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How To Do Local Wound Infiltration

By

Richard Pescatore

, DO, Delaware Division of Public Health

Last full review/revision Oct 2021| Content last modified Oct 2021
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Local anesthetic can be injected directly into the exposed subcutaneous tissue of an open skin wound before cleansing, repair, and closure.

Local wound infiltration (infiltration anesthesia) is commonly done and often considered procedurally simpler than nerve blockade (regional anesthesia).

Indications

  • Laceration or other surgically treated skin lesion

  • Foreign body removal

  • Incision and drainage

Contraindications

Absolute contraindications

  • History of allergy to the anesthetic agent or delivery vehicle (choose a different anesthetic)

Relative contraindications

  • Large wounds (local infiltration of which may require toxic amounts of anesthetic)*

  • Wounds requiring precise anatomic alignment (eg, vermilion border lip lacerations), for which wound edge distortion caused by infiltration is problematic*

Complications

Equipment

  • Nonsterile gloves

  • Barrier precautions as indicated (eg, face mask, safety glasses or face shield, cap and gown)

  • Antiseptic solution (eg, chlorhexidine, povidone-iodine, alcohol)

  • Syringe (eg, 1 to 10 mL) and needle (eg, 25 or 27 gauge) for anesthetic injection

  • Injectable local anesthetic* (eg, 1% lidocaine† with or without epinephrine‡ 1:100,000, 25-gauge needle)

  • Topical anesthetic§ (eg, LET solution: 4% lidocaine, 0.1% epinephrine, 0.5% tetracaine) plus cotton ball or dental pledget; optional and often used for children

  • Tissue forceps (eg, Adson forceps), tissue hook as needed to expose the sides of the wound

  • #11 scalpel blade for tissue undermining and debridement (if needed)

† Maximum dose of local anesthetics: Lidocaine without epinephrine, 5 mg/kg; lidocaine with epinephrine, 7 mg/kg; bupivacaine, 1.5 mg/kg. NOTE: A 1% solution (of any substance) represents 10 mg/mL (1 g/100 mL).

Epinephrine causes vasoconstriction, which enhances hemostasis and prolongs the anesthetic effect. Patients with cardiac disease should receive only limited amounts of epinephrine (maximum 3.5 mL of solution containing 1:100,000 epinephrine); alternatively, use local anesthetic without epinephrine. Consider avoiding epinephrine in the distal extremities of patients with peripheral vascular disease.

§ The maximum dose of LET topical solution is 3 mL. When LET and lidocaine infiltration are used together, the sum of the lidocaine doses must not exceed 5 mg/kg.

Additional Considerations

Relevant Anatomy

  • Intradermal anesthetic injection is painful. Inject subdermally (subcutaneously) to cause less pain during local wound infiltration.

Positioning

  • Position the patient comfortably, with the wound exposed and well-illuminated.

Step-by-Step Description of Procedure

  • Do a neurovascular examination of structures distal to the wound.

  • Wear gloves and use appropriate barrier precautions.

  • Cleanse the skin from the wound edges outward, making several outwardly expanding circles with antiseptic solution. Do not introduce a cleansing agent directly into the wound because many are toxic to tissues and may interfere with wound healing.

Topical anesthesia (optional, for children and anxious adults)

  • Soak a cotton dental pledget (or cotton ball) the length of the wound in several mL of the topical solution and place it within the wound for 30 minutes.

  • If anesthesia is incomplete, give supplementary local infiltration anesthesia through the partially anesthetized wound edges (usually resulting in only minimal pain).

Local infiltration anesthesia

  • Hold the local anesthetic syringe at a shallow angle to the skin.

  • Insert the needle directly into the exposed subdermal layer of the wound edge (ie, do not insert the needle percutaneously) and advance the needle to the hub.

  • Aspirate to exclude intravascular placement and then slowly inject the anesthetic while withdrawing the needle.

  • Redirect the already injected needle into unanesthetized skin to maximize the area anesthetized with a single needlestick. Continue to anesthetize, covering the entire wound circumference.

    For grossly contaminated or infected wounds, consider injecting instead percutaneously through the intact, uninfected (or otherwise disinfected) skin around the wound (field block).

  • Allow several minutes for the anesthetic to take effect. You may gently massage the overlying skin with your fingertip to facilitate spread of the anesthetic in the tissues.

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