Skin graft fixation in severe burns: use of topical negative pressure

Summary

Over the last 50 years, the evolution of burn care has led to a significant decrease in mortality. The biggest impact on survival has been the change in the approach to burn surgery. Early excision and grafting has become a standard of care for the majority of patients with deep burns; the survival of a given patient suffering from major burns is invariably linked to the take rate and survival of skin grafts. The application of topical negative pressure (TNP) therapy devices has demonstrated improved graft take in comparison to conventional dressing methods alone. The aim of this study was to analyze the impact of TNP therapy on skin graft fixation in large burns. In all patients, we applied TNP dressings covering a %TBSA of >25. The following parameters were recorded and documented using BurnCase 3D: age, gender, %TBSA, burn depth, hospital length-of-stay, Baux score, survival, as well as duration and incidence of TNP dressings. After a burn depth adapted wound debridement, coverage was simultaneously performed using split-thickness skin grafts, which were fixed with staples and covered with fatty gauzes and TNP foam. The TNP foam was again fixed with staples to prevent displacement and finally covered with the supplied transparent adhesive film. A continuous subatmospheric pressure between 75-120 mm Hg was applied (VAC®, KCI, Vienna, Austria). The first dressing change was performed on day 4. Thirty-six out of 37 patients, suffering from full thickness burns, were discharged with complete wound closure; only one patient succumbed to their injuries. The overall skin graft take rate was over 95%. In conclusion, we consider that split thickness skin graft fixation by TNP is an efficient method in major burns, notably in areas with irregular wound surfaces or subject to movement (e.g. joint proximity), and is worth considering for the treatment of aged patients.

Introduction

Over the last 50 years, the evolution of burn care has led to a significant decrease in mortality. Major advances have been made concerning early resuscitation, respiratory care, infection control, modulation of the hypermetabolic response and nutritional support.^1-3 The biggest impact on survival, however, has been the change in the approach to burn wound treatment.^2,3 Today, early excision and grafting by various techniques has become a standard of care, whereas the survival of a given patient suffering from major burns is invariably linked to the take rate and survival of skin grafts. The application of topical negative pressure (TNP) has demonstrated improved graft take vs. conventional dressing methods alone.⁵ TNP therapy is a modified dressing, consisting of open-cell foam and suction tubing that is secured to the wound with an occlusive dressing. TNP exposes the wound bed to negative pressure using a closed system. Edema fluid is removed from the extravascular space, thus eliminating an extrinsic cause of microcirculatory impairment and improving blood supply. ^5-7 Furthermore, the mechanical tension due to the vacuum may also directly stimulate cellular proliferation and thereby formation of reparative granulation tissue.^5-8

TNP can be applied in various clinical contexts, e.g. pressure sores, leg ulcers, acute and chronic wounds with skin defects and burns.^5-7,9-11 In burns, TNP has demonstrated improved wound healing conditions, showing a decrease of burn wound progression^8,12 and improved skingraft take,⁵ notably in areas subject to repeated motion (e.g. in the joint region). One major hypothesis of the efficacy of TNP is, put simply, a continuous contact between the skin graft and the wound bed allowing for optimal take.

The aim of this study was to present our experiences with TNP skin graft fixation in major burns, and provide advice for usage in daily clinical routine.

Materials and methods

In all patients, we applied TNP dressings covering a %TBSA of >25. The following parameters were recorded and documented using BurnCase 3D:¹³ age, gender, %TBSA, burn depth, hospital length-of-stay, Baux score, survival, as well as duration and incidence of TNP dressings.

Treatment

After a burn depth adapted wound debridement, coverage was simultaneously performed using split-thickness skin grafts, which were fixed with staples and covered with fatty gauzes and TNP foam. The TNP foam was again fixed with staples to prevent displacement and finally covered with the supplied transparent adhesive film. A continuous subatmospheric pressure between 75-120 mm Hg was applied (VAC®, KCI, Vienna, Austria). The first dressing change was performed on day 4.

Results

Thirty-seven patients received a large VAC® dressing (KCI, Vienna, Austria), covering more than 25% TBSA, for skin graft fixation. Nineteen patients were male, 18 female. The mean age was 59.4 ± 21.5 years and the mean Baux score 88.6 (± 24.4). Eight patients even had a Baux score larger than 100. The median application time was 4 days. In 30 cases just one TNP device was used, while 6 cases required 2 devices and 1 case required 4 at the same time. The median hospital length-of-stay was 46.6 days. Thirty-six out of the 37 patients were discharged with completely healed wounds. One patient (84 years, 37% TBSA, Baux score of 121) died due to multiple organ failure. There was no sign of either local skin graft infections or systemic infections and the take rate was above 95%.

Cases

Patient 1

A 32-year-old male with 52.8% TBSA, inhalation injury and burns to the face and both lower and upper extremities (Fig. 1). On day 3 after admission, necrotic tissue (all 4 extremities) was excised and covered with autologous and allogeneic skin grafts; skin graft fixation was performed in all areas by TNP (covering 47% TBSA). The face was dermabraded and covered with allogeneic keratinocytes. In the second operation two weeks after skin grafting, the allografts were replaced by autografts. Thirtysix days after admission and completed wound coverage, the patient was transferred from the burn center to the surgical ward in a hospital close to where he lived.

Fig. 1. 52.8% TBSA (5.8% TBSA deep dermal; 47.0% TBSA full thickness): all full thickness areas were excised and covered with skin grafts. All grafted areas were covered with a large TNP system (47% TBSA) (VAC®, KCI, Austria). (Use of 2 VAC® systems).

Patient 2

An 85-year-old female with 25% TBSA and no inhalation injury; suffering from burns to the back, flank, thorax and the gluteal region (Fig. 2). The patient was transferred to our institution 2 weeks after trauma with “contaminated non-healing wounds.” On the same day, a tangential excision and skin grafting was performed. Skin graft fixation was performed with TNP for 4 days using 2 devices (covering 25% TBSA). Two weeks after admission to our burn center the patient was discharged with completely healed wounds.

Fig. 2. 85-year-old female, 25% TBSA, no inhalation injury; suffering from burns to the back, flank, thorax and the gluteal region. All full thickness areas were excised and covered with skin grafts. All grafted areas were covered with a large TNP system (25% TBSA) (VAC®, KCI, Austria). (Use of 1 VAC® system).

Hints and tips

For very large burns (for example, complete extremity, complete thorax) or wounds located in areas with or difficult TNP dressing application (for example, shoulder gluteal region) the customized foam is fixed by use of staples before application of the supplied transparent drapes. (Figs. 3 and 4)

Fig. 3. Large VAC® (gluteal region and both lower extremities) including the Zassi-system®, staple fixation. (Use of 2 VAC® systems).

Fig. 4. Large VAC® (43% TBSA; complete back, gluteal region, partly both lower and both upper extremities) (Use of 4 VAC® systems).

When using XL foam or multiple XL foam applications (for example, to cover the complete trunk – front and back) all foams should first be fastened with staples. (Figs. 3 and 4) In these cases, we applied negative pressure by use of surgical suction units before switching to the supplied TNP units after 5-10 minutes. TNP dressings in the hand and feet can be covered by use of specially designed TNP gloves or, in the case of burns to the feet, by use of the sterile glove technique.¹⁴

Discussion

Argenta and Morykwas1⁵ first presented TNP for wound treatment. It is a method of increasing the rate of wound healing by secondary intention and of preparing a wound bed to allow for successful closure by use of skin grafts. The technique is hypothesized to reduce chronic edema, leading to increased localized blood flow, and enhanced formation of granulation tissue. The TNP technique entails placing open-cell foam dressings into the wound cavity and applying a controlled subatmospheric pressure (125 mm Hg below ambient pressure). The authors found that TNP-assisted wound closure is an efficacious modality for treating chronic and difficult wounds. The technique is based on the theory of induced mechanical stress resulting in angiogenesis and tissue growth. It has also been suggested that the application of subatmospheric pressure to edematous chronic wounds results in decreased local tissue turgor by fluid removal, which in turn theoretically decompresses small blood vessels and increases blood flow locally. TNP has also been successfully applied for securing skin grafts to the wound bed and resulting improved take rates by having a splinting-like effect on the tissues.^6-12 Immobilization of skin grafts on uneven or mobile surfaces, such as the nuchal area, axilla, web spaces, and perineal area can also be successfully achieved by using negative pressure dressings.^7,16 With regard to TNP, Scherer et al.¹⁷ suggested that the vascular response was related to the polyurethane foam, whereas tissue strains induced by the vacuum-assisted closure device stimulated cell proliferation.

In a previous study by the aforementioned authors, TNP dressings were applied for skin graft fixation to the following types of small wounds (2-8% TBSA): burns, soft tissue loss and fasciotomy site coverage. Moisidis et al.⁵ demonstrated that use of TNP therapy on split thickness skin grafts significantly improved the quality of the skin graft’s appearance postoperatively. In 75% of cases, skin grafts receiving TNP displayed epithelialization rates equal to or better than those in control grafts. Skin grafts receiving TNP were also qualitatively equal to or better than control grafts in 85% of cases.

Conclusion

In summary, the application of TNP for skin graft fixation has demonstrated reliable clinical feasibility in the context of major burns and, institutional and financial circumstances permitting, we would recommend its usage.