Wound Anesthesia

  All local anesthetics carry the risk of systemic adverse reactions

The user must be aware of the risks and limitations of each medication. Whether topical application or infiltration is planned, care must be taken to administer safe doses to avoid systemic toxicity.

True allergy to local anesthetics is rare but does occur. Allergic reaction is more common with ester preparations.
Topical Agents—Options

EMLA:

Apply a thick layer (1-2 g/10 cm²) of EMLA to intact skin under an occlusive dressing for approximately 30 minutes to 1 hour before a procedure. For minor procedures such as needle insertions, apply 2.5 g of EMLA over 20-25 cm² for at least 1 hour. Preparation of two potential sites is recommended when an intravenous line is started, in the event of technical difficulties at the initial site. When a more painful procedure is anticipated, 2 g of EMLA per 10 cm should be applied for at least 2 hours.
Lidocaine:

   1. Apply lidocaine topically as a liquid, ointment, jelly, or viscous fluid (2%-10%). Absorption is rapid. Do not exceed 3 mg/kg total dose.
   2. Use benzocaine and/or tetracaine spray primarily for oral or nasal procedures. To avoid toxicity, spray application should not exceed 2 seconds.
   3. Other topical patches or creams as prescribed (such as Synera, etc.): Use as directed noting absorbtion times and maximum doses or lenght of application.

Anesthetic solutions per physician orders:

   1. Use lidocaine (5%), epinephrine (1:2000), and tetracaine (1%) solution (LET) primarily for minor facial and scalp lacerations. The use of tetracaine-adrenaline-cocaine (TAC) is no longer recommended because of safety concerns related to cocaine absorption. Because it contains epinephrine, LET should not be used on mucous membranes, the nose, the pinna of the ear, fingers, toes, and the penis.
   2. Apply LET by saturating sterile gauze and applying it to the wound with firm pressure for 15-20 minutes with gloved hands to prevent skin absorption by the caregiver. The solutions may also be applied by dripping into a wound with a syringe or by applying to a wound with sterile cotton swabs. Clean the wound to remove debris and clots before using LET to increase its efficacy.
   3. Take care to ensure that LET does not run or drip into the eyes, nasal passages, or mouth. Observe the patient carefully during and after administration.
   4. If the first dose of LET is not effective, request that the physician or nurse practitioner infiltrate the laceration with local anesthesia rather than repeating a dose of LET.
   5. The clinician assesses adequacy of anesthesia by testing sharp–dull sensation and observing blanching (if an epinephrine containing was solution was used) before beginning the procedure.

Wound Infiltration

   1. Collaborate with the physician or nurse practitioner to implement strategies to decrease the pain of wound infiltration:
   2. Use buffered lidocaine. Lidocaine is alkalinized by adding 1 ml of sodium bicarbonate (8.4%) to every 10 ml of lidocaine solution.
   3. Use warm solutions because they cause less discomfort during injection.
   4. Use the smallest possible needle for infiltration. A 27-gauge needle is usually adequate except for digital blocks, the scalp, or calloused areas; in these situations, a 25-gauge needle may be required.
   5. The clinician infiltrates the wound edges through the dermis and not through the skin and continues to infiltrate as the needle passes through the dermis, injecting as infiltration is performed. Some clinicians recommend injection through surrounding intact skin if the wound is grossly contaminated
   6. The clinician assesses sharp–dull sensation to ensure adequate anesthesia before beginning the procedure. If epinephrine has been used, observe the wound edges for blanching.



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