Contaminated Wounds

Wounds that are contaminated may be obvious; however, contamination with liquids (such as water) is not always apparent. The potential for contamination should be considered in any open wound.

Determination of contamination is based on historical evaluation and wound inspection. Establish whether the wounding implement was clean or grossly soiled. Common knife contaminants include meat, poultry, and dirt. A laceration over the knuckle that occurred when the fist struck a human mouth is always considered contaminated. Likewise, a retained foreign body may provide a nucleus of infection. Fungal infections may occur in the presence of retained wood fragments. Wound irrigation, debridement, and foreign body removal are critical for healing to occur without infection.⁹

Hair Removal

Wounds in hairy areas heal best without hair in the approximated edges. Unfortunately, shaving abrades the skin, increases wound infection rates, and is cosmetically irritating. Snip hair with scissors or trim it with an electric clipper if removal is necessary. One area that should never be shaved is the eyebrow, as eyebrows provide important landmarks for approximating wound margins and, once shaved, may fail to grow back.¹¹

Mechanical Irrigation

Irrigation is helpful to wash away small foreign bodies, including soil. Irrigation is essential in wounds caused by bites and in those with fecal contamination.

Remove sand, dirt, and other large particles using low-pressure irrigation with a syringe. However, small particles such as clay and bacteria require higher-pressure irrigation. Forcing fluid through a narrow catheter or needle (e.g., a 19-gauge needle on a 12- or 35-mL syringe) provides an irrigation pressure of 5 to 8 pounds per square inch.

Regardless of the solution or type of irrigation apparatus, place the needle perpendicular to the wound (as close as possible to the surface) and forcefully depress the syringe plunger. Use protective equipment to guard against fluid splatter to the face and eyes and prevent blood-borne pathogen exposure. Splash guards can be attached between the syringe and the catheter to decrease splatter, but they are not a substitute for personal protective equipment.⁴

Anesthetic Agents

The most common anesthetic for local infiltration or regional use is lidocaine, primarily because of its low tissue toxicity. Additionally, lidocaine has a short duration of action, which is desirable for repairs of areas such as the mouth or lip, where recovery of sensation reduces the incidence of unintentional biting of the wound. Likewise, prompt return of sensation to a finger prevents further injury as the patient begins to use the hand.

One disadvantage of lidocaine is the pain associated with injection. Warming the solution to 37° C (98.6° F) can minimize this effect. Sodium bicarbonate also reduces the pain associated with lidocaine injection. Buffer lidocaine by adding one part 8.4% sodium bicarbonate (1 mEq/mL) to 10 parts 1% lidocaine (i.e., add 1 mL of sodium bicarbonate to 10 mL of lidocaine). However, this mixture reduces the shelf life of lidocaine from 3 years to a few days, after which the solution will precipitate in the bottle.¹²

Preparations of lidocaine with epinephrine are also available. Epinephrine increases the duration of anesthesia and decreases bleeding. Use of this combination is contraindicated in heavily contaminated wounds or those with a tentative blood supply such as avulsions. Adverse effects of epinephrine include an increased rate of infection and ischemia when lidocaine with epinephrine is injected into the ear, tip of the nose, digits, or penis.

Another anesthetic agent used for infiltration is bupivacaine (Marcaine, Sensorcaine). The effects of this drug last four times longer than lidocaine. This makes bupivacaine ideal for situations in which wound closure will require longer than 2 hours or when prolonged local anesthesia is desirable.

Anesthetic Allergy

Patients frequently report an allergy to lidocaine; however, true allergy to injected anesthetics is uncommon.¹² Many reported allergies are actually adverse reactions such as hyperventilation, vasovagal syncope or light-headedness, cardiovascular stimulation from epinephrine, and various idiosyncratic reactions to the injury and subsequent wound repair. Contact dermatitis, caused by topical local anesthetics, also has been reported. This type of reaction is not immunoglobulin E–mediated and poses little risk. If a true allergy is suspected, an anesthetic from a different chemical class can be used. Sterile saline infiltration, guided imagery, and hypnosis are nonpharmacological options. If local anesthesia is not possible, needleless wound closure techniques such as tying hair on the scalp or applying adhesive closure strips (e.g., Steri-Strips) or wound glue should be considered.

Infiltration Anesthesia

Direct injection of an anesthetic agent into the wound is the most common anesthetic technique used in the ED. Infiltration of lidocaine along wound edges anesthetizes subcutaneous nerves. Some have recommended injecting through intact, antiseptically cleansed skin at the periphery of the wound to prevent spread of contamination. However, injecting through the edge of the wound is less painful. Several methods are available to reduce discomfort from anesthetic infiltration:

Digital Block

Digital blocks can be used when the nerve supply to the wound is superficial. This technique is particularly superior to infiltration anesthesia in regions where the skin is sensitive, especially the digits, palms, soles, and face. Another advantage of digital or other regional nerve blocks is that they do not distort the wound or interfere with approximation.