Clinical evaluation of improvised gauze‐based negative pressure wound therapy in military wounds

Abstract

The use of negative pressure wound therapy (NPWT) in civilian and military wounds is found effective in promoting granulation tissue, decreasing exudate and improving patient comfort. The Use of gauze‐based NPWT is increasing in civilian trauma cases with availability of proprietary systems using gauze as filler material rather than the traditionally used reticulated open‐cell foam. Military trauma wounds differ from civilian trauma wounds in energy of impact, degree and nature of contamination as well as the hostile environments. The Use of gauze as filler material for NPWT in military trauma wounds is less well studied. This study is a retrospective analysis of use of improvised gauze‐based NPWT in military trauma wounds. The whole assembly was constructed from commonly available operation theatre supplies and no proprietary system was used. Results were very encouraging and the use of this improvised method can be useful and cheap alternative to costly proprietary systems.

Introduction

Despite surgical and technological advances, managing combat‐related injuries remains challenging. These are usually high‐energy injuries with devitalised tissue, contaminants and high risk of infection 1. Unique characteristics of a war such as environmental contamination, delayed evacuation procedures and varying levels of medical care in the field add to the complexity of care of such injuries.

Negative pressure wound therapy (NPWT), also known as negative pressure therapy (NPT), topical negative pressure (TNP), vacuum pack technique (VPT) or vacuum‐assisted wound closure (VAC®), is one of the most important technological advancements in wound care. It entails exposure, either continuously or intermittently, of a wound to subatmospheric pressure to promote and assist wound healing 2. It has been used to reduce the size of open wounds, improve the quality of wound bed by increasing the amount of granulation tissue and contribute towards infection control in preparation for split‐thickness skin grafting as well as post‐grafting for improving graft uptake 3, 4. Over the years, NPWT has become an accepted option for managing severe trauma cases as well as battle wounds 1, 5.

In NPWT, subatmospheric pressure is delivered to a wound bed through a filler material. Traditionally, this filler material had been the reticulated open‐cell polyurethane foam (ROCF). Nowadays, non‐adherent gauze is gaining popularity as alternative wound filler in a method of NPWT known as the Chariker‐Jeter system 6. This method uses a layer of saline‐moistened antimicrobial gauze that is 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 to seal the wound. The use of Chariker‐Jeter method of NPWT has been described in battle casualties with favourable results 7. This study is a retrospective analysis of our experience with gauze‐based NPWT in managing complex military injuries at our institute from September 2010 to September 2012.

Materials and methods

All the patients who suffered from military wounds and were treated by gauze‐based NPWT were included in this study. Initially, wounds were irrigated and underwent level 2 (marginal) of debridement according to Granick and Chehade classification of debrided wounds. The wound was then covered with fluffed gauze dressing and relook surgery was performed after 24 hours. Wounds were debrided and dressed until there was no necrotic material on two sequential dressing changes, then they were treated with NPWT per Chariker‐Jeter technique. Presterilised regular surgical chest swabs or gauze roll (depending upon the size of the wound) fluffed and soaked in pyodine solution were used as the filler material. A fenestrated silicone drain (Redivac drain) was then sandwiched between the layers of gauze. The whole assembly was secured with transparent semipermeable adhesive dressing (OPSITE—Smith & Nephew, Hull, UK) (Figure 1). Tincture of benzoin was applied to intact skin at wound margins to strengthen the seal of adhesive dressing. Drain tubing was connected to a regular portable suction machine, set at providing 100 mm Hg negative pressure. Subatmospheric pressure was delivered to the wound for 10 minutes every 30 minutes by turning the machine on and off by the patient or nursing staff.

Figure 1.

(A) Sterilised pyodine‐soaked gauze (black arrow) loosely packed in the wound. (B) A fenestrated Redivac drain (red arrow) sandwiched between the layers of gauze. (C) The whole assembly is then covered by airtight adhesive dressing (white arrow).

The negative pressure dressing was left in place for 2–4 days depending on the patient's need for additional surgery, dressing malfunction and operating room availability. Dressing was changed earlier in case of loss of seal or suction machine malfunction. Each VAC dressing change was accomplished by a surgeon in the operating room under sterile conditions, with additional lavage and debridement as necessary. On occasions, two drain tubes were used in case of large wound area or if there was an exceptionally large amount of exudate to clear.

Patients underwent serial operative irrigation and debridement until wounds appeared clean to gross inspection and deemed fit to undergo final management with delayed primary closure, skin grafting or local or microvascular‐free tissue transfer. In some instances, delayed primary closure was started during these repeat irrigations with reapplication of smaller VAC dressings as the wound was sequentially closed.

The data for the study were retrospectively collected from hospital records of the patients, which were prospectively maintained. Parameters analysed were patient age, type of injury, number of wounds treated by NPWT, number of dressing changes required and any complication of the wound or dressing method. Outcomes measured were appearance of healthy granulation tissue and final method of wound closure.

Results

A total of 497 gauze‐based vacuum dressings were applied on 106 wounds in 85 male soldiers. Mean patient age was 27·54 ± 7·163 years. Of the 106 wounds, 79 (74·5%) were due to improvised explosive devices (IEDs) or mine blast injuries, whereas 27 (25·4%) were bullet injuries; 64 wounds were on lower limbs and feet (including amputation stumps), 27 were on arms and hands, 8 were on abdomen and 7 in groin and perineum. Eleven were fasciotomy wounds, and 17 wounds had associated long bone fractures (when NPWT was applied in association with an external fixator) or exposed bone (as amputation stumps) (Figure 2).

Figure 2.

Anatomical distribution of wounds.

Median wound duration prior to placement of gauze‐based NPWT (including time in field hospitals when TNP was not available) was 5·33 days (range, 2–10 days). The duration of vacuum therapy averaged 12·50 ± 6·8 days (range, 6–32 days). Number of NPWT dressing changes for a wound ranged from 2 to 13 (mean 4·29 ± 2·63). Healthy granulation tissue and clean wound bed was the universal result. A total of 52 (49%) wounds were closed in delayed primary fashion (8 had some portion healed by secondary intention),·26 (24·5%) wounds required split‐thickness skin grafts, 12 local flaps were used and 16 wounds healed by secondary intention alone.

No wounds in this series had to be taken back for early redebridement because of patient sepsis. No patients had to be returned to the operating room for bleeding complications. However, 17 incidences (3·42%) of loss of seal led to return of patient to the operating room prematurely to replace wound VAC dressings. Loss of seal occurred only in wounds at groin and perineum, distal hand and foot with intact fingers and toes owing to complex geometry of areas. In ten cases, NPWT had to be temporarily abandoned.·Four patients were temporarily shifted to regular dressings because of temporary malfunction of suction apparatus. In three cases, patient non‐compliance with turning the apparatus on led to maceration of skin edges and NPWT was temporarily discontinued to let skin margins get dry. In three patients, NPWT was temporarily discontinued as they required further debridement and were transferred to daily dressings. When no further obviously necrotic material remained they were restarted on NPWT.

None of the patients in the series experienced acute in‐hospital wound complications. One patient died of systemic sepsis due to methicillin‐resistant Staphylococcus aureus (MRSA) although he had a negative wound culture. The remaining patients left the hospital with clean closed wounds. No patient with wounds closed by skin grafting had to be regrafted because of poor graft ‘take’.

Discussion

One of the most important technological advances in wound care, NPWT, has been used as a ‘bridge’ technique for wounds that cannot be immediately closed by either primary intention or plastic surgical techniques. The first successful application of NPWT to manage exudate and accelerate wound healing was reported by Raffel in 1952 8. Later, it was applied by using hemispherical glass chambers in the treatment of purulent lactational mastitis 9. The use of subatmospheric pressure for an extended period to promote debridement and healing of the wound was first described by Fleischmann et al. in 1993 10. Milestone work of Argenta and Morykwas in 1997 on animal wounds, using foam as contact layer (filler material) for delivering NPWT, led to the development of the earliest commercialised system known as VAC (KCI, Oxford, UK) 11.

Management and outcomes of traumatic injuries have been dramatically changed by NPWT following its potential to promote wound healing, alleviate wound symptoms and improve quality of life for patients with wounds 12. Its application has favoured skin grafts and decreased the need for flaps owing to resultant abundant granulation tissue even on exposed tendons and bones 13. More than 1 million patients have been treated for chronic pressure ulcers, abdominal wounds, diabetic ulcers and acute civilian trauma wounds with NPWT in combination with ROCF (NPWT/ROCF) 14.

Mechanisms proposed for beneficial effects of NPWT include increased wound perfusion, stimulation of granulation tissue formation through microdeformation and macrodeformation of wound, reduction in tissue oedema and interstitial tissue fluid, removal of free radicals from the wound, reverse tissue expansion, reduced bacterial colonisation and maintenance of a moist wound healing environment 9, 15. NPWT has been studied for at least half a century, but optimum pressure intensity, duration of treatment and intervals between treatments are still a subject of debate. Microvascular blood flow is observed to increase above baseline values with negative pressures of up to −125 mm Hg 15. Another study recommended −100 mm Hg pressure for soft tissues such as muscles and a lower suction pressure of −75 mm Hg for softer tissues such as fat and subcutaneous tissue 16. It is recommended that dressing changes should take place every 48–72 hours 2.

Negative pressure wound dressing consists of a negative pressure source, a wound filler material and non‐permeable, usually transparent adherent dressing. The filler obliterates dead spaces in wounds, prevents occlusion of the perforations in the drain by contact with the base or edges of the wound, ensures that the entire surface of the wound is uniformly exposed to this negative pressure effect and prevents formation of localised areas of high pressure and resultant tissue necrosis.

Until recently, the filler material has almost exclusively consisted of a ROCF or polyvinyl alcohol (white) foam [devices include VAC (KCI, San Antonio, TX) and Renasys (Smith & Nephew)]. An alternative wound filler (non‐adherent gauze) based on the method now known as the Chariker‐Jeter technique is now commercially available in several alternative NPWT devices, including VISTA (Smith & Nephew) and Wound ASSIST TNPTM (ArjoHuntleigh, Lund, Sweden) 6, 17. The commercially available gauze‐based systems involve the application of moistened antimicrobial dressing gauze impregnated with polyhexamethylene biguanide (Covidien, Hampshire, UK) as the filler material. In vivo studies have shown that foam and gauze are equally able to transmit negative pressure to the wound bed and are equally efficient in promoting changes in microvascular wound blood flow and creating mechanical deformation of the wound 18, 19. Gauze‐based NPWT has been shown at par to polyurethane foam in reducing wound area and volume (at about 15% per week) in a range of difficult wounds 3, 20.

Military wounds, whether sustained through gunshots, multiple fragmentation injury secondary to grenades, IEDs, landmines or suicide bombings, are frequently high‐energy wounds with devitalised tissues and contaminants including dirt, shrapnels and clothing, leading to high risk of infection and wound complications 1. Injuries sustained in current theatres of war are becoming ever increasingly survivable owing to improved body armours, immediate first aid through the use of combat tourniquets and novel haemostatic agents, as well as rapid evacuations to definitive care centres. As a result, seriously injured soldiers are surviving with increasingly mangled limbs and complex wounds requiring lengthy, multifaceted care. Treatment doctrine is the result of lessons learned in conflicts over the past few centuries, dating back to early 19th century Europe through the Vietnam, Persian Gulf War and recent war against terror. Debridement, irrigation and closure by secondary intention are fundamental principles of management of these injuries 1.

The use of NPWT for the care of war injuries at battlefield trauma hospitals, aboard aeromedical evacuation transport system and/or tertiary care centres is a relatively new application. Since its first reported successful use in military wounds in 2006, NPWT/ROCF has been applied in multiple case series with favourable outcomes 1, 6, 14, 21, 22, 23. All these studies have recorded improved rates of healing, reduced levels of infection, decreased hospital stay, simplified nursing care and improved quality of the wound beds when compared with historical experiences. Most of these studies used proprietary NPWT systems based on ROCF (mostly VAC, KCI).

Since the start of war against terror in northwestern areas of Pakistan, our institute has been frequently faced with challenging trauma wounds, caused by improvised incendiary devices, land mine explosions and gunshot wounds. These injuries are associated with extensive soft tissue stripping and contamination, high levels of exudate and are particularly prone to infection both by bacteria and fungi. Our objectives in managing these wounds were to debride necrotic tissue, stabilise soft tissue, salvage compromised tissue, reduce oedema, infection, wound size, the number and frequency of dressing changes and finally the complexity of the wound itself to facilitate further reconstructive surgery. We have been treating chronic wounds such as bed sores and diabetic ulcers with foam‐based NPWT for some years with good results. The sheer number of battle casualties being evacuated to our hospital during the early period of war against terror, and the extensive, complicated geometry of these wounds directed us to try gauze‐based NPWT, which was later adopted as the routine method owing to its excellent results in our experience. Because of low economic thresholds we were not able to use patented systems as VAC (KCI, San Antonio, TX) or VISTA (Smith & Nephew) for NPWT and had to resort to the improvised method as detailed earlier.

We found that seal creation was made easier if an adhesive solution was applied to the intact skin adjacent to the wound, particularly in junctional areas that are prone to loss of complete seal (e.g. the groin in a high amputation). Tincture of benzoin (Friar's balsam) was used for this purpose. Creation of a sleeve of adhesive dressing around the drain (called ‘mesentery’) also helped in creation of effective seal (Figure 3).

Figure 3.

Mesentery (black arrow) helps creation of seal around the Redivac drain.

Jeffery reported the use of Chariker‐Jeter method in three cases of combat‐related injuries using VISTA device in 2009 with favourable outcomes 6. Application of field expedient gauze‐based VAC in field had been reported previously, which was quickly changed to proprietary VAC system (KCI Inc.) 23. Until the time of submission of manuscript, this study incorporates the largest number of combat‐related injuries treated by NPWT and especially by Chariker‐Jeter system. We constructed our own NPWT dressings from regular operation theatre supplies and did not use any proprietary system. It was subjectively found to be effective in reducing periwound oedema, removing exudate, promoting granulation of wound bed, reducing complexity and volume of wounds and optimising wound beds for skin grafting or flap coverage. As already noted in some studies, we found that the highly conformable nature of gauze makes it easier to apply compared to foam, especially in deep wounds with irregular shape and surface (commonly encountered in combat injuries) and on wounds around body curvatures 6, 7. Gauze‐based NPWT has been associated with less pain than foam‐based NPWT owing to less tissue ingrowth and non‐adherent property of gauze 24.

The drawback of our method is the failure of suction machines, which we observed on 17 instances, and noisy machines (although we are unaware of breakdown rate and noise of proprietary NPWT systems). Another issue noted on seven occasions is non‐compliance of patient or attendant to turn the machine on or off.

Clearly, this large case series is limited because of its observational and descriptive nature. It does not compare ROCF method or commercialised Chariker‐Jeter NPT dressings either in efficacy or cost. These aspects and the unconventional timing of negative pressure delivery (10 minutes in every 30 minutes) instead of continuous or intermittent pressure delivery systems are open to future studies in more controlled environments.

Conclusion

Evidence in favour of use of NPWT for combat‐related injuries is getting strong. NPWT systems help to improve wound granulation, remove exudate, reduce wound infection rate, improve patient comfort and make nursing care simple and easy. Gauze‐based NPWT is more versatile and capable of treating a larger variety of traumatic wounds with ease of application. The use of locally assembled gauze‐based NPWT, when used in combination with comprehensive surgical assessment, exploration and meticulous debridement, is both effective and cost‐effective in treating military wounds.