Advanced Wound Therapies in the Management of Severe Military Lower Limb Trauma: A New Perspective

INTRODUCTION: HOLISTIC APPROACH TO LARGE, COMPLEX, EXUDATING WOUNDS

Since British forces have been engaged in recent conflicts in Iraq and Afghanistan, the University Hospital Birmingham Foundation Trust and the Royal Centre for Defence Medicine in Birmingham, through which all injured UK troops are transferred for treatment, have been frequently faced with challenging trauma wounds, caused by improvised incendiary devices, land mine explosions, and gunshot wounds. Improvements in body armor have resulted in fewer trunk injuries and therefore relatively more limb injuries, particularly of the lower limbs. These injuries are associated with extensive soft tissue stripping and contamination, and high levels of exudate, and are particularly prone to infection both by bacteria and fungi.

Because of the extent of the trauma involved, our primary strategy was to stabilize the patient and salvage as much of the limb as possible without exposing him or her to an unnecessarily high risk of infection. We have found that a holistic approach that includes negative pressure wound therapy (NPWT) and encompasses wound bed preparation, exudate management, and infection control is an effective way to strive for eventual wound closure and the improvement of the patient's overall condition.

In recent years, NPWT has become an accepted option for managing and treating trauma cases.¹ It is also beginning to be appreciated more widely both in open fractures of the lower extremity and in both high- and low-energy trauma wounds because of its ability to handle high volumes of exudate and provide a closed wound environment.

With NPWT, subatmospheric pressure is applied to the wound bed through a wound-filler material, which is covered with an airtight seal, and exudate is drawn off into a collection device. Until recently, the only filler available was an open-cell polyurethane (PU) foam, supplied as part of the V.A.C system (KCI, San Antonio, Tex).

An alternative wound filler (nonadherent gauze) is now commercially available in several alternative NPWT devices, including VISTA (Smith & Nephew, Hull, United Kingdom), based on the method now known as the Chariker-Jeter system.² This method uses a single layer of saline-moistened antimicrobial gauze that is impregnated with polyhexamethylene biguanide and laid directly onto the wound bed. A silicone drain is placed on the gauze and then more gauze is placed over the drain to fill the wound. This is then covered with a clear semipermeable film, cut so that there is a 2- to 3-cm border around the wound allowing it to be sealed onto healthy skin.

We have found NPWT with the VISTA device (and a larger version, the EZCARE pump) to be invaluable in managing trauma wounds and featured 3 cases to illustrate how it can be used, within the context of wound bed preparation, to achieve wound closure. In these wounds, NPWT must be used in combination with comprehensive surgical assessment, exploration, and meticulous debridement. Our objectives were to stabilize soft tissue, salvage compromised tissue, reduce edema, infection, wound size, the number and frequency of dressing changes, and finally the complexity of the wound itself to facilitate further reconstructive surgery.

A comparative investigation of the long-term overall cost-effectiveness of this treatment has not yet been undertaken, but the author feels that this could be a very valuable study for the future.

CASE 1: TRAUMATIC INJURY TO BOTH LEGS, SACRUM, AND BUTTOCKS

A 19-year-old soldier was injured when he stood on a land mine in Afghanistan. He suffered extensive injuries to both his legs and his buttocks. He also suffered abdominal and upper limb injuries (Fig 1). His injury severity score was 25 and his new injury severity score was 34. Microbiological investigation revealed the presence of methicillin-resistant Staphylococcus aureus, Acinetobacter species, and the Aspergillus fungus within the patient's leg wounds.

Figure 1. Land mine injury.

To begin with, a colostomy was fashioned and extensive debridement of this patient's wounds was carried out with the VERSAJET hydrosurgery system (Smith & Nephew). Meticulous debridement is essential prior to attempted wound closure to promote wound healing and minimize the risk of infection (Fig 2).

Figure 2. Debridement using the VERSAJET hydrosurgey system.

Topical NPWT was applied with the VISTA system, as EZCARE was not available then in the United Kingdom. NPWT was applied for 10 days to prepare the wounds for skin grafting.

Before applying NPWT, the wound and surrounding skin were carefully dried: It is essential to do this thoroughly to ensure that a good seal can be maintained when vacuum pressure is applied. We also used an alcohol preparation, such as chlorhexidine in alcohol, to degrease the skin. This was applied around the wound and allowed to dry.

We then created a seal. This is made easier if an adhesive solution is then applied to the skin adjacent to the wound, particularly in areas that are prone to loss of complete seal such as junctional areas (eg, the groin in a high amputation). Whitehead's varnish offers the most adhesion, but tincture of benzoin (Friar's balsam) is also effective. The small sachets of adhesive that are supplied by the manufacturers are sufficient only for small wounds.

Our next procedure was to lay the gauze in the wound. In heavily exudating wounds, we apply gauze while it is still dry rather than wetting it beforehand. It is important to lightly pack the gauze into any crevices so that all parts of the wound are in contact with it.

A drain is then placed onto the gauze, with further gauze packed on top of the drain. Film could then be laid over the entire area to complete the seal.

With this system, negative pressure can frequently be applied at -80 mm Hg. However, for heavily exudating wounds such as we are describing, our practice is to connect the drain and apply suction (on “maximum” setting) before attempting to seal the film. Increasing the pressure temporarily provides a local tamponade effect, removes any exudate that may drip out and ruin the seal, and also helps identify any possible leaks before adjusting the pressure to between -80 and -100 mm Hg. Getting a good seal is critical to the success of the procedure so that theatre staff should take their time and make sure that every part of the skin in contact with the film is absolutely dry. Manufacturers supply “ostomy strip paste,” which can be useful to help seal around the drain, but care should be taken to ensure that none of the holes in the drain are near the paste because there is a risk that the paste will be sucked up into the drain, causing a blockage and therefore a failure of the dressing system.

It is not unusual for some of our large wounds to drain 4.5 L of fluid every 24 hours, and such fluid loss needs to be considered when calculating overall fluid requirements. On occasions, we have used 2 VISTA pumps if there is an exceptionally large amount of exudate to clear. In such cases, we now prefer to use the bigger EZCARE pump, which copes with a higher flow rate.

After a period of 10 days, the wounds were ready for skin grafting. NPWT was applied as the dressing, this time with a layer of Telfa between the skin graft and the gauze to prevent accidental removal of the skin graft at dressing changes.

Coverage of the remaining sacrum was later achieved with a rotation flap (Fig 3). In spite of his injuries, the soldier's condition continues to improve (Fig 4).

Figure 3. Coverage using a rotation flap.

Figure 4. Soldier postsurgery.

CASE 2: TRAUMATIC INJURY TO RIGHT LEG

This soldier was injured when he stood on a pressure plate improvised explosive device in Afghanistan (Fig 5). On arrival in Birmingham, he required emergency above-the-knee amputation of his right leg. Radical debridement left a healthy wound bed, but it was a difficult wound to dress. We did not feel that conventional dressings would have been suitable for this patient. The use of a gauze-based NPWT system (in this case, VISTA) allowed for optimal wound healing, exudate management, and a secure dressing that was not able to slip off. Wound healing was completed with the use of skin grafts, and the soldier now walks with a prosthesis (Fig 6).

Figure 5. Pressure plate improvised explosive device injury.

Figure 6. Site of wound after debridement, application of negative pressure wound therapy, and skin grafting.

CASE 3: AMPUTATION OF 3 LIMBS

A 26-year-old soldier suffered injuries to all 4 of his limbs. He required bilateral above-the-knee amputations and a left above-the-elbow amputation (Fig 7). He also developed a fungal wound infection, requiring multiple debridements, NPWT using gauze provided optimal dressings and exudate management (Fig 8).

Figure 7. Amputated limb postdebridement.

Figure 8. Treatment with gauze-based negative pressure wound therapy over wound area.

Again, after 10 days' treatment with NPWT, skin grafting was performed with gauze-based NPWT (Fig 9). Telfa was used as an antishear layer in the dressing.