Speed of onset of sensory block for elective extradural caesarean section: choice of agent and temperature of injectate.

We have studied the effects of choice of local anaesthetic and temperature of extradural injectate on speed of onset of sensory block for elective extradural Caesarean section in a double-blind trial in 120 women allocated randomly to one of four groups to receive either plain 0.5% bupivacaine or 2% lignocaine with 1:200,000 adrenaline at either room temperature or 38 degrees C. The onset time of lignocaine with adrenaline was shorter than that of bupivacaine regardless of temperature (P < 0.01). Warmed lignocaine produced the most rapid block overall (P < 0.025). The incidence of hypotension, ephedrine requirement, shivering, quality of analgesia and additional analgesic requirements were similar for all groups.