Discussion
Under the different combinations of ropivacaine and sufentanil, the observation and analysis of the two anesthesia methods in this study showed that CSEA was superior to CEA in analgesic effect and maternal satisfaction.
CSEA refers to a method of injecting a small amount of anesthetic drug into the subarachnoid space after successful epidural puncture.[13] Currently, the combination of local anesthetic and opioid is the common compatibility program for CSEA, including bupivacaine, ropivacaine, fentanyl and sufentanil.[14,15] Ropivacaine (1-propyl-2′, 6′-pipecoloxylidide, chemical structure) is an amino acid local anesthetic and was recently introduced for labor analgesia, since it has less cardiac toxicity and provide more differential block between sensory and motor.[7,16] For opioids, the analgesic effect of sufentanil is 3 to 5 times more potent than fentanyl due to the strong affinity for opioid receptors.[17,18]
Clinically, ropivacaine combined with low-dose sufentanil has been widely used in labor analgesia.[19] The combination of the two drugs allows use of lower doses of both drugs, thus decreasing the rate and severity of adverse effects.[20] However, previous studies[21,22] have shown that ropivacaine combined with sufentanil injected into the subarachnoid space after the spinal anesthesia pierced the dura mater resulted in a higher pruritus rates than ropivacaine alone. In this study, ropivacaine combined with sufentanil were used for CEA group. While for CSEA group, ropivacaine were used alone before epidural catheter were placed and ropivacaine combined with sufentanil were used thereafter. As a result, better analgesic effect was achieved in CSEA group compared with CEA group according to the VAS scores. Besides, the overall incidence of adverse drug reactions in CSEA group was lower than CEA group, including the lower nausea and vomiting rates and pruritus rates. The reduced dose of sufentanil were responsible for this result since complications of anesthetics were dose-dependent.[18,23] Additionally, delaying sufentanil injection may exert the maximum effect of ropivacaine, which has long analgesic duration, less adverse drug reactions and differential block between sensory and motor.[24]
In this study, CSEA group has a relative shorter onset time compared with CEA group, which is inconsistent with a previous study,[25] showing that there were no differences between groups for onset time and analgesia evaluation. We assume that this possibly due to the different doses of ropivacaine and sufentanil in both studies. We found no statistically significant differences with regard to the Apgar scores of the newborns at 1, 5 and 10 min and adverse pregnancy outcomes between the two groups suggesting that CSEA could achieve the same newborn conditions as CEA with lower doses of ropivacaine and sufentanil. Maternal satisfaction were improved due to the fewer adverse drug reactions associated with intrathecal sufentanil that can be disconcerting for subjects.
The limitation of this study was that pregnant women with contraindication to epidural anesthesia were not suitable for this method. Therefore, more studies should be carried out in the future to further improve the labor analgesia method.
BMC Anesthesiol. 2020;20(1) © 2020 BioMed Central, Ltd.
