Topic

• Introduction
• Indications
• Procedure
• Coding Information

Figure(s)

• The Field Block in a Square Pattern
• Field Block for Ear
• Field Block for Nose
• Forehead Anesthesia
• Penile Block

• Field block anesthesia describes infiltration of local anesthetic in a circumferential pattern around the surgical site. Similar to nerve blocks, field blocks are used to anesthetize large areas of skin.
• Field blocks differ from nerve blocks in that >1 nerve experiences interruption of nerve transmission. The technique permits large areas to be anesthetized, and it is useful for large dermatologic procedures. Field block does not disrupt the architecture of the surgical site and often is administered for facial or cosmetic repairs.
• Field block provides adequate anesthesia around an abscess by working in normal surrounding tissue. Localized structures are often amenable to field block technique. Facial (e.g., cheek, eyelid, nose, pinnae) and genital structures (e.g., penis, perineum) are particularly well suited for this technique.
• Administration of anesthetic into distensible skin surrounding the taut skin (e.g., tissues surrounding nose or ear) permits more comfortable injections for the patient.
• Epinephrine can be added to lidocaine for some field blocks if vasoconstrictive or anesthetic-prolonging action of epinephrine is desired. Epinephrine permits safe use of larger amounts of lidocaine because it prevents clearance of anesthetic from tissue. Avoid epinephrine in areas where vascular compromise could prove problematic, especially in individuals with vasculitis or vasoconstrictive disorders—e.g., Raynaud's phenomenon. Many authorities discourage addition of epinephrine for field blocks on digits, around the ear, on the nasal tip, or surrounding penis.

Indications and Common Locations for Field Blocks

• Surrounding large lesions to provide large area of anesthesia
• Around infected cysts or abscesses
• To prevent distortion of skin landmarks from administration of local anesthesia
• Around facial structures (e.g., nose, pinnae, forehead, cheek, eyelids, upper lip)
• Digital blocks (see Chap. 29, Digital Nerve Block)
• Surrounding localized structures (e.g., penis, perineum)

• Field block can be performed in a square pattern around the wound (Fig. 23-1). Only 2 needlesticks are required. The needle passes along 1 side, anesthetic is administered as the needle is withdrawn, and the needle is then redirected 90 degrees without coming out from the initial puncture site. This same technique is used on the opposite side of wound.
• Nerve distribution for the pinna is demonstrated in Fig. 23-2A. Field block is performed around the entire pinna (Fig. 23-2B). To avoid motor paralysis of the facial nerve anterior to the pinna, the needle should not pass in a superficial plane (i.e., subdermally in front of the ear). Separate injections may be needed for concha and external auditory canal (Fig. 23-2C).
• Triangulated injections provide adequate circumferential anesthesia. Additional lidocaine without epinephrine must be administered to the tip of the nose to anesthetize the external nasal nerve, which arises from deep tissues (Fig. 23-3).
• Administration of anesthetic in a linear pattern through both eyebrows produces anesthesia of the supraorbital and supratrochlear nerves on each side. Use a long (1.5-in.) needle to provide near-complete anesthesia of the entire forehead to the scalp (Fig. 23-4).
• The penis is lifted upward (into position of erection). 2 skin wheals can be administered near the internal inguinal rings (Fig. 23-5A). A long needle is placed subdermally to encircle the base of the penis with lidocaine without epinephrine (Fig. 23-5B). The single injection method is described in Chap. 45, Gomco Clamp Circumcision.

• Anesthesia codes (00100–01999) are usually limited to anesthesiologists providing patient services for surgical procedures. Local anesthesia is not reported in addition to the surgical procedure.
• Some insurance providers permit billing of regional or general anesthesia by the physician or surgeon performing the procedure. If reporting additional anesthesia services, attach –47 modifier to surgical code.
• It is unlikely that additional reimbursement will be provided for field blocks; service is considered part of the reporting of the surgical procedure.