Comparison of different approaches to combined spinal epidural anesthesia (CSEA) under the guidance of ultrasound in cesarean delivery obese patients: A randomized controlled trial

Comparison of different approaches to combined spinal epidural anesthesia (CSEA) under the guidance of ultrasound in cesarean delivery obese patients: A randomized controlled trial | 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 Help Center Sign In Submit a Preprint Cite Share Download PDF Research article Comparison of different approaches to combined spinal epidural anesthesia (CSEA) under the guidance of ultrasound in cesarean delivery obese patients: A randomized controlled trial Yilu Zhou, Zhendong Xu, Zhiqiang Liu This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-33022/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 7 You are reading this latest preprint version Abstract Background: Combined spinal epidural anesthesia (CSEA) is commonly performed in cesarean deliveries. However, it is difficult to perform in obese parturients because of positioning challenges. The aim of this study was to compare the effect of different approaches to CSEA under the guidance of ultrasound. Methods: One hundred obese patients (BMI≧30 kg/m 2 ) who underwent elective cesarean section were randomly enrolled. Patients were assigned to a median approach group and a paramedian approach group randomly. Clinical characteristics were compared between groups. First puncture success rate, ultrasonic time needed for positioning and puncture time, ultrasonic predicted anesthesia puncture depth, actual puncture depth, adverse reactions to anesthesia, complications after anesthesia, and patient satisfaction with the epidural puncture were recorded. Results: The first puncture success rate was significantly different between the two groups (92% vs 86%, P <0.05). The positioning time and total puncture time in the paramedian approach group were higher than those in the median approach group (217.7 s vs 201.6 s, P <0.05; 251.3 s vs 247.4 s, P＞0.05). The incidence of postanesthesia complications in the paramedian approach group was significantly lower than that in the median approach group (2% vs 12%, P <0.05), and patient satisfaction was higher in the paramedian approach group than in the median approach group (P <0.05). Conclusion: The ultrasound-guided paracentesis approach for intrauterine spinal anesthesia for cesarean section patients is time-consuming, but it can effectively improve the success rate of the first puncture, reduce the incidence of anesthesia-related adverse reactions, and improve patient satisfaction. Trial registration: This study was registered with the Chinese Clinical Trial Registry (ChiCTR1900024722) on July 24, 2019. Anesthesiology & Pain Medicine different approaches combined spinal epidural anesthesia ultrasound cesarean delivery obese patients Figures Figure 1 Figure 2 Background Combined spinal epidural anesthesia (CSEA) has the advantages of quick onset, good effect and controllable action time. It has been widely used in clinical practice and has become the preferred anesthesia method for cesarean section[ 1 ]. However, failure of intraspinal anesthesia puncture caused by a large abdominal circumference, a nonideal anesthesia position, obesity and tissue edema, as well as anesthesia-related complications, such as nerve injury, unsatisfactory anesthetic effect and postpartum lumbago, are not uncommon[ 2 ]. Therefore, it is particularly important to improve the success rate of CSEA for pregnant women, especially for obese patients. Ultrasound technology has the advantages of easy operation and noninvasiveness and has been widely valued in clinical practice. Previous studies have shown that ultrasound imaging of the spine has the ability to assist in locating the epidural space[ 3 , 4 ] and can also be used to measure the distance from the skin to the epidural space to predict the penetration depth of the puncture needle to avoid the o puncture of the dura mater caused by a too-deep puncture. Some studies have shown that although there is a certain difference between the ultrasonic prediction of puncture depth and the actual operation of epidural puncture depth, there is still a good correlation between them[ 5 ]. This provides some guidance for anesthesiologists for conducting ultrasound-guided epidural puncture. Epidural puncture by anesthesiologists under the guidance of ultrasound has become one of the hot topics of clinical anesthesia and pain treatment research[ 6 ]. Studies have found that there may be no significant difference in the timing between traditional intraspinal puncture by experienced anesthesiologists and ultrasound-guided epidural puncture [ 7 – 9 ], which does not reflect the application advantage of ultrasound in epidural puncture. However, ultrasound localization is helpful for epidural puncture in patients with difficult surface localization or abnormal anatomical markers. A recent study found that ultrasound positioning can be used for intraspinal anesthesia in cesarean section of obese pregnant women[ 10 ]. The first puncture success rate in the ultrasound group was significantly improved, the number of punctures was significantly reduced, the incidence of postoperative low back pain of parturients was reduced, and the safety of anesthesia was increased. These findings are consistent with the conclusions of other researchers[ 11 ]. However, some studies have found that the incidence of postpartum low back pain was high in overweight or obese women after spinal anesthesia[ 12 ], and the incidence of postpartum low back degeneration was high in obese women[ 13 ]. There are two puncture approaches for combined spinal epidural anesthesia: median approach puncture and paramedian approach puncture. Early studies have noted that the success rate of paramedian approach puncture was higher than that of median approach puncture and that it is associated with fewer complications and postoperative complications[ 14 ]. To date, we found that all the relevant studies on intraspinal anesthesia have used the median approach puncture by ultrasound; however, it is still unknown whether the paramedian approach under ultrasound can improve the success rate of puncture and reduce complications when compared with the median approach. Methods Materials And Methods This study was approved by the Ethics Committee of Shanghai First Maternity and Infant Hospital and was registered with the Chinese Clinical Trial Registry (ChiCTR1900024722). A total of one hundred obese pregnant women who underwent elective cesarean section in Shanghai First Maternity and Infant Hospital from August 2019 to March 2020 were selected. The inclusion criteria were as follows: age ≥ 18 years, normal singleton pregnancy, gestational age ≥ 37 weeks, and body mass index (BMI) ≥ 30 kg/m 2 (based on weight measured the day before delivery). The exclusion criteria were as follows: rejection of spinal anesthesia; twins; a history of spinal deformity or spinal surgery; contraindications to spinal anesthesia (infection of the puncture site, coagulation dysfunction, allergy to local anesthesia, insufficient blood volume or abnormal spinal anatomy); and emergency cesarean section. Combined spinal epidural anesthesia was performed on all patients, and the L3-4 or L2-3 interspace was selected. According to the different puncture approaches, 50 patients were divided into a median approach group and a paramedian approach group. No sedation was provided before or during anesthesia. One anesthesiologist with more than three years of clinical experience in spinal anesthesia was selected as the operator. Ultrasound was performed by a single researcher trained in the technique, and more than 150 ultrasound-guided spinal block experiences were performed. Anesthesia care The patient was placed in the right-side position with the arms embracing the knees and the back arched. A Sonosite convex array probe was used for ultrasonic scanning. The ultrasonic probe was placed at the middle level of the sacrococcygeal region, and a scan was performed horizontally and moved to the lumbosacral region. The L3 vertebra, L4 vertebra and L3-L4 interspace were identified, the skin was marked, and the probe was turned to the horizontal position while keeping it centered. Then, the position of the L3 vertebra was determined and marked, and the intersection of the longitudinal and transverse lines at the L3-L4 interspace was determined as the puncture point for the median approach. In longitudinal sagittal ultrasound imaging, it is necessary to identify the L3 and L4 articular processes and the ligamentum flavum in the middle of the articular processes and to measure the distance between the skin and ligamentum flavum to predict the puncture depth (Fig. 1 A). In the paramedian approach group, the L3-L4 interspace was selected, and the puncture point was 1.5 cm below this area in the median vertical paracentesis. And the distance between the skin and the ligamentum flavum was measured by ultrasound at the puncture point to predict the depth of anesthesia puncture (Fig. 1 B). After the skin was marked, the skin was disinfected, a towel was spread, 1% lidocaine was injected into the skin for local anesthesia, and it was confirmed that the 16G epidural puncture needle had entered into the epidural space (negative pressure method). The patient was instructed to keep still, and the subarachnoid cavity was entered through the epidural needle cavity with a 25G lumbar anesthesia needle. After cerebrospinal fluid appeared in the lumbar puncture needle, the needle tip was pointed toward the patient's head, and 0.5% ropivacaine 2 ~ 3 mL was injected at rate of approximately 0.1 mL/s. After injection, the spinal needle was pulled out, an epidural catheter was placed, and the patient was moved to left supine position. In the paramedian approach group, the angle between the needle and the skin was 75°, and other steps were as the same as in the median approach group. The L3-L4 interspace was the first choice for puncture, and the L2-L3 interspace was used for the follow-up attempt. A maximum of 3 skin puncture attempts (needle withdrawn from the skin and then readvanced) were allowed for one interspace and a maximum of 5 needle passes (needle withdrawn and readvanced without complete withdrawal from the skin) were allowed for each skin puncture attempt. If dural puncture was unsuccessful after attempts at the L2–L3 interspace, the operator was allowed to use other means to perform anesthesia, including changing the operator or anesthesia mode. Successful spinal anesthesia was defined by a bilateral T4 block five minutes after injection. The incidence of hypotension (mean blood pressure below 90 mmHg or systolic pressure reduction of > 25% from the initial value) was recorded. Other complications, such as bloody tap or paresthesia, were also recorded by an independent observer blinded to the group allocation. A blinded attending anesthesiologist recorded all the outcomes. Measurement The clinical data of the patients, including age, gestational age, height, weight and BMI, were recorded. The primary outcome was the rate of successful dural puncture on the first attempt. Secondary outcomes were the location time (from the time the operator placed the ultrasonic probe on the back of the patient to the end of positioning), puncture time (total operation time, location time), adverse reactions during puncture (incidence of nerve stimulation, bleeding), total operation time (the time from disinfection to the time when the patient changed to supine position), and complications after anesthesia (incidence of postoperative low back pain). Statistical analysis Statistical analysis was performed using SPSS Version 22.0 (IBM, Armonk, NY). Continuous data were tested for normality using Q-Q plots and the Shapiro–Wilk W statistic. Normally distributed outcome data were summarized as the mean (standard deviation) values and were compared between groups using independent measures t test. Categorical data were analyzed using the χ 2 test or Fisher’s exact test. The primary outcome (the first-attempt success rate) was analyzed using the χ2 test, while Fisher’s exact test was used for subgroup analyses for subgroups with P values considered statistically significant. Results A total of 133 women were recruited for the study from August 2019 to March 2020,after exclusion there were 100 patient in analysis.There were fifty patients in the paramedian approach group and fifty patients in the median approach group. No patients were excluded due to loss of data or failed follow-up (Fig. 2 ). There were no significant differences in age, gestational age, height, weight, BMI, ASA grade or operation time between the two groups (Table 1 ). Table 1 Patient Characteristics Median approach group (n = 50) Paramedian approach group (n = 50) P value Age (y) 32.53 ± 8.53 32.02 ± 10.02 0.443 Gestational age (d) 273.6 ± 6.56 274.1 ± 6.13 0.171 Height (cm) 160.57 ± 11.43 161.36 ± 12.64 0.426 Weight (kg) 83.21 ± 15.79 84.47 ± 19.53 0.380 ASA Grade - - - Grade I 8 10 0.380 Grade II 42 40 0.264 Duration of surgery (min) 36.66 ± 23.33 33.57 ± 7.43 0.510 BMI (kg/m 2 ) 32.37 ± 4.13 32.41 ± 6.09 0.921 Obesity grading - - - 30 ≦ BMI ≦ 34.9 38 (76%) 39 (78%) 0.652 34.9 ≦ BMI ≦ 39.9 7 (14%) 5 (10%) 0.584 40 ≦ BMI 5 (10%) 6 (12%) 0.813 Data related to intraspinal anesthesia from the two groups are shown in Table 2 . The success rate of the first attempt in the paramedian approach group was significantly higher (92% vs 86%, P < 0.05) than that in the median approach group. Two groups of patients achieved bilateral T4 block after successful anesthesia, and there were no cases in which the mode of anesthesia of changed. There was no significant difference between the two groups in the total operation time of puncture (time from disinfection to supine position) (P > 0.05), but the location time of the paramedian approach group was significantly longer than that of the median approach group (P < 0.05). In addition, there were some differences in anesthesia-related adverse reactions between the two groups. Compared with that in the median approach group, lower nerve stimulation occurred during anesthesia puncture (1/50 vs 2/50, P > 0.05) in the paramedian approach group. Blood returned after epidural catheter implantation (2/50 vs 3/50, P > 0.05), and there was a significant difference in the incidence of postoperative lumbar back pain between the two groups (1/50 vs 6/50, P < 0.05). Patients in the paramedian approach group had higher satisfaction (P < 0.05) than those in the median approach group. Table 2 Comparisons of Procedure-Related Data Between Groups Median approach group (n = 50) Paramedian approach group (n = 50) P value First-attempt success rate 43(86%) 46(92%) 0.041 * Location time 201.6(169.3-219.5) 217.7(183.7-231.8) 0.037 * Total operation time 247.4(225.3-272.8) 251.3(228.7-276.8) 0.145 Anesthesia adverse reactions - - - Nerve stimulation 2 1 0.742 Epidural catheter bleeding 3 2 0.686 Low back pain 6 1 0.026 * Puncture dura mater 0 0 - Satisfaction - - 0.032 * Very satisfied 17 25 - Satisfied 30 24 - Dissatisfied 3 1 - Table 3 shows the data of the ultrasonic predicted anesthesia puncture depth and actual puncture depth in the two groups. There was no significant difference in the actual puncture depth between the two groups (in the median approach group, P = 0.927; in the paracentral approach group, P = 0.726). Table 3 Comparison of the ultrasonic prediction anesthesia puncture depth and the actual puncture depth Ultrasonic prediction puncture depth Actual puncture depth P value Median approach group (n = 50) 5.63 ± 1.52 5.67 ± 1.67 0.927 Paramedian approach group (n = 50) 5.66 ± 1.82 5.81 ± 1.74 0.726 Discussion In this randomized controlled study, we found that the first puncture success rate in the paramedian approach group was 92%, which was significantly higher than the 86% in the median approach group (P < 0.05). In the paramedian approach, the superior and interspinous ligaments were avoided so that the epidural space was entered directly from the ligamentum flavum. There were fewer ligaments and other anatomical structures; therefore, the first puncture success rate was higher in the paramedian approach group than in the median approach group. In addition, based on the analysis of the anatomical structure of the spine, the paramedian approach is not limited by the inclination of the spinous process and the bone structure. When entering the epidural space, the end of the puncture needle is more inclined to form an angle on the side of the head, the cerebrospinal fluid returns smoothly after the insertion of the lumbar anesthesia needle, and it is easier to place the epidural catheter after the completion of the lumbar anesthesia. Some studies have confirmed that the puncture interspace of the paramedian approach is wider than that of median approach, which reduces the difficulty of puncture, avoids repeated puncture and increases the success rate of puncture[ 15 ]. At the same time, the controversy over the use of ultrasound to assess the distance between the skin and the epidural space should be considered. In theory, the actual puncture depth is deeper than that predicted by ultrasound. Our study found that the actual depth of extradural puncture was deeper than that predicted by ultrasound, but there was no significant difference between groups (P < 0.05). The reason may be that when the operator evaluates the success of epidural puncture, the needle insertion is stopped immediately when negative pressure is felt during the puncture to avoid placing the puncture needle too deeply, especially for anesthesiologists with more puncture experience. There was no significant difference between the predicted puncture depth and the actual puncture depth in the median approach group, which suggested that ultrasound could effectively predict the epidural puncture depth in different approaches of combined spinal epidural anesthesia. However, it should be pointed out that the actual puncture depth of both groups of data was deeper than that predicted by ultrasound. Considering the possible influence of fat thickness or tissue edema on the backs of obese pregnant women, our study compressed the maternal skin to avoid its influence when ultrasound placed the puncture point. In this study, a high-frequency convex array probe was used to accurately determine the best puncture point of anesthesia in the median approach group. The selection of puncture point in the paramedian approach group was based on the lateral paracentesis of 1.5 cm at the median approach puncture point, and on this basis, ultrasound was used to predict the puncture depth. Therefore, it was found that the positioning time of the paramedian group was higher than that of the median group (P 0.05). Considering that the first puncture success rate of the two groups was high, the number of attempts was small, and the skilled operation of anesthesiologists had a certain relationship. Anesthesia safety is also an important factor in this study. Among the one hundred obese pregnant women included in this study, there were adverse effects of anesthesia in both groups, such as epidural catheter bleeding, nerve stimulation signs and the occurrence of low back pain after anesthesia, and there were significant differences between the two groups in the occurrence of low back pain (P < 0.05). We considered that the paramedian approach group could avoid the supraspinous ligament and part of the interspinous ligament and allow entrance into the epidural space through the ligamentum flavum in the process of puncture. The analysis shows that the main reason for the difference in the incidence of low back pain between the two groups is the difference in ligament injury caused by the dural puncture needle. There was no significant difference in nerve stimulation between the two groups. It is worth mentioning that there were no cases of unexpected dural puncture in the either of the groups, further suggesting the advantage of ultrasound in obese women. There was a higher degree of satisfaction in the paramedian approach group than in the median approach group (P < 0.05). Previous studies have found that there is no significant difference in the success rate of traditional intraspinal puncture when ultrasound is used and when it is not in normal pregnant patient[ 16 ], which does not reflect the application advantages of ultrasound in epidural puncture. Therefore, this study is more valuable for the application of ultrasound-guided epidural puncture in obese cesarean section women. In addition, it should be pointed out that the technology of ultrasound intervention in epidural puncture can be divided into prepuncture positioning and real-time guiding operation, but the real-time guiding requires aseptic treatment of the probe, the operation process is complex, and the advantage is not obvious compared with the prepuncture ultrasound positioning; additionally, in the operation process, elimination of air/liquid resistance is still used to determine whether the tip of the needle reaches the epidural cavity[ 17 ]. Therefore, in this study, we chose to place the epidural catheter before ultrasound-guided puncture rather than under real-time ultrasound-guided puncture. Of course, there are some limitations in our research. First, although we used the same anesthesiologist with much experience in using spinal ultrasound, the results are still controversial. Second, we had a relatively small number of cases and fewer positive results. More samples are needed for further study. Conclusion Our conclusion is that the ultrasound-guided paramedian approach puncture for combined spinal anesthesia for cesarean section patients is more time-consuming, but it can effectively improve the success rate of the first puncture, reduce the incidence of anesthesia-related adverse reactions, and improve patient satisfaction. Abbreviations CSEA: Combined spinal epidural anesthesia; BMI: Body mass index; ASA: American Society of Anesthesiologists classification Declarations Acknowledgements Not applicable. Authors’ contributions Zhiqiang Liu designed the study and drafted the manuscript.Yilu Zhou participated in the design of the study and interpreted the results. Zhendong Xu participated in the interpretation of the results. All authors read and approved the final manuscript. Funding This study received no funding from the public, commercial or nonprofit sectors that provide special grants for this research. Availability of data and materials All data generated or analyzed during this study are presented in this manuscript and/or additional supporting files. The additional datasets are also available from the corresponding author on reasonable request. Ethics approval and consent to participate This study was approved by the Ethics Committee of Shanghai First Maternity and Infant Hospital and was registered in the Chinese Clinical Trial Registry (ChiCTR1900024722) on July 24, 2019.The registry can be monitored at this link http://www.chictr.org.cn/index.aspx . Written informed consent to participate was obtained from each participant. Consent for publication Not applicable. Competing interests There was no conflict of interest in this study. Conflicts of interest None References Reynolds F, Seed PT. Anaesthesia for Caesarean section and neonatal acid-base status: a meta-analysis. ANAESTHESIA. 2005;60(7):636 – 53. 'doi:'10.1111/j.1365-2044.2005.04223.x. Gaiser R. Anesthetic Considerations in the Obese Parturient. CLIN OBSTET GYNECOL. 2016;59(1):193–203. 'doi:'10.1097/GRF.0000000000000180. Voloshin AG. Four-dimensional ultrasound guidance during epidural anaesthesia. Journal of Ultrasound. 2015;18(2):135 – 42. 'doi:'10.1007/s40477-014-0150-1. Beigi P, Malenfant P, Rasoulian A, Rohling R, Dube A, Gunka V. Three-Dimensional Ultrasound-Guided Real-Time Midline Epidural Needle Placement with Epiguide: A Prospective Feasibility Study. Ultrasound in Medicine & Biology. 2017;43(1):375-9. 'doi:'10.1016/j.ultrasmedbio.2016.08.033. Sahota JS, Carvalho JCA, Balki M, Fanning N, Arzola C. Ultrasound estimates for midline epidural punctures in the obese parturient: paramedian sagittal oblique is comparable to transverse median plane. ANESTH ANALG. 2013;116(4):829 – 35. 'doi:'10.1213/ANE.0b013e31827f55f0. Shaikh F, Brzezinski J, Alexander S, Arzola C, Carvalho JCA, Beyene J, et al. Ultrasound imaging for lumbar punctures and epidural catheterisations: systematic review and meta-analysis. BMJ: British Medical Journal. 2013;346(7902):11. 'doi:'10.1136/bmj.f1720. Chin A, Crooke B, Heywood L, Brijball R, Pelecanos AM, Abeypala W. A randomised controlled trial comparing needle movements during combined spinal-epidural anaesthesia with and without ultrasound assistance. ANAESTHESIA. 2018;73(4):466 – 73. 'doi:'10.1111/anae.14206. Tawfik MM, Atallah MM, Elkharboutly WS, Allakkany NS, Abdelkhalek M. Does Preprocedural Ultrasound Increase the First-Pass Success Rate of Epidural Catheterization Before Cesarean Delivery? A Randomized Controlled Trial. Anesthesia & Analgesia. 2017;124(3):851-6. 'doi:'10.1213/ANE.0000000000001325. Arzola C, Mikhael R, Margarido C, Carvalho JCA. Spinal ultrasound versus palpation for epidural catheter insertion in labour. EUR J ANAESTH. 2015;32(7):499–505. 'doi:'10.1097/EJA.0000000000000119. Li M, Ni X, Xu Z, Shen F, Song Y, Li Q, et al. Ultrasound-Assisted Technology Versus the Conventional Landmark Location Method in Spinal Anesthesia for Cesarean Delivery in Obese Parturients. Anesthesia & Analgesia. 2019;129(1):155 – 61. 'doi:'10.1213/ANE.0000000000003795. Sahin T, Balaban O, Sahin L, Solak M, Toker K. A randomized controlled trial of preinsertion ultrasound guidance for spinal anaesthesia in pregnancy: outcomes among obese and lean parturients. J ANESTH. 2014;28(3):413-9. 'doi:'10.1007/s00540-013-1726-1. Duarte VM, Meucci RD, Cesar JA. Dor lombar intensa em gestantes do extremo Sul do Brasil. Ciência & Saúde Coletiva. 2018;23(8):2487-94. 'doi:'10.1590/1413-81232018238.22562016. Bliddal M, Pottegård A, Kirkegaard H, Olsen J, Jørgensen JS, Sørensen TIA, et al. Degenerative musculoskeletal conditions in women according to pre-pregnancy BMI, pregnancy-related weight changes and parity. ARTHRITIS RHEUMATOL. 2015: n/a-n/a . 'doi:'10.1002/art.39565. Cushnie D, Urquhart JC, Gurr KR, Siddiqi F, Bailey CS. Obesity and spinal epidural lipomatosis in cauda equina syndrome. SPINE J. 2018;18(3):407 – 13. 'doi:'10.1016/j.spinee.2017.07.177. T G, R. W L, R C, E M. Ultrasound control for presumed difficult epidural puncture. ACTA ANAESTH SCAND. 2001;45(6):766 – 71. 'doi:'10.1034/j.1399-6576.2001.045006766.x. Malik T, Malas O, Thompson A. Ultrasound guided L5-S1 placement of labor epidural does not improve dermatomal block in parturients. INT J OBSTET ANESTH. 2019;38:52 – 8. 'doi:'10.1016/j.ijoa.2018.11.005. Schummer W, Koditz JA, Schelenz C, Reinhart K, Sakka SG. Pre-procedure ultrasound increases the success and safety of central venous catheterizationdagger. Br J Anaesth. 2014;113(1):122-9. 'doi:'10.1093/bja/aeu049. Supplementary Files supplement1.doc Cite Share Download PDF Status: Under Review Version 1 posted Review # 1 received at journal 06 Jul, 2020 Reviewer # 1 agreed at journal 02 Jul, 2020 Reviewers invited by journal 18 Jun, 2020 Editor assigned by journal 03 Jun, 2020 First submitted to journal 02 Jun, 2020 Submission checks completed at journal 02 Jun, 2020 Editor invited by journal 02 Jun, 2020 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. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-33022","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research article","associatedPublications":[],"authors":[{"id":648335,"identity":"3d6479bf-4977-426c-8d40-132dd7d1b431","order_by":0,"name":"Yilu Zhou","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA6UlEQVRIiWNgGAWjYBACNvbm459//PjHzM/efPBBQkUNYS18PMfSmBl7DrBL9hxLNnhw5hhhLXISOWbMDGwH+A1u5JhJPmxhJsJhPAfMHhfw3JFmOHPArCKxgY2Bv707gYBfGtKNZ1g8M2Zsb0i7kbhDhkHizNkNhGw5IMHDw5zMzHPg2I3EM2wMBhK5BLRIJDZI8LAx17dJJLYVJLYxE6MlmU2ah+0wMw+QwUCcFp5jzIYze9KYJYAMiYQzx3gI+kW+vf/jgw8/bJjtj/d//PijokaOv70XvxYMwEOa8lEwCkbBKBgFWAEA4WZLm8KC3HcAAAAASUVORK5CYII=","orcid":"","institution":"Shanghai first maternity and children hospital","correspondingAuthor":true,"submittingAuthor":false,"prefix":"","firstName":"Yilu","middleName":"","lastName":"Zhou","suffix":""},{"id":648336,"identity":"00619d90-fa47-4efe-a7b5-2c96100a3b1b","order_by":1,"name":"Zhendong Xu","email":"","orcid":"","institution":"Shanghai First Maternity and Infant hospital","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Zhendong","middleName":"","lastName":"Xu","suffix":""},{"id":648337,"identity":"a254f0f8-daed-439b-9b78-40427702fe02","order_by":2,"name":"Zhiqiang Liu","email":"","orcid":"","institution":"Shanghai first maternity and infant hospital","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Zhiqiang","middleName":"","lastName":"Liu","suffix":""}],"badges":[],"createdAt":"2020-06-02 03:43:25","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-33022/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-33022/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":1299321,"identity":"949a9206-d70d-41bc-9cd8-40611ca3f8e3","added_by":"auto","created_at":"2020-06-10 16:51:36","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":99904,"visible":true,"origin":"","legend":"(A) The distance from the skin to the epidural space guided by ultrasound in the median approach group. (B) The distance from the skin to the epidural space guided by ultrasound in the paramedian approach group.","description":"","filename":"Fig1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-33022/v1/Fig1.jpg"},{"id":1299322,"identity":"93d146c7-2043-4d88-a99a-e14121078e98","added_by":"auto","created_at":"2020-06-10 16:51:36","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":126083,"visible":true,"origin":"","legend":"Flowchart of the subject recruitment process","description":"","filename":"Fig2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-33022/v1/Fig2.jpg"},{"id":13538274,"identity":"5293a750-9d36-4e68-9999-8c47ee017193","added_by":"auto","created_at":"2021-09-17 01:38:53","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":464981,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-33022/v1/93e6065a-0ec0-492f-a393-2f1fb529b9b9.pdf"},{"id":2625558,"identity":"dfbe471b-bd67-4df5-a9bc-944eede5e139","added_by":"acdc","created_at":"2020-09-25 21:02:00","extension":"doc","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":202378,"visible":true,"origin":"acdc-supplements-supplement","legend":"","description":"{\"primaryId\":\"undefined\",\"secondaryId\":\"BANE-D-20-00500\",\"acdcId\":\"undefined\",\"revision\":\"undefined\",\"timestamp\":\"2020-06-07T15:00:26\",\"document\":\"supplements\",\"linkRel\":\"supplement\"}","filename":"supplement1.doc","url":"https://assets-eu.researchsquare.com/files/rs-33022/v1/supplement_1.doc"}],"financialInterests":"","formattedTitle":"Comparison of different approaches to combined spinal epidural anesthesia (CSEA) under the guidance of ultrasound in cesarean delivery obese patients: A randomized controlled trial","fulltext":[{"header":"Background","content":" \u003cp\u003eCombined spinal epidural anesthesia (CSEA) has the advantages of quick onset, good effect and controllable action time. It has been widely used in clinical practice and has become the preferred anesthesia method for cesarean section[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. However, failure of intraspinal anesthesia puncture caused by a large abdominal circumference, a nonideal anesthesia position, obesity and tissue edema, as well as anesthesia-related complications, such as nerve injury, unsatisfactory anesthetic effect and postpartum lumbago, are not uncommon[\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. Therefore, it is particularly important to improve the success rate of CSEA for pregnant women, especially for obese patients.\u003c/p\u003e \u003cp\u003eUltrasound technology has the advantages of easy operation and noninvasiveness and has been widely valued in clinical practice. Previous studies have shown that ultrasound imaging of the spine has the ability to assist in locating the epidural space[\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e] and can also be used to measure the distance from the skin to the epidural space to predict the penetration depth of the puncture needle to avoid the o puncture of the dura mater caused by a too-deep puncture. Some studies have shown that although there is a certain difference between the ultrasonic prediction of puncture depth and the actual operation of epidural puncture depth, there is still a good correlation between them[\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. This provides some guidance for anesthesiologists for conducting ultrasound-guided epidural puncture.\u003c/p\u003e \u003cp\u003eEpidural puncture by anesthesiologists under the guidance of ultrasound has become one of the hot topics of clinical anesthesia and pain treatment research[\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. Studies have found that there may be no significant difference in the timing between traditional intraspinal puncture by experienced anesthesiologists and ultrasound-guided epidural puncture [\u003cspan additionalcitationids=\"CR8\" citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e], which does not reflect the application advantage of ultrasound in epidural puncture. However, ultrasound localization is helpful for epidural puncture in patients with difficult surface localization or abnormal anatomical markers. A recent study found that ultrasound positioning can be used for intraspinal anesthesia in cesarean section of obese pregnant women[\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. The first puncture success rate in the ultrasound group was significantly improved, the number of punctures was significantly reduced, the incidence of postoperative low back pain of parturients was reduced, and the safety of anesthesia was increased. These findings are consistent with the conclusions of other researchers[\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eHowever, some studies have found that the incidence of postpartum low back pain was high in overweight or obese women after spinal anesthesia[\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e], and the incidence of postpartum low back degeneration was high in obese women[\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. There are two puncture approaches for combined spinal epidural anesthesia: median approach puncture and paramedian approach puncture. Early studies have noted that the success rate of paramedian approach puncture was higher than that of median approach puncture and that it is associated with fewer complications and postoperative complications[\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. To date, we found that all the relevant studies on intraspinal anesthesia have used the median approach puncture by ultrasound; however, it is still unknown whether the paramedian approach under ultrasound can improve the success rate of puncture and reduce complications when compared with the median approach.\u003c/p\u003e "},{"header":"Methods","content":" \u003ch2\u003eMaterials And Methods\u003c/h2\u003e \u003cp\u003eThis study was approved by the Ethics Committee of Shanghai First Maternity and Infant Hospital and was registered with the Chinese Clinical Trial Registry (ChiCTR1900024722). A total of one hundred obese pregnant women who underwent elective cesarean section in Shanghai First Maternity and Infant Hospital from August 2019 to March 2020 were selected. The inclusion criteria were as follows: age\u0026thinsp;\u0026ge;\u0026thinsp;18 years, normal singleton pregnancy, gestational age\u0026thinsp;\u0026ge;\u0026thinsp;37 weeks, and body mass index (BMI)\u0026thinsp;\u0026ge;\u0026thinsp;30\u0026nbsp;kg/m\u003csup\u003e2\u003c/sup\u003e (based on weight measured the day before delivery). The exclusion criteria were as follows: rejection of spinal anesthesia; twins; a history of spinal deformity or spinal surgery; contraindications to spinal anesthesia (infection of the puncture site, coagulation dysfunction, allergy to local anesthesia, insufficient blood volume or abnormal spinal anatomy); and emergency cesarean section. Combined spinal epidural anesthesia was performed on all patients, and the L3-4 or L2-3 interspace was selected. According to the different puncture approaches, 50 patients were divided into a median approach group and a paramedian approach group. No sedation was provided before or during anesthesia. One anesthesiologist with more than three years of clinical experience in spinal anesthesia was selected as the operator. Ultrasound was performed by a single researcher trained in the technique, and more than 150 ultrasound-guided spinal block experiences were performed.\u003c/p\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003eAnesthesia care\u003c/h2\u003e \u003cp\u003eThe patient was placed in the right-side position with the arms embracing the knees and the back arched. A Sonosite convex array probe was used for ultrasonic scanning. The ultrasonic probe was placed at the middle level of the sacrococcygeal region, and a scan was performed horizontally and moved to the lumbosacral region. The L3 vertebra, L4 vertebra and L3-L4 interspace were identified, the skin was marked, and the probe was turned to the horizontal position while keeping it centered. Then, the position of the L3 vertebra was determined and marked, and the intersection of the longitudinal and transverse lines at the L3-L4 interspace was determined as the puncture point for the median approach. In longitudinal sagittal ultrasound imaging, it is necessary to identify the L3 and L4 articular processes and the ligamentum flavum in the middle of the articular processes and to measure the distance between the skin and ligamentum flavum to predict the puncture depth (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eA). In the paramedian approach group, the L3-L4 interspace was selected, and the puncture point was 1.5\u0026nbsp;cm below this area in the median vertical paracentesis. And the distance between the skin and the ligamentum flavum was measured by ultrasound at the puncture point to predict the depth of anesthesia puncture (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eB).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eAfter the skin was marked, the skin was disinfected, a towel was spread, 1% lidocaine was injected into the skin for local anesthesia, and it was confirmed that the 16G epidural puncture needle had entered into the epidural space (negative pressure method). The patient was instructed to keep still, and the subarachnoid cavity was entered through the epidural needle cavity with a 25G lumbar anesthesia needle. After cerebrospinal fluid appeared in the lumbar puncture needle, the needle tip was pointed toward the patient's head, and 0.5% ropivacaine 2\u0026thinsp;~\u0026thinsp;3\u0026nbsp;mL was injected at rate of approximately 0.1\u0026nbsp;mL/s. After injection, the spinal needle was pulled out, an epidural catheter was placed, and the patient was moved to left supine position. In the paramedian approach group, the angle between the needle and the skin was 75\u0026deg;, and other steps were as the same as in the median approach group.\u003c/p\u003e \u003cp\u003eThe L3-L4 interspace was the first choice for puncture, and the L2-L3 interspace was used for the follow-up attempt. A maximum of 3 skin puncture attempts (needle withdrawn from the skin and then readvanced) were allowed for one interspace and a maximum of 5 needle passes (needle withdrawn and readvanced without complete withdrawal from the skin) were allowed for each skin puncture attempt. If dural puncture was unsuccessful after attempts at the L2\u0026ndash;L3 interspace, the operator was allowed to use other means to perform anesthesia, including changing the operator or anesthesia mode. Successful spinal anesthesia was defined by a bilateral T4 block five minutes after injection. The incidence of hypotension (mean blood pressure below 90\u0026nbsp;mmHg or systolic pressure reduction of \u0026gt;\u0026thinsp;25% from the initial value) was recorded. Other complications, such as bloody tap or paresthesia, were also recorded by an independent observer blinded to the group allocation. A blinded attending anesthesiologist recorded all the outcomes.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003eMeasurement\u003c/h2\u003e \u003cp\u003eThe clinical data of the patients, including age, gestational age, height, weight and BMI, were recorded. The primary outcome was the rate of successful dural puncture on the first attempt. Secondary outcomes were the location time (from the time the operator placed the ultrasonic probe on the back of the patient to the end of positioning), puncture time (total operation time, location time), adverse reactions during puncture (incidence of nerve stimulation, bleeding), total operation time (the time from disinfection to the time when the patient changed to supine position), and complications after anesthesia (incidence of postoperative low back pain).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003eStatistical analysis\u003c/h2\u003e \u003cp\u003eStatistical analysis was performed using SPSS Version 22.0 (IBM, Armonk, NY). Continuous data were tested for normality using Q-Q plots and the Shapiro\u0026ndash;Wilk W statistic. Normally distributed outcome data were summarized as the mean (standard deviation) values and were compared between groups using independent measures t test. Categorical data were analyzed using the χ\u003csup\u003e2\u003c/sup\u003e test or Fisher\u0026rsquo;s exact test. The primary outcome (the first-attempt success rate) was analyzed using the χ2 test, while Fisher\u0026rsquo;s exact test was used for subgroup analyses for subgroups with P values considered statistically significant.\u003c/p\u003e \u003c/div\u003e "},{"header":"Results","content":" \u003cp\u003eA total of 133 women were recruited for the study from August 2019 to March 2020,after exclusion there were 100 patient in analysis.There were fifty patients in the paramedian approach group and fifty patients in the median approach group. No patients were excluded due to loss of data or failed follow-up (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). There were no significant differences in age, gestational age, height, weight, BMI, ASA grade or operation time between the two groups (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003ePatient Characteristics\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMedian approach group (n\u0026thinsp;=\u0026thinsp;50)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eParamedian approach group (n\u0026thinsp;=\u0026thinsp;50)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cem\u003eP\u003c/em\u003e value\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAge (y)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e32.53\u0026thinsp;\u0026plusmn;\u0026thinsp;8.53\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e32.02\u0026thinsp;\u0026plusmn;\u0026thinsp;10.02\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.443\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGestational age (d)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e273.6\u0026thinsp;\u0026plusmn;\u0026thinsp;6.56\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e274.1\u0026thinsp;\u0026plusmn;\u0026thinsp;6.13\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.171\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHeight (cm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e160.57\u0026thinsp;\u0026plusmn;\u0026thinsp;11.43\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e161.36\u0026thinsp;\u0026plusmn;\u0026thinsp;12.64\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.426\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eWeight (kg)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e83.21\u0026thinsp;\u0026plusmn;\u0026thinsp;15.79\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e84.47\u0026thinsp;\u0026plusmn;\u0026thinsp;19.53\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.380\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eASA Grade\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGrade I\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.380\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGrade II\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e42\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e40\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.264\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDuration of surgery (min)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e36.66\u0026thinsp;\u0026plusmn;\u0026thinsp;23.33\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e33.57\u0026thinsp;\u0026plusmn;\u0026thinsp;7.43\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.510\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBMI (kg/m\u003csup\u003e2\u003c/sup\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e32.37\u0026thinsp;\u0026plusmn;\u0026thinsp;4.13\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e32.41\u0026thinsp;\u0026plusmn;\u0026thinsp;6.09\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.921\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eObesity grading\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e30\u0026thinsp;≦\u0026thinsp;BMI\u0026thinsp;≦\u0026thinsp;34.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e38 (76%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e39 (78%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.652\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e34.9\u0026thinsp;≦\u0026thinsp;BMI\u0026thinsp;≦\u0026thinsp;39.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e7 (14%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e5 (10%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.584\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e40\u0026thinsp;≦\u0026thinsp;BMI\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e5 (10%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e6 (12%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.813\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eData related to intraspinal anesthesia from the two groups are shown in Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e. The success rate of the first attempt in the paramedian approach group was significantly higher (92% vs 86%, P\u0026thinsp;\u0026lt;\u0026thinsp;0.05) than that in the median approach group. Two groups of patients achieved bilateral T4 block after successful anesthesia, and there were no cases in which the mode of anesthesia of changed. There was no significant difference between the two groups in the total operation time of puncture (time from disinfection to supine position) (P\u0026thinsp;\u0026gt;\u0026thinsp;0.05), but the location time of the paramedian approach group was significantly longer than that of the median approach group (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05). In addition, there were some differences in anesthesia-related adverse reactions between the two groups. Compared with that in the median approach group, lower nerve stimulation occurred during anesthesia puncture (1/50 vs 2/50, P\u0026thinsp;\u0026gt;\u0026thinsp;0.05) in the paramedian approach group. Blood returned after epidural catheter implantation (2/50 vs 3/50, P\u0026thinsp;\u0026gt;\u0026thinsp;0.05), and there was a significant difference in the incidence of postoperative lumbar back pain between the two groups (1/50 vs 6/50, P\u0026thinsp;\u0026lt;\u0026thinsp;0.05). Patients in the paramedian approach group had higher satisfaction (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05) than those in the median approach group.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eComparisons of Procedure-Related Data Between Groups\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMedian approach group (n\u0026thinsp;=\u0026thinsp;50)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eParamedian approach group (n\u0026thinsp;=\u0026thinsp;50)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eP value\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFirst-attempt success rate\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e43(86%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e46(92%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.041\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLocation time\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e201.6(169.3-219.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e217.7(183.7-231.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.037\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTotal operation time\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e247.4(225.3-272.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e251.3(228.7-276.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.145\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAnesthesia adverse reactions\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNerve stimulation\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.742\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eEpidural catheter bleeding\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.686\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLow back pain\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.026\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePuncture dura mater\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSatisfaction\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.032\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVery satisfied\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e17\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e25\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSatisfied\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e24\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDissatisfied\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eTable\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e shows the data of the ultrasonic predicted anesthesia puncture depth and actual puncture depth in the two groups. There was no significant difference in the actual puncture depth between the two groups (in the median approach group, P\u0026thinsp;=\u0026thinsp;0.927; in the paracentral approach group, P\u0026thinsp;=\u0026thinsp;0.726).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eComparison of the ultrasonic prediction anesthesia puncture depth and the actual puncture depth\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eUltrasonic prediction puncture depth\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eActual puncture depth\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eP value\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eMedian approach group (n\u0026thinsp;=\u0026thinsp;50)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e5.63\u0026thinsp;\u0026plusmn;\u0026thinsp;1.52\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e5.67\u0026thinsp;\u0026plusmn;\u0026thinsp;1.67\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.927\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eParamedian approach group (n\u0026thinsp;=\u0026thinsp;50)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e5.66\u0026thinsp;\u0026plusmn;\u0026thinsp;1.82\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e5.81\u0026thinsp;\u0026plusmn;\u0026thinsp;1.74\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.726\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e "},{"header":"Discussion","content":" \u003cp\u003eIn this randomized controlled study, we found that the first puncture success rate in the paramedian approach group was 92%, which was significantly higher than the 86% in the median approach group (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05). In the paramedian approach, the superior and interspinous ligaments were avoided so that the epidural space was entered directly from the ligamentum flavum. There were fewer ligaments and other anatomical structures; therefore, the first puncture success rate was higher in the paramedian approach group than in the median approach group. In addition, based on the analysis of the anatomical structure of the spine, the paramedian approach is not limited by the inclination of the spinous process and the bone structure. When entering the epidural space, the end of the puncture needle is more inclined to form an angle on the side of the head, the cerebrospinal fluid returns smoothly after the insertion of the lumbar anesthesia needle, and it is easier to place the epidural catheter after the completion of the lumbar anesthesia. Some studies have confirmed that the puncture interspace of the paramedian approach is wider than that of median approach, which reduces the difficulty of puncture, avoids repeated puncture and increases the success rate of puncture[\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eAt the same time, the controversy over the use of ultrasound to assess the distance between the skin and the epidural space should be considered. In theory, the actual puncture depth is deeper than that predicted by ultrasound. Our study found that the actual depth of extradural puncture was deeper than that predicted by ultrasound, but there was no significant difference between groups (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05). The reason may be that when the operator evaluates the success of epidural puncture, the needle insertion is stopped immediately when negative pressure is felt during the puncture to avoid placing the puncture needle too deeply, especially for anesthesiologists with more puncture experience. There was no significant difference between the predicted puncture depth and the actual puncture depth in the median approach group, which suggested that ultrasound could effectively predict the epidural puncture depth in different approaches of combined spinal epidural anesthesia. However, it should be pointed out that the actual puncture depth of both groups of data was deeper than that predicted by ultrasound. Considering the possible influence of fat thickness or tissue edema on the backs of obese pregnant women, our study compressed the maternal skin to avoid its influence when ultrasound placed the puncture point.\u003c/p\u003e \u003cp\u003eIn this study, a high-frequency convex array probe was used to accurately determine the best puncture point of anesthesia in the median approach group. The selection of puncture point in the paramedian approach group was based on the lateral paracentesis of 1.5\u0026nbsp;cm at the median approach puncture point, and on this basis, ultrasound was used to predict the puncture depth. Therefore, it was found that the positioning time of the paramedian group was higher than that of the median group (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05). However, there was no significant difference in the total operation time between the two groups (P\u0026thinsp;\u0026gt;\u0026thinsp;0.05). Considering that the first puncture success rate of the two groups was high, the number of attempts was small, and the skilled operation of anesthesiologists had a certain relationship.\u003c/p\u003e \u003cp\u003eAnesthesia safety is also an important factor in this study. Among the one hundred obese pregnant women included in this study, there were adverse effects of anesthesia in both groups, such as epidural catheter bleeding, nerve stimulation signs and the occurrence of low back pain after anesthesia, and there were significant differences between the two groups in the occurrence of low back pain (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05). We considered that the paramedian approach group could avoid the supraspinous ligament and part of the interspinous ligament and allow entrance into the epidural space through the ligamentum flavum in the process of puncture. The analysis shows that the main reason for the difference in the incidence of low back pain between the two groups is the difference in ligament injury caused by the dural puncture needle. There was no significant difference in nerve stimulation between the two groups. It is worth mentioning that there were no cases of unexpected dural puncture in the either of the groups, further suggesting the advantage of ultrasound in obese women. There was a higher degree of satisfaction in the paramedian approach group than in the median approach group (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05).\u003c/p\u003e \u003cp\u003ePrevious studies have found that there is no significant difference in the success rate of traditional intraspinal puncture when ultrasound is used and when it is not in normal pregnant patient[\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e], which does not reflect the application advantages of ultrasound in epidural puncture. Therefore, this study is more valuable for the application of ultrasound-guided epidural puncture in obese cesarean section women. In addition, it should be pointed out that the technology of ultrasound intervention in epidural puncture can be divided into prepuncture positioning and real-time guiding operation, but the real-time guiding requires aseptic treatment of the probe, the operation process is complex, and the advantage is not obvious compared with the prepuncture ultrasound positioning; additionally, in the operation process, elimination of air/liquid resistance is still used to determine whether the tip of the needle reaches the epidural cavity[\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. Therefore, in this study, we chose to place the epidural catheter before ultrasound-guided puncture rather than under real-time ultrasound-guided puncture. Of course, there are some limitations in our research. First, although we used the same anesthesiologist with much experience in using spinal ultrasound, the results are still controversial. Second, we had a relatively small number of cases and fewer positive results. More samples are needed for further study.\u003c/p\u003e "},{"header":"Conclusion","content":" \u003cp\u003eOur conclusion is that the ultrasound-guided paramedian approach puncture for combined spinal anesthesia for cesarean section patients is more time-consuming, but it can effectively improve the success rate of the first puncture, reduce the incidence of anesthesia-related adverse reactions, and improve patient satisfaction.\u003c/p\u003e "},{"header":"Abbreviations","content":"\u003cp\u003eCSEA: Combined spinal epidural anesthesia; BMI: Body mass index; ASA: American Society of Anesthesiologists classification\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgements \u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors\u0026rsquo; contributions \u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eZhiqiang Liu designed the study and drafted the manuscript.Yilu Zhou participated in the design of the study and interpreted the results. Zhendong Xu participated in the interpretation of the results. All authors read and approved the final manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding \u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study received no funding from the public, commercial or nonprofit sectors that provide special grants for this research.\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 presented in this manuscript and/or additional supporting files. The additional datasets are also available from the corresponding author on reasonable request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate \u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study was approved by the Ethics Committee of Shanghai First Maternity and Infant Hospital and was registered in the Chinese Clinical Trial Registry (ChiCTR1900024722) on July 24, 2019.The registry can be monitored at this link \u003ca href=\"http://www.chictr.org.cn/index.aspx\"\u003ehttp://www.chictr.org.cn/index.aspx\u003c/a\u003e. Written informed consent to participate was obtained from each participant.\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\u003eThere was no conflict of interest in this study.\u003c/p\u003e\u003cp\u003e\u003cstrong\u003eConflicts of interest\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNone\u003c/p\u003e "},{"header":"References","content":"\u003col\u003e\u003cli\u003e \u003cspan\u003eReynolds F, Seed PT. Anaesthesia for Caesarean section and neonatal acid-base status: a meta-analysis. ANAESTHESIA. 2005;60(7):636 \u0026ndash; 53. 'doi:'10.1111/j.1365-2044.2005.04223.x.\u003c/span\u003e \u003c/li\u003e \u003cli\u003e \u003cspan\u003eGaiser R. Anesthetic Considerations in the Obese Parturient. CLIN OBSTET GYNECOL. 2016;59(1):193\u0026ndash;203. 'doi:'10.1097/GRF.0000000000000180.\u003c/span\u003e \u003c/li\u003e \u003cli\u003e \u003cspan\u003eVoloshin AG. Four-dimensional ultrasound guidance during epidural anaesthesia. Journal of Ultrasound. 2015;18(2):135 \u0026ndash; 42. 'doi:'10.1007/s40477-014-0150-1.\u003c/span\u003e \u003c/li\u003e \u003cli\u003e \u003cspan\u003eBeigi P, Malenfant P, Rasoulian A, Rohling R, Dube A, Gunka V. Three-Dimensional Ultrasound-Guided Real-Time Midline Epidural Needle Placement with Epiguide: A Prospective Feasibility Study. Ultrasound in Medicine \u0026amp; Biology. 2017;43(1):375-9. 'doi:'10.1016/j.ultrasmedbio.2016.08.033.\u003c/span\u003e \u003c/li\u003e \u003cli\u003e \u003cspan\u003eSahota JS, Carvalho JCA, Balki M, Fanning N, Arzola C. Ultrasound estimates for midline epidural punctures in the obese parturient: paramedian sagittal oblique is comparable to transverse median plane. ANESTH ANALG. 2013;116(4):829 \u0026ndash; 35. 'doi:'10.1213/ANE.0b013e31827f55f0.\u003c/span\u003e \u003c/li\u003e \u003cli\u003e \u003cspan\u003eShaikh F, Brzezinski J, Alexander S, Arzola C, Carvalho JCA, Beyene J, et al. Ultrasound imaging for lumbar punctures and epidural catheterisations: systematic review and meta-analysis. BMJ: British Medical Journal. 2013;346(7902):11. 'doi:'10.1136/bmj.f1720.\u003c/span\u003e \u003c/li\u003e \u003cli\u003e \u003cspan\u003eChin A, Crooke B, Heywood L, Brijball R, Pelecanos AM, Abeypala W. A randomised controlled trial comparing needle movements during combined spinal-epidural anaesthesia with and without ultrasound assistance. ANAESTHESIA. 2018;73(4):466 \u0026ndash; 73. 'doi:'10.1111/anae.14206.\u003c/span\u003e \u003c/li\u003e \u003cli\u003e \u003cspan\u003eTawfik MM, Atallah MM, Elkharboutly WS, Allakkany NS, Abdelkhalek M. Does Preprocedural Ultrasound Increase the First-Pass Success Rate of Epidural Catheterization Before Cesarean Delivery? A Randomized Controlled Trial. Anesthesia \u0026amp; Analgesia. 2017;124(3):851-6. 'doi:'10.1213/ANE.0000000000001325.\u003c/span\u003e \u003c/li\u003e \u003cli\u003e \u003cspan\u003eArzola C, Mikhael R, Margarido C, Carvalho JCA. Spinal ultrasound versus palpation for epidural catheter insertion in labour. EUR J ANAESTH. 2015;32(7):499\u0026ndash;505. 'doi:'10.1097/EJA.0000000000000119.\u003c/span\u003e \u003c/li\u003e \u003cli\u003e \u003cspan\u003eLi M, Ni X, Xu Z, Shen F, Song Y, Li Q, et al. Ultrasound-Assisted Technology Versus the Conventional Landmark Location Method in Spinal Anesthesia for Cesarean Delivery in Obese Parturients. Anesthesia \u0026amp; Analgesia. 2019;129(1):155 \u0026ndash; 61. 'doi:'10.1213/ANE.0000000000003795.\u003c/span\u003e \u003c/li\u003e \u003cli\u003e \u003cspan\u003eSahin T, Balaban O, Sahin L, Solak M, Toker K. A randomized controlled trial of preinsertion ultrasound guidance for spinal anaesthesia in pregnancy: outcomes among obese and lean parturients. J ANESTH. 2014;28(3):413-9. 'doi:'10.1007/s00540-013-1726-1.\u003c/span\u003e \u003c/li\u003e \u003cli\u003e \u003cspan\u003eDuarte VM, Meucci RD, Cesar JA. Dor lombar intensa em gestantes do extremo Sul do Brasil. Ci\u0026ecirc;ncia \u0026amp; Sa\u0026uacute;de Coletiva. 2018;23(8):2487-94. 'doi:'10.1590/1413-81232018238.22562016.\u003c/span\u003e \u003c/li\u003e \u003cli\u003e \u003cspan\u003eBliddal M, Potteg\u0026aring;rd A, Kirkegaard H, Olsen J, J\u0026oslash;rgensen JS, S\u0026oslash;rensen TIA, et al. Degenerative musculoskeletal conditions in women according to pre-pregnancy BMI, pregnancy-related weight changes and parity. ARTHRITIS RHEUMATOL. 2015:\u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003en/a-n/a\u003c/span\u003e\u003c/span\u003e. 'doi:'10.1002/art.39565.\u003c/span\u003e \u003c/li\u003e \u003cli\u003e \u003cspan\u003eCushnie D, Urquhart JC, Gurr KR, Siddiqi F, Bailey CS. Obesity and spinal epidural lipomatosis in cauda equina syndrome. SPINE J. 2018;18(3):407 \u0026ndash; 13. 'doi:'10.1016/j.spinee.2017.07.177.\u003c/span\u003e \u003c/li\u003e \u003cli\u003e \u003cspan\u003eT G, R. W L, R C, E M. Ultrasound control for presumed difficult epidural puncture. ACTA ANAESTH SCAND. 2001;45(6):766 \u0026ndash; 71. 'doi:'10.1034/j.1399-6576.2001.045006766.x.\u003c/span\u003e \u003c/li\u003e \u003cli\u003e \u003cspan\u003eMalik T, Malas O, Thompson A. Ultrasound guided L5-S1 placement of labor epidural does not improve dermatomal block in parturients. INT J OBSTET ANESTH. 2019;38:52 \u0026ndash; 8. 'doi:'10.1016/j.ijoa.2018.11.005.\u003c/span\u003e \u003c/li\u003e \u003cli\u003e \u003cspan\u003eSchummer W, Koditz JA, Schelenz C, Reinhart K, Sakka SG. Pre-procedure ultrasound increases the success and safety of central venous catheterizationdagger. Br J Anaesth. 2014;113(1):122-9. 'doi:'10.1093/bja/aeu049.\u003c/span\u003e \u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"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":"different approaches, combined spinal epidural anesthesia, ultrasound, cesarean delivery, obese patients","lastPublishedDoi":"10.21203/rs.3.rs-33022/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-33022/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eBackground: \u003c/strong\u003eCombined spinal epidural anesthesia (CSEA) is commonly performed in cesarean deliveries. However, it is difficult to perform in obese parturients because of positioning challenges. The aim of this study was to compare the effect of different approaches to CSEA under the guidance of ultrasound.\u003c/p\u003e\u003cp\u003e\u003cstrong\u003eMethods: \u003c/strong\u003eOne hundred obese patients (BMI≧30 kg/m\u003csup\u003e2\u003c/sup\u003e) who underwent elective cesarean section were randomly enrolled. Patients were assigned to a median approach group and a paramedian approach group randomly. Clinical characteristics were compared between groups. First puncture success rate, ultrasonic time needed for positioning and puncture time, ultrasonic predicted anesthesia puncture depth, actual puncture depth, adverse reactions to anesthesia, complications after anesthesia, and patient satisfaction with the epidural puncture were recorded.\u003c/p\u003e\u003cp\u003e\u003cstrong\u003eResults: \u003c/strong\u003eThe first puncture success rate was significantly different between the two groups (92% vs 86%, P \u0026lt;0.05). The positioning time and total puncture time in the paramedian approach group were higher than those in the median approach group (217.7 s vs 201.6 s, P \u0026lt;0.05; 251.3 s vs 247.4 s, P＞0.05). The incidence of postanesthesia complications in the paramedian approach group was significantly lower than that in the median approach group (2% vs 12%, P \u0026lt;0.05), and patient satisfaction was higher in the paramedian approach group than in the median approach group (P \u0026lt;0.05).\u003c/p\u003e\u003cp\u003e\u003cstrong\u003eConclusion: \u003c/strong\u003eThe ultrasound-guided paracentesis approach for intrauterine spinal anesthesia for cesarean section patients is time-consuming, but it can effectively improve the success rate of the first puncture, reduce the incidence of anesthesia-related adverse reactions, and improve patient satisfaction.\u003c/p\u003e\u003cp\u003e\u003cstrong\u003eTrial registration: \u003c/strong\u003eThis study was registered with the Chinese Clinical Trial Registry (ChiCTR1900024722) on July 24, 2019.\u003c/p\u003e","manuscriptTitle":"Comparison of different approaches to combined spinal epidural anesthesia (CSEA) under the guidance of ultrasound in cesarean delivery obese patients: A randomized controlled trial","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2020-06-10 16:51:35","doi":"10.21203/rs.3.rs-33022/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"editorInvitedReview","content":"","date":"2020-07-06T12:00:00+00:00","index":1,"fulltext":"Recommendation: Reviewer's comments unavailable pending editorial decision\n"},{"type":"reviewerAgreed","content":"","date":"2020-07-02T12:00:00+00:00","index":1,"fulltext":""},{"type":"reviewersInvited","content":"","date":"2020-06-18T12:00:00+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2020-06-03T12:00:00+00:00","index":"","fulltext":""},{"type":"submitted","content":"","date":"2020-06-02T12:00:00+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2020-06-02T12:00:00+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2020-06-02T12:00:00+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":"734578b5-b64c-47ee-bb60-7a9e2b215b53","owner":[],"postedDate":"June 10th, 2020","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[{"id":117023,"name":"Anesthesiology \u0026 Pain Medicine"}],"tags":[],"updatedAt":"2020-06-10T16:51:35+00:00","versionOfRecord":[],"versionCreatedAt":"2020-06-10 16:51:35","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-33022","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-33022","identity":"rs-33022","version":["v1"]},"buildId":"wLkW0s4AflPzk-lpfg-fK","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}