The field block is an anesthetic technique in which local anesthesia is injected into the tissues surrounding the area targeted for surgery to block pain transmission. This method creates an anesthetized field around the target area while leaving the surgical site itself unaffected by the injection of anesthetics. The technique is distinct from other, more common anesthetic methods, such as nerve blocks or general anesthesia, and is useful for several clinical situations (1).
The mechanism of action in a field block relies on the interruption of nerve impulses in the area surrounding the surgery site. When the local anesthetic, often agents like lidocaine or bupivacaine, is injected circumferentially around the area, it blocks the nerve fibers from transmitting signals to the central nervous system (2). Epinephrine may be added to the anesthetic mixture to induce vasoconstriction and prolong the anesthetic effect, as the vasoconstriction delays the absorption of the drug into the systemic circulation (1). This allows for extended periods of numbness and analgesia, which can be especially useful in procedures requiring sustained pain relief.
Field block anesthesia can be used in both minor and major surgery, especially in settings where general anesthesia would pose higher risks or is not necessary. For example, this technique is often used for head and neck surgery or for dermatologic procedures such as lesion excision or laceration repair (3). It is also beneficial in patients for whom nerve blocks are contraindicated or when precise control of the anesthetized area is required.
The safety profile of field block anesthesia is generally favorable, as it typically involves lower doses of anesthetic agents compared to systemic anesthesia. However, like all medical procedures, complications may arise. Some risks associated with field block anesthesia include infection at the injection site, hematoma formation, allergic reactions to the anesthetic agents, and inadvertent systemic absorption, leading to toxicity. In rare cases, inadequate block of the target field may occur, necessitating additional anesthetic administration or the use of adjunctive anesthetic techniques (3).
Compared to other anesthetic techniques, a field block provides a more controlled and localized effect, reducing the risk of systemic complications. The effectiveness of this technique depends primarily on the skill of the clinician, particularly in achieving an accurate and complete block around the surgical field. Proper patient selection, awareness of potential contraindications, and careful anesthetic administration all contribute to the success of the procedure. Studies have shown that field blocks are as effective as more extensive regional blocks in some procedures and offer similar pain control while decreasing recovery time (3).
The field block is a useful and effective method of anesthesia for multiple types of surgery. It provides local pain relief by infiltrating anesthetics around the surgical site while leaving the operative area unaffected. With its minimal invasiveness and relatively low complication rates, it continues to be an important tool for anesthesiologists and surgeons.
References
1. Salam GA. Regional anesthesia for office procedures: part I. Head and neck surgeries. Am Fam Physician. 2004;69(3):585-590.
2. Playing the Field: A Review of Local Anesthetic Infiltration Technique. Available at: https://pemcincinnati.com/blog/playing-the-field-a-review-of-local-anesthetic-infiltration-technique/
3. Field Block Anesthesia | Procedures – 5MinuteConsult. Available at: https://5minuteconsult.com/collectioncontent/30-156254/procedures/field-block-anesthesia