Determination of the effects of blood depth in the dermis on skin colour in a novel skin phantom using digital imaging.

A phantom of human port wine stain (PWS) skin, previously described by the authors, that takes into account its light propagation and scattering properties, was used to model varying depths of blood within PWS skin. Digital images of these phantoms were then acquired under controlled conditions, and the colour information was abstracted with a digital image processing suite. These colour data were analysed quantitatively for each depth of blood, and the relationship between depth of blood and colour was defined. A linear relationship was observed between depth of blood within the phantom and hue, hue being an intuitive measure of how colour is perceived by the human eye. As PWS clearance by laser treatment is dependant, to a large degree, on vessel depth within the skin, the ability to abstract colour data from PWS or, in fact, any vascular lesion within the skin, may help predict the degree of clearance before treatment is actually instigated. In the future, the comparison of phantom colour data with data from actual digital images of affected PWS skin, combined with a knowledge of laser light penetration depths, may provide a useful adjunct to clinical judgement in the prediction of PWS treatment outcomes.

Construction of a novel port wine stain phantom and measurement of colour by digital imaging and reflectance spectrophotometry.

A novel skin phantom is described that is constructed with quantifiable amounts of skin pigments, as well as a light scattering medium in the form of barium sulphate suspension. The two predominant skin pigments (melanin and haemoglobin) are varied in controlled amounts within the phantoms to simulate skin colour in different situations. The phantoms were devised in order to simulate the changes in skin colour particularly after laser treatment of port wine stains, where superficial cutaneous vascularity is reduced. Preliminary investigations of two techniques for skin colour assessment were subsequently carried out so that their suitability for measuring colour in the skin phantoms could be considered. A specifically designed device was constructed to enable repeatable digital image capture of the phantoms. Further development of this skin phantom may enable comparison of techniques for skin colour assessment.

Advances in wound healing: topical negative pressure therapy.

In clinical practice many wounds are slow to heal and difficult to manage. The recently introduced technique of topical negative pressure therapy (TNP) has been developed to try to overcome some of these difficulties. TNP applies a controlled negative pressure to the surface of a wound that has potential advantages for wound treatment and management. Although the concept itself, of using suction in wound management is not new, the technique of applying a negative pressure at the surface of the wound is. This paper explores the origins and proposed mechanisms of action of TNP therapy and discusses the types of wounds that are thought to benefit most from use of this system.

Using the pulsed dye laser to influence scar formation after breast reduction surgery: a preliminary report.

Many patients undergoing bilateral breast reduction surgery develop problems. Foremost among these problems is scar hypertrophy and its attendant symptoms. Although there is as yet no firm prognostic indicator for hypertrophy, scars that become hypertrophic often have a particular blood vessel pattern, observable by transcutaneous microscopy, showing vessels that lay transversely across the incision line with minimal crosslinks between them. Hypertrophic scars that develop in incision lines become wide, with the final width of the scar dependent on the maximum thickness during the growth stages before maturation and resolution. Close monitoring of scars forming in the incision line using the transcutaneous microscope detected this aligned vessel pattern before overt hypertrophy was seen. Use of the Pulsed Dye Laser caused disruption in the vessel pattern, appeared to inhibit additional hypertrophic development, and promoted early maturation of scars.

Treatment of hereditary haemorrhagic telangiectasia by the pulsed dye laser.

Hereditary haemorrhagic telangiectasia (Osler-Weber-Rendu syndrome, Osler's disease) is an inherited abnormality of the vasculature characterized by abnormal subepithelial vessels. Treatment has included repeated intranasal cautery, intra-arterial embolization and arterial ligation. Historically, the operation of septodermoplasty and the use of systemic/topical oestrogens have been the most effective and lasting treatments, but over time the telangiectasias recur. There is increasing interest in the use of a variety of lasers for intranasal photocoagulation. A report of nine patients suffering from hereditary haemorrhagic telangiectasia who have undergone laser treatment with the Chromos pulsed dye laser is presented. This laser produces light energy at a wavelength of 585 nm and causes localized thermal damage to the blood vessel wall. Initially, no patient saw an improvement in their symptoms, but following an average of approximately three courses of treatment, all have reported a measurable reduction in the number of epistaxes suffered. Although no treatment completely resolves the epistaxis associated with this condition, we have found the pulsed dye laser to be effective at treating telangiectasias within the anterior nasal cavity.

Timing of the thermographic assessment of burns.

The thermographic assessment of burns using infrared imaging has previously been shown to be a useful aid in the estimation of burn depth. In this study, thermographic images of burns, obtained from 65 patients over a 4-year period, were reviewed. An infrared transparent, water-impermeable membrane was used as a wound cover to abolish evaporative cooling artefacts. Single images were obtained from patients with burns to various parts of the body, excluding the hands. A significant change in the temperature of deep burns was observed between days 2 and 3 after injury (chi-square, P < 0.01; Fisher exact probability test between days 2 and 3, P < 0.01). The results of this study suggest that thermography of burns, to assess depth, should be performed within 3 days following the injury.

Involvement of proteolytic enzymes--plasminogen activators and matrix metalloproteinases--in the pathophysiology of pressure ulcers.

The role of matrix-degrading enzymes, particularly plasminogen activators and matrix metalloproteinases, in the acute wound healing response has been the focus of many scientific studies. Only recently have these classes of endogenously produced proteinases been studied with regard to their involvement in the chronic wound environment. Using both in situ histologic zymography and immunohistochemical techniques, we examined the distribution of plasminogen activators and matrix metalloproteinase in the granulation tissue of pressure ulcers. Using in situ histologic zymography, urokinase was found to be the predominant plasminogen activator activity in the chronic wound granulation tissue, with little or no tissue-type plasminogen activator activity. These results were confirmed with the use of immunohistochemical techniques. In contrast, tissue-type plasminogen activator was found to be constitutively expressed in normal skin. Levels of matrix metalloproteinases were also found to be elevated in the granulation tissue of pressure ulcers. Immunohistochemical localization of leukocyte-associated proteinases (PMN elastase and cathepsin G) suggested a highly inflamed environment within the pressure ulcer granulation tissue. These results suggest a highly proteolytic environment within the chronic wound.