Recent Advances in Wound Care

Authors:

Michael K. Abraham, MD, MS, Clinical Instructor, Department of Emergency Medicine, University of Maryland Medical Center, Baltimore, MD.

Jason S. Oh, MD, Third-Year Resident, Department of Emergency Medicine, University of Maryland Medical Center, Baltimore, MD.

Peer Reviewer:

Steven M. Winograd, MD, FACEP, Attending, Emergency Medicine, St. Joseph Medical Center,Yonkers, NY.

In the United States, wound care constitutes a large part of the care provided in any emergency department (ED). While many lacerations and traumatic injuries can be repaired easily, some require complex and time-consuming management. Patients seek treatment for wounds in EDs for several reasons: emergency physicians, with expertise in wound management, are available around the clock; many primary care offices are not equipped to treat complicated wounds; and some primary care physicians are not comfortable with complex wound closure techniques. Patients are most concerned about cosmetic outcomes, functional preservation, relief from pain, and preventing infection.3 Successful outcomes are provider- and patient-dependent: If the practitioner provides perfect care but the patient does not comply with post-treatment instructions, the outcome can be less than optimal. If the initial treatment is inadequate, then healing is impeded from the beginning.

Due to the sheer volume of patients with injuries requiring wound care, their visits account for a significant amount of litigation directed toward emergency physicians. Between 5% and 20% of all malpractice claims and more than 10% of all malpractice dollars are spent on issues associated with wound care.1 According to the National Hospital Ambulatory Medical Care Survey, in 2005 there were more than 11 million visits to EDs for wound-related issues.2 Although wound care is not a new topic, the continued use of older methods for cleaning and treating wounds can lead to poor outcomes. In this article, we discuss newer techniques for irrigating, anesthetizing, and closing wounds, which lead to better functional and aesthetic outcomes.

— The Editor

Introduction

The clinical features of any wound depend on the type of trauma that caused it. Lacerations are violations of the skin caused by penetrating or blunt trauma, resulting in a linear defect. Depending on the mechanism of injury, the wound may be contaminated or foreign bodies may be present. Avulsions are a "tearing away" of a portion of skin or soft tissue, which usually results in an open or gaping defect. Puncture wounds are caused by penetrating trauma (e.g., contact with a nail or mammalian bites). Abrasions are relatively superficial wounds compared with the others, and are commonly sustained in motor vehicle crashes, especially when a passenger is ejected from the vehicle. Each type of wound requires a unique approach to treatment.

Wounds with little risk of infection are typically closed upon presentation after adequate debridement and irrigation; primary closure is the most frequently used method of wound care in the ED. Wounds with a higher risk of infection tend not to be closed, but allowed to heal by secondary intention: the wound "fills in" by granulation, contraction, and epithelialization. The downside of secondary intention is that the scar is often significant. Tertiary intention, or delayed primary closure, used for a contaminated or infected wound, is the repair of a wound four to five days after injury. The wound is packed with sterile gauze in a "wet–to-dry" fashion. On day 4 or 5, if the wound is clean, it is then closed.

Physiology and Pathophysiology

To understand wound management principles, the clinician must understand the anatomy, histology, physiology, and pathophysiology of the skin and its appendages. The skin provides a strong barrier against infection and aids in thermal as well as metabolic regulation. Its basic histologic makeup consists of the epidermis, dermis, and subcutaneous tissues. The deeper structures vary according to their anatomic locations. In addition, the patient's body habitus influences the depth of each layer and the presence of deeper structures.

The epidermis is an avascular layer composed of five sublayers. Given its avascular nature, the epidermis is nourished by diffusion of nutrients. The dermis consists mostly of dense connective tissue made of collagen. It houses most of the structures responsible for thermal and metabolic regulation as well as sensation.4 Hair follicles and blood and lymphatic vessels are a few of the many specialized structures located within the dermis. The subcutaneous layer (also called the hypodermis) consists mainly of adipose tissue, which is organized into lobules supported by a framework of fibrous septations. It is along these septations that lymphatics and blood vessels course. The superficial and deep fascia are connective tissue layers within the hypodermis that provide the skin's structural integrity. Together, these layers form a tightly knit barrier of defense and support for the body's internal organs.

Any insult to the integumen is essentially a forceful division of cells. The resultant discontinuity of the skin varies in depth and involves one or more layers. Along with bleeding, the exposure of collagen, various proteins, and endothelium provide the stimulus for hemostasis. Coagulation occurs when activation of various points along the intrinsic and extrinsic pathways leads to the production of thrombin. Thrombin converts fibrinogen to fibrin and initiates platelet activation. Thrombus formation occurs when platelets aggregate at the site of injury in response to the presence of thrombin and exposed collagen. Fibrin forms additional scaffolding upon which the platelets can bind.

Once hemostasis is achieved, the next step in healing is fueled by the inflammatory response. Although the inflammatory response is essential for healing, it has the adverse effect of damaging surrounding healthy tissue. This is important to explain to all patients, since essentially all wounds leave scars caused by the healing process. Interventions are available to limit this damage, but ultimately there will be a scar. Cell proliferation typically occurs during days 4 through 12 after the injury. This stage of rebuilding is dominated by fibroblasts, smooth muscle cells, and endothelial and epithelial cells. During this stage, granulation tissue forms. The epidermis thickens at the wound edges while basal cells at the margins elongate. The epithelial cells continue to migrate across the wound until they contact, forming a single layer of cells. These cells then replicate to form the multi-layer epidermis once again.

The final and longest stage of wound healing is maturation and strengthening, which begins during the first week after injury and lasts as long as 1.5 years. The collagen matrix is continuously reabsorbed and deposited for remodeling and strengthening of the newly repaired wound. Given the delicate balance between breakdown and remodeling, there is an increased risk of dehiscence during days 7 through 10.5 With reabsorption and remodeling, the wound slowly gains strength, achieving 30% of original strength at three weeks and peaking at 80% after three months.6, 7

ED Evaluation

As for any ED visit, the evaluation of a patient in need of wound care begins by addressing the ABCs (airway, breathing, circulation). Assuming that the wound is not responsible for making the patient unstable, wound management is addressed in the secondary survey. As with any patient encounter, the history should be obtained first. When approaching any wound, the first aspect of the history to consider is the mechanism of injury. For example, highly contaminated wounds or bites require careful and thorough irrigation to prevent infection; early administration of an antibiotic may be warranted. Another important part of the history is the anatomic location of the injury. Injuries to the face and hands are important for cosmetic and functional reasons; injuries to the lower extremities confer an increased tendency for infections.

Although this basic practice may seem mundane, failure to ascertain any of these elements can lead to improper wound management and, ultimately, a bad outcome for both parties. A thorough history of the injury usually makes the proper treatment evident. Some of the "red flags" that necessitate meticulous care include a delay in seeking medical care after the injury, occurrence of the injury in a highly contaminated environment, and injury to a diabetic or immunocompromised patient. These are discussed in this article as they pertain to individual wounds.

Another crucial aspect of the history is the patient's immunization status. Although cases of tetanus from wounds are rare, the Centers for Disease Control and Prevention (CDC) have recommendations that pertain to types of wounds and age of the patient. (See Table 1.) Briefly, adults between the ages of 19 and 64 years should receive Tdap if they have not been immunized in the past 10 years. If the wound is highly contaminated, then tetanus immune globulin should also be administered in the ED.

Anesthesia

A critical aspect of wound care is patient comfort. The outcome of a wound closure may depend not on the closure itself, but on an accurate assessment and comprehensive management. If the patient is comfortable, irrigation can be thorough, all aspects of the injury ascertained (including tendon injuries), and a potentially better cosmetic outcome can be achieved. For extremely large wounds, the patient may require procedural sedation or even general anesthesia, depending on the extent of the wound, the expertise of the practitioner, and the resources available. Procedural sedation and general anesthesia are not required for most wounds, and a discussion of it is beyond the scope of this article.

Most wound repairs in the ED can be done solely with local or regional anesthesia. Local anesthetics can be divided into two groups based on their chemical structure: the amides and the esters. (See Table 2.) Pharmacologically, both groups function by blocking nerve conduction via binding to sodium channels on the nerve cell membrane. Each drug has a different potency, duration of action, and time to onset. Those with higher lipid solubility have higher potency, as they cross the cell membrane more readily, allowing better blockade. The duration of action is determined by the affinity to the receptor. For example, bupivacaine, which binds more tightly than lidocaine, has a longer duration of action. The pKa (the pH at which the concentrations of the ionized and uncharged forms of the medication are equal) determines the time to onset. Since the uncharged form crosses the cell membrane easily, a drug with a pKa closer to a pH of 7 has a quicker time to onset.8 A higher pH allows a quicker time to onset, as more uncharged forms of the drug are present.

Unfortunately, anesthetics can induce toxicity, mainly central nervous system (CNS) and cardiovascular. The degree of toxicity is related to the drug's potency, the dose, and host factors such as metabolism and excretion. Generally speaking, the amides metabolize more slowly and therefore have a higher potential for toxicity. Toxic effects can be precipitated by intravascular injection, especially arterial injection. CNS effects can be as mild as lightheadedness, tongue numbness, and tinnitus to as severe as peri-oral paresthesias, seizures, coma, or death. Similar to drugs' effectiveness, CNS toxicity is related to lipid solubility. As lipid solubility increases, the therapeutic window narrows. Seizures caused by anesthetic use may be treated with benzodiazepines or thiopental. Cardiac effects include hypotension or hypertension, palpitations, ventricular dysrrhythmias, atrioventricular (AV) blocks, and even complete cardiovascular collapse. In the event of collapse, the Advanced Cardiac Life Support (ACLS) protocol should be followed, with the exception of using lidocaine as an antiarrhythmic.

To avoid these potential toxic effects, carefully consider the recommended dosages as well as patient factors, such as renal or hepatic impairment. Using epinephrine as an adjunct can reduce the overall systemic absorption of the medicine. Good technique, with frequent aspiration to avoid intravascular injection and use of a more dilute solution, decreases the incidence of adverse effects.9

True allergies to anesthetics are quite rare. In many cases, the reported "reaction" is an effect of inadvertent administration into the vasculature. True allergic reactions are often caused by a preservative such as para-aminobenzoic acid. If a true allergy is suspected, use a preservative-free anesthetic of the other class. In the rare instance that an allergy to both classes exists, diphenhydramine can be combined with benzyl alcohol for local anesthesia.8,10

Lidocaine is the most commonly used local anesthetic. It is available as a 1% or 2% solution. Its time of onset is 2-5 minutes, with a duration of action of approximately two hours. The maximum dose that can be administered is 3-5 mg/kg as a single dose of 300 mg. The addition of epinephrine increases the maximum allowable dose to 7 mg/kg and the duration of action to 3.5 hours. It was previously taught that lidocaine with epinephrine should be avoided when inducing digital blocks and injecting into other rich vascular areas. This limitation has been recently rejected, because numerous studies have pointed to the safety of using lidocaine and epinephrine for digital blocks.11-13

Bupivacaine, another commonly used anesthetic, is available in a 0.25% or 0.5% solution. Its time of onset is 10-15 minutes, with effects lasting 3-6 hours. The maximum dose of bupivicaine is 2-2.5 mg/kg. The addition of epinephrine increases the maximum dose to 3-3.5 mg/kg. Administration can be repeated every three hours; however, the total dose over a 24-hour period should not exceed 400 mg. Bupivacaine is associated with higher toxicity when compared to others in its class, given its higher potency and protein-binding potential.

For most wounds, local infiltration into the wound edge induces adequate anesthesia for debridement, irrigation, and repair. A small needle (25-27 gauge) is typically used. The depth of the injection is usually the subcutaneous or intradermal layer. Deeper placement of the needle heightens the risk of injecting the anesthetic into a blood vessel. When a deep injection is required, check for intravascular placement of the needle by aspirating and ensuring that no blood is returned.

The pain associated with administering a local anesthetic into the wound edge can be decreased by using a smaller needle, mixing the anesthetic with sodium bicarbonate, warming the anesthetic solution, and administering the drug slowly.14

Regional Blocks

In addition to local wound anesthesia, regional nerve blocks are good options for providing patient comfort during painful procedures. The benefits of regional blocks include a lower volume of the anesthetic agent and avoidance of the anatomic distortion that direct injection at the wound edge can cause. The disadvantages include the potential for inadvertent injection into a blood vessel (vessels run along nerves) and possible injury to the nerve. Regional nerve blocks are generally well tolerated by patients, and therefore are a valuable adjunct to wound closure in the ED. Knowledge of the local anatomy and cooperation of the patient are necessary to their success.

Nerve blocks used on the extremities include those for the digits, wrists, and ankles. Facial and oral blocks are used to dampen sensation from the supraperiosteal, superior and inferior alveolar, infraorbital, and mental nerves.

Topical Anesthetics

Topical anesthetics can be divided according to their site of application: mucous membranes, open wounds, and intact skin. Two anesthetics that can be used on the mucous membranes are cocaine and lidocaine. Given its potential for abuse, strict federal regulations, and cost, cocaine is not widely available or used in EDs. However, in specific situations, usually in conjunction with an ear-nose-throat specialist, cocaine is still used for its anesthetic and vasoconstrictive properties. In a 4% solution, cocaine provides good anesthesia for approximately 45 minutes. Because of its significant cardiovascular effects (tachycardia, hypertension, and coronary artery vasospasm/constriction), it should not be used in patients with significant coronary artery disease.

On the other hand, lidocaine is frequently used for topical anesthesia on mucous membranes. It is available in 1% to 4% solutions. Care must be taken to calculate and administer a dose that does not exceed the maximum weight-based limit (lidocaine is very easily absorbed across mucous membranes). One milliliter of a 1% solution contains 10 mg of lidocaine. Apply the drug as a nebulized solution, in an atomized form, or directly onto the target surface, depending on the area to be anesthetized.

Compounds that can be used for topical anesthesia on intact skin include eutetic mixture of local anesthetic (EMLA) and topical lidocaine (LMX-4®). EMLA is a cream consisting of 2.5% lidocaine and 2.5% prilocaine in equal ratios. A gram of EMLA contains 25 mg of each agent. EMLA also contains carboxypolymethylene to thicken the cream and sodium hydroxide to increase the pH to 9.4. The onset of action occurs in 45 to 60 minutes. After 60 minutes, the anesthetic has penetrated approximately 3 mm (approximately 5 mm after two hours). The maximum dose is 2 gm on 10 cm2 of skin. Possible adverse reactions include local skin irritation (redness, blanching, and dermatitis) as well as anesthetic toxicity. In infants younger than 3 months of age, it has been reported to cause methemoglobinemia. Despite the ease of application and use, EMLA's slow onset of action makes it especially cumbersome to use in the ED.

LMX-4® is a 4% lidocaine cream within a liposomal matrix. This vehicle of administration makes absorption quicker, because liposomes are more easily absorbed. Its onset of action occurs at 30 minutes.

TAC (tetracaine 0.5%, adrenaline 0.05%, and cocaine 11.8%) and LET (lidocaine 4%, epinephrine 0.1%, tetracaine 0.5%) are two topical anesthetics used for open wounds. TAC is administered by placing 5-10 mL on the open wound and covering the area with gauze for 10-20 minutes. Unfortunately, this compound has been associated with cases of respiratory distress or arrest, seizures, and even death in children. These complications, the high cost, and tight regulations due to the cocaine ingredient have limited the use of TAC in the ED.

LET is an attractive alternative. After application of 1-3 mL of the liquid form to an open wound, the anesthetic takes effect in 15-30 minutes. A gel form is also available, which is easier to contain to the affected area. Many clinicians prefer LET over TAC because of its advantages in price and safety profile.

Basic Wound Management

After the initial history has been obtained and the patient is anesthetized appropriately, the remainder of care can begin. One of the most important aspects of wound management is preparation prior to closure; namely, irrigation and examination for foreign bodies.

Preparation. Many publications have debated the best way to irrigate and cleanse a wound. Studies have examined the type of solution, amount of pressure, and various combinations. Generally, careful debridement and irrigation are the keys to decreasing the incidence of infection in traumatic wounds. A thorough search, with removal of visible contaminants and trimming of necrotic or non-viable tissue, is vital to debridement. Visualization to the base of the wound in a bloodless field is ideal; however, foreign bodies can still be missed.15 If bleeding occludes complete visualization of the wound, steps must be taken to achieve hemostasis. Techniques include applying a temporary tourniquet to the digit or extremity, using direct pressure, injecting an epinephrine-containing anesthetic into the subcutaneous tissue, or tying off the bleeding vessel.

Irrigation is best achieved with copious amounts of a physiologic solution. Larger volumes and irrigating at pressures of 5-8 psi are best for decreasing rates of infection.16-20 Although sterile normal saline is preferred, tap water is just as safe in smaller, lower-risk wounds.21-23 To achieve the appropriate pressure, use a 20- to 60-mL syringe with a 19- or 20-gauge needle or angiocatheter. Caution must be used, as over-zealous irrigation at pressures higher than needed may result in further damage to the tissue. A pressure of 50-100 mL/cm is a good target. For highly contaminated wounds (with higher risk of infection), larger volumes are suggested for irrigation.24 Some sources suggest use of a dilute (1%) provodine-iodine solution in infection-prone wounds, but this practice remains controversial because this antiseptic, especially in a 10% concentration, impairs wound healing.20 Hydrogen peroxide should never be used in wounds because it devitalizes granulation tissue and creates a medium for bacteria to flourish.25,26 Areas that have hair pose a separate impediment to preparing the wound for closure. Shaving is not recommended because it increases the risk of infection; if necessary, hair may be clipped.18 As an alternative, an antibiotic ointment can be used to move hair on the head away from the treatment area, "plastering" it to the scalp and allowing direct access to the wound edges.

Wound Closure. The decision to close the wound is also one of some controversy. This decision involves weighing the risk of infection against the importance of good cosmetic outcome. Infection risk is determined by the mechanism of injury, time of presentation relative to time of injury, the patient's age, and co-morbidities. For the most basic lacerations, simple interrupted sutures are placed for approximation of the wound's edges. The technical aspect of suturing becomes important in ensuring good cosmesis and decreasing the risk of infection. Regardless of which method is used for wound closure, repair following the Langer's lines distribution will result in better wound strength and cosmesis.

In most cases, suturing is accomplished by using a needle driver, which holds a curved needle attached to the suture. Whenever possible, hold the needle driver with the dominant hand. Place the thumb and fourth finger in the loops, with the second finger extended toward the tip to steady the instrument and the third finger grasping the top of the loop next to it. Although this is the "proper" method, sometimes the instrument is "palmed" without placement of the thumb in the loop.

Position the needle perpendicular within the tip of the needle driver at one fourth or one third the distance from the back where the suture is attached. Then "drive" the needle into the skin at 90° to minimize the amount of trauma to the skin. Use the non-dominant hand to gently evert the wound edge with pick-ups to ensure appropriate placement of the needle. Be careful not to crush the skin, as any further trauma may devitalize the skin further. After initial entrance into the skin, turn the wrist to drive the needle completely through and to follow the curvature of the needle, avoiding unnecessary trauma. For smaller wounds, drive the needle across the wound in one motion. For larger wounds, after the needle exits at the wound opening, it may need to be reloaded onto the needle driver for the second "bite" into the opposite wound edge. This second bite should be placed to ensure that the exit site of needle is a similar distance from the wound edge as the original site of entry and that the suture will lay across the wound at 90°.

Meticulous knot-tying is necessary to ensure that the wound edges remain closely approximated. To keep adequate tension across the wound edge, use a surgeon's or square knot as the first knot. The number of knots necessary to maintain closure depends on the type of suture being used and the tension that is being placed on the suture by the skin. In general, more knots are required with smaller suture material, because they have a higher tendency to become undone. General practice is to use the same number of throws as the number of the suture, with a minimum of three or four throws. The type of suture is dependent on the area of the laceration and the amount of tension. (See Tables 3 and 4.)

See table 3

Certain types of wounds call for specific suturing techniques or other methods of closure. For gaping or high-tension wounds, horizontal or vertical mattress sutures provide better approximation with less tension at the actual wound edge. Running sutures, with or without suture locking, are often used for long wounds to decrease the time required for wound repair. The subcuticular technique can be used to optimize cosmetic appearance. This technique is used less commonly in the ED than in the operating room because of the presumed contamination of the wounds in the ED. Regardless of technique, wound-edge eversion upon approximation facilitates wound healing.

Staples are an alternative to suturing. They commonly are used to close scalp wounds, but their use is limited at other anatomic locations because of a propensity to significant scars. One advantage offered by staples is that they can be placed in less time than required for suturing. Metallic staples have similar infection rates and cosmetic outcomes to sutures.27-29 If staples or sutures are not available for a scalp wound 3-10 cm in length, the hair apposition technique can be used if the hair is long enough (at least 3 cm). In this technique, hair on either side of the wound is twisted together, and the twist is then reinforced with tissue glue.26

Cyanoacrylate adhesives are excellent alternatives to sutures and staples, and are best used on areas of low tension and little movement. Their application is generally much quicker and less painful than the placement of sutures. However, glues can cause an exothermic reaction that produces mild discomfort. On higher tension areas, deep sutures may need to be placed prior to use of a cyanoacrylate. Studies show comparable rates of short-term infection, wound dehiscence, and three-month cosmesis for adhesives and sutures.30 Before applying an adhesive to a wound, careful debridement and irrigation are necessary. Application is best done in a bloodless field. Care must taken to avoid placement of the compound within the wound and between wound margins. Adhesives may be applied in multiple layers to strengthen the repair. Advise the patient that bathing and the application of antibiotic ointments and petroleum-based gels shorten the life of cyanoacrylates. Removal of the glue is not necessary, because it is sloughed off with the top keratinized layer of the epithelium.

Steri-strips, or skin tape, may also be used for wound approximation. These are typically used with some type of adhesive such as tincture of benzoin, as they may not retain their adhesion when used alone. Some data suggest they may be as effective as sutures in achieving acceptable cosmetic outcomes.31 There is some controversy as to the method of application; some sources suggest application perpendicular to the wound and others recommend placement parallel to the wound. Two disadvantages of using tape are that placement can be difficult, if not impossible, in hair-bearing areas, and the tape must be kept dry.

Wound Care after Closure

Care of the wound after closure is almost as important as the closure itself. After placement of sutures, apply an antibiotic ointment before covering the area with a dry, non-adherent dressing. Despite its widespread acceptance, the ability of antibiotic ointment to decrease rates of infection is associated with some controversy. Multiple studies have shown a decrease in bacterial load with the use of topical antibiotics.32-34 There have been mixed results when comparing topical antibiotic ointment with petroleum jelly.35,36 Topical antibiotics provide the advantage of creating a moist environment and thus preventing tissue adherence to dressings, aiding in patient comfort.37 When staples, tape, or cyanoacrylates are used, antibiotic ointment is not applied. The wound should be kept clean and dry. The patient should avoid scrubbing or soaking the wound. Dressing changes should be done at least once daily to allow adequate inspection and monitoring for signs and symptoms of infection, dehiscence, and suboptimal healing. The wound should not be exposed to sunlight. Sunblock should be applied after the first 48 hours, as hyperpigmentation may not occur for as long as six months after injury. If the wound is over a joint, placing a splint to limit range of motion of that joint may improve healing.

Diagnostic Evaluation

Some mechanisms of injury may lead to the introduction of foreign bodies into the wound. As mentioned previously, missed foreign bodies are the fifth-leading cause of malpractice claims against emergency physicians.1 Direct visualization of a wound to its base in a bloodless field is ideal, but even if this view can be achieved, the possibility that a foreign body is present remains. Moyedi and Torres reported that if the entire wound can be examined, there is a 7% chance that a foreign body is present, and if the entire wound cannot be visualized, there is more than a 20% chance that a foreign body has been retained.15 Certain aspects of the history can alert the practitioner to the possibility of a retained foreign body. These include injuries caused by glass, persistent pain or drainage, or a foreign-body sensation described by the patient. The most likely retained foreign body is glass; therefore, any injury in which glass was involved should be considered for evaluation with an imaging modality.

Plain Radiographs

In the past, the use of plain films was the only way to evaluate for foreign bodies. This modality has significant limitations, since many foreign bodies are radiolucent (e.g., wood, thorns, and certain plastics). Unfortunately, lacerations and wounds caused by these objects are some of the most likely to become infected. Many objects do not show up on plain x-ray films, and even if a foreign body is observed, it is often difficult to localize. The use of multiple views and markers can be helpful in determining the location of foreign bodies when using plain films.

CT Scan, Ultrasound, MRI

In addition to plain films, computed tomography (CT) scanning, ultrasound, and magnetic resonance imaging (MRI) can assist the practitioner in the evaluation of a wound. CT scanning has gained popularity because it compensates for many of the inadequacies of plain radiography. Many radiolucent objects that are normally not picked up on plain film can be seen on CT scan, especially if performed in the first 48 hours after injury. By 48 hours, organic material will have absorbed water and thus have the same density as the surrounding soft tissue, which makes it indistinguishable radiographically.38 The other benefit of CT scanning is its ability to define the object's 3D location and its proximity to any vital structures, such as neurovascular bundles. Regardless of the age of the wound, CT scanning is 100 times more sensitive for detecting foreign bodies than plain films.

Real-time visualization of an object by ultrasound allows the practitioner to identify the area directly overlying the foreign body, unlike any other imaging modality. In a technique described by Dean and colleagues, the sonographer rotates the 7.5-MHz probe perpendicular to the skin, allowing visualization of the object in cross-section.39 A 7.5-MHz linear probe allows about 3 cm of penetration. If the object is thought to be superficial, commercially available gel pads can be used as spacers. If these pads are not available, a 250-mL bag of saline, with the air removed, can be used as a spacer. Another option is to place a large mound of ultrasound gel over the area of interest and then move the ultrasound probe over the area without making skin contact. In all of these approaches, the spacer places the object in the center of the probe's field, which increases its sensitivity. Ultrasound used for this purpose is not perfect. Shadows, fascial planes, and significant edema can all limit its effectiveness. Gaping wounds also make for a difficult medium for ultrasound, since the probe has no uniform area to rest against, causing a significant amount of artifact.

Although MRI is very sensitive and specific, its use in the ED is not very practical, owing to the time needed for the study and its limited availability. If MRI is chosen for determination of the presence of a foreign body, there must be no possibility of the presence of metal in the patient's body. If metal is present in the wound, the MRI process will cause the metal to heat rapidly, may burn or cause significant pain to the patient.

Antibiotic Prophylaxis

The use of antibiotics in the treatment of wounds has been controversial. The ED care provider must be able to recognize high-risk injuries that warrant antibiotic prophylaxis. Invariably, all wounds are contaminated with at least a small amount of bacteria. Whether this translates into a clinically relevant infection depends on multiple factors. Routine use of systemic antibiotics for prophylaxis in immunocompetent patients with simple wounds is not recommended.40 In many cases, this practice does not decrease the rate of infection, but instead changes the bacterial profile toward unusual and more resistant organisms.41,42 Sound clinical judgment must be employed when choosing antibiotic prophylaxis.Table 5 lists wounds that require prophylactic antibiotics.

There is no debate that open fractures and penetrating abdominal wounds require prophylactic antibiotics. However, the debate continues in regard to plantar puncture wounds and bite wounds. Generally, the choice of antibiotic for prophylaxis should be similar to coverage for an established infection.43

Challenging Laceration Repairs

Fingertip. Distal tuft injuries are very common and can be quite time consuming for the emergency physician to manage. Since the majority of these injuries are usually caused by a crushing force to the digit; for example, being struck by a hammer or caught in a car door, the initial management should include three dedicated plain radiographs of the affected digit. Along with the fracture, there is usually some injury to the nail and nail bed, as well. If the fracture is "open," the wound requires intense irrigation, intravenous antibiotics, and appropriate tetanus prophylaxis. On initial examination, it may be difficult to examine the patient because of the significant pain associated with these wounds. Before anesthesia is induced, a neurovascular exam should take place, including a two-point discrimination test. The best tolerated form of anesthesia is typically a regional block. This can be induced at the wrist or the forearm if the operator is skilled with this ultrasound-guided procedure.18,44 After proper anesthesia has been established, the patient can be reexamined, usually with more success since the patient is more comfortable. Next, apply a digital tourniquet to allow examination under a bloodless field. If the nail is intact and a subungual hematoma has formed, leave the nail in place and drain the hematoma with trephination. Patient studies have shown that simple trephination provides good functional and cosmetic outcomes, and contradicts previous teachings calling for removal of the nail if the hematoma occupied more than 25% of the nail bed.45 If the nail is damaged, it should be removed and the bed repaired with absorbable sutures. The nail can be replaced and serve as a physiologic splint. This can be achieved by placing a horizontal mattress suture at the base of the nail, carefully avoiding the nail matrix. This procedure should be done with a 3-0 or 4-0 non-absorbable suture, which should remain in place for 14-21 days. If the nail is not damaged, but the fracture is open, the soft tissue must be repaired with the intention of maintaining the normal anatomy as much as possible. A thorough evaluation should ensure that there is no tendinous involvement, as this requires emergent referral. If there is no tendon involvement, these injuries require close follow-up (referral to a plastic surgeon or orthopedist is advised) to ensure that there is no infection and that healing is occurring properly.

Ear. Lacerations of the ear are important to repair properly for both cosmetic and functional reasons. The shape of the ear focuses sound into the external auditory meatus to amplify hearing; disruption can alter hearing. Since cartilage is avascular, improperly repaired wounds can lead to the development of a fibrotic, calcified mass described as "cauliflower ear." Since these injuries require meticulous repair of both the skin and the cartilage, local anesthesia is often not sufficient. A ring block can be administered, which will anesthetize everything except the concha and the external auditory canal. After the area is anesthetized, it can be irrigated. In contrast to other areas of the body that require high-pressure irrigation, the ear should be irrigated at low pressures to prevent separation of the cartilage from its nutrient tissue.46 Small injuries to the cartilage can be cleaned, and then the overlying skin repaired. In larger injuries, however, the cartilage should be repaired first with 5-0 or 6-0 absorbable suture. The amount of debridement should be limited, but up to 5 mm of tissue can be removed without anatomic disruption.47 Next, repair the posterior skin and then the anterior skin, with careful attention to the tension on the skin. Constantly evaluate the work by comparing it with the undamaged ear, using the uninjured ear as a guide in suturing the damaged ear. Fill the pinna with petroleum gauze and then apply a pressure dressing. Any damage to the cartilage requires antibiotic coverage with an agent that is effective against Pseudomonas species (e.g., ciprofloxacin). Complex or highly involved repairs may necessitate consultation with ENT or plastic surgery.

Lip. Very few areas are as sensitive or cosmetically important to a person as the lips. Unfortunately, the lips are often injured since they are exposed to the sharp teeth, which form a knife-like structure that can inflict damage. In addition, lip injuries are easily infected secondary to oral contamination, so care must be taken to provide thorough irrigation. The key to successful repair of labial lacerations is alignment of the vermillion border, where the skin of the face meets the skin of the lip.

Before repairing a lip laceration, it is crucial to completely anesthetize the patient using a mental or infraorbital nerve block for the lower and upper lips, respectively. A mental nerve block is created by placing 2-3 mL of anesthetic anterior to the mental foramen just inferior to the second bicuspid. An infraorbital block is created by placing a similar amount of anesthetic inferior to the infraorbital foramen, which is just superior to the upper canine. The nerve can also be blocked through a transdermal approach; however, the intraoral approach has proved to be more reliable and last longer.48,49 Injection of an anesthetic agent directly into the injured area can distort the wound edges. Anesthetizing the patient is important because of the precise nature of the repair. Patients can be displeased with as little as 1 mm of discordance of the vermillion border.47 Approximate the border with 6-0 non-absorbable suture material. Then position the remainder of the mucosa with 5-0 absorbable sutures from an inside-out direction. Close the exterior skin with 6-0 absorbable suture.

The management of intra-oral lesions is debatable. Some physicians do not close oral wounds because cosmesis is not an issue; however, data suggest that closure of certain intraoral wounds is beneficial to the patient. Gaping wounds or wounds that interfere with occlusion of the teeth may become infected or cause discomfort to the patient and therefore should be repaired. All patients with oral lacerations should be instructed to practice good oral hygiene and "swish and spit" with mouthwash or chlorhexidine gluconate (Peridex) after eating.

Tongue. The tongue is composed mainly of muscle groups with tight fascia connections, and most tongue lacerations do not need to be repaired. Fortunately, these injuries have a very low incidence of infection. However, if the lingual artery is involved, there is the possibility of airway compromise due to the large amount of hemorrhage. As with any emergent condition, the airway should be addressed primarily, with control of bleeding after the airway has been protected. Small lacerations of the tongue that are less than 1 cm, linear, and do not gape usually heal without intervention or infection.50 If necessary, anesthesia is best achieved by use of topical 4% lidocaine. If extensive repair is needed, a lingual nerve block can be established. After proper anesthesia, the tongue can be grasped without much discomfort. Use commercially available bite blocks or tongue depressors to prevent the patient from biting as the closure is completed. The recommended material is 4-0 or 5-0 absorbable suture, preferably chromic gut. Synthetic material has sharper edges and can actually lacerate the tongue when it swells. All three layers should be closed with one stitch and should be tied loosely. The tongue can swell significantly during the first 48 hours after injury; sutures tied too tightly can cause necrosis.8,50 A patient with a tongue injury should be instructed to perform oral rinses and good oral hygiene until significant healing has occurred.

Eye Lid. Lacerations to the ocular area can instill fear in both the patient and the practitioner. The delicate nature of the skin and the possibility of long-term visual complications guide the management of this area. Injuries to most aspects of the upper and lower lids should be closed with 5-0 or 6-0 nonabsorbable sutures. Care must be taken that knots and loose ends do not impair vision or even approach the cornea. Corneal abrasions caused by improperly applied sutures are not acceptable. More important than repairing the wound is appreciating when to obtain an ophthalmologic consultation. If the laceration involves either the upper or lower tarsal plate or the lacrimal system, it is best closed by an ophthalmologist. Additionally, if there is any evidence of orbital fat in the wound, the patient should be referred emergently for exploration of the orbit.51 If the patient has a horizontal lid laceration and evidence of ptosis, clinical suspicion should be high for levator palpebrae involvement, which requires referral. Many eyelid wounds may be left to heal by secondary intention. Lacerations affecting less than 25% of the lid, that are superficial, and do not have exposed bone or cartilage are good candidates for healing by secondary intention.52

Mammalian Bites. Dog, cat, and human bites account for a significant number of visits to EDs each year. Wounds caused by each species present a distinct challenge to the practitioner. Large dogs are capable of exerting tremendous forces with their jaws. This, coupled with the fact that they usually have dull teeth, account for both puncture and crush injuries. The tissue involved in the crush injury is devitalized and can easily become infected. In contrast, cats have sharper teeth and apply less force, accounting for more puncture wounds. The depth of the wounds and the associated bacterial contamination provide an ideal scenario for infection. Human bites are the most worrisome of the mammalian bites. The large bacterial load in the human mouth and the circumstances of lacerations caused by teeth produce heavily infected wounds.

All bites should be irrigated thoroughly, proceeding under the assumption that they are, or will be, infected. Antibiotic prophylaxis is warranted if the patient is at high risk for infection. (See Table 5.) Pasteurella, Staphylococcus, and Streptococcus species are the most prevalent aerobic pathogens. Dog and cat bites tend to produce polymicrobial infections.53 Human bites have a similar bacterial contamination profile, with the addition of Eikenella.54 The choice of antibiotic should be made with the species and the individualized patient in context. The recommended prophylaxis is either a β-lactam with a β-lactamase inhibitor or the combination of a fluoroquinolone and clindamycin.55 Patients who present more than 72 hours after the event and show no signs of clinical infection do not require an antibiotic.15 Any dog or cat that causes a wound requiring medical care should be checked for rabies, and the patient should start treatment with rabies immune globulin or vaccine if indicated.

Conclusion

The area of wound care is an extensive topic. A shift in the ED rarely passes without the need to administer some form of wound care. Unfortunately, wound management can be time-consuming and worrisome, owing to the threat of poor outcomes. Many of the complications that can be associated with wound care can be prevented by a thorough history, proper wound preparation, and judicious use of antibiotics. The proper use of irrigation techniques, use of the appropriate suture material, and knowing when to consult specialists will also contribute to successful outcomes of wound care.

(The authors wish to thank Linda J. Kesselring, MS, ELS, technical editor/writer, Department of Emergency Medicine at the University of Maryland School of Medicine, for editing assistance.)

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