A 7 year old male presents to the emergency department 30 minutes after sustaining a right shin laceration. He fell off his bicycle, causing his right lower extremity to collide with the edge of a cement park bench. This resulted in a 2 cm laceration to his right shin, which started to bleed. The patient's mother firmly applied a towel to the wound to control the bleeding, and drove him to the emergency room for treatment. He denies pain in any other areas besides his wound. He denies difficulty walking or increased pain while bearing weight.

PMH is unremarkable. Immunizations are up to date.

Exam: VS are normal. He is alert and comfortable. There are no signs of trauma elsewhere. His exam is unremarkable except for his lower extremity, where he has a 2 cm vertical laceration lateral to his tibia, 6 cm inferior to the patella. The depth of the laceration is approximately 5 mm. The laceration is not actively bleeding at this time. His perfusion, sensation and motor function are intact distally. No bony tenderness or deformity is present.

The wound is infiltrated with buffered 1% lidocaine. The wound is then irrigated and explored. The laceration is closed in two layers with a 4-0 absorbable suture closure of the subcutaneous layer, followed by a 5-0 skin closure with black nylon. The nylon sutures are removed 9 days later.

Traumatic wounds are a common reason for presentation to the emergency department. A wound is defined as a physical disruption of tissue from trauma. They can be accidental as a result of trauma or intentional from surgery. Generally, wounds include abrasions, punctures, lacerations, burns and larger wounds. This chapter will focus mainly on minor abrasions and lacerations. Larger wounds, such as those requiring extensive debridement or grafts, are beyond the scope of this chapter. Burns are covered in a separate chapter.

Effective management of wounds requires a basic understanding of the physiologic process of wound healing. Wound healing can be divided into three phases: the inflammation (exudative or substrate) phase, the proliferative phase, and the remodeling (maturation) phase. The inflammation phase involves vasodilatation of capillaries in wound edges and migration of plasma, polymorphonuclear leukocytes and macrophages into the wound space. The macrophages are particularly important in removing debris and bacteria, stimulating fibroblasts, and promoting angiogenesis. The proliferative phase involves the development of granulation tissue (a new vascular and cellular tissue comprised of new capillaries, inflammatory cells, collagen, fibronectin and proteoglycans). This phase does not occur until the surface has completely epithelialized. Finally in the remodeling phase, the collagen structure becomes more organized through cross-linking and forms the appearance of a flatter, stronger scar. However, at 3 weeks, the wound has only about 40% the strength of normal tissue. At 6 to 8 weeks, the wound achieves close to 70% of its strength. Although remodeling will increase the strength of the wound for at least 2 years, the scar will never reach the strength of its original, undivided tissue.

While all wounds go through the above three phases, they do not all close in the same way. There are three distinct methods in which wounds heal and close: by primary intention, secondary intention, and tertiary intention.

In healing by primary intention, the edges of the wound are well approximated (e.g., via suturing) and allow for more rapid healing and less granulation tissue and scarring.

In secondary intention, the wound is left open with the wound edges far apart from each other. Thus, there is a greater production of granulation tissue which then must undergo contraction and epithelialization. Myofibroblasts are the cells responsible for helping the wound to contract. Epithelial cells grow from the wound edges until the wound surface is totally covered. This is a slow process; epithelialization takes place at a rate of about 1 mm/day. A clinician may intentionally allow a wound to heal by secondary intention to prevent infection in wounds in which there is significant bacterial contamination, foreign bodies, or extensive tissue trauma. By leaving the wound open, there is less chance that bacterial colonization will occur (i.e., the risk of wound infection is reduced).

Healing by tertiary intention (delayed primary closure) is intentional closure after a delay of days to weeks. Similar to secondary intention, the wound is allowed to heal open for a period of time. However, the wound is then closed once the risk of infection has decreased significantly.

Urgent problems such as active bleeding should be addressed first. Then a history should be obtained and the patient should be screened for systemic conditions that put them at risk for infection or delayed healing and wound closure. Other risk factors for infection include wounds that have been open for longer than 1 hour and contaminated wounds. Also, the history of the mechanism of injury is essential to identify wound contaminants and foreign bodies that can lead to infection or delayed closure. Depending on the degree of contamination of the wound and the patient's immunization status; cultures, antibiotics, and tetanus prophylaxis should be considered. Then, utilizing universal precautions, the wound should be examined and assessed for location, length and depth, and extent of injury. One should also look for foreign bodies, damage to nerves or tendons, and the need for debridement. A neurovascular examination is important to document before anesthesia is applied. If a fracture or foreign body is suspected, radiographs should be obtained.

The mechanism of injury is important in several specific examples. If a sharp object such as a knife or glass is responsible for a laceration over the path of a tendon, then a severed tendon or a nick in the tendon should be suspected even if the tendon function appears to be intact. Similarly, such injuries over the path of digital nerves should lead one to suspect that the digital nerve may be severed. If broken glass is responsible for a laceration, then x-rays of the wound should be strongly considered to look for glass fragment foreign bodies which are difficult to identify on wound exploration. Most glass fragments are radiopaque. Stepping on a nail which pokes through a tennis shoe puts the patient at risk of a foreign body consisting of foam rubber from the insole of the shoe once the nail is removed. Such injuries have caused wound infections and osteomyelitis due to a retained foam rubber foreign body.

Abrasions are common. An abrasion occurs when a physical force scrapes and damages superficial layers of epithelium, usually with little damage to the underlying dermis. Abrasions tend to be very simple to manage and often only require thorough cleansing of the wound. Afterwards, the wound should be dressed with ointment and a sterile bandage and kept fairly moist to prevent desiccation to allow rapid and effective epithelialization. Healed abrasions often leave the skin hyperpigmented when exposed to the sun, thus sunscreen for 6 months post-injury may be helpful to prevent hyperpigmentation.

Puncture wounds are usually caused by a sharp and pointed object and may have variable depth of penetration through the tissues. Thus, one must consider possible damage to underlying structures. Also, these wounds may contain foreign material and are ideal sites for bacteria to flourish, making infection very common. Most uncomplicated, clean puncture wounds presenting less than 6 hours after injury will only require irrigation and cleansing to remove debris and aid in visualization of the wound. These wounds can usually be dressed with a light bandage. Irrigation under pressure is controversial since it may push foreign material and bacteria deeper into the wound. Some have recommended excision of the puncture wound (core out) for puncture wounds at high contamination risk; however, this is aggressive and unnecessary in most instances.

Antibiotic therapy in wound management is greatly dependent on the timing of administration, the mechanism of injury, the severity of the wound, and the degree of bacterial contamination. In heavily contaminated wounds, it has been shown that infection usually results despite antibiotic therapy. Thus, irrigation and debridement are more important to prevent infection by reducing the bacteria count within the wound. Also, the effect of antibiotics depends on the length of time the wound has been open. The longer the wound is exposed, the less effective antibiotics become.

For lacerations, the wound must also be cleansed. If local anesthesia is planned, then cleansing is more effectively done after local anesthesia. Several local anesthesia and wound closure options are available. Ideally, these options should be discussed with the family and a decision should be made based the medical considerations while considering patient and family preferences.

Local anesthesia will be required for most wound closures. Lidocaine is commonly used to infiltrate wounds which has a rapid onset and a duration of about 1-2 hours. Some techniques to reduce the pain associated with infiltration include buffering the lidocaine (by adding sodium bicarbonate), warming the anesthetic solution, using fine gauge needles (e.g., 30 gauge), injecting through (i.e., from inside) the wound rather than through the skin (2), and slowing the speed of injection (3). Lidocaine with epinephrine may be used under some circumstances instead of plain lidocaine. Epinephrine is a vasoconstrictor which slows the rate of lidocaine entering the general circulation, allowing a higher total dose to be given (important for large wounds), extending the duration of action, and reducing the amount of bleeding. However, vasoconstriction agents should not be used in areas with end arterioles (such as the fingers, toes, ear, penis, and the tip of the nose) to prevent ischemia and tissue necrosis (5). Flap type lacerations may also be adversely affected by epinephrine if the perfusion to this flap is marginal. Optionally, longer acting local anesthetics such as bupivacaine can be used, but many consider this drug to be more expensive with a higher risk of toxicity.

Topical anesthesia can also be used alone or as a premedication preparation for subsequent infiltrated local anesthesia. Topical anesthesia does not utilize needles and administration is relatively painless. Tetracaine-adrenaline-cocaine (TAC) gel is no longer used because the cocaine component can be absorbed by mucous membranes potentially causing seizures and death (4). Lidocaine-adrenaline-tetracaine (LAT) gel is just as effective with fewer adverse effects. LAT's major disadvantage is that it requires 30 minutes for its local anesthesia effect to take place. EMLA cream (eutectic mixture of local anesthetics) is another topical local anesthetic (6) but its onset time is similarly slow.

After local anesthesia, the wound is cleansed to help prevent bacterial infection by removing foreign bodies and reducing the bacterial count within the wound. Direct inspection and exploration of the wound is necessary to remove visible foreign bodies. Irrigation is used to reduce surface bacterial counts and to rinse microdebris from the wound. Although many irrigation fluids have been studied, sterile normal saline is inexpensive and effective. Concentrated povidone-iodine, hydrogen peroxide, and detergents can cause significant tissue toxicity and are not recommended for internal wound irrigation (7). These agents are more effective on intact skin and possibly abrasions. Thus, povidone-iodine can be used to sterilize the skin as a skin prep for suture closure, but the wound should be irrigated with saline and not with povidone-iodine.

Sutures are the most common method of wound closure for lacerations. They have the greatest tensile strength and the lowest rate of dehiscence. However, one must consider the requirement of local anesthesia and sometimes sedation, cost issues (sutures are inexpensive, but they require a set of instruments and often, suture removal at a follow up visit), and more time and skill to apply.

Non-absorbable sutures made of nylon or polypropylene are commonly used for closing the skin layer of a laceration. Advantages include their ability to retain tensile strength for more than 60 days, and their relatively low tissue reactivity. These sutures require a follow-up visit for suture removal. In contrast, absorbable sutures such as chromic gut and polyglactin do not need to be removed. They are typically used for deeper layers or for subcuticular tissues. Deep sutures are beneficial in reducing the skin tension required for the skin sutures and the prevention of hematomas, dead space, and scarring. Some physicians prefer to use special fast absorbing sutures in the outer skin layers to avoid the pain and anxiety associated with suture removal (5) (popular products include fast absorbing gut and Vicryl Rapide). Otherwise, sutures should be removed after about 3-14 days depending on their location: face (3-5 days), scalp (5-7 days), trunk (7-10 days), extremities (10-14 days). Facial sutures should be removed earlier to prevent the formation of sinus tracts. After suture removal, wound closure tape is usually applied to reinforce the wound and prevent dehiscence.

The advantages of wound closure tape are that there is almost no tissue reactivity and they can be applied very rapidly. However, they are not able to evert the wound edges or close deep tissue. Tape should not be used alone in areas of high tension since they have low tensile strength and a high rate of dehiscence. Wound closure tape would be acceptable for smaller lacerations which are under little or no tension.

Tissue adhesives, which are cyanoacrylates, have been found to have negligible tissue toxicity, bacteriostatic properties, and good tensile strength (7). Histoacryl Blue (HAB or N-butyl-2-cyanoacrylate) has been in use for the past 20 years in Europe and Canada, but it is not approved for use in the U.S. (9). 2-octylcyanoacrylate (2-OCA, Dermabond trade name) was approved for use in the U.S. in 1998. After holding the two edges together, it is applied to the surface of the skin, requiring about 30 seconds for polymerization, forming a strong bond to the uppermost layer of the skin (10). This polymer holds the edges of the laceration together, allowing for good wound approximation and healing. The adhesive should never be placed inside the wound, since this results in a foreign body effect and impedes the wound edges from approximating. Aside from increased flexibility, 2-OCA has been found to be 3 to 4 times stronger than HAB, allowing it to be used on larger lacerations and incisions (11). 2-OCA can be used on almost any size laceration with an intact epidermis, although subcutaneous sutures are recommended on lacerations to extremities (7). This is due to the high tissue tension in these areas. For deeper lacerations to the epidermis, absorbable sutures can be used in the deep tissues in conjunction with tissue adhesive applied to the surface edges of the wound. After about 7-10 days, 2-OCA peels off, avoiding the need for the patient to return for suture removal. However, water can disrupt the 2-OCA bonds and cause premature peeling off of the adhesive. Thus, children should be encouraged to keep the affected area dry. Some of the other advantages of 2-OCA over sutures include ease of application, quicker application time (less than half the time needed for sutures), and fewer cases requiring local anesthesia (10). Tissue adhesives have been found to have comparable cosmetic results when compared with sutures (3,4,12). Some disadvantages include less tensile strength compared to sutures, and increased wound dehiscence over joints and high-tension areas. Tissue adhesives are seemingly simple, but they should be used by experienced personnel since they have many adverse effects described which are preventable if used in the correct manner, and if their use is avoided in wound conditions which are unsuitable for tissue adhesives (e.g., highly mobile areas and on the feet).

Questions

1. What is the purpose of using epinephrine in local infiltration and topical anesthesia?

2. Name the drawbacks of tissue adhesives in laceration repair.

3. What has the best cosmetic result in the repair of lacerations: sutures or tissue adhesives?

4. How long does it take for the tissue adhesive 2-OCA to fall off after application?

5. What are the adverse effects of using tetracaine adrenaline cocaine (TAC) gel?

6. What is the major clinical reason for preferring healing by secondary or tertiary intention (as opposed to primary closure)?

7. True/False: Antibiotics have only a modest effect on reducing the rate of wound infections in contaminated wounds.

References

1. Singer AJ, Clark RA. Cutaneous wound healing. N Engl J Med 1999;341(10):738-746.

2. Brogan GX Jr, Giarrusso E, Hollander JE, et al. Comparison of plain, warmed, and buffered lidocaine for anesthesia of traumatic wounds. Ann Emerg Med 1995;26:121-125.

3. Knapp JF. Updates in wound management for the pediatrician. Pediatr Clin North Am 1999;46(6):1201-1213.

4. Ernst AA, Marvez-Valls E, Nick TG, Weiss S. LAT (lidocaine-adrenaline-tetracaine) versus TAC (tetracaine-adrenaline-cocaine) for topical anesthesia in face and scalp lacerations. Am J Emerg Med 1995;13:151-154.

5. Singer AJ, Hollander JE, Quinn JV. Evaluation and management of traumatic lacerations. N Engl J Med 1997;337(16):1142-1148.

6. Zempsky WT, Karasic RB. EMLA versus TAC for topical anesthesia of extremity wounds in children. Ann Emerg Med 1997;30(2):163-166.

7. Dire DJ, Welsh AP. A comparison of wound irrigation solutions used in the emergency department. Ann Emerg Med 1990;19:704-708.

8. Bruns TB, Simon HK, McLario DJ, et al Sullivan KM, Wood RJ, Anand KJS: Laceration repair using a tissue adhesive in a children's emergency department. Pediatrics 1996;98;673-675.

9. Hollander JE, Singer AJ. Laceration management. Ann Emerg Med 1999;34(3):356-367.

10. Bruns TB, Robinson BS, Smith RJ, et al. A new tissue adhesive for laceration repair in children. J Pediatr 1998;132(6):1067-1170.

11. Quinn J, Wells G, Sutcliffe T, et al. A randomized trial comparing octylcyanoacrylate tissue adhesive and sutures in the management of lacerations. JAMA 1997;277:1527-1530.

12. Simon HK, McLario DJ, Bruns TB, et al. Long-term appearance of lacerations repaired using a tissue adhesive. Pediatrics 1997;99(2):193-195.

Answers to questions

1. Since epinephrine is a vasoconstrictor, it slows the rate of local anesthetic release into the general circulation permitting a higher total dose of local anesthetic that can be given (useful if the wound is large), it extends the duration of action, and decreases bleeding.

2. Lower tensile strength compared to sutures and thus it can't be used in areas of high tension such as wounds over joints. If it gets wet, the adhesive may fall off prematurely.

3. The research done on the comparisons between sutures and tissue adhesives have shown that they have comparable cosmetic results.

4. Approximately 7 to 10 days

5. Cocaine component: arrhythmia, urticaria, drowsiness, excitation, seizure, vomiting, flushing, and death. TAC should be avoided near mucous membranes. TAC is no longer available in most centers.

6. Significantly contaminated wounds, are at greater risk of infection if closed by primary intention.

7. True. Heavily contaminated wounds will develop infection despite antibiotic treatment.