A Randomized Trial of Breakthrough Pain During Combined Spinal-Epidural Versus Epidural Labor Analgesia in Parous Women

BACKGROUND: There is controversy regarding the benefits and risks of combined spinal-epidural compared with epidural analgesia (CSE, EPID) for labor analgesia. We hypothesized that CSE would result in fewer patient requests for top-up doses compared to EPID. METHODS: One-hundred ASA physical status I or II parous women at term in early labor (<5 cm cervical dilation) requesting analgesia were randomized in double-blind fashion to the EPID group (epidural bupivacaine 2.5 mg/mL, 3 mL, followed by bupivacaine 1.25 mg/mL, 1.0 mL with fentanyl 50 mu g) or the CSE group (intrathecal bupivacaine 2.5 mg with fentanyl 2 mu g). Both groups received identical infusions of bupivacaine 0.625 mg/mL with fentanyl 2 mu g/mL at 12 mL/h. The primary outcome variable was the number of top-up doses requested to treat breakthrough pain. RESULTS: There was no significant difference between the two groups in the percentage of patients requesting top-up doses (44%, CSE vs 51% EPID; 95% confidence interval of the difference -280% to +14%) nor in the need for multiple top-up doses (1.4% CSE vs 15%, EPID). Visual analog scale scores were lower in the CSE group compared to the EPID group at 10 min after initiation of analgesia [median 0 cm (0, 0) vs 4 cm (1, 6) respectively, P < 0.001] and at 30 min [0 cm (0, 0) vs 0 cm (0, 1), respectively, P = 0.03]. CONCLUSIONS: We did not find a difference in the need for top-up doses in parous patients; however, CSE provided better analgesia in the first 30 min compared to EPID.