Open wounds account for up to one third of paediatric emergency presentations; two thirds of open wounds occur in boys, and 40% involve a fall. The scalp and face account for more than 50% of all open wounds, and about 30% occur on the hands.¹^–⁴ The goals of management of these wounds are to avoid infection, minimise discomfort, facilitate healing and minimise scar formation. Meticulous attention to wound care and repair should ensure the best possible outcome and functional result. In children this often requires sedation in addition to adequate local anaesthesia and analgesia. Universal precautions should always be followed when assessing or managing any wound. Gloves (preferably sterile), drapes and eye protection are mandatory.

Anatomy of the skin

Skin is composed of two layers: dermis and epidermis. The epidermis acts as a protective layer for the dermis, preventing infection and desiccation. It is avascular and relies on diffusion of nutrients from the dermis. The dermis is rich in collagen and thus provides most of the tensile strength of the skin. It has a rich network of nutrient vessels and capillaries. The subcutaneous fat is composed of loose connective and adipose tissues.

Pathophysiology of wound healing

The stages of wound healing are coagulation, inflammation, proliferation and maturation. Wound healing is a sequential process that begins immediately after tissue injury. Coagulation is initiated by platelet aggregation then by fibrin clot formation. This supplies haemostasis and allows accumulation of neutrophils and monocytes, which herald the inflammatory phase. The inflammatory phase provides phagocytosis of bacteria, other foreign matter, and dead tissue in the wound. The macrophages release factors that stimulate proliferation of local fibroblasts in the dermis. These provide a collagen network and stimulate new vessel growth. This phase is characterised by pink granulation tissue and wound contraction. A warm moist environment that is supplied either by dressings or scab formation aids this process. Collagen synthesis reaches its peak towards the end of the first week of healing. Remodelling continues to occur for up to 12 months; thus the scar will usually fade and contract over the first 2 to 3 months and the final appearance may not be obvious for up to 6 months post injury.

A number of factors affect the healing of a wound. Adequate nutrition (including vitamins C and A, which are required for collagen formation) is essential. Corticosteroids and immunosuppressive drugs interfere with cellular proliferation and immunity, and anticoagulants inhibit clot formation and initial wound stabilisation. Infection interferes with collagen synthesis and will delay wound healing and cause an increase in scar tissue formation.

Tensile forces of the surrounding skin affect the healing and scar formation of a wound. The most cosmetically pleasing outcome occurs when the long axis of the wound is in the direction of maximum skin tension – along Langer’s Lines of skin tension. Wounds that have long axis perpendicular to the lines of skin tension will heal with greater scarring, but there is significant inter-child variability. Dynamic skin tension caused by joint movement also impairs wound healing and causes increased scar formation, and immobilisation of joints while the laceration heals will minimise this effect.

Wound infection

Wound infection is relatively uncommon, occurring in about 5% of wounds presenting to emergency departments (EDs). In general, a wound in a child is less likely to become infected than a similar wound in an adult. Identified risk factors for infection include severe wound contamination, inadequate wound cleansing, inadequate debridement of dead tissue (especially in crush injuries), use of subcutaneous sutures, larger laceration (>5 cm) and site of injury. Specific sites identified as infection risks include axillae, perineum or groin, and feet. In general, limb wounds are at increased risk compared to head and neck wounds.^3,^5,⁶

Classification of wounds

Lacerations

Lacerations are the most common type of wound seen in the paediatric age group.⁶ The edges are usually ragged. If the wound penetrates into the dermal capillaries it will bleed and if it extends into the subcutaneous tissue it will gape. Lacerations can be caused by tension on the skin (usually seen in areas with significant subcutaneous tissue) or by compression of the skin between an object and bone. There is always damage done to surrounding tissues and healing is therefore delayed. Compression injuries usually have more surrounding tissue damage and thus tend to heal more slowly.

Incised wounds

A sharp object such as a knife blade or glass shard makes an incised wound. The wound has margins that are clearly defined and there is little or no surrounding tissue damage. These wounds heal faster than lacerations and, in general, have a lower incidence of infection.

Abrasions

Abrasions are caused by sheering forces on the surface of the skin. The upper layers of the epidermis and sometimes dermis are scraped away. The depth of injury usually varies throughout the wound. If the epidermis alone is involved there is no bleeding, but a transudation of fluid. If the dermis is involved the wound will bleed and there is said to be an increased incidence of infection and foreign body retention.

Evaluation of the patient with a laceration

The care of the patient as a whole should be the first management priority. The airway, breathing and circulation should be assessed and treated as appropriate and a thorough secondary survey undertaken in most patients to exclude or allow management of serious injuries as well as detecting other minor injuries.

History

The mechanism of trauma (cut, crush, fall, bite, burn) and the time of injury are important as they may alter the management of the wound. Crush and bite injuries characteristically cause significantly more surrounding tissue damage and thus are more likely to have delayed healing or infection. When possible, determine the cleanliness of the inflicting object, the amount of blood loss, the presence of a foreign-body sensation, and the motor function and sensation distal to the affected area. The location of the wound should be noted and the possibility of injury to other structures explored.

The health status of the patient should be explored, especially with regard to chronic illnesses that may impact on wound healing – such as diabetes mellitus, obesity, malnutrition, chronic renal impairment, cyanotic congenital heart disease, chronic respiratory illness, tumours, and bleeding disorders.³ Immunisation history should be obtained and further tetanus vaccination guided by the recommendations of the National Health and Medical Research Council (Table 4.1.1).⁷ Current medications are important for both drug interactions with antibiotics that may be prescribed and for medications that may interfere with wound healing – such as immunosuppressive drugs and corticosteroids. A history of allergies must be determined prior to use of cleansing agents, dressings and tapes and prescription of medication. A history of latex allergy should be specifically sought. In wounds that require management under general anaesthesia or sedation a history of when the child last ate or drank is important. Non-accidental injury should be considered, especially when the history and injury are inconsistent.

Examination

Once assessment and management of more serious injuries has occurred, the patient should be assessed for the current severity of any chronic illness, and appropriate management initiated.

The co-operation able to be gained and comprehension level of the child influence wound examination and the information gained. Distraction techniques, adequate topical anaesthesia and appropriate use of sedation can all aid in wound assessment. A calm, unhurried, friendly approach, involving the parents, will maximise the chances of co-operation. Examination of the wound should be done with optimal lighting and with bleeding minimised. Examination of function, sensation and circulation distal to the wound is best performed prior to exploration of the wound and prior to regional anaesthesia.⁸^–¹⁰

Functional assessment requires the movement of all joints distal to the wound. In an older child each joint is examined individually on command and the strength documented. In the child less than 5 years old, observation of posture, symmetry and general movement is required. In wounds to the flexor tendons of the hand, close attention should be paid to the resting position of the fingers (partial flexion). The finding of extension of one finger at rest and the failure of the finger to flex at play or after application of a noxious stimulus confirms the tendon injury.

Injury to nerves is classically assessed with two-point discrimination and this should be possible in older children. Using a paperclip bent so that its ends are separated 4–8 mm is useful in this process. In upper limb injuries formal assessment of the median, ulna and radial nerves is required. In children less than 5 years old this approach needs to be modified. A noxious stimulus applied to the fingers will illicit sensation but risks losing patient confidence. Another method of determining intact innervation is to look for sweating of the fingers. Since autonomic response includes sweating, denervated fingers do not sweat. An ophthalmoscope can be used to examine for sweat beads or the cleaned body of a pen can be run over the fingers, with less resistance in the denervated, thus dry, segment. Arterial circulation is assessed by palpation of peripheral pulses, capillary return distal to the injury, and skin colour and temperature.

Assessment of the wound should include site, size, depth, nature of the edges, cleanliness, and presence of foreign bodies. The wound should be explored to determine the depth and involvement of any underlying tissues including vessels, nerves, tendons, ligaments, muscles, joints, bones and specialised tissues (especially ducts and glands). Bones adjacent to the wound should be palpated for deformity or crepitus and the wound searched for foreign bodies (including the sound of glass on the metal forceps). This assessment and exploration should take place after appropriate anaesthesia of the wound and any required sedation.

Investigation

If presence of a foreign body is expected radiological investigation is advised. In wounds caused by glass, all but superficial wounds should be investigated with plain soft tissue X-ray of the region to exclude a glass foreign body. Most glass foreign bodies more than 2–3 mm in size should be visible. If a radiolucent foreign body is suspected, ultrasound can be useful to both confirm the presence of the foreign body and provide a guide to its depth and location in the wound.⁹^–¹¹ Other investigations should be determined by the findings of possible injuries to adjacent structures, such as bony X-rays for fractures.

Treatment of wounds

Wound anaesthesia

Analgesia and sedation are discussed in more detail in Section 20. Anaesthesia is required to adequately examine and then treat most wounds. Often, in children, analgesia and sedation will also be necessary, depending on the location of the wound, the involvement of underlying structures, and the age and anxiety of the child.

The options for anaesthesia include topical anaesthesia, local infiltration, regional anaesthesia, dissociative anaesthesia, or general anaesthesia.

Topical anaesthetics include ALA (adrenaline, lidocaine and amethocaine (tetracaine)) – commonly known as LET (lidocaine, epinephrine and tetracaine) in North America, or EMLA cream (eutectic mixture of local anaesthetics) – manufactured by AstraZeneca. ALA is highly effective on facial and head wounds but less so on limb wounds. It has replaced TAC (tetracaine, adrenaline and cocaine) in most institutions. Due to the vasoconstricting properties of adrenaline (epinephrine) these anaesthetics should not be used in areas of end arteries (finger tips, nose, lips, ears, genitalia). EMLA has been shown to be safe and effective when applied to limb wounds. Topical anaesthetics should be applied in the wound either as a liquid dripped onto a pledget of cotton wool placed into the wound or as a methylcellulose gel. The wound is then covered with an occlusive impermeable dressing and adequate anaesthesia is usually obtained within 30 minutes.¹²^–¹⁷

Local infiltration is the classical method of anaesthetising a wound. The anaesthetic is injected into the wound margins. Pain of injection can be minimised by using warmed anaesthetic, buffering the drug with sodium bicarbonate (mix 10 mL of 1% lidocaine with 1 mL of 8.4% sodium bicarbonate), infiltrating slowly, using the lowest concentration possible, and using needles sized 25 gauge or smaller. The most commonly used local anaesthetic is lidocaine 1 or 2% with or without adrenaline (epinephrine) 1:100 000. The onset of action is rapid, with duration of action of 30 minutes to 1 hour. Addition of adrenaline (epinephrine) is useful to prolong the duration of action and help minimise bleeding; however, adrenaline (epinephrine) should be avoided in regions of end arteries (fingers, nose, lips, ears, genitalia), and its use may increase the risk of infection. The safe dose of plain lidocaine is 3 mg kg^–1 or 6 mg kg^–1 for lidocaine mixed with adrenaline (epinephrine).³

Regional anaesthesia is useful for facial, hand and foot lacerations, where nerves are readily accessible near bony landmarks. A regional nerve block involves anaesthetising the nerve or nerves that supply a specific anatomic region. Regional anaesthesia is especially useful for large lacerations and lacerations where local infiltration causes distortion of tissue anatomy. Regional anaesthesia is especially useful for anaesthetising digits. Lidocaine or bupivacaine hydrochloride 0.5%, which has duration of action of 3 to 6 hours, are the most commonly used agents. The safe dose of bupivacaine is 2 mg kg^–1.

Sedation is often required when treating lacerations in children. Options for sedation include benzodiazepines – such as midazolam or diazepam, fentanyl, nitrous oxide, ketamine, or propofol. Sedation should only be undertaken by personnel experienced in its use and able to manage the complications of airway compromise, oxygen desaturation and respiratory depression. Adequate equipment to deal with these complications should also be available. Some form of physical restraint may also be necessary to prevent excessive movement during repair; however, the aim must be to provide adequate analgesia and anxiolysis.^13,¹⁸

Wound preparation and cleansing

Hair near the wound should only be removed if it interferes with the meticulous closure of the wound. If hair removal is desired the hair should be clipped, not shaved, as shaving disrupts hair follicles and increases the incidence of wound infection.¹⁹ Eyebrow hair should not be removed because this may lead to abnormal or delayed regrowth.

The surrounding skin and wound edges should be thoroughly cleaned. This should be undertaken in a manner and with a substance that provides adequate antisepsis without tissue damage or impairing wound defence mechanisms. A solution such as aqueous povidone-iodine or aqueous chlorhexidene applied with gauze or cotton wool should be used. Care should be taken to minimise the amount of cleanser to penetrate the wound to minimise damage to wound defences increasing the risk of infection.

Surgical debridement of crushed or non-viable tissue is vital to prevent wound infection or delayed wound healing. However, as little tissue should be debrided as possible. Manual removal with forceps of large particles of foreign material should also be meticulously undertaken. When a heavily contaminated wound contains specialised tissues such as tendons or nerves, consultation is recommended.

Once the wound is adequately anaesthetised it should be thoroughly cleaned. Irrigation is the method of choice for removing dirt and bacteria from wounds. In hospital, saline (0.9%) is the irrigation solution of choice, as it causes no tissue damage, but tap water can be used.²⁰ The ability of irrigation to decontaminate a wound is directly related to pressure of the irrigating stream, the size of the particles to be removed, and the volume of irrigant. At least 100–200 mL per 2 cm of laceration are required. The fluid should be injected from a 30–60 mL syringe via an 18 to 20 gauge cannula. Higher pressures should be avoided as they may cause tissue damage and increase the incidence of wound infection.^21,²² The volume and pressure of irrigation should be modified as necessary according to the location and cause of the wound. High-pressure irrigation does not enhance the dissemination of bacteria into soft tissue wounds, but excessive use can cause local tissue oedema enhancing risk of infection. Use of a device to minimise splashing of the irrigant is desirable and wearing of gloves, goggles and gown mandatory.^21,²²

Antibiotic prophylaxis

The use of prophylactic antibiotics in wound care is controversial. Decontamination with appropriate irrigation techniques is more beneficial than the use of prophylactic antibiotics.^2,^9,^23,²⁴ When indicated (Table 4.1.2), antibiotics should be given as soon as possible. The initial dose should be given intravenously and be relatively large to provide rapid reliable high tissue concentrations. The first dose should be given before wound closure to ensure an effective concentration of antibiotic in the wound tissue fluid at the time of wound closure. When choosing an antibiotic the likely causative organisms should be borne in mind: the organisms contaminating the wound and the commensal organisms found in that region of the body. In general, bites and wounds in regions with high bacterial counts (hands, feet, groin) should be treated with antibiotics to cover Staphylococcus epidermidis, S. aureus and Streptococcus sp. The likelihood of anaerobic bacteria needs to be considered. Specific circumstances also need to be borne in mind. Patients at risk of endocarditis should have all wounds treated with antibiotics to cover S. aureus and S. epidermidis. Ampicillin/amoxicillin is the currently recommended drug in Australia. However, in communities where the incidence of penicillin resistance is high a cephalosporin and an aminoglycoside are recommended.

Wound characteristics High risk anatomic site (hands, forefoot, groin, axilla) Devitalised tissue Extensive surrounding soft tissue injury Stellate lacerations Contaminated with body fluids or organic matter or dirt Large lacerations (> 5 cm) Closure delayed (> 12 hours) High risk for endocarditis Prosthetic heart valves Patent ductus arteriosis

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