Skin graft survival relies on imbibition, inosculation, and revascularization from the wound bed. When a wound bed is poorly vascularized, as in the case of exposed fascia, tendon or bone, skin grafting may be delayed until the wound bed improves. We propose that topical nutrient supplementation may be able to increase take of skin grafts applied over an avascular wound bed. Twenty full-thickness 5cm-diameter wounds were created on the dorsum of anesthetized swine and a dermal substitute (0.4mm, 0.8mm, 1.2mm, or 1.6mm thick) was placed on each wound. Negative pressure therapy with and without intermittent (3x per day) saline instillation was applied. Wounds were analyzed using a non-contact 3D camera at day 7 and day 14. Dermal substitutes of 0.8mm, 1.2mm, and 1.6mm thicknesses inhibited graft take significantly (p< 0.01, p=0.02, p< 0.01, respectively) for all wounds treated with wound vac alone. Addition of the normal saline instill showed a significant improvement in graft take (p=0.03) over wound vac alone for the wounds treated with the 0.8mm dermal substitute. Wounds covered with 1.2mm and 1.6mm dermal substitute continued to show significantly decreased graft take (p=0.03 and p=0.02, respectively). Wounds with 0.4mm dermal substitute showed similar graft take to control for both the wound vac and wound vac + instill treatments. Dermal substitutes ≥0.8mm create a successful model of an avascular wound bed. Vac + instill treatment overcame the impedance of an avascular wound bed only for the 0.8mm dermal substitute thickness. This thickness of dermal substitute creates an ideal avascular wound bed model from which to conduct further studies incorporating topical nutrients instilled directly onto skin grafts placed onto avascular wound beds. Single-stage skin grafting procedures onto avascular wound beds may become feasible with topical nutrient supplementation providing the environment to maintain graft survival until the wound bed is able to support the skin graft.

Skin burns are a significant source of injury in both military and civilian sectors. They are especially problematic in low resource environments where non-fatal injuries can lead to high morbidity rates, prolonged hospitalization, and disability. These multifaceted wounds can be highly complex and must be quickly diagnosed and treated to achieve optimal outcomes. When the appropriate resources are available, the current gold standard for assessing skin burns is through tissue punch biopsies followed by histological analysis. Apart from being invasive, costly, and time-consuming, this method can suffer from heterogeneous sampling errors when interrogating large burn areas. Here we present a practical method for the early visualization of skin burn severity using a topically applied fluorescein-loaded liquid bandage and an unmodified commercial digital camera. Quantitative linear mixed effects models of color images from a four day porcine burn study demonstrate that colorimetric changes within the HSB colorspace can be used to estimate burn depth severity immediately after burning. The finding was verified using fluorescence imaging, tissue cross-sectioning, and histopathology. This low-cost, rapid, and non-invasive color analysis approach demonstrates the potential of dye-loaded liquid bandages as a method for skin burn assessment in settings such as emergency medicine triage and low resource environments.

Abstract Introduction The ability of laser speckle contrast imaging (LSCI) to provide real-time images of blood flow makes this modality appealing in the assessment of burn wounds, particularly for clinicians making treatment decisions based on burn wound depth and presumed progression. Here we present 2 preclinical studies that used LSCI to assess wound progress, both immediately and months after injury. Methods LSCI images were taken 10-40cm away from the wound and captured with a 1388x1038-pixel CCD camera. In the first study, LSCI images were captured prior to and immediately following creation of superficial partial-thickness (SPTB, 10s), deep partial-thickness (DPTB, 15s), and full-thickness burns (FTB, 20s), and on post-burn day (PBD) 1, 2, and 3. In the second study, LSCI images were obtained before and after DPTB creation and on PBD 7, 14, 21, 28, 60, 90, and 120. Results 92 wounds from 9 swine were included. Speckle data was normalized to control sites and converted to percentages ([speckle wound/speckle control] x 100), producing speckle percentage of control (SPOC) which quantifies the relative decrease or increase in speckle output (vascularity). SPOC was significantly decreased for all burn times on PBD 0, 1, and 2. By PBD 3, only DPTB and FTB remained diminished (p=0.028 and p=0.005, respectively), and FTB SPOC was significantly less than the SPTB (p=0.015). In the second study, SPOC showed an increase post-debridement on PBD 7, noted as post-debridement day (PDD) 0. SPOC continued to increase significantly to a peak at PDD 7 (p< 0.0001) and remained elevated until PDD 28. By PDD 60, SPOC was no longer significantly increased. Conclusions LSCI is a reliable method for analyzing burn depth and wound progression in the preclinical setting. LSCI data shows an immediate decrease in vascularity at all burn depths immediately following burn creation, followed by a peak in vascularity on PDD 7, with a trend back to normal by PDD 60. Applicability of Research to Practice The correlation of wound bed vascularity based on LSCI to known data on burn depth and progression suggests that LSCI could be a useful measurement tool in the clinical setting for the provider determining wound viability.

Cooper, Laura E. MD; Kemp Bohan, Phillip M. MD; Everett, Tyler R. MLT; Chapa, Javier A. BS; Christy, Sean E. BS; Carlsson, Anders H. PhD; Chan, Rodney K. MD, FACS Author Information