A Synopsis of AFP's "Infiltrative Anesthesia in Office Practice"

A synopsis of;
Infiltrative Anesthesia in Office Practice
JOSHUA L. LATHAM, DO, and SEAN N. MARTIN, DO, Headquarters Air Armament Center Family Medicine Residency, Eglin Air Force Base, Florida
Am Fam Physician. 2014 Jun 15;89(12):956-962.
http://www.aafp.org/afp/2014/0615/p956.pdf

     The use of infiltrative anesthesia is part of any office procedure that requires pain relief. Lidocaine, lidocaine with epinephrine, and bupivacaine are in the amide class. Procaine and tetracaine are in the ester class. If there is an allergy to one medication, one from another class should be chosen. Both classes work by blocking sodium channels in the nerve. LIdocaine is the most common one used. Adding epinephrine prolongs the duration of action.  It IS safe for use on the nose, ears, digits, and penis. It is contraindicated in patients with peripheral artery disease. Bupivacaine has a higher risk of toxicity compared to lidocaine. It may also cause ventricular fibrillation and a wide QRS. It is contraindicated in pregnancy.
     With these agents, using the smallest needle possible (27 gauge or more) will be much less painful for the patient. Other techniques include pinching the skin or vibrating the area. The anesthesia should be injected slowly and steady, while withdrawing the needle. Buffering the lidocaine with bicarbonate and using room temperature medication can also reduce pain.
    When using infiltrative anesthetics, they can either be injected in an area locally, or they can directed specifically to block a nerve. Local infiltration is the most common technique. it is used for small lacerations or skin biopsies. A field block is used in skin abscesses, in contaminated areas, and in places where tissue distortion can affect outcome (vermillion border). Anesthetics are strategically placed around the area to block innervations circumferentially. 
     Nerve blocks are placed at specific anatomical locations to affect the nerve that lives there. I would consider reviewing the original article to see the figures provided and read the description of the proper anatomical location.  The forehead can be numbed by blocking the supraorbital and supratrochlear nerve (V1 of the trigeminal nerve). The lower eyelid and upper lip are innervated by the infraorbital nerve (V2 of the trigeminal nerve). The lower lip and chin are innervated by the mandibular nerve (V3 of the trigeminal nerve).
     Digital nerve blocks can be used if local infiltration is not possible due to the confined space. Each digit has two palmar digital nerves and two dorsal digital nerves. When the first or fifth digit is concerned, all four nerves must be blocked. When the middle three digits are concerned, only the palmar digital nerves need to be blocked.