Determination of the Minimum Local Analgesic Dose of Spinal Chloroprocaine in Labour

"In order to determine the minimum effective dose that is to be given spinally, an up-down sequential allocation will be used.~Efficacy of the analgesia will be evaluated by a 100mm visual analogue pain score (VAPS). There are two possible outcomes here:~* effective: the VAPS is 10mm or lower after the 15 minutes of monitoring. An effective result will decrease the test dose of chloroprocaine with 2mg for the next patient in this study.~* Ineffective: the VAPS is more than 10mm after 15 minutes of monitoring. An ineffective result will increase the test dose of chloroprocaine with 2mg for the next patient in this study. Patients who indicate an ineffective result will receive a rescue treatment by the administration of 12ml levobupivacaine epidurally."