The causes for failed conversion of epidural labor analgesia to epidural surgical anesthesia: A controlled before-after study

Abstract

Abstract Background: There are few specific reports on the possible reasons for the failure of epidural labor analgesia (ELA) conversion to epidural surgical anesthesia (ESA). We designed this study to investigate the possible reasons for the failure of ELA conversion to ESA by comparing the changes in the spinal canal of parturients after continuous epidural analgesia during delivery and 24 hours after drug withdrawal through lumbar magnetic resonance imaging (MRI) examination. Methods: The parturients who deliveried vaginally with ELA were included. Lumbar MRI examination was performed 2 hours after delivery and 24 hours after delivery. All data were transferred to a Siemens PACS workstation for measurement. The results of the MRI examinations 2 and 24 hours after delivery were compared. The primary outcomes were the area of the dural sac (DS) and epidural space (ES), and the secondary outcomes were the apparent diffusion coefficient (ADC) values of bilateral spinal ganglion and the longitudinal diameter and transverse diameter of the dural sac. Data related to ELA were also recorded. Results: MRI examination was completed at 2 hours after delivery in 11 parturients with ELA, and two of themrefused a second MRI. Among the 11 parturients, two were found to have obvious drug liquid accumulation in the epidural space, but one of the two refused the second MRI examination. Comparing the MRI examination completed at 2 hours with that completed at 24 hours after delivery, the area of the dural sac and the longitudinal diameter and transverse diameter (except L1-2) of the dural sac decreased at the L4-5, L3-4, L2-3 and L1-2 levels, while the area of the epidural space increased at the L4-5, L3-4, L2-3 and L1-2 levels. There were no signigicant differences in the bilateral ADC values between 2 and 24 hours after delivery. Conclusion: ELA may lead to dilation of the epidural space, compression of the epidural sac, and even accumulation of epidural fluid. The reason for the failure of epidural conversion might be that the low concentration of local anesthetics retained in the epidural space during labor analgesia diluted the high concentration of local anesthetics during cesarean section. It might also be that ELA leads to epidural expansion and dural sac compression, which affect the diffusion of high concentrations of local anesthetics during cesarean section. Trial registration: Chictr.org, ChiCTR2200059311. Registered on 28/04/2022. www.chictr.org.cn/showproj.aspx?proj=167814.