Effects of vasoconstrictor use on digital nerve block: systematic review with meta-analysis

Conventionally, the association of local anesthetics with vasoconstrictors is avoided at extremities due to the risk of ischemia. However, recent studies suggest that there is safety in the use of vasoconstrictors at extremities. Thus, we sought to evaluate the effectiveness and safety of vasoconstrictor use combined with local anesthetics in digital nerve block compared to the use of anesthetics without vasoconstrictors, through a systematic review with meta-analysis of randomized clinical trials. Until May 2019 we searched MEDLINE, LILACS, SciELO, ScienceDirect, Scopus, ClinicalTrials.gov, and gray literature databases, without date or language restrictions. The keywords were the following: digital block, vasoconstrictor, and ischemia. We included randomized clinical trials in which there was the use of local anesthetics with associated or not with vasoconstrictors in digital blocks. In the primary variables, the occurrence of ischemic complications and the duration of anesthesia were analysed; in the secondary variables, the need for anesthetic reapplication, bleeding control, and latency were observed. Ten studies were included in this review. The occurrence of ischemia was not observed, regardless of the use of vasoconstrictors or not. The use of vasoconstrictors at a concentration of 1:100,000 or less was associated with longer anesthesia duration (P<0.00001), lower need for anesthetic reapplication (P=0.02), lower need for bleeding control (P=0.00006), and lower latency (P<0.00001). We could conclude that the use of vasoconstrictors associated with local anesthetics in digital block proved to be a safe and effective technique.