What Lies Beneath: Why Some Pressure Injuries May Be Unpreventable for Individuals With Spinal Cord Injury.

OBJECTIVE: To investigate intersections between pressure injury (PrI) history, muscle composition, and tissue health responses under physiologically relevant loading conditions for individuals with spinal cord injury (SCI). DESIGN: Repeated measures study design with annual follow-up for up to 3 years. SETTING: Tertiary care center. PARTICIPANTS: Persons with SCI (N=38). Exclusion criteria included having an open pelvic region PrI at the time of recruitment, presence of systemic disease, and/or known sensitivity to contrast. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Gluteal muscle composition, ischial interface pressures, tissue oxygenation. RESULTS: Ischial region mean interface pressures are the same for individuals with or without a PrI history. Tissue oxygenation is lower during sitting for persons with a PrI history. Individuals with >15% gluteal intramuscular fat were statistically highly significantly (P<.001) more likely to have a history of severe or recurrent PrI. Intramuscular adipose tissue (IMAT) levels within the gluteal muscle may remain low over time or muscle tissue in the gluteal muscle region may be almost entirely replaced by IMAT. In the current study cohort, it was found that muscle composition also continues to change over time even for individuals with long-standing SCI. CONCLUSIONS: Soft-tissue compositional changes, specifically IMAT, provides a reliable indicator of PrI history and may provide a key to personalized PrI risk status for persons with SCI. The current findings confirm that interface pressure mapping alone is a limited indicator for PrI development.

Systemic Evaluation of Electrical Stimulation for Ischemic Wound Therapy in a Preclinical In Vivo Model.

Objective: In a systematic preclinical investigation of ischemic wound healing, we investigated the hypothesis that electrical stimulation (ES) promotes the healing of ischemic wounds. Approach: The effects of varying clinically relevant ES variables were evaluated using our modified version of the Gould F344 rat ischemic wound model. Stimulation was delivered using the novel lightweight integrated, single-channel, current-controlled modular surface stimulation (MSS) device. Stepwise variation allowed the effects of five different stimulation paradigms within an appropriate current density range to be studied. Within each group, 8-10 animals were treated for 28 days or until the ischemic wounds were healed and 5 animals were treated for 12 days. Eight rats received sham devices. A quantitative multivariable outcomes assessment procedure was used to evaluate the effects of ES. Results: Ischemic wounds treated with a decreased interpulse interval (IPI) had the highest rate of complete wound closure at 3 weeks. Wounds treated with decreased pulse amplitude (PA) had a lower proportion of closed wounds than sham ischemic wounds and showed sustained inflammation with a lack of wound contraction. Innovation: Our systematic study of varying ES paradigms using the novel MSS device provides preliminary insight into potential mechanisms of ES in ischemic wound healing. Conclusion: Clinically appropriate ES can more than double the proportion of ischemic wounds closed by 3 weeks in this model. Ninety percent of wounds treated with a decreased IPI healed by 21 days compared with only 29% of ischemic wounds treated with decreased PA, which appears to inhibit healing.

A wearable stimulation bandage for electrotherapy studies in a rat ischemic wound model.

The clinical efficacy of electro-therapy in the treatment of chronic wounds is currently debated, and a in-vivo evaluation of stimulation parameters will provide the statistical evidence needed to direct clinical guidelines. A low-cost, wearable electrical stimulation bandage has been developed for use with an established rat ischemic wound model. The bandage consists of a user-programmable stimulator PCB and a plastic bandage with two hydrogel electrodes. The battery-powered bandage may be used for up to seven days between dressing changes, and the stimulator may be reused. The microcontroller-based stimulator uses a boost converter circuit to generate pulses up to 90 V from a 3 V coin cell battery. Consistent operation of the boost converter over the wide input and output voltage ranges is achieved using voltage feedforward and soft-start techniques implemented in firmware. The bandages are laser-cut to shape, and electrical traces are applied using stencils and conductive nickel paint. Both the PCB and electrical traces are encapsulated to protect the animal. The device has been successfully demonstrated using the rat ischemic wound model for a period of seven days, and clinical experiments are ongoing.