1. Absolute: Infiltration anesthesia should not be performed in patients with contraindications to local anesthetics (eg, history of allergy; lidocaine should be used with caution in patients with shock, second-degree or third-degree atrioventricular block, or epilepsy).
2. Relative: Local anesthesia may be less effective in areas with severe local inflammation (eg, phlegmon, large abscesses). There is a relative contraindication to the use of local anesthetics with vasoconstrictive agents (eg, epinephrine) in areas with end-arterial blood supply (eg, digits, nose, tongue, penis), although observational evidence suggests that there is a minimal risk of digital ischemia.
Complications are most frequently associated with toxic or allergic adverse effects of local anesthetics; they are dose dependent (correlated with the concentration and volume of the administered solution) and significantly more severe in case of inadvertent intravascular administration. Early manifestations include vertigo, paresthesia, and tremor; more severe reactions may cause seizures, respiratory abnormalities, reduced cardiac output, and arrhythmia. The use of vasoconstrictors (eg, epinephrine) can lead to less systemic absorption, resulting in lower toxicity (allowing higher doses), longer duration of action, and less bleeding. For instance, the maximum dose of lidocaine is 3 mg/kg (lidocaine alone) or 7 mg/kg (lidocaine with epinephrine).
Obtain informed consent for the procedure. Place the patient in an appropriate position depending on the site of local anesthesia. Insert a peripheral intravenous catheter (see Peripheral Venous Catheter Placement).
Nonsterile disposable gloves, skin disinfectant (single-use alcohol swabs or single-use cotton swab with disinfectant solution), surgical field preparation kit (see Surgical Field Preparation for Small Procedures), needle bore 0.5 to 0.7 mm (25-22 gauge) for anesthetic injection, large-bore needle for drawing the drug from an ampoule, 5 or 10 mL syringe (depending on the site and surface of the area to be anesthetized), vial with local anesthetic (usually 1%-2% lidocaine solution, with or without epinephrine), sharps container for disposal.
1. Prepare the surgical field (see Surgical Field Preparation for Small Procedures).
2. Perform local anesthesia of the skin using subcutaneous lidocaine injection (usually 1%), then perform anesthesia of the subcutaneous tissue and other tissues at the desired depth. Aspirate before every lidocaine injection to make sure no blood backflow is present to avoid intravascular administration. Instead of withdrawing the needle from the skin after injection, redirect the needle in a different direction and inject as described above; this technique allows for a wide area of anesthesia using a minimum number of skin punctures, which can reduce bleeding. Anesthesia for minor procedures usually requires a few mL of lidocaine solution.