Appropriate length of epidural catheter in epidural space for labour analgesia with dural puncture epidural combined with programmed intermittent epidural bolus

Appropriate length of epidural catheter in epidural space for labour analgesia with dural puncture epidural combined with programmed intermittent epidural bolus | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Appropriate length of epidural catheter in epidural space for labour analgesia with dural puncture epidural combined with programmed intermittent epidural bolus Peng Liu, Yi Chen, Peng Ma, Rui Qin, Yongqiang Shi, Xinli Ni This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8037232/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 20 Jan, 2026 Read the published version in BMC Anesthesiology → Version 1 posted 16 You are reading this latest preprint version Abstract Background The dural puncture epidural (DPE) technique combined with programmed intermittent epidural bolus (PIEB) has been widely used in the clinical practice of labour analgesia. Whether varying the length of catheter threaded into the epidural space benefits for the resultant analgesia remains unclear. Methods 102 women in labour were enrolled, aged 18-45 years, with cervical dilation >3 cm and a numeric rating scale (NRS) score > 4, were randomly (1:1:1) assigned to three study groups (the epidural catheter threaded 3, 5, or 7 cminto the epidural space) for labour analgesia. The primary outcome was time to reach adequate analgesia, defined as a NRS≤3 after placement of the catheter and a test dose with 3 mL of 1.5% lidocaine, an additional 10 mL of 0.1% ropivacaine with 0.3 µg/mL sufentanil was administered. Secondary outcomes included pain score, anesthetic consumption, duration of labour, adverse events (pruritus, nausea, hypotension, unilateral block, catheter dislodgment, motor blockade) and Apgar scores. Results Median time to reach adequate analgesia was significant different among three group: 5.2 min vs.7.0 min vs. 8.1min in 3, 5 and 7 cm insertion, while, the incidence of pruritus was 32.4% vs. 20.6% vs. 5.9% in three group, P=0.001 , respectively. There were no differences in other severe adverse events among groups, but incidence of nausea was higher (32.4%) in 3cm group than that in 5cm（17.6%）or 7cm (14.7%) group. Hypotension developed in four patients in the 3 cm group and unilateral block was observed in four patients in the 7 cm group. Pain score, local anaesthetic consumption, labour duration, catheter dislodgment, motor blockade, and Apgar score of the newborns were statistically insignificant. Conclusion During labour analgesia with DPE combination with PIEB, when the epidural catheter is left 3 cm in the epidural space, the onset of action is faster, but the incidence of pruritus and nausea are higher. Therefore, in order to minimize either catheter or drug-related complications and provide satisfactory analgesia, the appropriate length of catheterization for epidural labour analgesia should be 5 cm. Trail registration ClinicalTrials.gov (NCT06602440); retrospectively registered on 17 September, 2024. dural puncture epidural programmed intermittent epidural bolus epidural catheter labour analgesia Figures Figure 1 Background Labour pain is defined as an moderate to severe acute pain, which predominantly arises from the uterine contraction and cervical dilatation during labour. Epidural analgesia (EA) is an important approach of pain management during labour throughout the world. 1 Based on the mechanisms of labour analgesia, origin and pathways at the different stages of labour. 2 First stage pain is mainly visceral pain and transmitted by the sympathetic nervous fibers originating from the inferior hypogastric plexus (T 10 -L 1 ), which begins with frequent uterine contractions with gradual cervix dilation. Second-stage labor pain is mainly somatic pain and transmitted by pudendal nerve (T 12 -L 1 ), and parasympathetic nerves (S 2–4 ). The safety and efficacy of various neuraxial analgesia technique include EA, combined spinal-epidural (CSE), dural puncture epidural (DPE), and the use of programmed intermittent epidural bolus(PIEB)means have been explored on labour pain relief. 3 DPE technique combined with PIEB mode can provide a faster onset and a greater anesthetic drug-sparing in labour analgesia. 4 It also has been proven that neuraxial opioids modulate both the visceral and the somatic pain of labour through acting on spinal cord opioid receptors in the dorsal horn. Epidural a low dose local anesthetic plus sufentanil has little or no effect on infants. 5 For postoperative analgesia, epidural catheter left 5 cm in the epidural space shows can help to overcome uneven distribution of local anesthetic and minimize catheter-related complications. 6,7 The aim of this study is to evaluate the appropriate length of epidural catheter in epidural space when DPE analgesia was initiated with a test dose of 1.5% lidocaine 3 mL, combined with PIEB volume of 0.1% ropivacaine 10 mL plus 0.3 µg/mL sufentanil was administered, followed by 8 mL bolus every 45 min on the overall quality of labour analgesia. Methods Ethics The study was approved by the Ethical Committee of the General Hospital of Ningxia Medical University (ethical approval number: KYLL-2024-0929) and was retrospectively registered on ClinicalTrials.gov (NCT06602440) on September 17, 2024. Written informed consent was obtained from all participants. Case collection was completed from September to December 2024.This manuscript adheres to the applicable CONSORT guidelines and Declaration of Helsinki. Inclusion criteria: women in labour, age 18–45 years; ASA I-II; BMI ≤ 40 kg/m²; gestational age between 37–42 weeks; cervical dilation > 3.0 cm, NRS > 4 during contractions, and parturients wishing to undergo epidural labour analgesia for a singleton, healthy pregnancy. Exclusion criteria: parturients with following conditions (1) contraindications for neuraxial anesthesia; (2) history of allergies to local anesthetics or opioids; (3) pregnancy-related diseases (e.g. gestational hypertension, preeclampsia, pregnancy with heart disease); (4) known fetal abnormalities or conditions associated with increased risk of cesarean delivery (e.g. macrosomia, nuchal cord); (5) use of opioids or sedatives within 4 hours before epidural analgesia. Study protocol All parturients who met the criteria for labour onset and had regular contractions, whether spontaneous or induced, were admitted to the delivery room and had an intravenous line established. If the parturient requested analgesia and the fetal monitoring indicated appropriate conditions, the investigator assessed the parturient’s NRS score (0–10, where 0 means no pain and 10 means the worst imaginable pain). When the score was greater than 4, the anesthesiologist performed DPE combined with PIEB for labour analgesia. At this stage, the anesthesiologist recorded the parturient’s blood pressure, heart rate, fetal heart rate, and contraction pressure from fetal monitoring just before administering labour analgesia. Before the initiation of labour analgesia, the parturient was administered 500 mL of crystalloid fluid intravenously and assumed a right lateral, flexed position to expose the intervertebral space. The anesthesiologist selected the L 3-4 intervertebral space for epidural puncture, using a 17-gauge Tuohy needle. The needle tip's position in the epidural space was confirmed using the loss-of-resistance technique. A 25-gauge Whitacre needle was then used to puncture the dura mater, and cerebrospinal fluid reflux was observed. A 19-gauge multi-orifice, bend-resistant stainless steel epidural catheter was inserted into the epidural space to depths of 3 cm, 5 cm, and 7 cm, as method of a random number table generated by a computer for allocation. After confirming the absence of blood and cerebrospinal fluid aspiration, the epidural catheter was connected to an electronic pulse pump, and the PIEB mode was initiated with an initial dose of 10 mL of 0.1% ropivacaine and 0.3 µg/mL sufentanil to initiate labour analgesia. The parturient’s NRS score during each contraction was recorded. The maintenance setting for labour analgesia was programmed for an intermittent bolus every 45 minutes, with 8 mL per bolus. The PCEA (patient-controlled epidural analgesia) single bolus dose was set at 5 mL, with a lockout time of 10 minutes, and the maximum pump volume was set at 30 mL. Within 20 minutes after the initial dose, the parturient was instructed not to use PCEA. After 20 minutes, PCEA was allowed, and another 20 minutes of observation followed. If the NRS score remained greater than 4, the anesthesiologist administering the analgesia gave a supplemental bolus of 8 mL of the same drug formulation. After supplemental administration, the PIEB mode resumed, and the interval time was recalculated. If the NRS score remained greater than 4 after 20 minutes of the supplemental dose, analgesia failure was diagnosed, and the patient was excluded from the study. For patients with an NRS score below 3, analgesia was considered satisfactory, and the time from the administration of the initial dose to achieving an NRS score below 3 was recorded as the time to satisfactory pain relief. The epidural catheter was removed after the third stage of labour in patients with satisfactory analgesia. The primary outcome was the time from the administration of the initial dose until the parturient 's NRS score dropped below 3 for each contraction. Secondary outcomes included the per unit time amount of ropivacaine consumed from the start of the initial dose to the end of the third stage of labour (total controlled drug dose + total PCEA dose + supplemental dose amount, divided by the time from the initial dose to the end of the third stage of labour),the duration of labour associated with epidural analgesia (from the start of analgesia to the delivery of the placenta),adverse events(included hypotension, unilateral block, nausea, catheter dislodgment, or lower limb motor function (modified Bromage score of 0–3: 0 = no motor block; 1 = unable to extend the leg, but can flex the knee; 2 = unable to flex the knee, but can move the ankle; 3 = unable to move the ankle), Apgar score of the newborns.In this trial, both the data statisticians and parturients were blinded to the group allocation. Statistical analysis Based on relevant literature 6,7 and preliminary trial data, the median time (interquartile range [IQR]) for NRS scores to drop below 3 in the 3 cm, 5 cm, and 7 cm groups were 5 .0(4.2, 6.0), 7.0 (5.0, 8.2), and 7 .0(6.1, 12.0) minutes, respectively, with the minimum significant difference (MDPE) set at 2. The first-type error rate was set at 0.05 and the second-type error rate at 0.1. The sample size was estimated to be approximately 31 per group, accounting for a 5%-10% dropout rate, resulting in 34 subjects per group, for a total of 102 participants. All statistical analyses were conducted using SPSS 27.0. The normality of continuous variables was assessed using the Shapiro-Wilk test. Normally distributed data were expressed as mean (standard deviation [SD]), and non-normally distributed data were expressed as median (interquartile range [IQR]). Chi-square tests were used to assess differences between dichotomous variables. One-way ANOVA was used to assess differences among three groups for normally distributed data, followed by Tukey's test for pairwise comparisons. The Kruskal-Wallis H test (K independent samples nonparametric test) was used to assess differences among three groups for skewed data, followed by Dunn's test. A P-value of < 0.05 was considered statistically significant. Results We recruited 102 subjects over a period of 3 months (Fig-1). The baseline characteristics of the three groups were similar (Table-1). Time to reach adequate analgesia significantly differs among the three groups, (recorded as 5.2 (5.0-6.2) vs. 7.0 (5.0-8.5) vs. 8.1 (6.2–11.0), P = 0.001 ). However, there is no significant difference in the consumption of ropivacaine per unit time across the groups.Regarding the duration of the first、second and third stages of labour, there were no statistical differences among the groups (Table-2). There was a significant difference in the incidence of pruritus among the three groups ( P = 0.001 ), with the highest incidence in the 3 cm group (11/34) and the lowest in the 7 cm group (2/34). No statistical differences were observed for other adverse events such as hypotension, unilateral block, nausea, catheter dislodgment or motor block (Table-3). For the remaining secondary outcomes, there were no statistical differences in the Apgar scores at 1 minute after birth among the groups. Additionally, there were no statistical differences in the incidence of emergency cesarean section rate among the groups (Table-4). Disscusion In this randomized study, we compared the effect of different catheter insertion depths (3 cm, 5 cm, 7 cm) on labor analgesia by DPE combined with PIEB. The results showed that the 3 cm group had the shortest onset time for analgesia, but the incidence of pruritus and nausea are higher. When catheter insertion to a depth of 7 cm was associated with the highest rate of unilateral block. In recent years, the DPE technique has gained widespread attention in obstetric anesthesia and has become an important innovative approach.DPE, first described by Cappiello et al. 8 , originated from an accidental procedure during epidural-based labour analgesia. Compared with traditional EA and CSE techniques, DPE involves puncturing the dura, allowing the drug to transfer from the epidural space to the subarachnoid space, thereby accelerating the onset of anesthesia and improving its quality. 9–11 Studies have shown that DPE can significantly shorten the onset time of anesthesia, especially during labour, where the onset time of DPE is about 4 minutes faster than traditional epidural anesthesia, and it demonstrates clear advantages in anesthetic range and symmetry. 12–14 Additionally, DPE can reduce the amount of local anesthetics used, achieving similar anesthetic effects to traditional epidural anesthesia but with significantly lower doses. 15 The effect is even more pronounced when DPE is combined with PIEB. Research has found that the optimal dose of PIEB is 10–12 mL, which effectively maintains analgesia, reduces the need for analgesic drugs, and results in fewer side effects, improving maternal satisfaction. 16 The combination of DPE and PIEB not only enhances analgesia but also reduces the total drug dose through intermittent bolus administration, further improving the safety and efficiency of anesthesia. DPE also has fewer side effects, particularly in terms of hypotension and nausea, and shows better tolerance compared to CSE. 17 In the current study, DPE has demonstrated numerous advantages. As the technique continues to improve and clinical data accumulate, DPE is expected to become a routine, safe, and effective choice in obstetric anesthesia. 18 This trial is the first to propose the hypothesis regarding the local high-pressure area generated by the PIEB mode during DPE combined with PIEB for labour analgesia. The better analgesic effect of DPE combined with PIEB is not only due to the migration of the drug from the epidural space into the subarachnoid space through the dural puncture but also related to the local high-pressure environment generated by the PIEB mode in the epidural space. 19,20 We hypothesized that when the local high-pressure area is near the dural puncture site, more drug from the epidural space would more rapidly pass through the dural puncture site to reach the subarachnoid space and provide analgesia. However, when the high-pressure area is far from the puncture site, PIEB may not exert its full potential in DPE. To test this hypothesis, we varied the depth of the epidural catheter placement to indirectly change the distance between the drug injection end and the dural puncture site. Since the spinal needle is inserted perpendicularly into the skin of the back, and the epidural catheter is placed perpendicularly to the spinal needle toward the maternal head, we assumed that, if the catheter is not kinked, the catheter depth can be approximated as the distance between the injection end and the dural puncture site. The results of the trial confirmed our hypothesis. As the catheter depth decreased, the analgesic onset time shortened further in the 3 cm, 5 cm, and 7 cm groups. The pairwise comparison clearly shows time to adequate analgesia in the 3 cm group was significantly shorter compared to the other two groups, but there was no difference between the 5 cm and 7 cm groups. Likely because at a 5 cm distance from the dural puncture site, the high-pressure zone created by PIEB is already at or beyond the puncture site. The use of labour analgesia during delivery, from the first stage of labour to the end of the third stage (delivery of the placenta), is subject to significant individual variation, influenced by multiple factors such as primiparity or multiparity, fetal position, uterine contractions, maternal cooperation, and whether or not labour analgesia is used . 1 Therefore, it is not reasonable to observe the total consumption of ropivacaine across different groups. To eliminate the time-related biases in ropivacaine consumption during different stages of labour, we calculated the consumption of ropivacaine per unit time for each patient, which can indirectly reflect the effectiveness of analgesia. The results showed no difference in ropivacaine consumption per unit time between the groups, indicating that while the catheter depth affects the onset time of labour analgesia using DPE combined with PIEB, once satisfactory analgesia is achieved, the ropivacaine consumption remains similar across groups. Among the adverse outcomes, the incidence of pruritus was highest in the 3 cm group, which may also be related to the increased amount and speed of sufentanil migrating into the subarachnoid space. Additionally, among the 102 participants, only the 3 cm group had 2 cases of catheter displacement, and the 3 cm group also had the highest incidence of nausea. However, the 7 cm group had the highest incidence of unilateral block. Therefore, when using DPE combined with PIEB for labour analgesia, selecting a shorter catheter insertion length can speed up the onset time but may increase the incidence of pruritus, nausea, and catheter displacement. On the other hand, selecting a longer catheter insertion length may result in a higher incidence of unilateral block. Regarding the incidence of emergency cesarean section, the 3 cm group had a higher incidence than both the 5 cm and 7 cm groups. The causes of cesarean section in descending order were: fever (chorioamnionitis), persistent occiput posterior position, and uterine inertia, with no direct evidence linking them to labour analgesia. The limitations of this trial include that it is a single-center study, so the results may not be applicable to other institutions. Furthermore, we did not differentiate between primiparous and multiparous women during screening, as there are differences in pain levels, labour duration, and psychological factors between these two groups. Additionally, if the epidural catheter is kinked or not placed perpendicularly to the maternal head, it may affect the actual depth of catheter insertion and bias the results. Since it is not feasible for pregnant women to use contrast agents for catheter localization, we observed the position of the catheter during removal to ensure it was placed perpendicularly and excluded patients with kinking. However, this method cannot completely rule out catheter position issues in the spinal canal and could lead to data biases. Finally, our trial was not fully blinded, as only the data collectors were unaware of the interventions given to the patients. In Conclusion During labour analgesia with DPE combination with PIEB, when the epidural catheter is left 3 cm in the epidural space, the onset of action is faster, but the incidence of pruritus and nausea are higher. Therefore, in order to minimize either catheter or drug-related complications and provide satisfactory analgesia, the appropriate length of catheterization for epidural labour analgesia should be 5 cm. Abbreviations DPE Dural Puncture Epidural PIEB Programmed Intermittent Epidural Bolus NRS Numeric Rating Scale EA Epidural Analgesia CSE Combined Spinal Epidural ASA American Society of Anesthesiologists BMI Body Mass Index PCEA Patient-Controlled Epidural Analgesia Declarations Author contributions Peng Liu, Yi Chen, Peng Ma，Rui Qin, and Yongqiang Shi contributed to all aspects of this manuscript, including conception and design; acquisition, analysis, and interpretation of data; and drafting the article. Xinli Ni contributed to the conception and design, analysis, and interpretation of data; and drafting the article. Funding This study was supported by the Program of Ningxia Medical University (grant number: XM2023055). Availability of data and materials All data generated or analyzed during this study are included in this published article. Ethics approval and consent to participate Ethical approval was obtained from the Human Research Ethics Committee of the General Hospital of Ningxia Medical University (approval NO.:KYLL-2024-0929). The study was registered in the ClinicalTrials.gov (NCT06602440, Principal investigator: Peng Liu, Date of registration: 09/17/2024). Written informed consent was obtained from all subjects participating in the trial, and all methods were performed in accordance with the relevant guidelines and regulations. This manuscript adheres to the applicable CONSORT guidelines. Consent for publication Not applicable. Competing interests The authors declare that they have no competing interests. References Callahan EC, Lee W, Aleshi P, George RB. Modern labor epidural analgesia: implications for labor outcomes and maternal-fetal health. Am J Obstet Gynecol. 2023 ;228(5S): S1260-S1269.https://doi.org/10.1016/j.ajog.2022.06.017. Minzter BH, Devarajan J. Mechanisms of labour analgesia. In: Cheng J, Rosenquist R, eds. Fundamentals of Pain Medicine. Cham: Springer; 2018. Coviello A, Iacovazzo C, Frigo MG,et al . Technical aspects of neuraxial analgesia during labor and maternity care: an updated overview. J Anesth Analg Crit Care. 2025 29;5(1):6.https://doi.org/10.1186/s44158-025-00224-3. Song Y, Sheng Z, Zhao Q,et al . Exploration of the optimal programmed intermittent epidural bolus volume with the dural puncture epidural technique for labour analgesia: a biased-coin up-and-down sequential allocation study. Can J Anaesth.2025 ;72(2):254-261..https://doi.org/ doi: 10.1007/s12630-024-02855-6. Lam KK, Leung MKM, Irwin MG. Labour analgesia: update and literature review. Hong Kong Med J. 2020 ;26(5):413-420.https://doi.org/10.12809/hkmj208632. Afshan G, Chohan U, Khan FA,et al . Appropriate length of epidural catheter in the epidural space for postoperative analgesia: evaluation by epidurography. 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Tables Table 1 : Comparison of baseline characteristics among the 3 cm group, 5 cm group, and 7 cm group , n=34 3cm Group 5cm Group 7cm Group P Value Age(y) 27.7(3.1) 29.8(3.7) 28.2(3.5) 0.328 Height(m) 1.6(0.1) 1.6(0.1) 1.6(0.5) 0.337 Weight(kg) 71.7(6.7) 70.4(9.8) 71.1(8.1) 0.780 BMI(kg/㎡) 27.0(2.2) 26.3(2.8) 27.2(2.8) 0.264 Primiparity n(%) 13(38.2%) 10(29.0%) 15(44.0%) Gestational age(w) 39.1(1.1) 39.7(1.0) 39.6(1.4) 0.096 Fetal Weight(g) 3236(253) 3194(301) 3207(275) 0.701 (Age,height,weight,BMI,gestational,fetal weight are expressed as mean (SD); Primigravida is expressed as n(%)） Table 2: Time to adequate analgesia, ropivacaine consumption per unit time and duration of labour for the 3 cm, 5 cm, and 7 cm groups, n=34 3cm Group 5cm Group 7cm Group P Value Time to Adequate Analgesia (min) 5.2(5.0-6.2)* 7.0(5.0-8.5) 8.1(6.2-11.0) 0.001 Block level(not feel cold) T10(T8-T10) T10(T8-T10) T10(T8-T10) 0.126 Ropivacaine Consumption per Unit Time (mg/h) 10.7(10.2-11.4) 10.5(10.2-11.4) 10.7(10.5-11.2) 0.672 Duration of first Stage(min) 510(369.5-592.5) 430(327.5-640) 541(415-757.5) 0.216 Duration of Second Stage(min) 42(50-57.5) 57.5(19-82) 32.5(27-60.5) 0.596 Duration of Third Stage(min) 9(8-11.5) 9(8.5-11) 10(9-10) 0.724 Duration of labour analgesia (min) 420(307.5-532.6) 401(298.4-504) 398(308.4-508) 0.408 (Values are median (IQR). Significant differences are indicated as follows: *p=0.001 for 3 cm group vs 5 cm group, *p<0.05 for 3 cm group vs 7 cm group, and p=0.11 for 5 cm group vs 7 cm group） Table 3: Incidence rates of hypotension, pruritus, unilateral blockade, nausea, catheter dislodgment, and motor block, n=34 3cm Group 5cm Group 7cm Group P Value Hypotension，n（%） 4（11.8%） 1（2.9%） 2（5.9%） 0.090 Pruritus，n（ %） 11（32.4%） 7（20.6%） 2（5.9%） 0.001* Unilateral Block，n（%） 1（2.9%） 2（5.9%） 4（11.8%） 0.119 Nausea，n（%） 11（32.4%） 6（17.6%） 5（14.7%） 0.272 Catheter Displacement，n（%） 2（5.9%） 0 0 0.164 Motor Block (Bromage >0), n (%) 1（2.9%） 2（5.9%） 2（5.9%） 0.737 (Hypotension, pruritus, unilateral block, nausea, catheter displacement,and motor block are expressed as frequencies. Differences are indicated by * P < 0.05 ） Table 4: Neonatal Apgar scores, cesarean conversion rates and causes . Values are median (IQR) or n(%) ,n=34 3cm Group 5cm Group 7cm Group P Value Apgar Score 9(9-9) 9(9-9) 9(9-9) 0.462 Cesarean Section Rate，n(%) 6(17.6%) 5(15.0%) 5(15.0%) 0.232 Cause of Cesarean Scetion Fever (Chorioamnionitis)，n(%) 3(8.8%) 1(2.9%) 2(5.9%) Persistent Occiput Posterior Position，n(%) 1(2.9%) 1(2.9%) 1(2.9%) Fetal Distress，n(%) 2(5.9%) 2(5.9%) 2(5.9%) Uterine Inertia，n(%) 0 1(2.9%) 0 (Apgar Score values are median (IQR);cesarean Section Rate and cause of Cesarean Scetion are expressed as frequencies.) Additional Declarations No competing interests reported. Cite Share Download PDF Status: Published Journal Publication published 20 Jan, 2026 Read the published version in BMC Anesthesiology → Version 1 posted Editorial decision: Revision requested 23 Dec, 2025 Reviewers agreed at journal 21 Dec, 2025 Reviews received at journal 20 Dec, 2025 Reviewers agreed at journal 20 Dec, 2025 Reviews received at journal 18 Dec, 2025 Reviewers agreed at journal 17 Dec, 2025 Reviewers agreed at journal 15 Dec, 2025 Reviewers agreed at journal 15 Dec, 2025 Reviewers agreed at journal 14 Dec, 2025 Reviews received at journal 12 Dec, 2025 Reviewers agreed at journal 12 Dec, 2025 Reviewers invited by journal 11 Dec, 2025 Editor assigned by journal 11 Dec, 2025 Editor invited by journal 02 Dec, 2025 Submission checks completed at journal 01 Dec, 2025 First submitted to journal 01 Dec, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. 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16:04:18","extension":"html","order_by":6,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":69191,"visible":true,"origin":"","legend":"","description":"","filename":"earlyproof.html","url":"https://assets-eu.researchsquare.com/files/rs-8037232/v1/c0e2c538f743d7b882247819.html"},{"id":98334609,"identity":"7bdbea69-f3c7-490b-98b8-e707f169cbe5","added_by":"auto","created_at":"2025-12-16 16:04:18","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":63243,"visible":true,"origin":"","legend":"\u003cp\u003eCONSORT flow diagram.\u003c/p\u003e","description":"","filename":"1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8037232/v1/9786d8532ae97acc2477cb1a.jpg"},{"id":101151653,"identity":"66b502bd-3e88-4dd6-b1a3-36c62fd0c782","added_by":"auto","created_at":"2026-01-26 16:00:50","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":597464,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8037232/v1/de1fa476-49b8-4fc8-abee-b0a24fc365fe.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Appropriate length of epidural catheter in epidural space for labour analgesia with dural puncture epidural combined with programmed intermittent epidural bolus","fulltext":[{"header":"Background","content":"\u003cp\u003eLabour pain is defined as an moderate to severe acute pain, which predominantly arises from the uterine contraction and cervical dilatation during labour. Epidural analgesia (EA) is an important approach of pain management during labour throughout the world.\u003csup\u003e1\u003c/sup\u003e Based on the mechanisms of labour analgesia, origin and pathways at the different stages of labour.\u003csup\u003e2\u003c/sup\u003e First stage pain is mainly visceral pain and transmitted by the sympathetic nervous fibers originating from the inferior hypogastric plexus (T\u003csub\u003e10\u003c/sub\u003e -L\u003csub\u003e1\u003c/sub\u003e), which begins with frequent uterine contractions with gradual cervix dilation. Second-stage labor pain is mainly somatic pain and transmitted by pudendal nerve (T\u003csub\u003e12\u003c/sub\u003e-L\u003csub\u003e1\u003c/sub\u003e), and parasympathetic nerves (S\u003csub\u003e2\u0026ndash;4\u003c/sub\u003e).\u003c/p\u003e \u003cp\u003eThe safety and efficacy of various neuraxial analgesia technique include EA, combined spinal-epidural (CSE), dural puncture epidural (DPE), and the use of programmed intermittent epidural bolus(PIEB)means have been explored on labour pain relief.\u003csup\u003e3\u003c/sup\u003e DPE technique combined with PIEB mode can provide a faster onset and a greater anesthetic drug-sparing in labour analgesia.\u003csup\u003e4\u003c/sup\u003e It also has been proven that neuraxial opioids modulate both the visceral and the somatic pain of labour through acting on spinal cord opioid receptors in the dorsal horn. Epidural a low dose local anesthetic plus sufentanil has little or no effect on infants.\u003csup\u003e5\u003c/sup\u003e For postoperative analgesia, epidural catheter left 5 cm in the epidural space shows can help to overcome uneven distribution of local anesthetic and minimize catheter-related complications. \u003csup\u003e6,7\u003c/sup\u003e\u003c/p\u003e \u003cp\u003eThe aim of this study is to evaluate the appropriate length of epidural catheter in epidural space when DPE analgesia was initiated with a test dose of 1.5% lidocaine 3 mL, combined with PIEB volume of 0.1% ropivacaine 10 mL plus 0.3 \u0026micro;g/mL sufentanil was administered, followed by 8 mL bolus every 45 min on the overall quality of labour analgesia.\u003c/p\u003e"},{"header":"Methods","content":"\u003cp\u003eEthics\u003c/p\u003e \u003cp\u003e The study was approved by the Ethical Committee of the General Hospital of Ningxia Medical University (ethical approval number: KYLL-2024-0929) and was retrospectively registered on ClinicalTrials.gov (NCT06602440) on September 17, 2024. Written informed consent was obtained from all participants. Case collection was completed from September to December 2024.This manuscript adheres to the applicable CONSORT guidelines and Declaration of Helsinki.\u003c/p\u003e \u003cp\u003eInclusion criteria: women in labour, age 18\u0026ndash;45 years; ASA I-II; BMI\u0026thinsp;\u0026le;\u0026thinsp;40 kg/m\u0026sup2;; gestational age between 37\u0026ndash;42 weeks; cervical dilation\u0026thinsp;\u0026gt;\u0026thinsp;3.0 cm, NRS\u0026thinsp;\u0026gt;\u0026thinsp;4 during contractions, and parturients wishing to undergo epidural labour analgesia for a singleton, healthy pregnancy. Exclusion criteria: parturients with following conditions (1) contraindications for neuraxial anesthesia; (2) history of allergies to local anesthetics or opioids; (3) pregnancy-related diseases (e.g. gestational hypertension, preeclampsia, pregnancy with heart disease); (4) known fetal abnormalities or conditions associated with increased risk of cesarean delivery (e.g. macrosomia, nuchal cord); (5) use of opioids or sedatives within 4 hours before epidural analgesia.\u003c/p\u003e \u003cp\u003eStudy protocol\u003c/p\u003e \u003cp\u003eAll parturients who met the criteria for labour onset and had regular contractions, whether spontaneous or induced, were admitted to the delivery room and had an intravenous line established. If the parturient requested analgesia and the fetal monitoring indicated appropriate conditions, the investigator assessed the parturient\u0026rsquo;s NRS score (0\u0026ndash;10, where 0 means no pain and 10 means the worst imaginable pain). When the score was greater than 4, the anesthesiologist performed DPE combined with PIEB for labour analgesia. At this stage, the anesthesiologist recorded the parturient\u0026rsquo;s blood pressure, heart rate, fetal heart rate, and contraction pressure from fetal monitoring just before administering labour analgesia.\u003c/p\u003e \u003cp\u003eBefore the initiation of labour analgesia, the parturient was administered 500 mL of crystalloid fluid intravenously and assumed a right lateral, flexed position to expose the intervertebral space. The anesthesiologist selected the L\u003csub\u003e3-4\u003c/sub\u003e intervertebral space for epidural puncture, using a 17-gauge Tuohy needle. The needle tip's position in the epidural space was confirmed using the loss-of-resistance technique. A 25-gauge Whitacre needle was then used to puncture the dura mater, and cerebrospinal fluid reflux was observed. A 19-gauge multi-orifice, bend-resistant stainless steel epidural catheter was inserted into the epidural space to depths of 3 cm, 5 cm, and 7 cm, as method of a random number table generated by a computer for allocation. After confirming the absence of blood and cerebrospinal fluid aspiration, the epidural catheter was connected to an electronic pulse pump, and the PIEB mode was initiated with an initial dose of 10 mL of 0.1% ropivacaine and 0.3 \u0026micro;g/mL sufentanil to initiate labour analgesia. The parturient\u0026rsquo;s NRS score during each contraction was recorded.\u003c/p\u003e \u003cp\u003eThe maintenance setting for labour analgesia was programmed for an intermittent bolus every 45 minutes, with 8 mL per bolus. The PCEA (patient-controlled epidural analgesia) single bolus dose was set at 5 mL, with a lockout time of 10 minutes, and the maximum pump volume was set at 30 mL. Within 20 minutes after the initial dose, the parturient was instructed not to use PCEA. After 20 minutes, PCEA was allowed, and another 20 minutes of observation followed. If the NRS score remained greater than 4, the anesthesiologist administering the analgesia gave a supplemental bolus of 8 mL of the same drug formulation. After supplemental administration, the PIEB mode resumed, and the interval time was recalculated. If the NRS score remained greater than 4 after 20 minutes of the supplemental dose, analgesia failure was diagnosed, and the patient was excluded from the study. For patients with an NRS score below 3, analgesia was considered satisfactory, and the time from the administration of the initial dose to achieving an NRS score below 3 was recorded as the time to satisfactory pain relief. The epidural catheter was removed after the third stage of labour in patients with satisfactory analgesia.\u003c/p\u003e \u003cp\u003eThe primary outcome was the time from the administration of the initial dose until the parturient 's NRS score dropped below 3 for each contraction. Secondary outcomes included the per unit time amount of ropivacaine consumed from the start of the initial dose to the end of the third stage of labour (total controlled drug dose\u0026thinsp;+\u0026thinsp;total PCEA dose\u0026thinsp;+\u0026thinsp;supplemental dose amount, divided by the time from the initial dose to the end of the third stage of labour),the duration of labour associated with epidural analgesia (from the start of analgesia to the delivery of the placenta),adverse events(included hypotension, unilateral block, nausea, catheter dislodgment, or lower limb motor function (modified Bromage score of 0\u0026ndash;3: 0\u0026thinsp;=\u0026thinsp;no motor block; 1\u0026thinsp;=\u0026thinsp;unable to extend the leg, but can flex the knee; 2\u0026thinsp;=\u0026thinsp;unable to flex the knee, but can move the ankle; 3\u0026thinsp;=\u0026thinsp;unable to move the ankle), Apgar score of the newborns.In this trial, both the data statisticians and parturients were blinded to the group allocation.\u003c/p\u003e \u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eStatistical analysis\u003c/h2\u003e \u003cp\u003eBased on relevant literature\u003csup\u003e6,7\u003c/sup\u003e and preliminary trial data, the median time (interquartile range [IQR]) for NRS scores to drop below 3 in the 3 cm, 5 cm, and 7 cm groups were 5 .0(4.2, 6.0), 7.0 (5.0, 8.2), and 7 .0(6.1, 12.0) minutes, respectively, with the minimum significant difference (MDPE) set at 2. The first-type error rate was set at 0.05 and the second-type error rate at 0.1. The sample size was estimated to be approximately 31 per group, accounting for a 5%-10% dropout rate, resulting in 34 subjects per group, for a total of 102 participants.\u003c/p\u003e \u003cp\u003eAll statistical analyses were conducted using SPSS 27.0. The normality of continuous variables was assessed using the Shapiro-Wilk test. Normally distributed data were expressed as mean (standard deviation [SD]), and non-normally distributed data were expressed as median (interquartile range [IQR]). Chi-square tests were used to assess differences between dichotomous variables. One-way ANOVA was used to assess differences among three groups for normally distributed data, followed by Tukey's test for pairwise comparisons. The Kruskal-Wallis H test (K independent samples nonparametric test) was used to assess differences among three groups for skewed data, followed by Dunn's test. A P-value of \u0026lt;\u0026thinsp;0.05 was considered statistically significant.\u003c/p\u003e \u003c/div\u003e"},{"header":"Results","content":"\u003cp\u003eWe recruited 102 subjects over a period of 3 months (Fig-1). The baseline characteristics of the three groups were similar (Table-1).\u003c/p\u003e \u003cp\u003eTime to reach adequate analgesia significantly differs among the three groups, (recorded as 5.2 (5.0-6.2) vs. 7.0 (5.0-8.5) vs. 8.1 (6.2\u0026ndash;11.0), \u003cem\u003eP\u0026thinsp;=\u0026thinsp;0.001\u003c/em\u003e). However, there is no significant difference in the consumption of ropivacaine per unit time across the groups.Regarding the duration of the first、second and third stages of labour, there were no statistical differences among the groups (Table-2).\u003c/p\u003e \u003cp\u003eThere was a significant difference in the incidence of pruritus among the three groups (\u003cem\u003eP\u0026thinsp;=\u0026thinsp;0.001\u003c/em\u003e), with the highest incidence in the 3 cm group (11/34) and the lowest in the 7 cm group (2/34). No statistical differences were observed for other adverse events such as hypotension, unilateral block, nausea, catheter dislodgment or motor block (Table-3).\u003c/p\u003e \u003cp\u003eFor the remaining secondary outcomes, there were no statistical differences in the Apgar scores at 1 minute after birth among the groups. Additionally, there were no statistical differences in the incidence of emergency cesarean section rate among the groups (Table-4).\u003c/p\u003e"},{"header":"Disscusion","content":"\u003cp\u003eIn this randomized study, we compared the effect of different catheter insertion depths (3 cm, 5 cm, 7 cm) on labor analgesia by DPE combined with PIEB. The results showed that the 3 cm group had the shortest onset time for analgesia, but the incidence of pruritus and nausea are higher. When catheter insertion to a depth of 7 cm was associated with the highest rate of unilateral block.\u003c/p\u003e \u003cp\u003eIn recent years, the DPE technique has gained widespread attention in obstetric anesthesia and has become an important innovative approach.DPE, first described by Cappiello et al.\u003csup\u003e8\u003c/sup\u003e, originated from an accidental procedure during epidural-based labour analgesia. Compared with traditional EA and CSE techniques, DPE involves puncturing the dura, allowing the drug to transfer from the epidural space to the subarachnoid space, thereby accelerating the onset of anesthesia and improving its quality.\u003csup\u003e9\u0026ndash;11\u003c/sup\u003e Studies have shown that DPE can significantly shorten the onset time of anesthesia, especially during labour, where the onset time of DPE is about 4 minutes faster than traditional epidural anesthesia, and it demonstrates clear advantages in anesthetic range and symmetry.\u003csup\u003e12\u0026ndash;14\u003c/sup\u003e Additionally, DPE can reduce the amount of local anesthetics used, achieving similar anesthetic effects to traditional epidural anesthesia but with significantly lower doses.\u003csup\u003e15\u003c/sup\u003e The effect is even more pronounced when DPE is combined with PIEB. Research has found that the optimal dose of PIEB is 10\u0026ndash;12 mL, which effectively maintains analgesia, reduces the need for analgesic drugs, and results in fewer side effects, improving maternal satisfaction.\u003csup\u003e16\u003c/sup\u003e The combination of DPE and PIEB not only enhances analgesia but also reduces the total drug dose through intermittent bolus administration, further improving the safety and efficiency of anesthesia. DPE also has fewer side effects, particularly in terms of hypotension and nausea, and shows better tolerance compared to CSE.\u003csup\u003e17\u003c/sup\u003e In the current study, DPE has demonstrated numerous advantages. As the technique continues to improve and clinical data accumulate, DPE is expected to become a routine, safe, and effective choice in obstetric anesthesia.\u003csup\u003e18\u003c/sup\u003e\u003c/p\u003e \u003cp\u003eThis trial is the first to propose the hypothesis regarding the local high-pressure area generated by the PIEB mode during DPE combined with PIEB for labour analgesia. The better analgesic effect of DPE combined with PIEB is not only due to the migration of the drug from the epidural space into the subarachnoid space through the dural puncture but also related to the local high-pressure environment generated by the PIEB mode in the epidural space.\u003csup\u003e19,20\u003c/sup\u003e We hypothesized that when the local high-pressure area is near the dural puncture site, more drug from the epidural space would more rapidly pass through the dural puncture site to reach the subarachnoid space and provide analgesia. However, when the high-pressure area is far from the puncture site, PIEB may not exert its full potential in DPE. To test this hypothesis, we varied the depth of the epidural catheter placement to indirectly change the distance between the drug injection end and the dural puncture site. Since the spinal needle is inserted perpendicularly into the skin of the back, and the epidural catheter is placed perpendicularly to the spinal needle toward the maternal head, we assumed that, if the catheter is not kinked, the catheter depth can be approximated as the distance between the injection end and the dural puncture site. The results of the trial confirmed our hypothesis. As the catheter depth decreased, the analgesic onset time shortened further in the 3 cm, 5 cm, and 7 cm groups. The pairwise comparison clearly shows time to adequate analgesia in the 3 cm group was significantly shorter compared to the other two groups, but there was no difference between the 5 cm and 7 cm groups. Likely because at a 5 cm distance from the dural puncture site, the high-pressure zone created by PIEB is already at or beyond the puncture site.\u003c/p\u003e \u003cp\u003eThe use of labour analgesia during delivery, from the first stage of labour to the end of the third stage (delivery of the placenta), is subject to significant individual variation, influenced by multiple factors such as primiparity or multiparity, fetal position, uterine contractions, maternal cooperation, and whether or not labour analgesia is used .\u003csup\u003e1\u003c/sup\u003e Therefore, it is not reasonable to observe the total consumption of ropivacaine across different groups. To eliminate the time-related biases in ropivacaine consumption during different stages of labour, we calculated the consumption of ropivacaine per unit time for each patient, which can indirectly reflect the effectiveness of analgesia. The results showed no difference in ropivacaine consumption per unit time between the groups, indicating that while the catheter depth affects the onset time of labour analgesia using DPE combined with PIEB, once satisfactory analgesia is achieved, the ropivacaine consumption remains similar across groups.\u003c/p\u003e \u003cp\u003eAmong the adverse outcomes, the incidence of pruritus was highest in the 3 cm group, which may also be related to the increased amount and speed of sufentanil migrating into the subarachnoid space. Additionally, among the 102 participants, only the 3 cm group had 2 cases of catheter displacement, and the 3 cm group also had the highest incidence of nausea. However, the 7 cm group had the highest incidence of unilateral block. Therefore, when using DPE combined with PIEB for labour analgesia, selecting a shorter catheter insertion length can speed up the onset time but may increase the incidence of pruritus, nausea, and catheter displacement. On the other hand, selecting a longer catheter insertion length may result in a higher incidence of unilateral block. Regarding the incidence of emergency cesarean section, the 3 cm group had a higher incidence than both the 5 cm and 7 cm groups. The causes of cesarean section in descending order were: fever (chorioamnionitis), persistent occiput posterior position, and uterine inertia, with no direct evidence linking them to labour analgesia.\u003c/p\u003e \u003cp\u003eThe limitations of this trial include that it is a single-center study, so the results may not be applicable to other institutions. Furthermore, we did not differentiate between primiparous and multiparous women during screening, as there are differences in pain levels, labour duration, and psychological factors between these two groups. Additionally, if the epidural catheter is kinked or not placed perpendicularly to the maternal head, it may affect the actual depth of catheter insertion and bias the results. Since it is not feasible for pregnant women to use contrast agents for catheter localization, we observed the position of the catheter during removal to ensure it was placed perpendicularly and excluded patients with kinking. However, this method cannot completely rule out catheter position issues in the spinal canal and could lead to data biases. Finally, our trial was not fully blinded, as only the data collectors were unaware of the interventions given to the patients.\u003c/p\u003e \u003cp\u003eIn Conclusion During labour analgesia with DPE combination with PIEB, when the epidural catheter is left 3 cm in the epidural space, the onset of action is faster, but the incidence of pruritus and nausea are higher. Therefore, in order to minimize either catheter or drug-related complications and provide satisfactory analgesia, the appropriate length of catheterization for epidural labour analgesia should be 5 cm.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cp\u003eDPE \u0026nbsp; \u0026nbsp;Dural Puncture Epidural\u003c/p\u003e\n\u003cp\u003ePIEB \u0026nbsp; \u0026nbsp;Programmed Intermittent Epidural Bolus\u003c/p\u003e\n\u003cp\u003eNRS \u0026nbsp; \u0026nbsp;Numeric Rating Scale\u003c/p\u003e\n\u003cp\u003eEA \u0026nbsp; \u0026nbsp; Epidural Analgesia\u003c/p\u003e\n\u003cp\u003eCSE \u0026nbsp; \u0026nbsp;Combined Spinal Epidural\u003c/p\u003e\n\u003cp\u003eASA \u0026nbsp; \u0026nbsp;American Society of Anesthesiologists\u003c/p\u003e\n\u003cp\u003eBMI \u0026nbsp; \u0026nbsp;Body Mass Index\u003c/p\u003e\n\u003cp\u003ePCEA \u0026nbsp; Patient-Controlled Epidural Analgesia\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAuthor contributions\u003c/strong\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003ePeng Liu, Yi Chen, Peng Ma，Rui Qin, and Yongqiang Shi contributed to all aspects of this manuscript, including conception and design; acquisition, analysis, and interpretation of data; and drafting the article.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eXinli Ni contributed to the conception and design, analysis, and interpretation of data; and drafting the article.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study was supported by the Program of Ningxia Medical University (grant number: XM2023055).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and materials\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll data generated or analyzed during this study are included in this published article.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eEthical approval was obtained from the Human Research Ethics Committee of \u0026nbsp;the General Hospital of Ningxia Medical University (approval NO.:KYLL-2024-0929). The study was registered in the ClinicalTrials.gov (NCT06602440, Principal investigator: Peng Liu, Date of registration: 09/17/2024). Written informed consent was obtained from all subjects participating in the trial, and all methods were performed in accordance with the relevant guidelines and regulations. This manuscript adheres to the applicable CONSORT guidelines.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have no competing interests.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eCallahan EC, Lee W, Aleshi P, George RB. Modern labor epidural analgesia: implications for labor outcomes and maternal-fetal health. Am J Obstet Gynecol. 2023 ;228(5S): S1260-S1269.https://doi.org/10.1016/j.ajog.2022.06.017.\u003c/li\u003e\n\u003cli\u003eMinzter BH, Devarajan J. Mechanisms of labour analgesia. In: Cheng J, Rosenquist R, eds. Fundamentals of Pain Medicine. Cham: Springer; 2018.\u003c/li\u003e\n\u003cli\u003eCoviello A, Iacovazzo C, Frigo MG,et al . Technical aspects of neuraxial analgesia during labor and maternity care: an updated overview. J Anesth Analg Crit Care. 2025 29;5(1):6.https://doi.org/10.1186/s44158-025-00224-3.\u003c/li\u003e\n\u003cli\u003eSong Y, Sheng Z, Zhao Q,et al . Exploration of the optimal programmed intermittent epidural bolus volume with the dural puncture epidural technique for labour analgesia: a biased-coin up-and-down sequential allocation study. Can J Anaesth.2025 ;72(2):254-261..https://doi.org/ doi: 10.1007/s12630-024-02855-6.\u003c/li\u003e\n\u003cli\u003eLam KK, Leung MKM, Irwin MG. Labour analgesia: update and literature review. Hong Kong Med J. 2020 ;26(5):413-420.https://doi.org/10.12809/hkmj208632.\u003c/li\u003e\n\u003cli\u003eAfshan G, Chohan U, Khan FA,et al . Appropriate length of epidural catheter in the epidural space for postoperative analgesia: evaluation by epidurography. Anaesthesia. 2011 ;66(10):913-8. https://doi.org/10.1111/j.1365-2044.2011.06820.x.\u003c/li\u003e\n\u003cli\u003eBeilin Y, Bernstein HH, Zucker-Pinchoff B. The optimal distance that a multiorifice epidural catheter should be threaded into the epidural space. Anesth Analg. 1995 ;81(2):301-4.https://doi.org/10.1097/00000539-199508000-00016.\u003c/li\u003e\n\u003cli\u003eYin H, Tong X, Huang H. Dural puncture epidural versus conventional epidural analgesia for labor: a systematic review and meta-analysis of randomized controlled studies. J Anesth. 2022;36(3):413-427. https://doi.org/10.1007/s00540-022-03061-8.\u003c/li\u003e\n\u003cli\u003eSuzuki N, Koganemaru M, Onizuka S, Takasaki M: Dural puncture with a 26-gauge spinal needle affects spread of epidural anesthesia. Anesth Analg 1996;82:1040\u0026ndash;2.https://doi.org/10.1097/00000539-199605000-00028.\u003c/li\u003e\n\u003cli\u003eHeesen M, Rijs K, Rossaint R,et al. Dural puncture epidural versus conventional epidural block for labor analgesia: A systematic review of randomized controlled trials. Int J Obstet Anesth 2019; 40:24\u0026ndash;31.https://doi.org/10.1016/j.ijoa.2019.05.007. \u003c/li\u003e\n\u003cli\u003eLayera S, Bravo D, Aliste J,et al .A systematic review of dural puncture epidural analgesia for labor. J Clin Anesth 2019; 53:5\u0026ndash;10.https://doi.org/10.1016/j.jclinane.2018.09.030.\u003c/li\u003e\n\u003cli\u003eChau A, Bibbo C, Huang CC,et al. Dural Puncture Epidural Technique Improves labor Analgesia Quality With Fewer Side Effects Compared With Epidural and Combined Spinal Epidural Techniques: A Randomized Clinical Trial. Anesth Analg. 2017;124(2):560-569. https://doi.org/10.1213/ANE.0000000000001798.\u003c/li\u003e\n\u003cli\u003eGunaydin B, Erel S. How neuraxial labor analgesia differs by approach: dural puncture epidural as a novel option. J Anesth 2019;33(1):125-130. https://doi.org/10.1007/s00540-018-2564-y.\u003c/li\u003e\n\u003cli\u003eSharawi N, Williams M, Athar W, et al. Effect of Dural-Puncture Epidural vs Standard Epidural for Epidural Extension on Onset Time of Surgical Anesthesia in Elective Cesarean Delivery: A Randomized Clinical Trial. JAMA Netw Open. 2023 1;6(8): e2326710.https://doi.org/10.1001/jamanetworkopen.2023.26710.\u003c/li\u003e\n\u003cli\u003eMaeda A, Villela-Franyutti D, Lumbreras-Marquez MI, et al. Labor Analgesia Initiation With Dural Puncture Epidural Versus Conventional Epidural Techniques: A Randomized Biased-Coin Sequential Allocation Trial to Determine the Effective Dose for 90% of Patients of Bupivacaine. Anesth Analg. 2024 ;138(6):1205-1214.https://doi.org/10.1213/ANE.0000000000006691. \u003c/li\u003e\n\u003cli\u003eXiao F, Yao HQ, Qian J, et al. Determination of the Optimal Volume of Programmed Intermittent Epidural Bolus When Combined With the Dural Puncture Epidural Technique for labor Analgesia: A Random-Allocation Graded Dose-Response Study. Anesth Analg. 2023;137(6):1233-1240.https://doi.org/10.1213/ANE.0000000000006451.\u003c/li\u003e\n\u003cli\u003eChau A, Tsen LC. Dural puncture epidural technique: a novel method for labour analgesia. Curr Anesthesiol Rep. 2017;7:49-54.\u003c/li\u003e\n\u003cli\u003eWilson SH, Wolf BJ, Bingham K, et al. Labor Analgesia Onset With Dural Puncture Epidural Versus Traditional Epidural Using a 26-Gauge Whitacre Needle and 0.125% Bupivacaine Bolus: A Randomized Clinical Trial. Anesth Analg. 2018;126(2):545-551.https://doi.org/10.1213/ANE.0000000000002129.\u003c/li\u003e\n\u003cli\u003eSong Y, Du W, Zhou S, et al. Effect of dural puncture epidural technique combined with programmed intermittent epidural bolus on labor analgesia onset and maintenance: a randomized controlled trial. Anesth Analg 2021; 132: 971\u0026ndash;8. https://doi.org/10.1213/ane.0000000000004768.\u003c/li\u003e\n\u003cli\u003eNi F, Wu Z, Zhao P. Programmed intermittent epidural bolus in maintenance of epidural labor analgesia: a literature review. J Anesth. 2023;37(6):945-960. https://doi.org/10.1007/s00540-023-03253-w.\u003c/li\u003e\n\u003c/ol\u003e"},{"header":"Tables","content":"\u003cp\u003e\u003cstrong\u003eTable\u0026nbsp;1\u003c/strong\u003e: Comparison of baseline characteristics among the 3 cm group, 5 cm group, and 7 cm group , n=34\u0026nbsp;\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 185px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e3cm Group\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 88px;\"\u003e\n \u003cp\u003e5cm Group\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e7cm Group\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 93px;\"\u003e\n \u003cp\u003e\u003cem\u003eP Value\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 185px;\"\u003e\n \u003cp\u003eAge(y)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e27.7(3.1)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 88px;\"\u003e\n \u003cp\u003e29.8(3.7)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e28.2(3.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 93px;\"\u003e\n \u003cp\u003e\u003cem\u003e0.328\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 185px;\"\u003e\n \u003cp\u003eHeight(m)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e1.6(0.1)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 88px;\"\u003e\n \u003cp\u003e1.6(0.1)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e1.6(0.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 93px;\"\u003e\n \u003cp\u003e\u003cem\u003e0.337\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 185px;\"\u003e\n \u003cp\u003eWeight(kg)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e71.7(6.7)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 88px;\"\u003e\n \u003cp\u003e70.4(9.8)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e71.1(8.1)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 93px;\"\u003e\n \u003cp\u003e\u003cem\u003e0.780\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 185px;\"\u003e\n \u003cp\u003eBMI(kg/㎡)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e27.0(2.2)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 88px;\"\u003e\n \u003cp\u003e26.3(2.8)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e27.2(2.8)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 93px;\"\u003e\n \u003cp\u003e\u003cem\u003e0.264\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 185px;\"\u003e\n \u003cp\u003ePrimiparity n(%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e13(38.2%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 88px;\"\u003e\n \u003cp\u003e10(29.0%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e15(44.0%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 93px;\"\u003e\n \u003cp\u003e\u003cem\u003e\u0026nbsp;\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 185px;\"\u003e\n \u003cp\u003eGestational age(w)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e39.1(1.1)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 88px;\"\u003e\n \u003cp\u003e39.7(1.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e39.6(1.4)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 93px;\"\u003e\n \u003cp\u003e\u003cem\u003e0.096\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 185px;\"\u003e\n \u003cp\u003eFetal Weight(g)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e3236(253)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 88px;\"\u003e\n \u003cp\u003e3194(301)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e3207(275)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 93px;\"\u003e\n \u003cp\u003e\u003cem\u003e0.701\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e(Age,height,weight,BMI,gestational,fetal weight are expressed as mean (SD); Primigravida is expressed as n(%)）\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 2:\u003c/strong\u003e Time to adequate analgesia, ropivacaine consumption per unit time and \u0026nbsp;duration of labour for the 3 cm, 5 cm, and 7 cm groups, n=34\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"568\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 198px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 110px;\"\u003e\n \u003cp\u003e3cm Group\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 105px;\"\u003e\n \u003cp\u003e5cm Group\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 102px;\"\u003e\n \u003cp\u003e7cm Group\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 52px;\"\u003e\n \u003cp\u003e\u003cem\u003eP Value\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 198px;\"\u003e\n \u003cp\u003eTime to Adequate Analgesia (min)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 110px;\"\u003e\n \u003cp\u003e5.2(5.0-6.2)*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 105px;\"\u003e\n \u003cp\u003e7.0(5.0-8.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 102px;\"\u003e\n \u003cp\u003e8.1(6.2-11.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 52px;\"\u003e\n \u003cp\u003e\u003cem\u003e0.001\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 198px;\"\u003e\n \u003cp\u003eBlock level(not feel cold)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 110px;\"\u003e\n \u003cp\u003eT10(T8-T10)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 105px;\"\u003e\n \u003cp\u003eT10(T8-T10)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 102px;\"\u003e\n \u003cp\u003eT10(T8-T10)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 52px;\"\u003e\n \u003cp\u003e\u003cem\u003e0.126\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 198px;\"\u003e\n \u003cp\u003eRopivacaine Consumption per Unit Time (mg/h)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 110px;\"\u003e\n \u003cp\u003e10.7(10.2-11.4)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 105px;\"\u003e\n \u003cp\u003e10.5(10.2-11.4)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 102px;\"\u003e\n \u003cp\u003e10.7(10.5-11.2)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 52px;\"\u003e\n \u003cp\u003e\u003cem\u003e0.672\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 198px;\"\u003e\n \u003cp\u003eDuration of first Stage(min)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 110px;\"\u003e\n \u003cp\u003e510(369.5-592.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 105px;\"\u003e\n \u003cp\u003e430(327.5-640)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 102px;\"\u003e\n \u003cp\u003e541(415-757.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 52px;\"\u003e\n \u003cp\u003e\u003cem\u003e0.216\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 198px;\"\u003e\n \u003cp\u003eDuration of Second Stage(min)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 110px;\"\u003e\n \u003cp\u003e42(50-57.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 105px;\"\u003e\n \u003cp\u003e57.5(19-82)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 102px;\"\u003e\n \u003cp\u003e32.5(27-60.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 52px;\"\u003e\n \u003cp\u003e\u003cem\u003e0.596\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 198px;\"\u003e\n \u003cp\u003eDuration of Third Stage(min)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 110px;\"\u003e\n \u003cp\u003e9(8-11.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 105px;\"\u003e\n \u003cp\u003e9(8.5-11)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 102px;\"\u003e\n \u003cp\u003e10(9-10)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 52px;\"\u003e\n \u003cp\u003e\u003cem\u003e0.724\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 198px;\"\u003e\n \u003cp\u003eDuration of labour analgesia\u0026nbsp;(min)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 110px;\"\u003e\n \u003cp\u003e420(307.5-532.6)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 105px;\"\u003e\n \u003cp\u003e401(298.4-504)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 102px;\"\u003e\n \u003cp\u003e398(308.4-508)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 52px;\"\u003e\n \u003cp\u003e\u003cem\u003e0.408\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u0026nbsp;(Values are median (IQR). Significant differences are indicated as follows: \u003cem\u003e*p=0.001\u003c/em\u003e for 3 cm group vs 5 cm group, \u003cem\u003e*p\u0026lt;0.05\u003c/em\u003e for 3 cm group vs 7 cm group, and \u003cem\u003ep=0.11\u003c/em\u003e for 5 cm group vs 7 cm group）\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 3:\u003c/strong\u003e Incidence rates of hypotension, pruritus, unilateral blockade, nausea, catheter dislodgment, and motor block, n=34\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"100%\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 35px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17px;\"\u003e\n \u003cp\u003e3cm Group\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18px;\"\u003e\n \u003cp\u003e5cm Group\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15px;\"\u003e\n \u003cp\u003e7cm Group\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 12px;\"\u003e\n \u003cp\u003e\u003cem\u003eP Value\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 35px;\"\u003e\n \u003cp\u003eHypotension，n（%）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17px;\"\u003e\n \u003cp\u003e4（11.8%）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18px;\"\u003e\n \u003cp\u003e1（2.9%）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15px;\"\u003e\n \u003cp\u003e2（5.9%）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 12px;\"\u003e\n \u003cp\u003e\u003cem\u003e0.090\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 35px;\"\u003e\n \u003cp\u003ePruritus，n（\u0026nbsp;%）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17px;\"\u003e\n \u003cp\u003e11（32.4%）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18px;\"\u003e\n \u003cp\u003e7（20.6%）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15px;\"\u003e\n \u003cp\u003e2（5.9%）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 12px;\"\u003e\n \u003cp\u003e\u003cem\u003e0.001*\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 35px;\"\u003e\n \u003cp\u003eUnilateral Block，n（%）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17px;\"\u003e\n \u003cp\u003e1（2.9%）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18px;\"\u003e\n \u003cp\u003e2（5.9%）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15px;\"\u003e\n \u003cp\u003e4（11.8%）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 12px;\"\u003e\n \u003cp\u003e\u003cem\u003e0.119\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 35px;\"\u003e\n \u003cp\u003eNausea，n（%）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17px;\"\u003e\n \u003cp\u003e11（32.4%）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18px;\"\u003e\n \u003cp\u003e6（17.6%）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15px;\"\u003e\n \u003cp\u003e5（14.7%）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 12px;\"\u003e\n \u003cp\u003e\u003cem\u003e0.272\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 35px;\"\u003e\n \u003cp\u003eCatheter Displacement，n（%）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17px;\"\u003e\n \u003cp\u003e2（5.9%）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 12px;\"\u003e\n \u003cp\u003e\u003cem\u003e0.164\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 35px;\"\u003e\n \u003cp\u003eMotor Block (Bromage \u0026gt;0), n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17px;\"\u003e\n \u003cp\u003e1（2.9%）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18px;\"\u003e\n \u003cp\u003e2（5.9%）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 15px;\"\u003e\n \u003cp\u003e2（5.9%）\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 12px;\"\u003e\n \u003cp\u003e\u003cem\u003e0.737\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e(Hypotension, pruritus, unilateral block, nausea, catheter displacement,and motor block are expressed as frequencies. Differences are indicated by *\u003cem\u003eP \u0026lt; 0.05\u003c/em\u003e）\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 4:\u0026nbsp;\u003c/strong\u003eNeonatal Apgar scores, cesarean conversion rates and causes .\u003c/p\u003e\n\u003cp\u003eValues are median (IQR) or n(%) ,n=34\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 272px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 81px;\"\u003e\n \u003cp\u003e3cm Group\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 79px;\"\u003e\n \u003cp\u003e5cm Group\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e7cm Group\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 60px;\"\u003e\n \u003cp\u003e\u003cem\u003eP Value\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 272px;\"\u003e\n \u003cp\u003eApgar Score\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 81px;\"\u003e\n \u003cp\u003e9(9-9)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 79px;\"\u003e\n \u003cp\u003e9(9-9)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e9(9-9)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 60px;\"\u003e\n \u003cp\u003e\u003cem\u003e0.462\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 272px;\"\u003e\n \u003cp\u003eCesarean Section Rate，n(%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 81px;\"\u003e\n \u003cp\u003e6(17.6%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 79px;\"\u003e\n \u003cp\u003e5(15.0%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e5(15.0%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 60px;\"\u003e\n \u003cp\u003e\u003cem\u003e0.232\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 272px;\"\u003e\n \u003cp\u003eCause of Cesarean Scetion\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 81px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 79px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 60px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 272px;\"\u003e\n \u003cp\u003e\u0026nbsp; Fever (Chorioamnionitis)，n(%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 81px;\"\u003e\n \u003cp\u003e3(8.8%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 79px;\"\u003e\n \u003cp\u003e1(2.9%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e2(5.9%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 60px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 272px;\"\u003e\n \u003cp\u003ePersistent Occiput Posterior Position，n(%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 81px;\"\u003e\n \u003cp\u003e1(2.9%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 79px;\"\u003e\n \u003cp\u003e1(2.9%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e1(2.9%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 60px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 272px;\"\u003e\n \u003cp\u003eFetal Distress，n(%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 81px;\"\u003e\n \u003cp\u003e2(5.9%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 79px;\"\u003e\n \u003cp\u003e2(5.9%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e2(5.9%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 60px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 272px;\"\u003e\n \u003cp\u003eUterine Inertia，n(%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 81px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 79px;\"\u003e\n \u003cp\u003e1(2.9%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 60px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e(Apgar Score values are median (IQR);cesarean Section Rate and cause of Cesarean Scetion are expressed as frequencies.)\u003c/p\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"bmc-anesthesiology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"bane","sideBox":"Learn more about [BMC Anesthesiology](http://bmcanesthesiol.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/bane","title":"BMC Anesthesiology","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"dural puncture epidural, programmed intermittent epidural bolus, epidural catheter, labour analgesia","lastPublishedDoi":"10.21203/rs.3.rs-8037232/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8037232/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eBackground\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe dural puncture epidural (DPE) technique combined with programmed intermittent epidural bolus (PIEB) has been widely used in the clinical practice of labour analgesia. Whether varying the length of catheter threaded into the epidural space benefits for the resultant analgesia remains unclear.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMethods\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e102 women in labour were enrolled, aged 18-45 years, with cervical dilation \u0026gt;3 cm and a numeric rating scale (NRS) score \u0026gt; 4, were randomly (1:1:1) assigned to three study groups (the epidural catheter threaded 3, 5, or 7 cminto the epidural space) for labour analgesia. The primary outcome was time to reach adequate analgesia, defined as a NRS≤3 after placement of the catheter and a test dose with 3 mL of 1.5% lidocaine, an additional 10 mL of 0.1% ropivacaine with 0.3 µg/mL sufentanil was administered. Secondary outcomes included pain score, anesthetic consumption, duration of labour, adverse events (pruritus, nausea, hypotension, unilateral block, catheter dislodgment, motor blockade) and Apgar scores.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eMedian time to reach adequate analgesia was significant different among three group: 5.2 min vs.7.0 min vs. 8.1min in 3, 5 and 7 cm insertion, while, the incidence of pruritus was 32.4% vs. 20.6% vs. 5.9% in three group, \u003cem\u003eP=0.001\u003c/em\u003e, respectively. There were no differences in other severe adverse events among groups, but incidence of nausea was higher (32.4%) in 3cm group than that in 5cm（17.6%）or 7cm (14.7%) group. Hypotension developed in four patients in the 3 cm group and unilateral block was observed in four patients in the 7 cm group. Pain score, local anaesthetic consumption, labour duration, catheter dislodgment, motor blockade, and Apgar score of the newborns were statistically insignificant.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusion\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eDuring labour analgesia with DPE combination with PIEB, when the epidural catheter is left 3 cm in the epidural space, the onset of action is faster, but the incidence of pruritus and nausea are higher. Therefore, in order to minimize either catheter or drug-related complications and provide satisfactory analgesia, the appropriate length of catheterization for epidural labour analgesia should be 5 cm.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTrail registration\u003c/strong\u003e ClinicalTrials.gov (NCT06602440); retrospectively registered on 17 September, 2024.\u003c/p\u003e","manuscriptTitle":"Appropriate length of epidural catheter in epidural space for labour analgesia with dural puncture epidural combined with programmed intermittent epidural bolus","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-12-16 16:04:14","doi":"10.21203/rs.3.rs-8037232/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-12-23T12:47:29+00:00","index":"","fulltext":""},{"type":"reviewerAgreed","content":"156723508804842997899974299969888341788","date":"2025-12-21T18:44:45+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-12-20T08:54:22+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"97103477960755379825970352312802106111","date":"2025-12-20T08:25:37+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-12-18T08:33:55+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"325401228297448919283985800921976840769","date":"2025-12-17T10:07:24+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"259947087693067183178056249837445366102","date":"2025-12-16T02:15:42+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"317191936543762772053215664241635730152","date":"2025-12-15T05:49:23+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"210347260737814738650980843443050100814","date":"2025-12-14T23:32:18+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-12-12T13:13:47+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"227985170669837442062271639674634485519","date":"2025-12-12T06:46:16+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-12-11T08:35:12+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-12-11T08:24:18+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2025-12-02T11:46:39+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-12-01T16:18:06+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Anesthesiology","date":"2025-12-01T15:55:13+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"bmc-anesthesiology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"bane","sideBox":"Learn more about [BMC Anesthesiology](http://bmcanesthesiol.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/bane","title":"BMC Anesthesiology","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"dba5c480-988d-4035-96e9-206a489f38f2","owner":[],"postedDate":"December 16th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2026-01-26T15:59:46+00:00","versionOfRecord":{"articleIdentity":"rs-8037232","link":"https://doi.org/10.1186/s12871-026-03637-x","journal":{"identity":"bmc-anesthesiology","isVorOnly":false,"title":"BMC Anesthesiology"},"publishedOn":"2026-01-20 15:57:04","publishedOnDateReadable":"January 20th, 2026"},"versionCreatedAt":"2025-12-16 16:04:14","video":"","vorDoi":"10.1186/s12871-026-03637-x","vorDoiUrl":"https://doi.org/10.1186/s12871-026-03637-x","workflowStages":[]},"version":"v1","identity":"rs-8037232","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8037232","identity":"rs-8037232","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}