Negative pressure wound therapy (NPWT) is a method to facilitate wound healing. NPWT uses a vacuum system consisting of a therapy unit that creates a subatmospheric pressure, which is transferred via tubes to a foam dressing placed directly on the wound.
Originally, NPWT was used for complicated chronic wounds. As described in literature reviews,1-3 the clinical indications for NPWT have been widely discussed. Review articles,4,5 clinical trials,6-8 and case series9,10 have shown NPWT to be effective in the treatment of diabetic wounds, pressure ulcers, and burns, as well as a preparatory method for skin grafts and flap surgery.
Important effects of applying subatmospheric pressure to wounds described in animal experiments,11,12 in vitro studies,13 case series,14-16 and randomized controlled trials17,18 include decrease in wound edema, promotion of granulation tissue formation, decrease of wound size due to mechanical creep of the wound edges, increased perfusion of the wound and the surrounding area, and reduction of bacterial load.
NPWT can be used for various anatomical regions, but problems maintaining an airtight seal with the NPWT system can occur in regions with irregular surfaces (such as skin folds, scars, or curved surfaces), a humid milieu, or mobile structures. To address these challenges, approaches have included pretreating the wound’s surrounding areas with dermal-adhesion agents, such as Compound Benzoine Tincture (3M Health Care, Inc, Neuss, Germany) or Skin-Prep (Smith & Nephew, Inc, Hamburg, Germany), to improve the adherence of the occlusive drape of the vacuum system.19 In a retrospective study, Andrews et al20 presented 12 patients who had undergone NPWT of complicated head and neck wounds. The authors maintained the airtight seal of the NPWT dressings using a combination of occlusive drape, Skin Prep, benzoine, and Tegaderm (3M Health Care, Inc, St. Paul, MN) on the surrounding skin. To protect the surrounding wound area and to prevent leakage of dressings under high-humidity conditions, Jerome’s21 guidelines and recommendations for use of NPWT include placing a hydrocolloid dressing around the wound. Bookout et al’s22 case series reports use of stoma paste to fill in crevices to achieve an airtight closure.
Silicone. Medical silicones have widespread applications in healthcare. Due to its excellent biocompatibility and biodurability,23,24 silicone can be used for intracorporeal and extracorporeal medical equipment such as joint implants, aesthetic implants, medical tubes or membranes, prosthetics, facial prostheses (epitheses), or dental impression materials.25 Its use also has been described for creating an intraoral vacuum dressing in a case of an extended keratocyst of the mandible.26 To enable intraoral NPWT, the authors applied silicone impression material, which is mainly used in dentistry and epithetics.
As manufacturer data show, silicone impression material combines the advantages of high biocompatibility and the possibility of application as a low-viscosity malleable silicone, its rapid setting comparable to an elastic material. Additionally, the authors` practical experiences in using the silicone impression material revealed easy, rapid, and painless removal from skin.
The material is dispensed in an automix cartridge delivery system, and manufacturer-provided, single-use tips aid in application.
Silicone impression materials mainly consist of vinyl polysiloxane and are commercially available in different viscosities, hardnesses, and setting times. The viscosity of silicones can be light, regular, or heavy. Degree of hardness is characterized by shore hardness A, which is between 20 and 80 Shore. Higher values of Shore hardness A characterize higher values of hardness of the elastomer and vice versa. The silicones are available as slow, regular, or fast-setting. Silicone should not be used in case of hypersensitivity against vinyl polysiloxanes. Per manufacturer instructions, contact with the eyes, uncontrollable application in body cavities, or use on open wounds must be avoided. The silicone (VPS Hydro, Light Body, Fast Set [Henry Schein, Inc., Melville, NY] used to achieve an airtight seal with NPWT (V.A.C. Therapy System (KCI, Inc., Wiesbaden, Germany with either polyurethane or polyurethane silver foam) has a Shore hardness A of 45±2 Shore.
The purpose of this case study was to describe the use of this silicone to achieve an airtight seal for NPWT in five patients.