Use of adrenaline in digital nerve blocks

To the Editor: Adrenaline is often added to local anaesthetic for injection because the vasoconstrictive effect of the catecholamine counteracts the dilative effect of the local anaesthetic, decreasing systemic absorption and prolonging its action.1 Traditionally, the use of this drug combination has been discouraged in structures supplied by end arteries — most notably the digits, but also the nose, ears and penis — on the basis that it may precipitate irreversible arterial vasospasm, leading to tissue necrosis.