The loading dose in continuous infusion extradural analgesia in obstetrics.

We have investigated the need for a loading dose of local anaesthetic before continuous extradural analgesia. After a standard test dose, patients received 0.08% bupivacaine 8 ml, isotonic saline 8 ml or nothing. A continuous infusion of 0.08% bupivacaine 20 ml h-1 was then commenced. The mean times to onset of satisfactory pain relief were similar in the first two groups, but prolonged significantly in the third. This group also required more interventions for inadequate analgesia, although not significantly so. Mean time to achieve highest level of block was significantly shorter in the first group.