoat™ dressings significantly influenced all BIS-predicted volumes (p ≤ 0.01) as determined by multilevel mixed effects (MLME) linear regression analysis. Validity of BIS was demonstrated by resistance variables significantly decreasing with increasing net ionic fluid shift and increased TBSA (severity of injury) and calculated fluid volumes increasing with increasing net fluid shift and TBSA. BIS resistance also decreased with time as oedema reduced. For clinical use, a calculator was developed to adjust BIS variables when an Acticoat™ dressing is in situ, thus facilitating BIS variable change estimates in real time, with dressings intact.

CONCLUSION

BIS may be used clinically to monitor fluid volume change in major acute burns.