an additional mechanical apparatus attached to the skin One more recently tested product is a self-contained topical patch containing lidocaine and prilocaine that generates heat once removed from its airtight pouch, allowing for a 20-minute onset of action This product offers the advantage of keeping the medication where it is placed, without the potential for leakage; however, it must also be applied well in advance of the procedure, requiring accurate site choice and potentially higher cost for application at more than one site Finally, recent products that use the combination of vibration and cold to decrease distal sensation through the “gate theory” of pain have been shown to reduce the pain of IV needle insertion similarly to topical analgesic application An example of one of these products is the Buzzy Nerve Blocks Lidocaine can be used for peripheral or regional nerve block if the physician has appropriate knowledge of anatomy and nerve supply to the wound The skin at the nerve site should be anesthetized, and then lidocaine (maximum to mg/kg) should be infiltrated more deeply around the nerve (never into the nerve) in the same manner as with local anesthesia During this infiltration, the physician should aspirate to ensure a blood vessel has not been penetrated inadvertently Examples of commonly used nerve blocks in the ED include digital blocks for finger or toe injuries, mental or infraorbital blocks for lip lacerations, and alveolar blocks for dental pain Femoral nerve block using ultrasound guidance (see Chapter 131 Ultrasound ) offers better and more prolonged analgesia than IV opioids for femur fractures Bier Blocks The preferred technique for fracture reduction at some institutions is a Bier block or “mini-Bier” block With this technique, a limb that is injured and requires a painful procedure is locally anesthetized A double pneumatic tourniquet or two blood pressure cuffs are placed proximal to the injury and inflated in order to exsanguinate the limb and an IV line is placed distal to the tourniquet Lidocaine is then injected into the limb and allowed to diffuse to the local tissues—everything below the tourniquet is anesthetized Please refer to a procedure handbook for more information on the specifics and materials necessary for a Bier block Bupivacaine is no longer recommended for Bier blocks due to risk of significant cardiotoxicity There