Combined spinal–epidural analgesia for labor pain: best timing of epidural infusion following spinal dose

The combined spinal–epidural analgesia (CSEA) technique for labor pain has attained wide spread popularity in obstetric anesthesia. The onset of analgesia is rapid and reliable, and maternal satisfaction is very high. However, the best timing of an epidural infusion following the spinal dose and its effect on the total local anesthetics consumption has not been well determined.

A total of 144 consenting healthy nulliparous parturients whose labor was induced and who labored under regional analgesia were enrolled in this study. Following induction of the CSEA with intrathecal injection of bupivacaine, 2.5 mg and fentanyl, 25 μg, the patients were randomized into one of four groups to receive a subsequent continuous epidural infusion [E (3), E (30), E (60) and E (90)], depending on the timing of the initiation of epidural infusion of 0.1% ropivacaine, 0.0002% fentanyl and 1:500,000 epinephrine at the rate of 10 ml/h. In study Groups E (3), E (30), E (60) and E (90), epidural infusion was initiated 3, 30, 60 and 90 min, respectively following spinal induction dose. Patients requesting additional labor analgesia were given an epidural bolus (8 ml) of ropivacaine, 0.2%. The number of parturients requesting additional boluses of ropivacaine and the total dose of ropivacaine required for labor analgesia were registered.

The numbers of patients who required additional boluses of ropivacaine in Group E (3) and Group E (30) were significantly less than those in Group E (60) and Group E (90). The total dose of ropivacaine required for labor pain in Group E (3) and Group E (30) was insignificantly smaller than the total dose required in Group E (60) and Group E (90).

Our results suggest that the best timing of epidural infusion following spinal dose was within 30 min of spinal induction dose.