Wound Management Principles

Key Concepts

Risk factors for wound infection include crush mechanism; long (>5 cm) deep penetrating wounds; high-velocity missiles; diabetes; and contamination with saliva, feces, soil, or other foreign matter.
Soaking wounds in povidone-iodine (Betadine) is toxic to healthy tissue. Prepare the skin with a chlorhexidine-alcohol solution.
The most effective intervention to decrease wound bacterial counts and infection is thorough cleansing, with use of saline or tap water irrigation at approximately 8 psi. Attaching an 18-gauge needle to a 30-mL syringe creates an irrigant force of 7 or 8 psi.
Bupivacaine is the preferred local anesthetic agent for the care of most wounds. In adults, the maximal reported safe dose is approximately 2 to 2.5 mg/kg without epinephrine and 3 to 3.5 mg/kg with epinephrine.
The discomfort associated with the injection of bupivacaine into wounds can be reduced by warming the anesthetic and by adding sodium bicarbonate (0.1 mL of sodium bicarbonate to 10 mL of bupivacaine).
High-risk wounds should not be sutured primarily but may be repaired in 4 or 5 days (i.e., delayed primary closure).
Tissue adhesives offer several advantages compared to the suturing of simple wounds. However, the use of adhesives is not recommended for lacerations longer than 4 cm, for high-tension wounds, or in areas subject to frequent repetitive movements, such as joints and hands.
Skin tears in elders are best treated with Steri-Strips, augmented with topical skin adhesives when tension exists.
Antibiotics are indicated for through-and-through intraoral lacerations, cat bites, some dog and human bites, puncture injuries to the foot in high-risk individuals, open fractures, and wounds involving exposed tendons or joints.
Tetanus immunization should be provided soon after injury but can be given days or weeks later as the incubation period for tetanus is 7 to 21 days (range, 3 to 56 days).
Tdap is recommended for patients 65 years old or older requiring tetanus prophylaxis.

Foundations

Background and Importance

The goals of emergency wound treatment are to restore function, repair tissue integrity with strength and optimal cosmetic appearance, and minimize risk of infection . Risk of infection depends on the location, mechanism, host factors, and wound care. The risk for a clean facial wound produced by incision is less than 1%, whereas a dirty crush injury to the lower extremity may have more than a 20% risk. Wound infection generally results in delayed healing, decreased strength, and a poor cosmetic result. These facts highlight the need for high-quality wound care. Understanding the biology of wound healing and the technical aspects of wound treatment facilitates emergency management of these patients.

Emergency clinicians must be aware of the medicolegal risk associated with soft tissue injuries. Including injuries to the hand, wound-related complaints are the fourth most common cause of malpractice claims against emergency clinicians with missed foreign body , wound infection, and missed tendon or nerve injury as the most common complications leading to claims.

Anatomy, Physiology, and Pathophysiology

An understanding of skin anatomy leads to better appreciation of wound closure concepts and techniques. The skin is a complex organ that protects the body against bacterial invasion, ensures thermoregulation, and helps to regulate water content and register sensory stimuli.

The skin and fascia vary in thickness from 1 to 4 mm, depending on the part of the body. The epidermis, the outermost layer, is several cell layers thick. The most important parts of the epidermis are the stratum germinativum (basal layer), where new cells originate, and the stratum corneum, the outermost cell layer that gives the skin its cosmetic appearance. The layer of skin directly beneath the epidermis is the dermis. It is a thicker, connective tissue layer and primarily responsible for ultimate wound healing. Removing debris and devitalized tissue from the dermis is key for optimal healing and minimal scar formation. The dermis also functions to anchor sutures placed percutaneously or subcutaneously.

The superficial fascia lies directly beneath the dermis and encloses the subcutaneous fat. This space must be irrigated and debrided to decrease the risk of infection. The deep fascia lies beneath the fat and is a strong, off-white sheath that covers and protects the underlying muscles and helps prevent superficial infection from spreading to deeper tissues. The deep fascia must be closed to maintain its protective and functional roles.

Normal wound healing is a well-choreographed sequence of biologic events. ¹ (1) These include coagulation, inflammation, collagen metabolism, wound contraction, and epithelialization. Maintaining the balance of these events is crucial for normal healing. Delaying any of the stages may result in a weak closure and dehiscence. Prolonging segments of the process may affect the ultimate scar appearance.

Soon after tissue integrity is altered, the process of coagulation begins. Platelets release factors that initiate and enhance a response from inflammatory cells. Capillary permeability increases to allow white blood cells to migrate into the wound. Neutrophils and monocytes act as scavengers to rid the wound of debris and bacteria. Monocytes transform into macrophages, which seem to have a major role in subsequent healing phenomena. In addition to providing wound defense, macrophages release chemotactic substances, signaling other monocytes to stimulate fibroblast replication and trigger neovascularization.

Collagen is the principal structural protein of most body tissues. Normal tissue repair depends on collagen synthesis, deposition, and cross-linking. Fibroblasts synthesize and deposit collagen compounds 48 hours after injury. Immature collagen is highly disorganized and has a gel-like consistency.

After a series of enzymatic processes, characteristic fibrils are produced followed by intermolecular cross-links that bolster their strength. The entire process depends on tissue lactate and ascorbic acid and is directly related to tissue arterial carbon dioxide partial pressure. In the absence of vitamin C, prolyl and lysyl hydroxylase do not activate, and oxygen is not transferred to proline or lysine. Under-hydroxylated collagen is produced, and characteristic collagen fibers are unable to form. As a result, wound healing is poor, and capillaries are fragile. Without oxygen to hydroxylate proline and lysine, a local condition resembling scurvy occurs.

Under normal conditions, collagen synthesis peaks by day 7, coincident with rapid increases in tensile strength. The healing wound has the greatest mass at 3 weeks but remodels itself during the next 6 to 12 months. However, the wound achieves less than 15% to 20% of its ultimate strength by 3 weeks and only 60% by 4 months.

Wound contraction is the movement of whole-thickness skin toward the center of the skin defect. Immediately after injury, the wound edges retract and increase the size of the defect. Normal skin tension along the lines of minimal tension produces this retraction ( Figs. 50.1 and 50.2 ). Wounds perpendicular to these lines are under greater tension and result in a larger scar.

Fig. 50.1, Skin Tension Lines of the Face.

Fig. 50.2, Skin Tension Lines of the Body Surface.

During the next 3 or 4 days, the wound size shrinks as its edges move toward the center. This phenomenon is independent of epithelialization, and the presence of collagen is not necessary for it to occur. This process is considered beneficial to healing and should not be confused with contracture that results from scar shortening.

Contracture becomes more apparent when the normal healing process is prolonged often producing a disfiguring hypertrophic scar. Optimizing the duration of the inflammatory phase and minimizing wound tension help to produce a more “appealing” scar.

Epithelialization is a process whereby epithelial cells migrate across the wound. Mitosis appears at the wound edge near the basal cell layer within hours of injury. Eschar or other debris impedes this process. Epithelialization proceeds most efficiently when a wound is properly cleansed, debrided, and kept moist and protected.

In a surgically repaired laceration, epithelialization bridges the defect by 48 hours. The new tissue proceeds to thicken and grow downward, beginning to resemble the layered structural characteristics of uninjured epidermis within 5 days. Simultaneously, keratin formation loosens the overlying scab.

Various forces (lines of tension) exist as a result of skin elasticity from collagen fibers. These static forces may vary more than fivefold with the respective area of body skin surface, but the static tension of a given area of skin remains constant. These static forces are shown clinically by the gaping of wounds after incision. The magnitude of static skin tension is directly related to ultimate scar width.

Uneven, jagged wounds have greater surface area than do linear lacerations. The skin tension distributed over a greater area is less per unit length of tissue. Meticulous reapproximation of the jagged edges results in a more appealing scar. Sharp debridement, converting a jagged wound to a linear laceration, is often unwise because it may result in too much tissue loss and produce a wider, more visible scar. Skin forces produced by muscular contraction and movements of flexion and extension influence healing and scar size. These dynamic forces are greatest where skin elasticity is necessary for function. Lacerations parallel to skin folds, lines of expression, and joints do not impair function or produce unattractive scars. Wounds that traverse the skin lines heal with conspicuous scars and may impair function. Knowledge of these lines and forces is necessary for optimal wound repair. In addition, the patient should be educated about wound healing and scarring potential.

Clinical Features

History

A detailed history should be obtained as part of routine wound evaluation. Serious complications can result when basic information is not obtained. Wound care decisions may be changed if the patient has significant peripheral vascular disease, is immunocompromised, or has a high risk of a retained foreign body. Essential historical information includes past medical history, mechanism and setting of injury, and tetanus status.

Risk factors for wound morbidity include prolonged time since injury; crush mechanism; long (>5 cm) and deep wounds; patient age; high-velocity missiles; location on lower extremities; and contamination with saliva, feces, soil, or other foreign matter ( Box 50.1 ).

BOX 50.1

Risk Factors for Wound Infection

1.
Location: Leg and thigh, then arms, then feet, then chest, then back, then face, then scalp
2.
Contamination with devitalized tissue, foreign matter, saliva, or stool
3.
Blunt (crush) mechanism
4.
Presence of subcutaneous sutures
5.
Type of repair: Risk greatest with sutures > staples > tape
6.
Anesthesia with epinephrine
7.
High-velocity missile injuries
8.
Diabetes

Three hours after acute trauma, bacteria proliferate to a level that may result in infection. Standard wound care guidelines for routine wound care recommend closure within 8 to 12 hours of injury yet more recent data suggest that timing is less important than the other risk factors. All risk factors must be considered to optimize wound care, and flexibility is required. Lacerations produced by fine cutting forces resist infection better than crush injuries. Reduction of blood flow to wound edges in the latter may increase the infective concentration of bacteria by a hundredfold. High-velocity missile injuries produce damage remote from the missile tract. The extent of injury may not be apparent for several days. Clean, finely cut lacerations on the face may be safely closed in some patients 24 or more hours after injury, whereas blunt lacerations to the leg or thigh may be treated with delayed primary closure as early as 4 to 6 hours after injury. For sutured wounds, location has the strongest association with infection. Lacerations repaired on the leg and thigh may have an infection rate greater than 20%, those on the torso and other extremities greater than 10%, and those on the face and scalp less than 4%.

Optimal physical assessment of wounds requires patience, diligence, and an organized approach. Wound closure decisions involve an individualized approach for each laceration and patient. In addition to the history, host-specific data will influence management decisions: (1) immunocompetence of the host, (2) physical characteristics of the host (e.g., peripheral vascular disease), and (3) structural defects that invite bacterial seeding (e.g., damaged or prosthetic heart valves).

Physical Examination

Physical examination errors are minimized with optimal visualization and anesthesia. When the injury occurs on an extremity, use of a sphygmomanometer may help to ensure a bloodless field. The blood pressure cuff is placed proximal to the injury, and the extremity is elevated above the heart for at least 1 minute. Exsanguinating the extremity may be hastened by wrapping the limb tightly with an elastic bandage, beginning distally and ending at the base of the cuff. The sphygmomanometer is inflated to a pressure greater than the systolic pressure of the patient. Although this process is uncomfortable at first, the cuff can safely remain inflated for 2 hours. Peripheral nerve blocks are often used if inflation is anticipated to be longer than several minutes.

Adequate anesthesia is required for a thorough wound examination. Subcutaneous tissues quickly reapproximate after injury, giving the appearance of a shallow wound. In addition, significant subcutaneous swelling lends to this appearance and renders examination of the laceration more difficult, as in wounds of the scalp and face. Careful probing and examination are needed to avoid missing damage to structures deep to the skin and subcutaneous tissue. This warning is more crucial for wounds on the distal aspects of upper and lower extremities. Finger lacerations are rarely gaping, but crucial structures (e.g., tendons, nerves, and vessels) are often damaged. The examiner must carefully pry the wound margins apart, ensure a blood-free field, and examine the tissues as the digit or extremity is placed through range of motion. The injured section of tendon may have been in a different state of tension and in a more proximal or distal location at the time of injury. Wounds that cannot be explored adequately and wounds with probable trauma to underlying tissues or with foreign matter require additional studies. A laceration can be extended if visualization of wound depth and extent is challenging.

Sterile gloves may not be a necessary part of wound closure. Although data are limited, one study found that the use of sterile gloves does not change infection rates. However, clean nonsterile gloves may be worn during wound assessment and closure to offer some protection for both the patient and the provider.

No single method can guarantee the identification and removal of all foreign matter from wounds. The key is to document all efforts and to explain to the patient the possibility of a foreign body. Physical examination with wound exploration will discover about 78% of foreign bodies; plain radiography will detect glass foreign bodies in about 75% of cases, metal in 99%, but wood in only 7%. Good documentation and follow-up can protect the patient as well as the health care provider.

Differential Diagnoses

While a list of differential diagnoses is not required since the presence of soft tissue wound is self-evident, a differential list of causes is helpful as the mechanism can affect management decisions about closure technique, antibiosis and follow-up. Careful history-taking and visual inspection are typically all that are required to differentiate high energy wounds from low energy injuries, determine whether contamination risk is high (e.g., cat bites) or low (e.g., laceration from a clean knife), or if foreign material is likely to be present.

Diagnostic Testing

Standard radiography will not detect all foreign matter. The radiodensity of an object depends on the relative density of the matter and the adjacent tissue. Pieces of glass more than 1 mm thick are visible when appropriate views are ordered. Many organic substances, such as wood, are not visible on plain films, but specifically requested soft tissue views may increase the yield. A radiolucent shadow may be seen on close inspection because the foreign substance displaces tissue in its path. A computed tomography (CT) scan is excellent for identifying all foreign substances but is expensive and results in exposure to radiation. Ultrasonography is a good technique, but the small size of many foreign bodies and pockets of air, edema, pus, and some calcifications may produce confusing echoes, limiting its clinical usefulness. When simpler, standard methods fail to locate a foreign body that is likely or definitely present, we recommend that ultrasonography or a CT scan be performed.

Management

Anesthesia

After an appropriate neurovascular examination is documented, the involved tissue is anesthetized. Careful physical examination and thorough cleansing, irrigation, and debridement require that the patient be free of pain. Regional anesthesia may be preferable for wounds innervated by one superficial nerve. Injections along the wound margins produce swelling and further distortion of landmarks. With a regional block, more than one laceration may be repaired in the same nerve distribution without additional anesthesia. Lacerations on the face, hands, fingers, feet, and toes and in the mouth are often well suited for regional anesthesia.

Anesthetic Agents

Lidocaine and bupivacaine are the most common agents used for local and regional anesthesia. Both are safe and fast acting. For lidocaine, onset of action following direct infiltration occurs within seconds, and the effects last 20 to 60 minutes. When lidocaine is administered as a regional nerve block, onset occurs in 4 to 6 minutes and the effects generally last 75 minutes, although the block may remain effective for up to 120 minutes. A 1% lidocaine solution contains 10 mg/mL. It is safe to use 3 to 5 mg/kg, not exceeding 300 mg at a single injection. More volume can be added safely every 30 minutes. When epinephrine is added, the resulting vasoconstriction prolongs the effect for 2 to 6 hours, and the safe dose increases to 5 to 7 mg/kg. However, the addition of epinephrine has been shown to delay healing and lower resistance to infection. Lidocaine with epinephrine should be avoided in wounds with a high risk of infection and when tissue viability is of concern. Traditionally, epinephrine was not used in the fingers and toes because of the risk of vasoconstriction in small arterioles resulting in digital ischemia. However, literature from case studies in hand surgery suggests that with careful screening, epinephrine can be safely used in digital blocks. Digital artery vasospasm, accidentally induced by local injection of epinephrine, can be reversed successfully with a local injection of 0.5 to 2 mg of subcutaneous phentolamine or application of topical nitroglycerin.

Bupivacaine provides anesthesia that is equal to that of lidocaine. Onset of action is slightly slower than that of lidocaine, but the duration of anesthesia is four to eight times longer. These benefits suggest that bupivacaine is the preferred local anesthetic agent for the care of most wounds. In adults, the maximal reported safe dose is approximately 2 to 2.5 mg/kg without epinephrine and 3 to 3.5 mg/kg with epinephrine. The dose can be repeated every 3 hours, not exceeding a total of more than 400 mg in a 24-hour period. The maximal intraoral dose is 90 mg.

Local injection of lidocaine is best performed with a 27-gauge needle and slower injections are less painful. The rate of injection through a 30-gauge needle is too slow, and the thin needle is fragile and difficult to control. A 25-gauge needle is acceptable, but the more rapid injection can result in greater patient discomfort. The needle should be introduced through the cut margin to minimize the pain of the injection. Concerns of spreading bacteria into the adjacent uninvolved tissue and increasing the frequency and severity of wound infections are unfounded. Bicarbonate will buffer lidocaine and reduce the pain of injection. The shelf life of the lidocaine-bicarbonate mixture decreases, but it remains effective for 1 week at room temperature and for 2 weeks if refrigerated. Adding sodium bicarbonate in a 1:10 volume ratio to lidocaine (1 mL bicarbonate and 10 mL lidocaine) decreases the pain of injection without compromising the quality of anesthesia. A much smaller dose of bicarbonate is added to bupivacaine because the alkalinization results in precipitation. A 1:100 volume ratio (0.1 mL of bicarbonate and 10 mL of bupivacaine) has been found to be effective. Warming the anesthetic solution is also an effective means of decreasing the pain of injection.

Topical anesthesia can act synergistically with injectable agents. Studies show that a combination of lidocaine (4%), epinephrine (0.1%), and tetracaine (0.5%) (LET) can function effectively on skin lacerations, especially on the face and scalp. LET may be administered by soaking a cotton ball with 3 mL of the combined solution and applying it to the wound for 20 minutes. A gel formulation is available and may be preferred because it’s easier to control and has less run-off which can inadvertently contact mucous membranes. The duration of action is 45 to 60 minutes following the removal of the gel from the wound. Toxicity is rare when the dose administered is less than 3 mL and mucous membranes are avoided. Potential toxic effects of lidocaine and tetracaine are related to the cardiovascular and central nervous systems. Cardiovascular effects may include dysrhythmias, decreased myocardial contractility, and cardiac arrest. Central nervous system toxicity may include headache, irritability, restlessness, blurred vision, and seizures. Topical anesthetics reduce repair time, preserve landmarks, and improve patient (and family) satisfaction. If additional anesthesia is required, the pain of the subsequent injection is lessened by the topical anesthesia.

Although LET has been found to be very safe, weight-based dosing has been recommended for children weighing less than 17 kg. Administering a maximum of 0.175 mL/kg of LET will prevent the application of more than 5 mg/kg of lidocaine. No cases of methemoglobinemia have been reported, but given the small risk associated with tetracaine extra caution is advised in neonates.

Tetracaine, adrenaline (epinephrine), and cocaine (TAC) was the original topical anesthetic solution. This combination is as effective as LET on the face and scalp and more effective elsewhere on the body, but the higher risk of complications and the complexities tied to handling cocaine limit its utility. Dripping 1% lidocaine into mucosal lacerations was demonstrated to be effective in one small case series, an interesting painless alternative that deserves further investigation. ²

Eutectic mixture of local anesthetics (EMLA) is a cream used to produce anesthesia of wounds and intact skin. The active ingredients are lidocaine (2.5%) and prilocaine (2.5%). The micron-sized particles of the cream are designed to penetrate the skin and lessen the pain of needle penetration. Studies have demonstrated efficacy in venipuncture, immunization administration, lumbar puncture, and laceration repair. Peak effect is seen at 1 hour and continues for 30 to 60 minutes after removal of the cream.

Allergy

Allergy to local anesthetics is uncommon. Two distinct groups of “caine” anesthetics exist. The esters include procaine, tetracaine, and benzocaine. The second group, including lidocaine and bupivacaine, belong to the amide family. Allergy to the esters is uncommon. True allergy to agents in the amide family is rare.

The subject of allergy is further complicated because multi-dose vials contain the preservative methylparaben, an ester structurally related to anesthetics in the ester family. Allergic reactions to lidocaine or bupivacaine may be a reaction to this preservative. Single-dose, preservative-free vials of lidocaine and bupivacaine should be standard stock in every emergency department (ED).

When allergy to a local anesthetic is known or strongly suspected, alternatives are available. No cross-reactivity occurs between the amide and ester families, so an agent from a different group may be chosen. If clarification is required, a test dose of 0.1 mL may be administered intradermally before proceeding. The patient is then observed for 30 minutes before proceeding. As with any allergy testing, the emergency clinician should be prepared to treat all complications. Injectable diphenhydramine (1%) has also been shown to provide effective local anesthesia.

Skin Preparation

Disinfection of the skin (not the wound itself) may be accomplished with several different agents. The ideal agent is fast acting and has a broad spectrum of antimicrobial activity and a long shelf life. Povidone-iodine (Betadine) and chlorhexidine (Hibiclens) have all three characteristics. Although excellent as skin disinfectants, both products are toxic to wound defenses and may increase the incidence of wound infection. Avoid spilling these substances into the wound. Povidone-iodine is effective against gram-positive and gram-negative bacteria, fungi, and viruses. Chlorhexidine is less effective against gram-negative bacteria and its efficacy against viruses is unknown. Eye exposure to these agents can be detrimental. Chlorhexidine has been shown experimentally and in case reports to produce serious permanent corneal opacification. Current data suggest that chlorhexidine-alcohol preparations are safe and more effective at limiting infection compared with povidone-iodine solutions.

Body, facial, and head hair is usually removed to clean and examine a wound, although this is not necessary to reduce the risk of wound infection. Hair removal makes it easier for the patient to keep the area clean and ultimately facilitates accurate suture placement and subsequent removal. Exceptions include parts of the body where hairlines provide important landmarks for the accurate reapproximation of tissue margins, most notably the eyebrow. Eyebrow hair should not be shaved since regrowth may be inconsistent or absent.

Surgical studies show that hair removal with a razor is three to nine times more likely to result in a wound infection than clipping the hair. The razor damages the infundibulum of the hair follicle and provides access for bacterial invasion and infection. For wounds at high risk of infection, clipping may be done with electric shears or scissors. Another option is application of a petroleum-based product to the hair adjacent to the wound margins, allowing the provider to keep the hair away from the surgical field.

Wound Preparation

Debridement

Debridement is the removal of foreign matter and devitalized tissue from the wound. With respect to ultimate wound healing and risk of infection, debridement remains the most important step in wound care. Devitalized wound tissue delays healing and significantly increases the risk of infection. The benefits of debridement, however, are weighed against the consequences of producing a larger tissue defect. Higher tension in the resultant closure may result in a wider scar. Skin edges that are clearly devitalized are debrided before wound closure. On the trunk, where there is little concern for specialized tissue, wide excision and debridement are feasible. On the face and hands, where as much tissue as possible must be saved, the process is more difficult. Meticulous sharp excision of small fragments of nonviable tissue is performed only by experienced clinicians. When the viability of large areas of skin or muscle is a significant concern, the wound should be prepared for delayed primary closure.

Wound Cleansing

An ideal wound cleanser has broad antimicrobial activity with a rapid onset. It is nontoxic to the tissue and does not reduce tissue resistance to infection, delay healing, or decrease the tensile strength of the healing wound. Many antiseptic solutions have been used clinically yet, despite multiple studies, there is still debate regarding which agent comes closest to possessing these qualities. Povidone-iodine in various concentrations, saline, and, more recently, tap water have received the most attention.

Evidence suggests that a 0.9% normal saline solution or tap water are effective irrigants when used with high-pressure syringe irrigation. While saline has been the traditional wound- irrigating fluid of choice, tap water has consistently shown equivalent rates of infection and cosmetic outcomes. Tap water irrigation allows a large volume of irrigation rapidly and inexpensively and is especially suited to upper extremity and scalp injuries.

Free iodine, although possessing broad, rapid antimicrobial activity, is too tissue toxic to have therapeutic value in the open wound. Iodophor is a complex of iodine with a carrier to increase its solubility and decrease the availability of free iodine. The most widely used iodophor is povidone-iodine, in which the carrier molecule is povidone (formerly polyvinylpyrrolidone). It is available in a 10% solution, which is 1% free iodine. It is well documented that even a 5% povidone-iodine solution is toxic to polymorphonuclear neutrophil leukocyte activity and may increase the infection rate. A 1% solution is safe and effective with little or no toxicity. Detergent-containing cleansers, such as povidone-iodine scrub, may be excellent for skin preparation but are toxic to tissue defenses and should never be allowed to contaminate open wounds.

Although many different irrigation solutions may be beneficial, the key to cleansing is high-pressure irrigation rather than the type of solution used. Tap water is the preferred wound irrigation solution, because it is safe, effective, requires no preparation, and is less expensive than other options. ³ Distilled water is preferred to tap water for nasal irrigation.

Irrigation

The quality of mechanical cleansing is one of the most important determinants of wound prognosis. The most effective form of wound cleansing is high-pressure irrigation. Irrigating with pressures greater than 7 pounds per square inch (psi) significantly decreases bacterial counts and the incidence of infection. Several commercial devices are available; however, one can be made by attaching an 18-gauge needle to a 30-mL syringe which will yield a force of 7 or 8 psi. High pressures of 50 to 70 psi may be obtained with a commercial water pick. These pressures may cause some tissue damage, but the beneficial effect of reduced bacterial load and debris outweighs this risk. Simply soaking the wound in an antiseptic solution is not beneficial and may be harmful. Scrubbing the wound with a sponge with large-pore cells inflicts tissue trauma and impairs the ability to resist infection. Using a sponge with a fine pore cell size will decrease tissue damage. Adding a surfactant further minimizes mechanical trauma. Flooding the wound under low pressure via a bulb syringe or gravity alone does not reduce the incidence of infection, regardless of the agent used.

At least one study has shown little benefit to any irrigation in facial and scalp lacerations. This study prospectively compared outcomes of almost 2000 immunocompetent patients. Infection rates and cosmetic outcomes were similar in the irrigation and non-irrigation groups. We recommend irrigation only for scalp wounds more than 5 cm long and those with other high-risk features.

Wound Closure

Decision-Making

The first determination required is whether the wound should be treated open or closed. Each wound, patient, and clinical circumstance must be handled individually. Most wounds have a low risk of infection and can safely be closed primarily. A small study from Europe failed to show a difference in infection risk for wounds sutured greater than 6 hours after injury compared with those sutured in less than 6 hours. At the other end of the spectrum, some wounds must never be closed at the time of the initial ED visit. A large stellate laceration to the foot produced by blunt force and contaminated with dirt and grease must be cleaned and left open to be closed later. Human and animal bites to the hand are additional examples of wounds that should not be closed primarily given the high rate of infection. Physician judgment is often the best method for deciding when it is safe to close a wound. In one study in which hand wounds were described as dirty, 22% became infected. When the injury was documented to be clean, the incidence of infection was 7.1%.

Three wound closure options are available. The wound may be ( ) closed primarily in traditional fashion, ( ) closed in 4 or 5 days (delayed primary closure), or ( ) left open and allowed to heal on its own. A safe alternative to traditional primary closure, delayed primary closure does not change overall healing time and the risk of infection is greatly decreased if proper technique is used. When a wound is slated for delayed primary closure, it is prepared, debrided, and irrigated in the same manner as for immediate closure. Initially, the wound is packed with sterile gauze to prevent it from closing on its own. If the wound is on an extremity, the injury is splinted and dressed, and appropriate wound care instructions are provided. The patient returns for a wound check and packing change in 24 hours and is instructed to follow up in another 72 hours for definitive repair, with wound closure undertaken 96 to 120 hours after injury. No studies offer guidelines for prophylactic antibiotic use when delayed primary closure is the treatment option. Extrapolation from other wound studies strongly suggests that antibiotics offer no benefit.

Individuals who do not seek medical care after an injury select the option of leaving a wound open to heal on its own. Most patients who visit an ED with a laceration undergo some form of wound closure. Yet one study that examined unsutured hand lacerations less than 2 cm long found that there was no significant difference in cosmetic appearance or time to resumption of activities of daily living after 3 months.

Closing a wound loosely is not a good choice although it is often discussed as an option in the treatment of contaminated wounds. This choice should rarely be considered. The loosely closed wound approximates the tissue margins enough to allow the wound to seal itself completely within 48 hours. The infection risk when this method is used is the same as when the wound is closed traditionally.

Wound Tension

The goal of wound closure is optimal anatomic and functional reapproximation of tissue with minimal risk of complications. Wounds with high static and dynamic tension that require meticulous closure cannot be closed with tape or staples. Delicate approximation of wound edges under tension can be accomplished only with suture.

Several techniques may be used to reduce wound tension. Deep sutures placed in subcutaneous tissue help bring the wound margins closer together. In this manner, forces on the skin are reduced and potential dead space can be closed. Avoid suturing adipose tissue because it may become necrotic, increasing the likelihood of infection. The number of dermal sutures depends on the characteristics of the wound. In general, the number should be kept to a minimum, because suture material acts as foreign matter in the wound and can increase the risk of infection. Subcutaneous sutures are rarely placed in the hand or foot because of the major structures that reside near the surface. Another method of ameliorating static tension from cut edges of the wound is to undermine at the lacerated margin. Undermining helps free the dermis from its deeper attachments, allowing the skin edges to be approximated with less force. It is crucial to preserve the blood supply to the wound margins and not increase dead space in the process.

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