Optimal Anesthesia Scheme for Transfer to Emergency Cesarean Section in Failed Labor Analgesia Trial Delivery

Objective ： To explore the optimal anesthetic method of transferring to emergency cesarean section after the failure of labor analgesia. Methods: A retrospective study included 1154 patients who underwent cesarean section in Hubei Maternal and Child Health Hospital from January 2019 to January 2020, of which 586 patients were transferred to cesarean section after labor analgesia, They were divided into two groups according to the method of anesthesia: Epidural labor analgesia / Epidural anesthesia (ELA/EA) group : After the failure of natural labor during labor analgesia, local anesthetics continue to be added to the epidural(n=282);Epidural labor analgesia/Combined spinal and epidural anesthesia(ELA/CSEA) group: Combined spinal-epidural anesthesia was performed after spontaneous labor failure during epidural labor analgesia(n=304); Combined spinal and epidural anesthesia(CSEA) group: Patients who undergo emergency cesarean section without labor analgesia(n=568). The case data were reviewed and the anesthetic methods, basic vital signs, medication, time, maternal and infant outcome of the three groups were descriptively analyzed. Results: There was a difference in the time of admission to neonatal delivery, the maximum decrease of diastolic blood pressure and the difference of neonatal 1min apgar score between ELA/EA group and ELA/CSEA group. There was a difference in the dosage of spinal anesthesia between ELA/CSEA group and CSEA group. Conclusion: When the obstetrician anesthesiologist fails during labor analgesia and needs to be transferred to cesarean section, they can choose to re-perform combined spinal-epidural anesthesia, which is beneficial to the early outcome of newborns, but the long-term effect on newborns needs to be further studied.


Introduction
Labor analgesia can relieve the pain in the process of delivery, prevent the parturient from refusing natural delivery because of pain, and require cesarean section. Painless delivery reduces the proportion of cesarean section in China, which is widely carried out in China. Among them, epidural labor analgesia is the most commonly used and safe method of labor analgesia. However, due to the need for emergency cesarean section in the process of delivery, it is a dilemma to choose which anesthetic method can effectively and quickly complete the cesarean section. Epidural anesthesia can be used when the function of epidural catheter is good, but epidural anesthesia may lead to poor anesthetic effect and need to change to other anesthetic methods, resulting in a series of adverse consequences 1 . When emergency cesarean section is performed after the failure of labor analgesia，Whether it is more beneficial to re-use spinal anesthesia is the subject of our discussion in this article. This study retrospectively analyzed the emergency cesarean section after the failure of vaginal trial of labor analgesia in our hospital from January 2019 to January 2020 and the anesthetic implementation process and maternal and infant outcome of emergency cesarean section after vaginal trial delivery without labor analgesia, and summarize the experience in order to provide reference for the choice of anesthesia for this kind of cesarean section.

1.Approved by the Ethics Committee.
2.From January 2020 to January 2021, a total of 705 people underwent emergency cesarean section after failed vaginal delivery after intravertebral delivery analgesia in Maternal and Child Health Hospital of Hubei province. A total of 783 people were transferred to cesarean section after vaginal trial labor without intraspinal labor analgesia. Among them, a total of 586 patients who were transferred to cesarean section after labor analgesia were included in the group. They were divided into two groups according to the method of anesthesia: ELA/EA group : After the failure of natural labor during labor analgesia, local anesthetics continue to be added to the epidural(n=282); ELA/CSEA group: Combined spinal-epidural anesthesia was performed after spontaneous labor failure during epidural labor analgesia(n=304); CSEA group: Patients who undergo emergency cesarean section without labor analgesia(n=568). Exclusion criteria: Direct general anesthesia for emergency cesarean section, poor labor analgesia, twin pregnancy, placental abruption, placenta previa, umbilical cord prolapse, lack of case records, patients with serious cardio-cerebrovascular complications.
3.Details of each method of anesthesia.
3.1 Methods of labor analgesia: All parturients were in the left supine position, Percutaneous extradural lateral catheterization in lumbar 2-3 intervertebral space, All parturients were placed in left recumbent position with epidural lateral catheterization in lumbar 2-3 intervertebral space with a depth of 4cm, and continuous epidural labor analgesia (ELA) was performed with analgesia pump. Epidural regimen: 0.08% ropivacaine combined with 0.5 μ g / ml sufentanil, the first dose was 6-12 ml/h. When incomplete analgesia occurred during analgesia (visual analog score ≥ 4), the patient-controlled dose was 9.9 ml and the limit was 35ml/h. 1500ml lactate Ringer's solution was infused intravenously during labor analgesia. During the process of labor analgesia，1500ml lactate Ringer's solution was infused intravenously.
3.2 Anesthesia for cesarean section: If the epidural catheter function of the patient transferred to emergency cesarean section after labor analgesia is good, the anesthesiologist on duty can choose epidural anesthesia or re-puncture combined spinal-epidural anesthesia. If the function of the epidural catheter is not good, the epidural catheter will be removed and re-punctured for combined spinal-epidural anesthesia. General anesthesia in other special cases was not included in this study.
The criteria for judging the good function of epidural catheters should meet the following three points: (1) The parturient reported that the analgesic effect was good during labor analgesia, and there was no frequent medication. (2) No obvious exfoliation was found in the epidural catheter.      Table 1.

Basic information data
2.Results of anesthesia for cesarean section: In the data of the time(min) of admission to fetal delivery, the ELA/EA group was 24min,Higher than the other two groups, It is statistically significant. The total of subarachnoid ropivacaine(mg) injection in ELA/CSEA group was 12.0 mg, which was higher than that in CSEA group (15.8mg).
The diastolic blood pressure drop of 30 (20-40) mmHg in ELA/CSEA group was higher than that of 20 (15-25) mmHg in ELA/ESA group. The details are shown in Table 2.
Maternal and newborn status: Among the 282 cases in ELA/EA group, 2 cases had sensation level to chest 2 level after anesthesia, and the patients complained of chest tightness, but did not receive respiratory support and only inhaled oxygen routinely.
0.5-1 hour after operation, the sensory level dropped to chest 10 and returned to the ward. 6 cases were changed to general anesthesia: among them, 4 cases did not reach the level of chest 6 10 minutes after epidural injection, and then changed to general anesthesia; One case was changed to general anesthesia because the surgeon thought that the muscle was too tight to take out the fetus or suture; One patient developed limb anesthesia on one side and weak anesthesia on the other side, so it was changed to general anesthesia. In 2 cases of ELA/CSEA group, the sensory plane was higher than the level of chest 4, and one patient complained of hand numbness and weakness of swallowing saliva, but could breathe on his own and did not need additional respiratory support. In one case, there was no sensory plane block 5 minutes after CSEA. The analysis may be due to the failure of the operation. The local anesthetic was not injected into the subarachnoid space and was changed to general anesthesia.
In CSEA group, there were 3 cases whose sensory plane was above the level of chest 2, but no respiratory support was needed; There was a case of anesthetic failure converted to general anesthesia due to insufficient spinal anesthesia and epidural bleeding, and finally transferred to general anesthesia. There was no need for respiratory support or general spinal anesthesia in the three groups. The parturients with postoperative anesthesia level above chest 4 or low blood pressure were transferred to PACU for further observation. There were 1 case (0.4%) in ELA/EA group, 2 cases (0.7%) in ELA/CSEA group and 5 cases (0.9%) in CSEA group.
Among the three groups, 11 cases were treated with ligation of uterine double arteries because of perioperative blood loss, and the parturients were transferred to intensive care unit (ICU) for observation after operation. There was significant difference in neonatal 1min apgar score between ELA/EA group and ELA/CSEA group ； There was no difference in 5min apgar score and neonatal in neonatal intensive care unit(NICU) among the three groups. The details are shown in Table 3. 3%, the proportion of conversion from intraspinal anesthesia to general anesthesia for elective cesarean section is less than 1%, the proportion of general anesthesia for emergency cesarean section is less than 5% 8 . However, studies have found that patients who fail to perform epidural anesthesia after labor analgesia are as likely to switch to general anesthesia as high as 21% 9 .

Discussion
The biggest disadvantage of anesthetic failure is to prolong the interval between the decision of emergency cesarean section and fetal delivery. However, it is generally believed that shortening the interval between decision-to-delivery interval(DDI) is related to the improvement of early neonatal outcome,Neonatal Apgar score and umbilical blood pH value were lower when DDI was prolonged 10 . Therefore, in epidural labor analgesia, how to choose anesthesia for emergency cesarean section due to changes in maternal or fetal conditions is a great challenge.
A total of 586 patients who were transferred to cesarean section during labor analgesia were included in this study. In ELA/EA group, 6 cases (2.1%) were converted to general anesthesia because of incomplete block; In ELA/CSEA group, 1 case (0.3%) was transferred to general anesthesia due to the failure of anesthesia puncture. Therefore, the success rate of anesthesia in ELA/CSEA group was significantly higher than that in ELA/EA group. At the same time, our study showed that there was no significant increase in the incidence of hypotension in ELA/CSEA group, and there was no occurrence of total spinal anesthesia. This may be related to the fact that the local anesthetic dosage of ELA/CSEA in our study is 12.0mg, which is significantly lower than that of CSEA in 15.8mg. Therefore, it is suggested that during spinal anesthesia after labor analgesia,when the demand for local anesthesia is about 3.8mg less than that of cesarean section, It can achieve good analgesic effect and the incidence of high nerve block is low. In this study, the decrease of systolic blood pressure was not obvious in ELA/CSEA group, but the decrease of diastolic blood pressure was more obvious than that of systolic blood pressure, which was related to the supplement of lactate Ringer's solution 1500ml during labor analgesia.
Another result of this study was that the time of admission to fetal delivery(min) in ELA/CSEA group was 19 (16-23) min, Lower than ELA/EA (98) group 24 (19-27) min; There was no significant difference in neonatal birth weight, 5min Apgar score and neonatal NICU entry between the two groups (P>0.05); However, there was significant difference in 1minApgar score between the two groups (P ＜0.05 ). This shows that the ELA/CSEA group has an advantage over ELA/EA in shortening DDI, and it is related to the improvement of early neonatal outcome, and whether the long-term neonatal outcome is related to this needs further study. It is suggested that in order to strive for relatively sufficient anesthesia time, once a decision is made for cesarean section, the conversion process from epidural analgesia to epidural anesthesia should begin in the delivery room [11][12] . However, our hospital did not do this, because we considered that during maternal transport, it was still possible to cause the epidural tube to shift to the subarachnoid space or prolapse. The epidural anesthesia for parturients who needed emergency cesarean section in our hospital began after entering the operating room, which is also the reason why the ELA/EA group had a longer time to enter the room and deliver the fetus. It increases the risk of EA failure after ELA and increases the conversion rate of general anesthesia. In this study, the probability of requiring additional analgesics in the ELA/EA group is higher, and some studies have also found that EA after ELA is more prone to intraoperative pain than spinal anesthesia (SA) (15.3% vs 2.5%) 13 , which further shows that EA is prone to insufficient analgesia. Insufficient maternal analgesia not only causes harm to the body and mind of the parturient, but also affects the operation of the surgeon, which may further lead to an increase in the amount of bleeding and poor long-term wound healing. Considering the onset time of anesthesia and the degree of muscle relaxation, CSEA after ELA has more advantages 14 . At the same time, compared with women who underwent elective cesarean section under regional anesthesia, parturients who underwent cesarean section after vaginal trial delivery may experience more serious anxiety during operation, and increased anxiety may aggravate intraoperative pain and increase the need for anesthesia. In addition, tissue injury and pain during delivery can reduce the pain threshold of CS during delivery through central sensitization mechanism. therefore, CSEA with dense sensory block may be more effective in inhibiting intraoperative pain than EA 15 .
However, re-puncture of CSEA after ELA is more difficult than that of ordinary emergency cesarean section. In this study, one case failed to re-puncture and was transferred to general anesthesia. In practice, we found that if the dura mater is more elastic when re-punctured in the same space as the labor analgesia puncture, it is not easy to be punctured by the spinal anesthesia needle, we consider that this may be To sum up, in this retrospective cohort analysis, In this study, we use a small dose of spinal anesthesia to make the advantages of CSEA after ELA more reflected. We believe that spinal anesthesia has more advantages than epidural anesthesia when labor analgesia needs to be transferred to emergency cesarean section, which is mainly reflected in: (1).Faster delivery of the fetus can lead to a better early outcome of the newborn. (2). The success rate of anesthesia is higher, and the anesthesia satisfaction of parturients and surgeons is improved.