A double-blind comparison of carbonated lidocaine and lidocaine hydrochloride in epidural anaesthesia

Twenty patients having a standard epidural anaesthetic were randomly assigned to receive 20ml of either carbonated lidocaine 1.73 per cent or lidocaine hydrochloride 2.0 per cent, containing epinephrine 1:200,000. An observer unaware of the solution used measured speed of onset, quality of block, and duration of action. No significant difference was demonstrated in the speed of onset or duration of the block. Carbonated lidocaine gave an improved motor block and showed a trend towards giving fewer missed segments than lidocaine hydrochloride.