How to evaluate scar colour after burn injuries - A clinical comparison of the Mexameter® and the subjective scar assessment (POSAS/VSS).

INTRODUCTION: Scarring after burn injuries remains one of the major challenges in burn medicine and is the subject of current research. Accurate and high-quality assessment of scars is needed to enable exact outcome evaluation of different treatments. Our aim was to evaluate the most common subjective scar evaluation scores-the POSAS (Patient and Observer Scar Assessment Scale) and VSS (Vancouver Scar Scale)-in comparison with the objective device Mexameter® for colour evaluation. METHODS: A prospective monocentre study was performed, which included 120 examined scar areas of 60 patients with third degree burns who had received skin grafts between 1975 and 2018 with a total burned surface area (TBSA) > 2%. Two different scar areas in comparison with one healthy skin area concerning 'colour', 'pigmentation', and 'vascularization' were evaluated by the Mexameter® MX 18, the OSAS, and the VSS by the same examiner, as well as the PSAS by the patient. RESULTS: The mean TBSA of the 60 patients was 24.3%. In the OSAS, 61% of the scars were evaluated as 'hyper-', 19% as 'hypo-', and 19% as 'mix-pigmented'. Furthermore, 65% of the scars were estimated as highly vascularized. In the Mexameter®, the melanin index values of the scar areas compared to the healthy skin areas showed a small difference of 12 (p < 0.05). The mean difference of erythema between the scar and the healthy skin areas was 84 (p < 0.001). For the Mexameter®, moderate correlations were found when comparing 'erythema' with the OSAS category 'vascularization' (r = 0.33, p < 0.05) and 'melanin' with the OSAS parameter 'pigmentation' (r = 0.28, p < 0.05). When comparing the Mexameter® measurements to the OSAS questionnaire, 27% of the scars were wrongly evaluated as 'hyperpigmented' by the observer and 21% as 'hypervascularized', while showing low measurements in the device. Additionally, a novel Mexameter® ordinal scare scale was calculated. CONCLUSION: In this study, we were able to show on a relatively large patient population that with the Mexameter®, the subjectivity of the scar colour assessment by examiner/patient can be overcome, but precise differentiation can still be ensured with subjective evaluation tools. We further introduced a novel Mexameter® Scar Scale. It is necessary to further investigate the vast range of objective devices and develop scar panels for with an incorporation of objective and subjective devices to further improve reliability with reduced bias in terms of scar assessment.

Evaluation of facial blood flow using three-dimensional scanning.

The Vectra X3 3-dimensional face scanner allows us to visualise the erythema of superficial layers of skin in addition to its regular scanning functions. The aim of our study was to find out whether changes we provoked in the circulation of the skin would be registered and displayed by the face scanner. We measured the circulation in the skin of the cheeks of 20 volunteers with a face scanner, a laser Doppler device, and a skin pigmentation analyser before and after the application of a nitric oxide cream. The results were compared in terms of grey tones, local concentrations of haemoglobin, and erythema. All methods showed significant changes (p<0.001) before and after application of the cream. The study proved that the Vectra X3 recognises changes in skin circulation and displays them in a simple and evident way.

A new approach of in vivo musculoskeletal tissue engineering using the epigastric artery as central core vessel of a 3-dimensional construct.

The creation of musculoskeletal tissue represents an alternative for the replacement of soft tissue in reconstructive surgery. However, most of the approaches of creating artificial tissue have their limitations in the size as the maximally obtainable dimension of bioartificial tissue (BAT) is limited due to the lack of supporting vessels within the 3-dimensional construct. The seeded myoblasts require high amounts of perfusion, oxygen, and nutrients to survive. To achieve this, we developed a 3-dimensional scaffold which features the epigastric artery as macroscopic core vessel inside the BAT in a rat model (perfused group, n = 4) and a control group (n = 3) without the epigastric vessels and, therefore, without perfusion. The in vivo monitoring of the transplanted myoblasts was assessed by bioluminescence imaging and showed both the viability of the epigastric artery within the 3-dimensional construct and again that cell survival in vivo is highly depending on the blood supply with the beginning of capillarization within the BAT seven days after transplantation in the perfused group. However, further studies focussing on the matrix improvement will be necessary to create a transplantable BAT with the epigastric artery as anastomosable vessel.

Dermal application of nitric oxide in vivo: kinetics, biological responses, and therapeutic potential in humans.

Many local hemodynamic and vascular disorders may be the result of impaired bioavailability of nitric oxide (NO). Previous findings point to a therapeutic potential of dermal NO application in the treatment of hemodynamic disorders, but no reliable data are available on the mechanisms, kinetics, or biological responses relating to cutaneous exposure to NO in humans in vivo. Here we show that, owing to its excellent diffusion capacity, cutaneously applied NO rapidly penetrates the epidermal barrier in significant amounts, strongly enriching skin tissue and blood plasma with its vasoactive derivates. In parallel, it significantly increased vasodilatation and blood flow and reduced thrombocyte aggregation capacity. Data presented here for the first time show that, in humans, dermal application of NO has strong potential for use in the therapy of local hemodynamic disorders arising from insufficient availability of NO or its bioactive derivates.