Single injection digital block: comparison between three techniques

Regional anesthesia of a single finger is commonly achieved by the traditional ring block. The major drawback of this technique is the need for at least two painful injections in the digit. Single injection techniques have been described. A comparison of their results could help health professionals select the most appropriate technique.

A prospective randomized study was designed to compare three techniques in term of patient tolerance, distribution of anesthesia and efficiency: the modified transthecal digital block, the subcutaneous digital block and a combination of the two. Digits were randomized in three groups (n = 30). Blocks were performed by a single investigator. A visual analogic scale was used to evaluate pain associated with the injection. Prick-testing was used to evaluate anesthesia at the volar and dorsal aspects of the phalanxes. Statistical analysis of the results was performed.

All techniques allowed surgery to be performed without complementary injection most of the time (25/30). The dorsum of the proximal phalanx, however, was unpredictably included in the anesthetized territory. The highest rate of full digital block was achieved with the combined technique.

The least invasive of equally effective techniques should be considered as the first choice. The subcutaneous single injection digital block is safe, efficient and easy to perform. It allows treatment of all conditions on the volar aspect of the finger and on the dorsal aspect of the distal and middle phalanxes. For surgery on the dorsal aspect of the proximal phalanx, a supplementary dorsal block should be used.