Transition from failed epidural labor analgesia to combined spinal–epidural anesthesia: What to do when encountering difficulties in spinal cord puncture? A case report

Introduction

Although labor epidural analgesia (LEA) can effectively alleviate pain during childbirth, inadequate analgesic effects may still be observed during its administration. Factors affecting the efficacy of LEA include epidural catheter displacement, dosage of local anesthetics, cervical dilation >7 cm, history of opioid tolerance, previous epidural anesthesia failure, and epidural procedures performed by trainee anesthesiologists.^1,2 For patients dissatisfied with the effect of epidural analgesia, 6–10 mL of an appropriate concentration of local anesthetic (such as 1.25 mg/mL of bupivacaine or an equivalent dose of other local anesthetics) could be manually supplemented once after confirming the correct position and depth of the epidural catheter. ³ For patients with insufficient analgesia after epidural supplementation or complete loss of sensory blockade, combined spinal–epidural (CSE) anesthesia is recommended for labor analgesia. However, as illustrated by the woman described in this case, for patients who have undergone prolonged LEA or received repeated manual epidural supplementation, the presence of local anesthetic solution in the epidural space and the resultant dilation of this space can make subsequent puncture of the spinal cord challenging. Thus, it remains unclear how anesthesiologists should proceed when encountering difficulties in spinal cord puncture.

Case

A primipara in her 20s, with no history of drug allergies, no relevant family history, and no complications, underwent regular prenatal check-ups during her pregnancy. In September 2024, when she was 40 weeks pregnant, she was admitted to the Obstetrics Department of West China Second University Hospital of Sichuan University. To alleviate childbirth-associated pain, she received LEA when her uterine opening dilated to 2 cm.

Epidural puncture was performed in the L2–L3 intervertebral space with the patient in the left lateral decubitus position, and the depth of the epidural catheter was 3.5 cm. The experimental dose comprised 1.5% lidocaine (15 µg epinephrine), followed by continuous analgesia with 0.5 mg/mL sufentanil and 0.1% ropivacaine, maintained at a rate of 9 mL/40 min through programmed intermittent epidural boluses. Initially, the anesthesia level was tested at T10, and the parturient was satisfied with the labor analgesia effect. However, approximately 4 h later, the parturient reported lumbosacral pain with a visual analog scale (VAS) score of 6. At this point, the fetal position was determined to be right occiput posterior, and the cervix was measured at 3 cm. The anesthesiologist used the acupuncture method and determined that the bilateral epidural block level was T10, Bromage score was 0, and the position of the epidural catheter was correct. The anesthesiologist manually injected 8 mL of 0.15% ropivacaine epidural. The pain was partially relieved 20 min later, the VAS score dropped to 4, the Bromage score was 0, and bilateral epidural block level of the parturient was T8. Approximately 1 h later, the parturient experienced severe back pain again, with a VAS score of 7. The anesthesiologist then administered a single injection of 8 mL of 0.2% ropivacaine. Upon re-assessment 20 min later, the pain was only partially relieved, the VAS score was 5, Bromage score was 0, and bilateral epidural block level of the parturient was still T8. Ultimately, replacement of the epidural catheter was considered.

The anesthesiologist intended to use the CSE technique for labor analgesia and selected the L3–L4 intervertebral space for puncture. When using a 16 G epidural puncture needle for puncture, we determined that the epidural needle had entered the epidural space through the loss-of-resistance technique. Additionally, a fluid was slowly flowing out of the epidural puncture needle. At the same time, the 25 G pen spinal needle could not reach and penetrate the arachnoid membrane. We speculated that the slow outflow of the fluid indicated the presence of local anesthetic solution injected previously into the epidural space for labor analgesia. The anesthesiologist carefully increased the insertion depth of the epidural puncture needle. After each insertion, he attempted to penetrate the arachnoid membrane with the pen spinal needle. After three attempts to increase the insertion depth of the epidural needle, the pencil-point spinal needle still could not penetrate the arachnoid membrane. To avoid accidental puncture of the dura mater, the anesthesiologist discontinued the puncture, removed the epidural needle, reconfirmed the puncture site, and sought assistance. An experienced obstetric anesthesiologist recommended using a standard-length epidural puncture needle to puncture the ligamentum flavum, followed by using an extended pen spinal needle to puncture the arachnoid membrane to provide spinal anesthesia. Finally, an epidural catheter was inserted through the epidural needle.

By using this method for another puncture, the extended spinal cord puncture needle could successfully puncture the arachnoid membrane. We observed a clear fluid emanating from the spinal puncture needle. We presumed that the fluid flowing back at this time was cerebrospinal fluid (CSF). After injecting 2.5 mg of ropivacaine intrathecally, the pain of the parturient was relieved within a few minutes, with a VAS score of 0, a Bromage score of 1, and an epidural block level of T8. After 50 min, epidural catheter analgesia was maintained. After 5 h, the patient delivered a baby girl vaginally with a postnatal Apgar score of 10-10-10. The duration of the second stage of labor was 15 h, and the duration of receiving LEA was 12 h and 10 min. Follow-up evaluations were performed at 2 h and 1 day after delivery. No post-procedural complications were observed in either the newborn or the parturient, and they were discharged from the hospital on the second day postpartum. This case report was published with the written consent of the patient and conformed to the Case Report (CARE) guidelines. ⁴

Discussion

Labor analgesia is the most effective approach for relieving the pain associated with vaginal delivery. However, it has been reported that 14.2%–23% of labor analgesia cases result in failure.^2,5,6 The European Society of Anaesthesiology and Intensive Care (ESAIC) ³ defines labor analgesia failure as follows: regardless of the cause, labor epidural analgesia fails to provide sufficient analgesia for the parturient. It is essential to record the motor and sensory block planes, which is important for anesthesiologists to assess inadequate epidural block and the complete ineffectiveness of epidural analgesia. After excluding mechanical factors, such as epidural catheter displacement or entry into blood vessels, for patients with sufficient anesthesia level (T10) but insufficient analgesic intensity, ESAIC recommends a single manual supplementation of 6–10 mL of epidural anesthetic at a higher concentration than before. ³ If the pain has not been completely relieved after manual administration of the drug, a higher concentration of the local anesthetic drug (6–10 mL) (such as 2.5 mg/mL bupivacaine or an equivalent dose of other local anesthetics) can be considered for a second manual injection, which is especially suitable for parturients with severe pain. Epidural catheter replacement should be considered if pain relief remains inadequate.

The CSE technique should be prioritized when resiting the epidural catheter. ⁷ It offers a faster onset of analgesia, a lower failure rate, and higher satisfaction among parturients.^8–11 The spontaneous return of CSF to the spinal needle during spinal anesthesia indicates a high success rate. ⁷ However, for some patients who had received prolonged LEA, the presence of local anesthetic fluid in the epidural space and the expansion of that space can make spinal cord puncture challenging. As in this case, the parturient received LEA for approximately 6 h before deciding to replace the epidural catheter. After the epidural puncture needle successfully reached the epidural space through the loss-of-resistance technique, the depth of the epidural puncture needle was adjusted three times; however, the spinal needle still failed to penetrate the arachnoid membrane. We presumed that long-term residual local anesthesia from the epidural administration had expanded the epidural space, thereby preventing the standard-length spinal puncture needle from reaching and puncturing the arachnoid membrane. The operation time was extended due to the ongoing adjustment of the epidural needle’s puncture depth; however, cooperating with laboring mothers who are enduring contraction pain could be challenging. Furthermore, several retrospective cohort studies have demonstrated that increasing the depth to the epidural space, increased number of puncture attempts, and longer procedure duration are risk factors for accidental dural punctures.^12,13 In addition, as a local anesthetic had been previously injected into the epidural space, an outflow of fluid from the epidural needle may occur when the space is punctured again. Some anesthesiologists may mistake the fluid slowly flowing out of the epidural puncture needle for CSF, which may increase the risk of spinal anesthesia failure.

Therefore, when dealing with patients who experience difficulty with spinal puncture during the transition from LEA to CSE anesthesia, we propose the use of an extended spinal needle as a modification to the CSE standard practice to facilitate successful spinal anesthesia. The operational steps are as follows: (a) upon reaching the epidural space with a standard epidural needle, spinal anesthesia is administered using an extended pen spinal needle (Figure 1); (b) the spinal needle is advanced only until the arachnoid membrane is punctured and then immediately halted; (c) the extended spinal needle is secured in place without further penetration; (d) once CSF is smoothly aspirated, spinal anesthesia is administered. For patients who have undergone prolonged epidural anesthesia and exhibit difficulty with spinal cord puncture upon re-attempt, we believe that this technique can shorten the puncture time, facilitate successful spinal anesthesia, and potentially decrease the risk of accidental dural puncture, which may increase due to prolonged operation time.

OPEN IN VIEWER

Figure 1.

Epidural puncture, normal spinal puncture, and extended spinal puncture needles.

However, it is important to note that we do not recommend this technique for every patient transitioning from LEA to CSE anesthesia. We only recommend its use for the following patients: (a) those who have received prolonged epidural analgesia during labor; (b) those who have accumulated excessive doses of local anesthetic within the epidural space; and (c) those who have received multiple drug injections in the epidural space and subsequently developed puncture difficulty. When replacing an epidural catheter, we still recommend using a standard spinal needle for CSE anesthesia. If the standard-length spinal puncture needle fails to puncture the arachnoid membrane after adjusting the depth of the epidural puncture needle twice, this modified CSE method may be considered.

Conclusion

For pregnant women who have undergone prolonged LEA or repeated manual epidural supplementation of local anesthetics, the presence of local anesthetic fluid in the epidural space and the dilation of this space may render subsequent puncture of the spinal cord challenging. In such cases, the use of an extended spinal needle may serve as a valuable modification to standard CSE practice to improve the likelihood of successful spinal anesthesia.