Principles of Wound Management

Management of acute traumatic wounds is one of the most common procedures in emergency medicine. Although many aspects of traumatic wound management remain controversial, the clinician can follow some basic principles to maximize the chance for successful healing. The purpose of this chapter is to give the clinician a general approach to wound care and to describe appropriate indications and techniques for wound management.

Wound care involves much more than closure of divided skin. The primary goal of wound care is not technical repair of the wound, but to provide optimal conditions so that the natural reparative processes of the wound may proceed. The cornerstones of wound care are cleaning, débridement, closure (when appropriate), and protection. The primary objectives in wound care are to:

1.
Preserve viable tissue and remove nonviable tissue
2.
Restore tissue continuity and function
3.
Optimize conditions for the development of wound strength
4.
Prevent excessive or prolonged inflammation
5.
Avoid infection and other impediments to healing
6.
Minimize scar formation
7.
Provide suitable anesthesia during wound management

Patients who seek care in the emergency department (ED) because of acute wounds report that their top priorities include prevention of infection, return to normal function, a good cosmetic outcome, and minimal pain during repair. This chapter reviews the current strategies for attaining these goals.

Background: Wound Healing

For centuries victims of wounds have commonly experienced inflammation, infection, and extreme scarring; in fact, these processes were considered part of normal wound repair. Emergency clinicians should have a basic understanding of the process of wound healing. Highlights of this complex phenomenon as they relate to clinical decision-making are presented here.

Wounds extending beneath the epithelium heal by forming scar tissue. Among the various proposed overlapping phases from injury to repair, inflammation, epithelialization, fibroplasia, contraction, and scar remodeling/maturation constitute the main phases of this natural repair process.

Inflammation is a beneficial response orchestrated by polymorphonuclear and mononuclear leukocytes that concentrate at the site of injury and phagocytose dead and dying tissue, foreign material, and bacteria in the wound, essentially performing a biologic débridement. As white blood cells die, their intracellular contents are released into the wound. In excessive amounts, the contents form the purulence that is characteristic of infected wounds. Some exudate is expected even in the absence of bacterial invasion, but infection with accumulation of pus interferes with epithelialization and fibroplasia, and impairs wound healing. Wounds contaminated with significant numbers of bacteria or foreign material may undergo a prolonged or persistent inflammatory response and not heal. Granuloma formation surrounding retained sutures is an example of chronic inflammation.

Although white blood cells remove debris within the wound, keratinocytes at the surface of the wound begin to migrate across the tissue defect during epithelialization . In most sutured wounds, the surface of the wound develops an epithelial covering impermeable to water within 24 to 48 hours. Surface debris, dead tissue, and eschar formation can impair this process. The epithelium thickens and grows downward into the wound along the course of skin sutures. Although there is some “adhesiveness” at the wound edges during the first few days, this is eventually lost because of fibrinolysis.

By the fourth or fifth day, newly transformed fibroblasts in the wound begin synthesizing collagen and protein polysaccharides, thereby initiating the stage of scar formation known as fibroplasia . Collagen is the predominant component of scar tissue. Wound strength is a balance between the lysis of old collagen and the synthesis of new collagen that “welds” the edges of the wound together. The amount of scar tissue that forms is influenced by physical forces (e.g., the stresses imposed by movement) acting across the wound. When the wound edges are approximated, either naturally or by mechanical closure within the first 24 hours, the wound can heal by “first intention”. In contrast, a wound with extensive tissue loss and not closed by sutures or other means heals by “secondary intention,” a combination of processes that include contraction, collagen formation, and epithelialization ( Fig. 34.1 ). Contraction consists of movement of the skin edges toward the center of the defect, primarily in the direction of underlying muscle.

Figure 34.1, Steps in wound healing by first intention (left) and second intention (right). Note the large amounts of granulation tissue and wound contraction in healing by secondary intention.

Significant gains in tensile strength do not begin until approximately the fifth day after the injury. Strength increases rapidly for 6 to 17 days, more slowly for an additional 10 to 14 days, and almost imperceptibly for as long as 2 years ( Fig. 34.2 ). The strength of scar tissue never quite reaches that of unwounded skin, approaching a maximum of 80%. Although the process of collagen formation is essentially completed within 21 to 28 days, the scar widens for another month, and collagen continues to remodel and strengthen the wound for up to 1 year. The normal desirable outcome of this complex process is a wound that is either fully re-epithelialized or filled with an avascular scar.

Figure 34.2, Graphic representation of the various phases of wound healing. Note that the tensile strength of scar tissue never reaches that of unwounded skin. The values of tensile strength displayed are approximate and demonstrate the general concept of wound healing.

Decisions regarding the optimal time for suture removal and the need for continued support of the wound with tape are influenced by the following: (1) the tensile strength of the wound, (2) the period of scar widening, and (3) the cosmetically unacceptable effect of epithelialization along the suture track. Scars are quite red and noticeable at 3 to 8 weeks after closure. The appearance of a scar should not be judged before the scar is well into its remodeling phase. The cosmetic appearance of wounds 6 to 9 months after injury cannot be predicted at the time of suture removal. Therefore scar revision, if necessary, should be postponed until 6 to 12 months after injury.

One of the most important factors in predicting the cosmetic result of a wound is its location. In general, wounds on concave surfaces heal with better cosmetic results than do wounds on convex surfaces. Other factors that affect cosmesis include wound size, wound depth, and skin color. Small, superficial wounds in lax, light-colored skin, especially areas where the skin is thin, result in less noticeable scars. Wounds on convex surfaces look better after primary closure than after secondary healing. Static and dynamic forces, along with the propensity toward keloid formation, may influence the long-term cosmetic appearance of wounds more than the surgical skills of the clinician who repaired the wound. Repigmentation occurs over a period of 3 to 5 years, even in large wounds that heal by secondary intention. Patients should be advised to wear sunscreen over the scar, especially during the first few years after injury, because unprotected exposure to the sun can alter the pigmentation as the wound heals and may result in noticeably darker pigmentation than the surrounding skin.

Initial Evaluation

The approach to management of a particular wound and the decision to close a wound immediately or after a period of observation is based primarily on factors that affect the risk for infection, and secondarily on cosmesis and long-term functionality. The history and physical examination should be directed toward identifying these factors. Some wounds may appear benign but conceal extensive and devastating underlying tissue damage. The following findings should alert the provider of a more complicated injury including an extremity wound caused by a roller or wringer device, a high-pressure injection gun, high-voltage electricity, heavy and prolonged compressive force, or the bite of a human or a potentially rabid animal. These findings radically alter the overall management of the patient. The American College of Emergency Physicians' Clinical Policy for the Initial Approach to Patients Presenting with Penetrating Extremity Trauma provides a useful approach to the evaluation of all wounds.

History

In the initial evaluation of a wound, identify all the extrinsic and intrinsic factors that jeopardize healing and promote infection, including: (1) the mechanism of injury, (2) the time of injury, (3) the environment in which the wound occurred, and (4) the patient's immune status.

Wound Age

In general, the likelihood of a wound infection increases with time, from the injury to definitive wound care. Definitive wound care does not always mean closing a wound. Some wounds should never be closed, such as small, contaminated lacerations on the bottom of the foot, whereas others can be closed many hours after the injury without increasing infection rates. A delay in wound cleaning is one of the most important factors in wound infection because it may allow bacteria contaminating the wound to proliferate. A delay of only a few hours in the treatment of a heavily contaminated wound can increase the risk for infection. Although no scientific data exist to fully answer the question, and there is no definitively accepted standard, it appears reasonable that most wounds that are not grossly contaminated can probably be closed safely 6 to 8 hours after injury, if the wound can be adequately cleaned. In contrast, some evidence suggests that wounds in highly vascular regions, such as the face and scalp, can be closed without increased risk for as long as 24 hours after injury. The “golden period”—the maximum time after injury that a wound may be closed safely without significant risk for infection—is an outdated term and not a fixed number of hours.

Many factors affect risk for infection, and closure decisions should not be based solely on time considerations. All data accumulated in the initial evaluation, both historical and physical, must be considered when making the decision to close a wound in a particular patient. Delayed primary closure is a reasonable alternative when there is clinical concern regarding closure at initial assessment. However, the techniques of wound care may extend the period; with skillful cleaning and débridement, a clinician may be able to convert a contaminated wound to a clean wound that can be safely closed in the ED. In most instances the clinician cannot totally eliminate infection risks but can favorably affect the probability and severity of infection with adequate wound care. Simply prescribing antibiotics in the hope that infection will somehow be averted is an unrealistic expectation, and can lead to antibiotic-resistant microorganisms.

In summary, any time frames offered are suggestions. Clinical judgment regarding potential for wound infection should be incorporated into the final decision-making process.

Other Historical Factors

Other factors that affect wound healing or the risk for infection include the patient's age and state of health. Patient age appears to be an important factor in host resistance to infection, and individuals who are at the extremes of age, such as young children and the elderly, have the greatest risk for infection. Infection rates are reported to be higher in patients with concurrent medical conditions such as diabetes mellitus, immunologic deficiencies, malnutrition, anemia, uremia, congestive heart failure, cirrhosis, malignancy, alcoholism, arteriosclerosis, arteritis, collagen vascular disease, chronic granulomatous disease, smoking, chronic hypoxia, renal failure, and liver failure. Morbid obesity, in addition to other conditions in which patients are taking steroids or immunosuppressive drugs, or undergoing radiation therapy, are also at higher risk for infection. Shock, remote trauma, distant infection, bacteremia, retained foreign bodies, denervation, and peripheral vascular disease also increase wound infection rates and can slow the healing process.

Additional information pertinent to decision making in wound management includes the following:

Associated symptoms (severe pain, paresthesia, or anesthesia)
Current medications (specifically, anticoagulants, steroids, and immunosuppressive drugs)
Allergies (especially to local anesthetics, antiseptics, analgesics, antibiotics, and tape)
Tetanus immunization status
Potential exposure to rabies (in bite wounds and mucosal exposures)
Potential foreign bodies (embedded in the wound, especially when the mechanism of injury is unknown or the injury was associated with breaking glass or vegetative matter)
Previous injuries and deformities (especially with extremity and facial injuries)
Associated injuries (underlying fracture, joint penetration, crush injury, deep penetrating injury, animal or human bite)
Other factors (availability for follow-up, patient understanding of wound care, compliance)

Physical Examination

All wounds should be examined for the amount of tissue destruction, degree of contamination, potential foreign bodies, and damage to underlying structures. The examiner should wear clean or sterile powder-free, latex-free gloves and avoid droplet contamination from the mouth. Examine the wound under good lighting and after the bleeding is controlled. Create a bloodless field, if necessary, with a tourniquet or sphygmomanometer (see for equipment). Assess distal perfusion, motor and sensory function (prior to the use of anesthetics), nearby tendon function, and document findings.

Mechanism of Injury and Classification of Wounds

The magnitude and direction of the injuring force and the volume of tissue on which the force is distributed determine the type of wound that is sustained. Three types of mechanical forces—shear, tension, and compression—produce soft tissue injury. The resulting disruption or loss of tissue determines the configuration of the wound. Wounds may be classified into six categories:

1.
Abrasions. Wounds caused by forces applied in opposite directions result in the loss of epidermis and possibly dermis (e.g., grinding of skin against a road surface).
2.
Lacerations. Wounds caused by shear forces produce a tear in tissues. Little energy is required to produce a wound by shear forces (e.g., a knife cut). Consequently, little tissue damage occurs at the wound edge, the margins are sharp, and the wound appears “tidy.” Tensile and compressive forces also cause separation of the tissues. The energy required to disrupt tissue by tensile or compressive forces (e.g., forehead hitting a dashboard) is considerably greater than that required for tissue disruption by shear forces because the energy is distributed over a larger volume. These lacerations often have jagged, contused, “untidy” edges, which have a higher risk for infection.
3.
Crush wounds. Wounds caused by the impact of an object against tissue, particularly over a bony surface, compress the tissue. These wounds may contain contused or partially devitalized tissue and have higher rates of infection if not appropriately débrided.
4.
Puncture wounds. Wounds with a small opening, whose depth cannot be entirely visualized, are caused by a combination of forces. They are particularly prone to infection because they are difficult to thoroughly clean and may retain foreign bodies.
5.
Avulsions. Avulsions are wounds in which a portion of tissue is completely separated from its base, which is lost, or left with a narrow base of attachment (a flap). Shear and tensile forces cause avulsions. Skin tear avulsions often result from low-force friction or shearing forces that separate the layers of the skin (epidermis and dermis) from the underlying tissue. These wounds often occur in older adults as a result of the combination of minimal impact and vulnerable thin skin.
6.
Combination wounds. Wounds can also have a combination of configurations. For example, a stellate laceration caused by compression of soft tissue against underlying bone can create wounds with elements of both crush injury and tissue separation. Missile wounds involve a combination of shear, tensile, and compressive forces that puncture, crush, and sometimes avulse tissue.

Contaminants (Bacteria and Foreign Material)

Infection rates in studies of traumatic wounds range from 1% to 38%. Numerous factors affect the risk for wound infection, but the primary determinants of infection are the amount of bacteria and dead tissue remaining in the wound, the patient's immune response, and local tissue perfusion.

Essentially all traumatic wounds are contaminated with bacteria to some extent. The number of bacteria remaining in the wound at the time of closure is directly related to the risk for infection. A critical number of bacteria must be present in a wound before a soft tissue infection develops. In experimental wounds, fewer bacteria are required to infect wounds caused by a compressive force (≥10 ⁴ bacteria/g of tissue) than by a shear force (≥10 ⁶ ).

The nature and amount of foreign material contaminating the wound often determines the type and quantity of bacteria implanted. In general, visible contamination of a wound increases the risk for infection. The presence of undetected, reactive foreign bodies in sutured wounds almost guarantees an infection. Although bullet or glass fragments by themselves rarely produce wound infection, these foreign bodies may carry particles of clothing, gun wadding, or soil into the wound. Minute amounts of organic or vegetative matter, feces, or saliva carry highly infective doses of bacteria. The bacterial inoculum from human bites often contains 1 billion or more organisms per milliliter of saliva. Inorganic particulate matter, such as sand or road surface grease, usually introduces few bacteria into a wound and has little chemical reactivity. These contaminants are relatively innocuous. Soil that contains a large proportion of clay particles or a high organic content (such as that found in swamps, bogs, and marshes), however, has a high risk for infection.

In industrialized countries most wounds encountered in the practice of emergency medicine have low initial bacterial counts. If wound cleaning and removal of devitalized tissue are instituted before bacteria within the wound enter their accelerated growth phase (3 to 12 hours after the injury), bacterial counts will generally remain below the threshold needed to initiate infection.

Devitalized Tissue

Devitalized and necrotic tissue in a traumatic wound should be identified and removed. If left in place, it will allow bacteria to proliferate, inhibit leukocyte phagocytosis, and create an anaerobic environment suitable for certain bacterial species.

Wound Location

The anatomic location of the wound has considerable importance in the risk for infection. Bacterial densities on the surface of the skin range from a few thousand to millions per square centimeter. Distal extremity wounds are more at risk for the development of wound infections than are injuries on most other parts of the body. Levels of endogenous bacteria on hairy parts of the scalp, the mouth, axilla, nails, foreskin, perineum, and vagina may be high enough to serve as a potential source of infection in wounds in these locations. The high vascularity in areas such as the scalp, face, or perineum appears to offset the risk posed by the large numbers of endogenous microflora, whereas wounds in ischemic tissue are notoriously susceptible to infection.

Underlying Structures

If injury to underlying structures such as nerves, vessels, tendons, joints, bones, or ducts is found, the clinician may choose to forego wound closure and consult a surgical specialist ( Fig. 34.3 ). Procedures such as joint space irrigation, reduction and débridement of compound fractures, neurorrhaphy, vascular anastomosis, and hand flexor tendon repair are best accomplished in the controlled aseptic setting of the operating room, where optimal lighting, proper instruments, and assistance are available.

Figure 34.3, This patient had weak, hesitant, but full flexion of the finger, thus suggesting at least a partial tendon laceration. The tendon was nearly 90% lacerated (arrow) and would have ruptured with any stress. Close examination of this wound, with careful blunt dissection down to the tendon itself and the finger in the position of injury , revealed significant trauma to the delicate flexor tendon that required consultation with a specialist. Use of a proximal tourniquet for a bloodless field and instruments to explore finger wounds is mandatory to increase sensitivity for finding injury to deep structures. This wound can be repaired within a few days by a hand specialist, but if discovered weeks later, problems are likely.

Cleaning

Clean the wound as soon as possible after evaluation. Although most wounds are initially contaminated with less than an infective dose of bacteria, given time and the appropriate wound environment, bacterial counts may quickly rise to infective levels. The goals of wound cleaning and débridement are as follows: (1) to remove bacteria and reduce their numbers below the level associated with infection, and (2) to remove particulate matter and tissue debris that would lengthen the inflammatory stage of healing or allow the growth of bacteria beyond the critical threshold.

There are two general wound-cleansing techniques: scrubbing and irrigation. Irrigation, which is recommended for most wounds, involves a steady flow of solution across the surface of the wound. This important step in wound management provides hydration to the wound, removes deeper debris, aids in visual examination, and also reduces the risk for infection. Normal saline or tap water is often used as an adequate irrigation fluid.

Soaking a wound in a saline or antiseptic solution before the clinician arrives is a common outdated practice that is of no proven value and may actually increase bacterial count; hence, it is not recommended.

Patient Preparation

Before examining, cleaning, exploring, or repairing a wound, allay the patient's fears and encourage cooperation by explaining the procedure and assuring the patient that everything possible will be done to minimize pain. In general, all wound care should be performed with the patient in a supine position because fainting is a common occurrence during wound preparation and repair ( Fig. 34.4 ). Relatives and friends can be allowed to stay with the patient, but they should be cautioned to report any dizziness or nausea, and they should remain seated throughout the procedure.

Figure 34.4, The ideal setup for evaluation and repair of a laceration is a supine patient, a seated clinician at the correct height for the procedure, and a bloodless field with good lighting.

Anyone cleaning, irrigating, or suturing wounds should wear protective eyewear and gloves because virtually any patient may be seropositive for human immunodeficiency virus (HIV). Although mucosal exposure to blood or tissue products that are contaminated by HIV is considered a relatively low risk for subsequent infection, universal precautions are currently recommended, and a mask should be considered. Minimal aseptic technique requires the use of gloves during the cleaning procedure.

Thorough cleansing of bacteria, soil, and other contaminants from a wound cannot be accomplished without the patient's cooperation. Scrubbing most open wounds is painful, and the patient's natural response is to withdraw the injured area away from the provider. Local or regional anesthesia should precede examination and cleansing of a wound ( ). Despite adequate anesthesia, the patient may be too apprehensive to cooperate. If reassurance does not alleviate the fears of young children, consider both sedation and physical restraining devices.

Mechanical Scrubbing

Scrubbing the internal surface of a wound is controversial. Although scrubbing a wound with an antiseptic-soaked sponge decreases the risk of infection by removing foreign particulates, bacteria, and tissue debris, an abrasive sponge may inflict more damage on the tissue. As the amount of damage caused by scrubbing correlates with the porosity of the sponge, a fine-pore sponge (e.g., 90 pores/inch) should be used to minimize tissue abrasion. Mechanical scrubbing should be reserved for wounds contaminated with significant amounts of bacteria or foreign material ( Fig. 34.5 A and B ), or should be considered if irrigation alone is ineffective in removing visible contaminants from a wound.

Initially scrub a wide area of skin surface surrounding the wound with an antiseptic solution to remove contaminants that might be transferred into the wound by instruments, suture material, dressings, or the clinician's gloved hand during wound management. It is important to remove all nonabsorbable particulate matter; any such material left in the dermis may be retained in the healed tissue and result in a disfiguring “tattoo” effect. Detergents have an advantage over saline in that they minimize friction between the sponge and tissue, thereby limiting damage to tissue during scrubbing. Detergents also dissolve particles and thus help dislodge them from the surface of the wound. Unfortunately, many of the detergents available are toxic to tissues. Use caution when considering detergents.

Antiseptics During Cleaning

For many years, antiseptic solutions have been used for their antimicrobial properties in and around wounds ( Table 34.1 ). Studies on the use of antiseptics in wounds demonstrate that there is a delicate balance between killing bacteria and injuring tissue. Intact skin can withstand strong microbicidal agents, whereas leukocytes and the exposed cells of skin and soft tissue can be damaged by these agents.

TABLE 34.1

Summary of Agents Used for Wound Care

AGENT	BIOLOGIC ACTIVITY	TISSUE TOXICITY ^a	SYSTEMIC TOXICITY ^a	POTENTIAL USES	COMMENTS
Povidone-iodine surgical scrub (Betadine 7.5%)	Virucidal; strongly bactericidal	Detergent component toxic to wound tissue	Painful in open wounds	Hand cleanser	Iodine allergy possible
Povidone-iodine solution (Betadine 10%)	Virucidal; bactericidal	Potentially toxic at full strength; 1% solution has no significant tissue toxicity	Extremely rare	Wound periphery cleanser; dilute to <1% for wound irrigation	Dilute 10 : 1 (saline to Betadine) if used to irrigate wounds
Chlorhexidine gluconate (Hibiclens)	Bactericidal	Toxic to tissues, including eyes	Extremely rare	Hand cleanser	Avoid in open wounds, eyes, or ears
Poloxamer 188 (Shur-Clens); Pluronic F-68	No antibacterial or antiviral activity	None known; does not inhibit wound healing	None known	Wound cleanser	Nontoxic in wounds and eyes
Hexachlorophene (pHisoHex)	Bacteriostatic against gram-positive bacteria	Potentially toxic to wound tissue	Possibly teratogenic with repeated use	Alternative hand cleanser	Systemic absorption causes neurotoxicity
Hydrogen peroxide	Very weak antibacterial agent	Toxic to tissue and red cells	Extremely rare	Wound periphery cleanser	Foaming activity removes surface debris and coagulated blood

a Based largely on in vitro studies and animal data.

Povidone-iodine (Betadine [Purdue Products L.P., Stamford, CT]) is widely available as a 10% stock solution. Although the undiluted solution may be used to prepare the skin surrounding a wound, it may be harmful to some tissue; therefore it should not be placed within the interior of the wound. Diluted povidone-iodine solution in concentrations of less than 1% appears to be safe and effective for cleaning contaminated traumatic wounds, but the precise concentration that provides the most benefit is unclear. Even dilute povidone-iodine may be particularly irritating when used for scrubbing contaminated wounds. In contrast, povidone-iodine surgical scrub (Betadine scrub, 7.5% iodine) and hexachlorophene (pHisoHex [sanofi-aventis U.S. LLC, Bridgewater, NJ]) both contain anionic detergents that are harmful to tissues. In vitro studies have demonstrated that chlorhexidine gluconate–alcohol (Hibiclens [Mölnlycke Health Care US, LLC, Norcross, GA]) is toxic to both fibroblasts and keratinocytes. When diluted to decrease its cytotoxic effect on these cells, it is no longer able to sufficiently kill Staphylococcus aureus . Its effect on the actual wound infection rate is unknown. Hydrogen peroxide is hemolytic, and there is little reason to use it except to clean surrounding skin encrusted with blood and coagulum, or to soak off adherent blood-saturated dressings. Peroxide should not be used on granulation tissue because oxygen bubbles lift newly formed epithelium off the wound surface.

Nonantiseptic, nonionic surfactants are attractive alternatives to these toxic cleansing agents. In contrast to antiseptic solutions, these preparations cause no tissue or cellular damage, leukocyte inhibition, or impairment of wound healing. The solutions cause no corneal injury, have low risk of conjunctival irritation, and do not cause pain on contact with the wound. Poloxamer 188 (Shur-Clens [ConvaTec, Greensboro, NC] or Pluronic F-68 [Thermo Fisher Scientific, Grand Island, NY]), a group of pluronic polyols, is nontoxic but has no antibacterial activity. Scrubbing experimental wounds with Shur-Clens reduced infection rates (though not statistically better than normal saline or povidone-iodine), thus proving it has the ability to cleanse a wound effectively and atraumatically. Pluronic polyols may be a good choice if the wound is near mucous membranes. The use of antiseptic preparations in wounds can be considered in high risk, contaminated wounds where the benefits outweigh the risks.

Irrigation

It is important to distinguish between skin antiseptics and irrigating solutions. As a general rule, commercially available antiseptics should be used only to clean intact skin and not exposed wound surfaces. Most open wounds can be irrigated effectively with copious amounts of saline or tap water. Concerns about introducing infection by the use of common tap water are unfounded.

Properly performed irrigation ( ) is effective in removing particulate matter, bacteria, and devitalized tissue that is loosely adherent to the edges of the wound and trapped within its depths. The effectiveness of irrigation is primarily determined by the hydraulic pressure at which the irrigation fluid is delivered. Low-pressure irrigation is defined at 1 to 2 psi, whereas high-pressure irrigation is greater than 8 psi. Port devices spiked into plastic intravenous bags that are squeezed by hand to deliver a stream of fluid, bulb syringes, or gravity flow irrigation devices all deliver fluid at very low pressures. Although irrigation at either low or high pressures will reduce levels of Staphylococcus aureus , higher pressures should be more effective at ridding wounds of small particulate matter. There appears to be no significant differences between tap water and saline delivered at high pressures. Although irrigation may not be required for low-risk, highly vascular, uncontaminated facial and scalp wounds, randomized, prospective trials are needed to answer this question.

Wound irrigation is best achieved with a large-volume syringe, 35 mL or 65 mL, and an 18- or 19-gauge catheter or needle to deliver irrigation volumes of at least 250 mL. The pressure that can be delivered with a syringe varies with the force exerted on the plunger and the internal diameter of the attached needle. A simple irrigation assembly consisting of a 19-gauge plastic catheter or needle attached to a 35-mL syringe produces 25 to 40 psi when the barrel of the syringe is pushed with both hands. High-pressure irrigation can also be achieved through IV tubing by placing a pressure cuff around a saline bag and inflating it to 400 mm Hg. A standard running faucet can also generate approximately 45 psi. Irrigating extremity lacerations by holding them under a faucet of tap water is a common and accepted practice for wound preparations, and fears of introducing infection with a nonsterile irrigant are unfounded. (Note: One must anticipate potential fainting if a patient stands near a sink for faucet water irrigation.) These high-pressure irrigation systems remove significant numbers of bacteria and a substantial amount of particulate matter from the wound surface. Care must be taken to ensure that any method of irrigation is not exerting too much pressure because tissue damage can occur at pressures of 70 psi. Irrigation should continue until all visible, loose particulate matter has been removed. Warmed irrigating solutions are more comfortable for patients, even after the wound is anesthetized.

A potential complication of wound irrigation is that infectious material can be splashed into the face of the clinician, even when the tip of the irrigation device is held below the surface of the wound. Several commercial devices are available to contain the splatter, including devices that fit on the end of a syringe (see Fig. 34.5 C and D ) and devices that fit on the screw top of saline bottles (for this particular device the company reported variable pressure from 4 to 15 psi). An alternative strategy is to pierce the base of a small medicine cup with a shorter, large-bore needle. The cup can be placed upside down to cover the area to be irrigated and the syringe with the 19-gauge needle can be inserted through the base of the cup (see Fig. 34.5 C ). The wound should be positioned to allow continuous drainage of fluid during irrigation by any method.

Antibiotic Solutions for Irrigation

A variety of antibiotic solutions have been instilled directly into wounds or used as irrigation solutions, including ampicillin, a neomycin-bacitracin-polymyxin combination, tetracycline, penicillin, kanamycin, and cephalothin. Although there have been no reports of topical sensitization or toxic tissue levels of the antibiotic, studies have found inconsistent effectiveness in reducing infection rates. The indications for using antibiotic solutions to clean wounds have not been defined, and this practice is not considered standard.

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