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Care of lacerations enables prompt healing, minimizes risk of infection, and optimizes cosmetic result.
Physiology
Healing begins immediately after injury with coagulation and introduction of WBCs; neutrophils and monocytes remove debris (including devitalized tissue) and bacteria. Monocytes also encourage fibroblast replication and neovascularization. Fibroblasts deposit collagen, typically beginning within 48 h and reaching a maximum in about 7 days. Collagen deposition is essentially complete in 1 mo, but collagen fiber strength builds more slowly as fibers undergo crosslinking. Wound tensile strength is only about 20% of ultimate by 3 wk, 60% by 4 mo, and maximum at 1 yr; strength never becomes equivalent to the undamaged state.
Epithelial cells from the wound edge migrate across the wound shortly after injury. In a surgically repaired wound (healing by primary intention), they form an effective protective barrier to water and bacteria in 24 to 48 h and resemble normal epidermis within 5 days. In a wound that is not repaired (ie, heals by secondary intention), epithelialization is prolonged proportionally to the defect size.
There are static forces on the skin from its natural elasticity and the underlying muscles (see
Fig. 1: Lacerations: Representative skin tension lines. ). Because scar tissue is not as strong as adjacent undamaged skin, these forces tend to widen scars, sometimes resulting in a cosmetically unacceptable appearance after apparently adequate wound closure. Scar widening is particularly likely when the forces are perpendicular to the wound edge. This tendency (and resultant scar stress) is readily observed in the fresh wound; gaping edges indicate perpendicular tension, and relatively well approximated edges indicate parallel forces.
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Fig. 1
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Representative skin tension lines.
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Direction of force is along each line. Cuts perpendicular to these lines are thus under greatest tension and most likely to widen.
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Scars tend to be red and prominent for about 8 wk. As collagen remodeling occurs, the scar shrinks and loses its erythema. In some patients, however, the scar hypertrophies, becoming unsightly and raised. Keloids are hypertrophic scars that extend beyond the limits of the original wound (see Benign Tumors: Keloids).
The main factors interfering with wound healing involve tissue ischemia, infection, or both. These occur for numerous reasons. Circulation can be impaired by disease (eg, diabetes, arterial insufficiency), features of the injury (eg, a crush-type injury, which damages the microvasculature), and factors in the repair such as overly tight sutures and perhaps use of a vasoconstrictor with the local anesthetic. Lower extremities are generally at greatest risk of circulatory problems. Wound hematoma, foreign material (including subcutaneous suture material), delayed treatment (> 6 h for lower extremities; > 12 to 18 h for face and scalp), and significant wound contamination predispose to bacterial proliferation. Bite wounds (see Bites and Stings: Human and Mammal Bites) are usually heavily contaminated.
Evaluation
The clinician must first find and treat serious injury (see Approach to the Trauma Patient: Evaluation and Treatment) before focusing on skin lacerations, however dramatic. Actively bleeding wounds require hemostasis before evaluation. Hemostasis is best obtained by direct pressure and, when possible, elevation; clamping bleeding vessels with instruments is generally avoided because of the possibility of damaging adjacent nerves.
The wound is evaluated for damage to underlying structures, including nerves, tendons, vessels, and bone, as well as the presence of foreign bodies or body cavity penetration (eg, peritoneum, thorax). Failure to recognize these complications is the most significant error in wound management.
Nerve injury is suggested by sensory abnormality distal to the wound; suspicion is increased for lacerations near the course of significant nerves. Examination should test light touch and motor function. Two-point discrimination is useful for hand and finger injuries; the clinician touches the skin with 2 ends of a bent paper clip simultaneously to determine the minimum separation that allows perception of 2 points. Normal varies among patients and by location on the hand; the identical site on the uninjured side is the best control.
Tendon injury is suspected in any laceration over the course of a tendon. Complete tendon laceration usually produces a resting deformity (eg, foot drop from Achilles laceration, loss of normal resting finger flexion with digital flexor laceration) because forces from antagonist muscles are unopposed. Resting deformity does not occur with partial tendon laceration, which may present with only pain or relative weakness on strength testing or be discovered only on exploration of the wound.
Serious injury to vascular structures is suggested by pallor, decreased pulses, or perhaps slowed capillary refill distal to the laceration (all compared with the uninjured side).
Bone is occasionally injured, particularly after penetrating trauma (eg, stab wound, bite), or when injury occurs over a bony prominence. If the mechanism or location of injury is concerning, plain x-rays are taken to rule out fracture.
Foreign bodies are sometimes present in wounds, depending on the mechanism; wounds involving glass are likely to have foreign bodies, lacerations from sharp metal rarely do, and wounds involving other substances are of intermediate risk. Although not very sensitive, a patient's complaint of feeling a foreign body is fairly specific and should not be ignored. Imaging studies are recommended for all wounds involving glass and for others if a foreign body is suspected because of mechanism or inability to examine the wound's full depth. If glass or inorganic material (eg, stones, metal fragments) is involved, plain x-rays are taken; glass bits as small as 1 mm can be seen. Organic materials (eg, wood splinters, plastic) are rarely detected on plain x-ray (although the outline of larger objects may be visible by their displacement of normal tissue); various other modalities have been used, including xerography, ultrasonography, CT, and MRI. None of these is 100% sensitive, but CT may offer the best balance between accuracy and practicality. A high index of suspicion and careful exploration of all wounds are always appropriate.
Penetration of the abdominal or thoracic cavity should be considered in any wound over those locations in which the bottom of the laceration is not clearly visible. Wounds should not be blindly probed; blind probing is unreliable and may cause further injury. Patients with suspected thoracic lacerations require a chest x-ray initially, with a repeat film after 6 h of observation; any slowly developing pneumothorax should be visible by that time. In patients with abdominal lacerations, local anesthesia facilitates exploration (lacerations can be extended horizontally if necessary). Patients with wounds penetrating the fascia should be observed in the hospital; sometimes abdominal CT is used to identify hemoperitoneum.
Treatment
Treatment involves cleansing, local anesthesia, exploration, debridement, and closure. Tissue should be handled as gently as possible.
Cleansing:
Both the wound and the surrounding skin are cleaned. Subepidermal tissue in the wound is relatively delicate and should not be exposed to harsh substances (eg, full-strength povidone iodine, chlorhexidine, hydrogen peroxide) and vigorous scrubbing.
Removing hair from laceration edges is not necessary for wound hygiene but can make markedly hairy areas (eg, scalp) easier to work on. If necessary, hair is removed by clipping with scissors, not shaving; razors create microtrauma, allowing skin pathogens to enter and increasing risk of infection. Hair is clipped before wound irrigation so that any clipped hair entering the wound is removed. Eyebrows are never trimmed because the hair-skin border is needed for proper alignment of wound edges.
Although wound cleansing is not particularly painful, local anesthesia (see below) is usually administered first, except for heavily contaminated wounds; these are best initially cleansed with running tap water and mild soap before local anesthesia administration. Tap water is clean, free of typical wound pathogens, and used in this manner does not seem to increase risk of infection. Wounds are then cleansed by a high-velocity stream of liquid, and sometimes scrubbed with a fine-pore sponge; brushes and rough materials are avoided. An appropriate irrigation stream can be created using a 20- or 35-mL syringe with a 20-gauge needle or IV catheter attached. Sterile 0.9% saline is an effective irrigant; specialized surfactant irrigants are costly and of doubtful additional benefit. If bacterial contamination is of particular concern (eg, bites, old wounds, organic debris), povidone iodine solution diluted 1:10 in 0.9% saline is beneficial and is not harmful to tissues at this concentration. The volume necessary varies. Irrigation continues until visible contamination is removed and at least 100 to 300 mL has been applied (more for large wounds).
Painting the skin with povidone iodine before suturing may reduce skin flora, but the substance should not be introduced into the wound.
Local anesthesia:
Generally, injectable local anesthetics are used, but topical agents are beneficial in certain cases.
Common injectable agents are lidocaine 0.5, 1, and 2%, and bupivacaine 0.25 and 0.5%, both from the amide group of local anesthetics; the ester group includes procaine, tetracaine , and benzocaine . Lidocaine is more commonly used. Bupivacaine has a slightly slower onset (several minutes vs almost immediate) and a significantly longer duration (2 to 4 h vs 30 to 60 min). Duration of action of both can be prolonged by adding epinephrine 1:100,000, a vasoconstrictor. Because vasoconstriction may impair wound defenses, epinephrine is generally used only for wounds in highly vascular areas (eg, face, scalp); to prevent tissue ischemia, it is avoided in lower extremities and other distal parts (eg, nose, ears, fingers, penis).
Maximum dose of lidocaine is 3 to 5 mg/kg (1% solution = 1 g/100 mL = 10 mg/mL), that of bupivacaine is 2.5 mg/kg. Addition of epinephrine increases the allowable dose of lidocaine to 7 mg/kg, and of bupivacaine to 3.5 mg/kg.
Adverse reactions to local anesthetics include allergic reactions (hives and, occasionally, anaphylaxis—(see Allergic and Other Hypersensitivity Disorders: Anaphylaxis) and sympathomimetic effects from epinephrine (eg, palpitations, tachycardia). True allergic reaction is rare, particularly to amide anesthetics; many patient-reported events represent anxiety or vagal reactions. Furthermore, allergic reactions are often due to methylparaben, the preservative used in multidose vials of anesthetic. If the offending agent can be identified, an agent from another class (eg, ester instead of amide) can be used. Otherwise, a test dose of 0.1 mL preservative-free (single-dose vial) lidocaine can be given intradermally; if there is no reaction in 30 min, that agent can be used.
Topical anesthesia avoids injection and is completely painless, which is of benefit in children and fearful adults. Two admixtures are common. TAC contains tetracaine 0.5%, epinephrine (adrenaline) 1:2000, and cocaine 11.8%. LET is lidocaine 2 to 4%, epinephrine 1:2000, and tetracaine 0.5 to 2%. A cotton dental pledget (or cotton ball) the length of the wound soaked in several milliliters of the solution and placed within the wound for 30 min usually provides adequate anesthesia; sometimes supplemental injectable anesthetic is required. Because of the presence of vasoconstrictors, the solutions are used mainly on the face and scalp, avoiding the ears, tip of nose, and distal extremities. Very rare deaths have occurred from mucosal absorption of cocaine, so it is not applied near the lips or eyes; LET appears safer.
Exploration:
The full extent of the wound is explored to look for foreign material and possible tendon injury. Foreign material may best be discerned by palpating gently with the tip of a blunt forceps, feeling for a characteristic click. Deep wounds near a major artery should be explored in the operating room by a surgeon.
Debridement:
Debridement uses a scalpel, scissors, or both to remove dead and devitalized tissue and sometimes firmly adherent wound contamination (eg, grease, paint). It is not used to convert irregular wounds to straight lines. Macerated or ragged wound edges are excised; usually 1 to 2 mm is sufficient. Sharply beveled wound edges are sometimes trimmed so that they are perpendicular.
Closure:
Decision to close a wound depends on wound location, age, cause, degree of contamination, and patient risk factors.
Most wounds can be closed immediately (primary closure). This is appropriate for clean wounds < 6 to 8 h old (< 18 to 24 h for face and scalp wounds) without signs of infection.
Many other wounds can be closed after several days (delayed primary closure). This is appropriate for wounds > 6 to 8 h old, particularly if signs of inflammation have begun, and those of any age with significant contamination, particularly if organic debris is involved. The threshold for using delayed primary closure is lowered for patients with risk factors for poor healing. At initial presentation, anesthesia, exploration, and debridement are carried out as for all wounds (if not more thoroughly), but the wound is loosely packed with moist gauze. The dressing is changed at least daily and evaluated for closure after 3 to 5 days. If there are no signs of infection, the laceration is closed by standard techniques (see below). “Loosely” closing such wounds initially is ineffective and inappropriate because the wound edges nonetheless seal shut.
Some wounds should not be closed. These include cat bites, any type of bite to hands or feet (see also Bites and Stings: Wound care), puncture wounds, and high-velocity missile wounds.
Materials and
methods:
Traditionally, sutures have been used for laceration repair, but metal staples, adhesive strips, and liquid tissue adhesives are now used for certain wounds. Whatever the material used, preliminary wound care is the same; a common error is to perform cursory exploration and no debridement because a noninvasive closure not requiring local anesthesia is planned.
Staples are quick and easy to apply and, because there is minimal foreign material in the skin, are less likely to cause infection than sutures. However, they are suited mainly for straight, smooth cuts with perpendicular edges in areas of low skin tension and no particular cosmetic significance. Successful application usually requires 2 people, one to approximate and evert skin edges with forceps and the other to operate the stapler; inadequate edge eversion is the most common error.
Tissue
adhesives in the US contain octylcyanoacrylate. It hardens within a minute; is strong, nontoxic, and waterproof; and has some antibacterial properties. However, adhesive should not be allowed into the wound. Infectious complications are very unlikely, and good cosmetic results are possible. Adhesive is best for simple, regular lacerations; it is not suited for wounds under tension. In wounds requiring debridement, subcutaneous suturing, or exploration under local anesthesia, the advantages of decreased pain and time are minimized. As with stapling, adhesives usually require a 2nd person to hold the skin edges together while the adhesive is applied. Three or 4 layers are applied for maximum strength. The adhesive sloughs spontaneously in about a week. Excess or inadvertently applied adhesive is removed with any petrolatum-based ointment or, in areas away from the eyes or open wounds, acetone.
Adhesive
strips are probably the quickest repair method and have a very low infection rate. They are useful for the same type wounds as tissue adhesives, with the same limitations. Additionally, use on lax tissue (eg, dorsum of hand) is difficult as edges tend to invert. Adhesive strips are particularly advantageous for lacerations in an extremity that is to be casted (thus blocking appropriate suture removal). Skin must be dry before application. Many clinicians apply tincture of benzoin to boost adhesion. Strips may be removed by the patient.
Sutures are the best choice for irregular or complex lacerations, areas of loose skin, areas under tension, and other wounds requiring subcutaneous closure. Because sutures can serve as an entry site for bacteria and there is a significant amount of foreign material under the skin, they have the highest rate of infection. Suture materials are generally classified as monofilament vs braided, and absorbable vs nonabsorbable. Characteristics and uses vary (see
Table 1: Lacerations: Suture Materials ); generally, absorbable material is used for subcutaneous stitches, and nonabsorbable is used for cutaneous ones. Braided material generally poses slightly higher risk of infection than does monofilament but is soft and easy to handle and has good knot security.
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Table 1
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Suture Materials
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Category
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Material
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Comments
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Nonabsorbable
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Preferred for cutaneous repair
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Nylon
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Strong, stiff, moderately hard to work with
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Polypropylene
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Poorest knot security, most difficult to work with
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Polybutester
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Somewhat elastic, so lengthens with wound edema and contracts as edema resolves
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Polyester
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Low reactivity; not preferred to monofilament for cutaneous use
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Silk
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Soft; easy to work with; good knot security; high tissue reactivity. Generally limited to mouth, lips, eyelids, intraoral, where patient comfort is significantly better
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Absorbable
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Preferred for subcutaneous sutures
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Polydioxanone
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Very strong and long lasting (absorption, 180 days); stiffer, more difficult to handle than other absorbable sutures
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Gut, chromic gut
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From sheep intima. Weak; poor knot security; rapidly absorbed (1 wk); high tissue reactivity. Not preferred
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Easy handling; good knot security; mild reactivity
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Polyglycolic acid
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Original absorbable; most strength gone in 1 wk
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Polyglactic acid
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Probably current preference
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Suture technique:
The goal is to closely approximate skin margins, evert the edges, and eliminate dead space while minimizing tension of individual sutures and the amount of subcutaneous material.
Sutures may be placed and tied individually (interrupted sutures) or be continuous (running suture). They may be completely buried under the skin (subcutaneous—sc) or enter and exit the skin to be tied externally (percutaneous—pc).
If the wound is gaping, sc suturing is typically used initially (see
Fig. 2: Lacerations: Simple subcutaneous suture.); the resultant narrow epidermal gap is then closed by pc sutures. For wounds on the face, any gaping past 2 to 3 mm may benefit from sc suturing (not used in nose and eyelids); in other body areas, a wider gap is acceptable. Interrupted sutures using size 4-0 or 5-0 (smaller numbers indicate thicker material) braided absorbable material (eg, polyglactic acid) are most common. They are placed with the knot at the bottom of the wound to avoid a palpable lump and must not be too tight. A running sc suture (subcuticular) is sometimes used in cosmetic repairs.
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Fig. 2
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Simple subcutaneous suture.
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The suture begins and ends at the bottom of the wound so that the knot is deeply buried.
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Epidermal closure is typically with simple, interrupted sutures (see
Fig. 3: Lacerations: Simple cutaneous suture.) of nonabsorbable monofilament (eg, nylon). Areas over large joints and the scalp receive size 3-0, the face receives 6-0, and most other areas receive 4-0 or 5-0. Sutures are placed about as deep as they are wide and are spaced as far apart as the distance from the needle entry point to wound edge (see
Fig. 4: Lacerations: Suture spacing.). Small “bites” are used for cosmetic repair and thin tissues, typically 1 to 3 mm from the wound edge. For other repairs, wider bites are used, varying with the tissue thickness.
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Fig. 3
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Simple cutaneous suture.
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The suture begins and ends equidistant from the wound margins. Points A and B are at the same depth.
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Fig. 4
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Suture spacing.
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Spacing between sutures is typically equal to the distance from needle entry to wound margin. Sutures should enter and exit at an equal distance from the wound margin.
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A vertical mattress suture (see
Fig. 5: Lacerations: Vertical mattress suture.) is sometimes used instead of a layered closure, provided skin tension is not marked; it also helps ensure proper edge eversion in loose tissue. A running suture (see
Fig. 6: Lacerations: Running suture.) is quicker to place than interrupted sutures and can be used when wound edges are well aligned.
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Fig. 5
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Vertical mattress suture.
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The first pass of the needle is the same as a large simple suture, but instead of tying off, another smaller bite is taken back across the wound to end on the starting side. Both ends are pulled up to approximate the wound. Points A and B must be at the same depth, as must points C and D; this gives proper vertical alignment.
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Fig. 6
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Running suture.
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It begins with a simple suture at one end of the wound. The tail is cut without the needle, and suturing is continued. Sutures are snugged up as they are done, except for the last one, which is left as a loop. The tail is tied to the loop.
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In all cases, epidermal closure must precisely realign edges horizontally using natural skin landmarks (folds, creases, lip margins). Vertical alignment is equally important to avoid a step-off deformity. Excess tension following closure is evidenced by indenting of the skin or a “sausage link” appearance. Such a repair should be redone, adding sc sutures, additional pc sutures, or both as needed.
Aftercare:
Tetanus vaccination is given if necessary ( see Table 1: Anaerobic Bacteria: Guidelines for Tetanus Immunization). Antibiotic ointment is not clearly necessary but appears to cause no harm and is believed by some to be beneficial; however, it is not used over tissue adhesive or adhesive strips. Prophylactic systemic antibiotics are not indicated except in certain bite wounds (see Bites and Stings: Antimicrobials), wounds involving tendons, bones, or joints, and possibly intraoral lacerations and massively contaminated wounds. If deemed necessary, antibiotics are given as early as possible and preferably parenterally for the first dose.
Excess movement of the affected area interferes with healing. Bulky dressings are used to immobilize fingers and hands. Patients with distal lower extremity lacerations (other than minor) should stay off their feet for several days; crutches may be helpful.
The wound is kept clean and dry; dressings are removed in 48 h and the wound inspected. A reliable patient may inspect minor, clean lacerations, but physician examination is preferable for higher risk wounds and in unreliable patients.
Wound infection occurs in 2 to 5% of lacerations; steadily increasing pain is often the earliest manifestation, and initial signs are redness and swelling. Systemic antibiotics effective against skin flora are begun; cephalexin 500 mg po qid (penicillin 500 mg po qid for oral infection) is typically used. Infection beginning > 5 to 7 days later suggests retained foreign body.
After 48 h, well-healing wounds can be cleansed gently of residual secretions with water or half-strength hydrogen peroxide (this can be done earlier and more frequently in facial wounds that are initially left uncovered) and can be left open. Brief wetting in the shower is safe, but prolonged soaking is avoided.
Closure material (except for tissue adhesive) is removed after various intervals depending on location. For facial lacerations, sutures are removed in 3 to 5 days to prevent cross-hatching and visible needle entrance marks; some clinicians apply adhesive strips to bolster the wound for a few more days. Sutures and staples on the torso and upper extremities are removed in 7 to 10 days. Those on the extensor surface of the elbow, knee, and anywhere below the knee should remain for 10 to 12 days.
Abrasions
Abrasions
are skin scrapes that do not fully penetrate the epidermis.
Abrasions are evaluated, cleansed, and debrided similarly to lacerations. They are harder to anesthetize, however, which is particularly problematic when large amounts of dirt, stones, or glass are embedded as is frequently the case; regional block or IV sedation may be needed. After thoroughly removing all debris, antibiotic ointment (eg, bacitracin ) and a nonadherent gauze dressing can be applied. Other commercial wound dressings may be used, the goals being to keep the wound from drying out, as this interferes with reepithelialization, and to keep the dressing from adhering.
Last full review/revision November 2005
Content last modified November 2005
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