Do not use epinephrine in digital blocks: myth or truth?

The purpose of this study was to examine the role for epinephrine augmentation of digital block anesthesia by safely prolonging its duration of action and providing a temporary hemostatic effect. After obtaining approval from the review board of the authors' institution, 60 digital block procedures were performed in a prospective randomized double-blinded study. The digital blocks were performed using the dorsal approach. All anesthetics were delivered to treat either posttraumatic injuries or elective conditions. Of the 60 digital block procedures, 31 were randomized to lidocaine with epinephrine and 29 to plain lidocaine. Of the procedures performed using lidocaine with epinephrine, one patient required an additional injection versus five of the patients who were given plain lidocaine (p = 0.098). The need for control of bleeding required digital tourniquet use in 20 of 29 block procedures with plain lidocaine and in 9 of 31 procedures using lidocaine with epinephrine (p < 0.002). Two patients experienced complications after plain lidocaine blocks, while no complications occurred after lidocaine with epinephrine blocks (p = 0.23). By prolonging lidocaine's duration of action, epinephrine may prevent the need for an additional injection and prolong post-procedure pain relief. This study demonstrated that the temporary hemostatic effect of epinephrine decreased the need for, and thus the potential risk of, using a digital tourniquet (p < 0.002). As the temporary vasoconstrictor effect is reversible, the threat of complication from vasoconstrictor-induced ischemia is theoretical.