Comparison of pain and extent of anesthesia in digital blocks for isolated finger lacerations: A randomized controlled trial

Abstract

Objectives: Digital injuries are among the most common presentations to the emergency department. In order to sufficiently examine and manage these injuries, adequate, prompt, and predictable anesthesia is essential. In this trial, we aim to primarily compare the degree of pain and anesthesia onset time between the two-injection dorsal block technique (TD) and the single-injection volar subcutaneous block (SV) technique. Further, we describe the temporal and anatomical effects of both techniques for an accurate delineation of the anesthetized regions.

Methods: This is a single-center prospective randomized controlled trial involving patients presenting with isolated wounds to the fingers requiring primary repair under local anesthesia. Patients were randomized to either the SV or TD blocks. The primary outcome was procedure-related pain (Numerical Rating Scale). Further, we assessed the extent of anesthesia along with the anesthesia onset time.

Results: A total of 100 patients were included in the final analysis, 50 on each arm of the study. The median pain score during injection was significantly higher in patients who received TD block than patients who received SV block (median [interquartile range] = 4 [2.25, 5.00] vs. 3.00 [2.00, 4.00], respectively, P = 0.006). However, anesthesia onset time was not statistically different among the groups (P = 0.39). The extent of anesthesia was more predictable in the dorsal block compared to the volar block.

Conclusion: The single-injection volar subcutaneous blocks are less painful with a similar anesthesia onset time. Injuries presenting in the proximal dorsal region may benefit from the two-injection dorsal blocks, given the anatomical differences and timely anesthesia of the region.

Keywords: Anesthetic techniques; digital nerve block; finger laceration; hand trauma; local anesthesia; nerve block.

Figure 1

CONSORT Flowchart displaying enrolment, allocation, follow up and analysis of participants

Figure 2

Distribution of (A) procedure-related pain and (B) anesthesia onset time between groups. Dorsal; TD, Volar; SV

Figure 3

Schematics depicting anaesthesia onset time measured at 30-second intervals in all participants. Values labelled according to their respective regions represent the median anaesthesia onset time in seconds. The grey colour gradient shows speed of anaesthesia from darkest (fastest) to lightest (slowest)