Development of an integrated surface stimulation device for systematic evaluation of wound electrotherapy.

Ideally, all chronic wounds would be prevented as they can become life threatening complications. The concept that a wound produces a 'current of injury' due to the discontinuity in the electrical field of intact skin provides the basis for the concept that electrical stimulation (ES) may provide an effective treatment for chronic wounds. The optimal stimulation waveform parameters are unknown, limiting the reliability of achieving a successful clinical therapeutic outcome. In order to gain a more thorough understanding of ES for chronic wound therapy, systematic evaluation using a valid in vivo model is required. The focus of the current paper is development of the flexible modular surface stimulation (MSS) device by our group. This device can be programed to deliver a variety of clinically relevant stimulation paradigms and is essential to facilitate systematic in vivo studies. The MSS version 2.0 for small animal use provides all components of a single-channel, programmable current-controlled ES system within a lightweight, flexible, independently-powered portable device. Benchtop testing and validation indicates that custom electronics and control algorithms support the generation of high-voltage, low duty-cycle current pulses in a power-efficient manner, extending battery life and allowing ES therapy to be delivered for up to 7 days without needing to replace or disturb the wound dressing.

Factors in rehospitalisation for severe pressure ulcer care in spinal cord injury/disorders.

OBJECTIVE: Repeated hospital admissions (RHA) for ongoing pressure ulcer (PU) care remains a significant challenge in the clinical management of the spinal cord injury/disorders (SCI/D) population. The current study investigated the significance of risk factors for PU treatment and RHA. METHOD: A retrospective chart review of veterans admitted to the Louis Stokes Cleveland Department of Veterans Affairs Medical Center (LSCDVAMC) Spinal Cord Injury (SCI) unit for Category III or IV PUs was carried out. A random sample of 105 individuals with SCI/D, evaluated by the Wound Care Team (WCT) from 2006 to 2009 was assessed. Multiple PU development risk factors were extracted from the electronic health record system using standardised data collection forms and entered into the Spinal Cord Injury Pressure Ulcer Database (SCIPUD). Potential associations with RHA were analysed. RESULTS: Twenty variables were initially identified as potentially related to PU development. Descriptive statistics and statistically significant associations between risk factors and RHA were determined. Demographic factors showed no significant association with RHA. Duration of injury, power wheelchair use and sub-optimally managed spasticity (SMS) were significantly associated with higher RHA. Sub-optimally managed neurogenic bowel (SMNB) at admission was significantly associated with reduced RHA. CONCLUSION: Factors previously found to be predictive of initial PU development may not, in fact, be predictive of RHA. Some protective trends were observed, such as polypharmacy and marital status, but these did not reach statistical significance in this preliminary study of admission characteristics, warranting further research. DECLARATION OF INTEREST: There were no external sources of funding for this study. The authors have no conflicts of interests to declare.

Repeatability and clinical utility in stereophotogrammetric measurements of wounds.

OBJECTIVE: To investigate the hypothesis that stereophotogrammetric wound size monitoring shows suitable inter-observer reliability and user acceptance for clinical practice use. METHOD: Veterans admitted for conservative management of severe pressure ulcers were eligible for inclusion in the study. Three-dimensional (3D) digital wound images were independently captured by two expert and two non-expert nurse-observers using a commercially available stereophotogrammetry system,weekly for 6 weeks.A double-blinded analyst generated 3D wound reconstructions, using software to determine geometry. Clinical opinion of wound progression was provided by an expert physician. RESULTS: Thirteen wounds were assessed with more than 80% of all images being readable. Interclass correlation of 0.9867 (p < 0.000 I) was observed. Compared with clinical opinion, 3D wound measurement was sensitive between improving and static wounds for wound perimeter, volume, depth and length. CONCLUSION: These preliminary findings suggest that 3D wound measurement minimises differences in wound measurement between expert and non-expert observers, suggesting it could be implemented with high reliability in health-care settings where several observers are involved in wound care management.

Electrical stimulation for pressure sore prevention and wound healing.

This paper reviews applications of therapeutic electrical stimulation (ES) specific to wound healing and pressure sore prevention. The application of ES for wound healing has been found to increase the rate of healing by more than 50%. Furthermore, the total number of wounds healed is also increased. However, optimal delivery techniques for ES therapy have not been established to date. A study of stimulation current effects on wound healing in a pig model has shown that direct current (DC) stimulation is most effective in wound area reduction and alternating current (AC) stimulation for wound volume reduction at current densities of 127 microA/cm2 and 1,125 microA/cm2, respectively. Preliminary studies have been carried out at two research centers to assess the role of ES in pressure sore prevention. Surface stimulation studies have shown that ES can produce positive short-term changes in tissue health variables such as regional blood flow and pressure distribution. The use of an implanted stimulation system consisting of intramuscular electrodes with percutaneous leads has been found to produce additional long-term changes. Specifically, gluteal muscle thickness increased by 50% with regular long-term ES application concurrent with a 20% decrease in regional interface pressures and increased tissue oxygen levels. These findings indicate that an implantable ES system may have great potential for pressure sore prevention, particularly for individuals who lack sensation or who are physically unable to perform regular independent pressure relief.

Early progressive changes in tissue viability in the seated spinal cord injured subject.

The patient with spinal cord injury is at high risk of tissue breakdown at all times due to a number of adverse factors, such as reduced mobility and anaesthesia. It is therefore essential that each patient is prescribed appropriate support media during initial rehabilitation. In this study, the effectiveness of prescribed wheelchair cushions has been assessed in terms of tissue response at the ischial tuberosities. A total of 42 subjects who had sustained traumatic spinal cord injury within 1 year were monitored on at least two occasions during initial rehabilitation. Changes in transcutaneous gas response (TcPO2 and TcPCO2) were monitored concurrently with regional interface pressures. A series of six transcutaneous gas variables were established, as markers of tissue viability. Non-parametric statistical analyses revealed some significant correlations between these variables. The results of this study also indicate that (1) spinal cord injury subjects with lesions below T6 show a progressive decrease in ability to maintain blood flow in sitting on prescribed support cushions and (2) SCI subjects with lesions above T6 show a progressive improvement in tissue viability status at the seating support interface. Therefore results imply that paraplegics are at a potentially higher risk of tissue breakdown than tetraplegics and thus require effective support cushions with strict adherence to a pressure relief regime.

Transcutaneous gas tensions in the sacrum during the acute phase of spinal cord injury.

The first few months following injury to the spinal cord requires constant care of the subject if tissue breakdown is to be avoided. The management of acute traumatic cases involves complete bedrest in a supine position with appropriately positioned pillows to minimize trauma to the bone prominences. This study assesses the effectiveness of the management procedure in terms of the tissue response at the sacrum of 15 acute spinal cord injured subjects. The measurement of mean interface pressures during a representative period of recumbency was performed and these were related to changes in transcutaneous gas tensions (TcPO2 and TcPCO2), which are reliable indices of tissue viability. A series of six variables was established which were compared to each other using non-parametric statistical analyses. It was shown that this group of subjects demonstrated a normal mechanism whereby the level of carbon dioxide was able to control the local vascular tone. The results also suggested that the practice of gapping at the sacrum should be revised to reduce mean sacral pressures and minimize the possibility of tissue breakdown, the risk of which is constant throughout the first three months following injury.