Acute Wound Care

Introduction

Traumatic wounds are common in civilian and military conflict.  Because of the unfortunate carnage of war, physicians have learned through a variety of conflicts methods to treat wounds to avoid death and to maximize disability.  In the American Civil War, surgeons learned that early amputation reduced rates of sepsis and death and frequently amputated limbs.  In World War I, trench warfare resulted in many craniofacial injuries, and many new techniques were developed to treat these wounds and restore form and function to the face.  In the Vietnam conflict, advances in antibiotics, reconstructive surgery and vascular surgery allowed for the preservation of limbs.  With this improved treatment, physicians now can focus their treatments on functional and aesthetic outcomes. 

In this chapter, we will focus on the initial treatment of acute wounds. Later-stage (i.e. non-acute) procedures for more complex wounds such as skin grafts and flaps are not covered in this chapter. Additionally, this chapter does not discuss burn injuries, which invoke specific alternative management practices.

Acute Traumatic Wound Etiology

The skin is a strong membrane composed of collagen, elastin and glycosaminoglycans that protect humans from minor external forces.  When forces overcome the innate ability of the skin to resist injury, a disruption in the skin occurs that is referred to as a wound. Depending on the etiology of the wound, there are additional considerations for management and concerns for damage to deeper tissues.

Many soft tissue injuries have the remarkable ability to heal over time.  This is done through the processes of wound contraction, epithelialization, and scarring.  Some have hypothesized that the scarring response, not seen in other animals such as salamanders, is an adaptation of humans to rapidly heal wounds, avoiding infection, with a tradeoff of scarring.  When bone, cartilage or tendon becomes exposed, injuries become more complex and often require treatment by clinicians familiar with techniques of stabilizing hard tissues. 

General Principles of Acute Wound Management

Initial Stabilization & Assessment

The patient must be acutely medically stabilized before performing any further wound management that does not directly relate to the cause of a patient’s present instability. This includes systemic stability as well as stopping potentially significant bleeding from the wound site(s) primarily with pressure or tourniquet. In massive trauma, this often involves transport to an appropriate facility where more definitive care can be rendered.  Blood loss can be a substantial issue and having blood available for transfusion as well as adequate anesthesia can be lifesaving.

A thorough evaluation of the wound is critical^[1]. One should make note of depth, tissues involved, presence of any fistulas or associated cavities, amount of tissue missing, and obvious contamination.

Wounds are contaminated with bacteria from the environment.  Antibiotics need to be carefully considered as they can result in resistant bacteria within the wound that are difficult to treat.  These bacteria can be transmitted to other patients most commonly through the hands of medical providers.  Hand hygiene and avoiding the use of dressing carts have shown to reduce cross-contamination between patients.

For large wounds, operative debridement with general anesthesia is preferred.  For smaller wounds, topical local anesthesia such as lidocaine can be helpful in some cases.  For frankly necrotic tissue, this can often be comfortably debrided without any anesthesia.  If needed, local wound anesthesia can be injected around the wound site with appropriate doses of lidocaine or bupivacaine^[3].

Debridement

The first step in wound management is to debride the wound of any foreign objects, infected material, or devitalized tissue that may compromise the normal wound healing process. Debridement techniques can be broadly categorized into irrigation, surgical, enzymatic, and biologic; in the context of providing care in an active combat zone, irrigation and surgical debridement are likely the most rapid and feasible techniques.

Copious irrigation with saline is common practice. In the setting of an actively bleeding wound, care must be taken not to disrupt clot formation and perpetuate bleeding with aggressive irrigation volume or force. High-pressure irrigation may drive any surface bacteria into the wound and is less commonly used^[4]. Irrigation with antibiotic solutions has mostly been abandoned due to poor data to support usage.

Enzymatic debridement is costly, slow and painful generally not used for acute wounds.  Similarly, biologic debridement using larvae or maggots is generally not used. 

Wound Dressing & Packing

A moist wound environment has shown to enhance wound healing as demonstrated by Winters in 1964 (Science Ref^[5]). Most commercial advanced wound care products including alginates and hydrogels utilize this principle.  There are few comparative studies showing the superiority of one dressing over another, so the experience of the clinician and the availability of dressings determine what will actually be used. A list of dressing properties to consider are listed below. ^[6-8] (Table 1)

Table 1.  Properties of an Ideal Dressing

1. Non-Inflammatory
2. Non-Allergic
3. Non-Immunogenic
4. Keep the wound moist while removing excess fluid
5. Avoid maceration of surrounding skin
6. A barrier to the external environment
7. Not cause bleeding
8. Not induce pain
9. Infrequent need for change
10. Resist infection

Dressing Types & Indications

There are over 1000 dressings on the market with none being ideal for all wounds.  The choice depends on the priorities of dressing properties desired and the availability in each clinical setting.  Some specific examples are listed below:

Gauze

Cotton gauze is by far the most utilized dressing today.  It nicely absorbs fluids and can be used to retain topical fluids such as normal saline.  Tissue can grow into gauze making it difficult or painful to remove.  It does not degrade in the wound, so caution needs to be used to make sure it is all removed, or it can cause difficult infections or chronic drainage of the wound.  Synthetic gauze made of polymers is an alternative to cotton gauze.

Polyurethane films

This are popular dressings providing an occlusive surface that blocks bacterial invasion with a controlled vapor loss allowing some transmission of water vapor but not allowing the wound to macerate.  They are easy to apply and remove and have an adhesive surface on one side.  Some patients have allergies to the adhesives, and they cannot be used.  In the setting of active infection, polyurethane films need to be used with care so as not to entrap pus in the wound.

Alginate dressings

These dressings keep the wound moist and allow for absorption of wound exudate.  They are soft and cause little pain when changed.  They are usually changed every 2 to 3 days and are comfortable for patients.  Care needs to be used in the setting of active wound infection.

Foams

There are a variety of foams that can absorb or transmit fluids through them.  Non-absorptive foams can be helpful in highly exudative wounds.  Typically, open pore reticulated polyurethane foams are used that very efficiently transmit fluids from the wound and transmit suction to the wound surface.  They are used extensively with Negative Pressure Wound Therapy (NPWT) devices. 

Antibacterial Dressings

Sodium Hypochlorite solution (Dakin’s) is a dilute bleach solution which has been used for years and is effective in treating infected wounds.  Often used in combination with gauze these dressing are changed at least daily to rapidly decontaminate the wound.  Another popular antimicrobial is silver which comes in a number of formulas and is frequently used on wounds at risk for infection or those that are heavily colonized by Bacteria.

NPWT devices

Negative pressure wound therapy (NPWT), often referred to as Vacuum Assisted Closure (VAC) is now the most common utilized dressing for complex acute wounds and for complex combat wounds.  These devices consist of an interface material applied to the wound,  often an open pore reticulated polyurethane foam, covered by an occlusive dressing.  The interface is connected to a suction source generally at 75 to 125 mm Hg.

These devices nicely evacuate excess fluids from wound at the same time while not allowing the wound to desiccate.  The suction draws the edges of the wounds together.  The interface material causes micro- deformations of the wound surface which stimulates angiogenesis and cellular proliferation.  These dressings are typically changed 3 times per week.  Because the wound is totally covered, they prevent external bacteria from entering the wound. 

Infection Management

While intact skin can normally protect from bacterial invasion, a disrupted skin barrier enables bacteria from the trauma itself or surrounding environment to infect the wound.  If inadequately managed, these bacteria can proliferate, causing local wound infections that could extend radially, penetrate underlying tissues or even progress systemically to sepsis. Early identification and treatment of a wound infection and its sequelae is therefore critical. Generally, clean open wounds that are managed well with dressing rarely become infected.  As such, systemic antibiotics are not routinely used for clean wounds. 

In some cases, aggressive bacteria such as Streptococcus, certain Staph species and certain polymicrobial mixes can cause a necrotizing infection requiring emergency radical debridement’s and antibiotics.

Clinical signs of wound infection that might warrant antibiotic therapy include symptoms that are local (pain, heat, swelling, redness, decreased function; spreading erythema, soft tissue crepitus, lymphangitis, wound breakdown or dehiscence) and systemic (pyrexia or hypothermia, tachycardia, tachypnea, raised or depressed white blood cell count; sepsis with or without multiorgan dysfunction or hypotension)^[9].

Tetanus

Tetanus is a life-threatening condition caused by Clostridium tetani, a bacterium often found in soil and thus is an important consideration when managing contaminated wounds. Prophylactic tetanus management in the setting of a contaminated wounds depends on both date of recent tetanus toxoid vaccination as well as degree of wound contamination and should be given according to one of the well-accepted guidelines ^[10].   

Special Considerations

Below are specific sources of acute traumatic wounds likely to be encountered in an active conflict setting that, in addition to the general principles outlined above, may require special considerations for management.

Ballistic Wounds & Blast Injuries

Ballistic injuries are those caused by projectile contact with the body; this includes injuries caused by a bullet, pellet or shrapnel. The extent of injury to surrounding tissues is dependent upon a number of projectile factors that influence kinetic energy transfer from the projectile to the surrounding tissues, including projectile size, stability, shape and overall construction ^[11]. These factors also determine the size and overall shape of the permanent cavity formed as the projectile travels through the tissue. The resulting wound may be broadly classified as penetrating (i.e. entrance wound without exit wound), perforating (i.e. entrance and exit wounds without appreciable tissue loss), or avulsive (i.e. entrance and exit wounds with acute tissue loss)^[12].

The basic tenants of acute wound management apply to projectile wounds; importantly, both entrance and exit wounds of each projectile that contacts the skin should be debrided accordingly. In all cases, tetanus prophylaxis will be almost certainly indicated. Further, complete removal of all foreign bodies following a projectile wound often cannot be guaranteed in the acute setting. Therefore, if there is any suspicion of remaining metal fragments, it is important to inform the patient and, if possible, document this exposure in the patient’s medical record as they may be unable to receive certain imaging studies (i.e. MRI) without great risk to their health. 

Other nuances of high yield projectile wound management vary according to projectile energy or other features, some of which are briefly explored below.

Low-Energy Gunshot Wounds

Low velocity, or “low energy”, gunshot wounds are typically penetrating with little tissue loss or avulsion and a limited zone of injury; bone fractures, if present, often demonstrate limited comminution^[13].

High-Energy Gunshot Wounds

High velocity, or “high energy”, gunshot wounds are often perforating or even avulsive, creating a larger zone of injury; associated bone fractures are typically grossly comminuted ^[13]. Many have referred to this process as cavitation which occurs in the wake of a projectile.  This larger zone of injury is associated with greater risk of necrosis due to disrupted blood supply and infection. Therefore, the wound may declare itself over a longer period and are more apt to require serial and/or more extensive debridement.

Shotgun Wounds

Shotgun wounds are made from multiple pellets, are avulsive and often associated with extensive tissue loss and injury zones; if present, bone fractures are most often grossly comminuted ^[13]. These massive injuries are particularly prone to contamination.

Blast Injuries

Blast injuries are common with explosives, which often produce a variety of high-speed projectiles that can be driven deep into soft (or less commonly hard) tissues during the blast. These injuries can occupy large areas of the body and often require repeat debridement.  These are commonly seen with Improvised Explosive Devices (IEDs).  As these are usually made largely from easy to find materials, the risk of contamination is high. 

Discussion

Acute traumatic wound management is built on the principles of debridement, dressing and infection control. Active conflict settings include a host of additional risk factors that must be considered and appropriately managed with the resources available. If possible, recognizing the limitations to access of medical infrastructure during times of acute conflict, records of injury and treatment management should be kept by the provider and/or the patient to inform future care maintenance and infection control considerations.  Getting the patient to the correct environment with adequate resources to address the specific injuries are critical.   

References

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5. Winter GD. Formation of the scab and the rate of epithelization of superficial wounds in the skin of the young domestic pig. Nature. 1962;193:293-4.
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10. Summary guide to tetanus prophylaxis in routine wound management [Internet]. Minnesota Dept. of Health. 2019. Available from: https://www.health.state.mn.us/diseases/tetanus/hcp/tetwdmgmt.html
11. Stefanopoulos PK, Filippakis K, Soupiou OT, Pazarakiotis VC. Wound ballistics of firearm-related injuries–part 1: missile characteristics and mechanisms of soft tissue wounding. Int J Oral Maxillofac Surg. 2014;43(12):1445-58.
12. Powers DB, Delo RI. Characteristics of ballistic and blast injuries. Atlas Oral Maxillofac Surg Clin North Am. 2013;21(1):15-24.
13. Stefanopoulos PK, Soupiou OT, Pazarakiotis VC, Filippakis K. Wound ballistics of firearm-related injuries–part 2: mechanisms of skeletal injury and characteristics of maxillofacial ballistic trauma. Int J Oral Maxillofac Surg. 2015;44(1):67-78.