Bioimpedance measurement device for chronic wound healing monitoring

A chronic wound is loosely defined as a wound that fails to heal within a time period of a few months. Elderly bedridden people and people suffering from certain underlying medical conditions, such as vascular diseases and type 2 diabetes, are particularly prone to develop chronic wound. The group of people exposed is increasing in numbers. Treatment of a chronic ulceration is very costly and the monitoring of healing is often based on visual inspection by medical professionals. There exists a need for objective and non-intrusive method for assessment of chronic wound healing. In this Master of Science Thesis a prototype of a bioimpedance device for monitoring of chronic wound healing was designed, constructed and tested. The device works from an indicator basis and measures the changes in the tissue impedance. The direction of the change correlates with the change in the volume and in the conductivity of the tissue, consequently in the swelling around the inflamed wound. Decrease in extracellular fluid can be detected as increasing low frequency impedance. The device measures impedance at 5kHz and 100kHz frequency by using triangular excitation. The emphasis of the design was on the simplicity of the device to provide a possibility for downscaling in the future. Ultimately the device would be integrated on a patch type platform together with a drug delivery system. The test measurements with the bioimpedance device were fairly extensive. The measurements were performed with a purely resistive load and a 2R-1C circuit. For 5kHz excitation the results for both load circuits did show only a slight mean error with a fairly small standard deviation. For 100kHz excitation the results did show larger mean error with a small standard deviation. Small standard deviation points to a systematic error. However, the 100kHz results are somewhat controversial since the difference between mean error for the purely resistive load and for the 2R-1C is fairly large. Restricted in vivo measurements were also performed. The in-vivo measurements did show large error compared to the reference measurements. Due to the limited nature of the measurements solid conclusions from these measurements cannot be made. All in all, the test measurements indicate the potential of simplified design. The accuracy of the device can be increased remarkably with certain improvements made to the design

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 (Zp) 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 of Zp on these parameters.Peer ReviewedPostprint (author's final draft

Bioimpedance method for monitoring venous ulcers: Clinical proof-of-concept study

Evaluation of wound status is typically based on means which require the removal of dressings. These procedures are often also subjective and prone to inter-observer bias. To overcome aforementioned issues a bioimpedance measurement-based method and measurement system has been developed to evaluate the state of wound healing. The measurement system incorporated a purpose-built bioimpedance device, a measurement software and a screen-printed electrode array. The feasibility and the performance of the system and method were assessed in an open non-randomized follow-up study of seven venous ulcers. Healing of ulcers was monitored until the complete re-epithelialization was achieved. The duration of follow-up was from 19 to 106 days (mean 55.8 +/- 25.2 days). A variable designated as the Wound Status Index (WSI), derived from the bioimpedance data, was used for describing the state of wound healing. The wound surface area was measured using acetate tracing for the reference. A strong correlation was found between the WSI and the acetate tracing data, r(93) = 0.84, p < 0.001. The results indicate that the bioimpedance measurement-based method is a promising quantitative tool for the evaluation of the status of venous ulcers

Nitrate stable isotopes and major ions in snow and ice samples from four Svalbard sites

Increasing reactive nitrogen (N-r) deposition in the Arctic may adversely impact N-limited ecosystems. To investigate atmospheric transport of N-r to Svalbard, Norwegian Arctic, snow and firn samples were collected from glaciers and analysed to define spatial and temporal variations (1 10 years) in major ion concentrations and the stable isotope composition (delta N-15 and delta O-18) of nitrate (NO3-) across the archipelago. The delta N-15(NO3-) and delta O-18(NO3-) averaged -4 parts per thousand and 67 parts per thousand in seasonal snow (2010-11) and -9 parts per thousand and 74 parts per thousand in firn accumulated over the decade 2001-2011. East-west zonal gradients were observed across the archipelago for some major ions (non-sea salt sulphate and magnesium) and also for delta N-15(NO3-) and delta O-18(NO3-) in snow, which suggests a different origin for air masses arriving in different sectors of Svalbard. We propose that snowfall associated with long-distance air mass transport over the Arctic Ocean inherits relatively low delta N-15(NO3-) due to in-transport N isotope fractionation. In contrast, faster air mass transport from the north-west Atlantic or northern Europe results in snowfall with higher delta N-15(NO3-) because in-transport fractionation of N is then time-limited

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 wholebody 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

Tephrochronology and its application: A review

Tephrochronology (from tephra, Gk ‘ashes’) is a unique stratigraphic method for linking, dating, and synchronizing geological, palaeoenvironmental, or archaeological sequences or events. As well as utilising the Law of Superposition, tephrochronology in practise requires tephra deposits to be characterized (or ‘fingerprinted’) using physical properties evident in the field together with those obtained from laboratory analyses. Such analyses include mineralogical examination (petrography) or geochemical analysis of glass shards or crystals using an electron microprobe or other analytical tools including laser-ablation-based mass spectrometry or the ion microprobe. The palaeoenvironmental or archaeological context in which a tephra occurs may also be useful for correlational purposes. Tephrochronology provides greatest utility when a numerical age obtained for a tephra or cryptotephra is transferrable from one site to another using stratigraphy and by comparing and matching inherent compositional features of the deposits with a high degree of likelihood. Used this way, tephrochronology is an age-equivalent dating method that provides an exceptionally precise volcanic-event stratigraphy. Such age transfers are valid because the primary tephra deposits from an eruption essentially have the same short-lived age everywhere they occur, forming isochrons very soon after the eruption (normally within a year). As well as providing isochrons for palaeoenvironmental and archaeological reconstructions, tephras through their geochemical analysis allow insight into volcanic and magmatic processes, and provide a comprehensive record of explosive volcanism and recurrence rates in the Quaternary (or earlier) that can be used to establish time-space relationships of relevance to volcanic hazard analysis. The basis and application of tephrochronology as a central stratigraphic and geochronological tool for Quaternary studies are presented and discussed in this review. Topics covered include principles of tephrochronology, defining isochrons, tephra nomenclature, mapping and correlating tephras from proximal to distal locations at metre- through to sub-millimetre-scale, cryptotephras, mineralogical and geochemical fingerprinting methods, numerical and statistical correlation techniques, and developments and applications in dating including the use of flexible depositional age-modelling techniques based on Bayesian statistics. Along with reference to wide-ranging examples and the identification of important recent advances in tephrochronology, such as the development of new geoanalytical approaches that enable individual small glass shards to be analysed near-routinely for major, trace, and rare-earth elements, potential problems such as miscorrelation, erroneous-age transfer, and tephra reworking and taphonomy (especially relating to cryptotephras) are also examined. Some of the challenges for future tephrochronological studies include refining geochemical analytical methods further, improving understanding of cryptotephra distribution and preservation patterns, improving age modelling including via new or enhanced radiometric or incremental techniques and Bayesian-derived models, evaluating and quantifying uncertainty in tephrochronology to a greater degree than at present, constructing comprehensive regional databases, and integrating tephrochronology with spatially referenced environmental and archaeometric data into 3-D reconstructions using GIS and geostatistics

RAKENNUKSEN KÄYTTÖTARKOITUKSEN MUUTTAMINEN : Vapaa-ajan asunnosta vakituinen asunto

Tämän opinnäytetyön tavoitteena oli selvittää, miten vapaa-ajan asunto voidaan muuttaa vakituiseksi asuinrakennukseksi. Tarkoitus oli suunnitella esimerkkikohde, johon käyttötarkoituksen muutos tehtäisiin. Opinnäytetyöhön koottiin yleisimmät lait, asetukset ja määräykset, jotka vaikut-tavat käyttötarkoituksen muutokseen. Näiden pohjalta tehtiin vapaa-ajan asuntoa koskevat muutossuunnitelmat, työssä suunnitelmat esitettiin tekstein ja kuvioin. Ongelmaksi tämän työn osalta ilmeni rakentamista koskeva lainsäädäntö, sillä se on parhaillaan muutoksen alla. Esimerkkikohteessa ei huomioitu tulevia lakimuutoksia, niillä voi olla paljonkin vaikutusta vapaa-ajan asunnon käyttötarkoituksen muutoksessa.The objective of this thesis was to examine how a free-time dwelling is changed to a residential building. In addition, the effects of the change were studied. The research was conducted only in the building, not in the building place. The laws, acts and regulations concerning construction were examined in this thesis. The change was planned in a typical free-time house that had originally been designed for a full year usage. The challenge in this study was the construction legislation that is currently being changed. The thesis did not take into account the future changes to the law which may also have an impact on the purpose of the change