Comparison of Fractionated Versus Bolus Administration of Different Doses of Hyperbaric Bupivacaine Combined With Opioids in Spinal Anesthesia for Caesarean Section – A Prospective, Randomized, Single Blind Clinical Trial

Comparison of Fractionated Versus Bolus Administration of Different Doses of Hyperbaric Bupivacaine Combined With Opioids in Spinal Anesthesia for Caesarean Section – A Prospective, Randomized, Single Blind Clinical 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 Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Comparison of Fractionated Versus Bolus Administration of Different Doses of Hyperbaric Bupivacaine Combined With Opioids in Spinal Anesthesia for Caesarean Section – A Prospective, Randomized, Single Blind Clinical Trial Iurii Kuchyn, Kateryna Bielka, Roman Nimkovych, Ihor Sirenko This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7847370/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 07 Apr, 2026 Read the published version in BMC Anesthesiology → Version 1 posted 10 You are reading this latest preprint version Abstract Background Spinal anesthesia with hyperbaric bupivacaine and neuraxial opioids is the preferred technique for cesarean section, but maternal hypotension remains a common complication. Fractionated administration of local anesthetic may provide hemodynamic stability while maintaining effective anesthesia. This study aimed to compare the efficacy and safety of fractionated versus bolus administration of different doses of hyperbaric bupivacaine combined with opioids in spinal anesthesia for cesarean section. Methods This prospective, randomized, single-blind clinical trial included 99 pregnant women (ASA II-III) scheduled for cesarean section. Patients were randomized into three groups (n = 33 each): Group B received a bolus injection of bupivacaine (0.07 mg/cm height); Group F7 received the same total dose but fractionated (i.e. divided into two injections separated by an interval); and Group F6 received a lower fractionated dose (0.06 mg/cm height). All patients also received 10 µg fentanyl and 100 µg morphine intrathecally. The primary outcome was hemodynamic stability, assessed by arterial pressure changes, incidence of hypotension and bradycardia, and vasopressor requirements. Secondary outcomes included block characteristics, duration of analgesia, and perioperative side effects. Results The three groups were comparable in demographic characteristics (age, height, BMI). The incidence of hypotension did not differ significantly: 24.2% in Group B, 27.3% in Group F7, and 27.3% in Group F6 (p > 0.05). Mean phenylephrine requirements were numerically lower in the fractionated groups (Group F6: 1325.2 ± 909.83 µg, Group F7: 1462.1 ± 1070.56 µg) than in the bolus group (Group B: 1616.7 ± 1182.2 µg), but the differences were not statistically significant (p > 0.05). The duration of analgesia was comparable between groups (Group B: 216 ± 49 min, Group F7: 212 ± 56 min, Group F6: 207 ± 57 min, p = 0.79). The duration of motor block showed a trend towards being shorter in the reduced-dose fractionated group (Group B: 178 ± 43 min, Group F7: 169 ± 53 min, Group F6: 155 ± 33 min, p = 0.12), though this difference did not reach statistical significance. Conclusions Fractionated administration of hyperbaric bupivacaine combined with opioids in our study did not significantly reduce hypotension incidence compared to bolus administration. However, the lower dose (0.06 mg/cm) fractionated technique showed a trend toward reduced vasopressor requirements and shorter duration of motor block. Moreover, both fractionated techniques provided effective postoperative analgesia, suggesting that fractionated spinal anesthesia may be a reasonable alternative for cesarean section. Trial Registration: Trial Registration Number on ClinicalTrials.gov: NCT07249814. The trial was registered retrospectively at ClinicalTrials.gov on November 25, 2025. Spinal Anesthesia Cesarean Section Fractionated Dose Bolus Dose Bupivacaine Hemodynamic Stability Hypotension Full Text Additional Declarations No competing interests reported. Supplementary Files CONSORT2025flowdiagramNimkovych.pdf CONSORT2025checklistNimkovych.pdf Cite Share Download PDF Status: Published Journal Publication published 07 Apr, 2026 Read the published version in BMC Anesthesiology → Version 1 posted Editorial decision: Revision requested 05 Jan, 2026 Reviews received at journal 01 Jan, 2026 Reviews received at journal 19 Dec, 2025 Reviewers agreed at journal 18 Dec, 2025 Reviewers agreed at journal 13 Dec, 2025 Reviewers invited by journal 10 Dec, 2025 Editor assigned by journal 10 Dec, 2025 Editor invited by journal 27 Nov, 2025 Submission checks completed at journal 26 Nov, 2025 First submitted to journal 26 Nov, 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. 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 Advisory Board 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-7847370","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":560711113,"identity":"6f76604b-48ac-43e4-ab02-64c50e72b6b4","order_by":0,"name":"Iurii Kuchyn","email":"","orcid":"","institution":"Bogomolets National Medical University","correspondingAuthor":false,"prefix":"","firstName":"Iurii","middleName":"","lastName":"Kuchyn","suffix":""},{"id":560711114,"identity":"c353a9cf-6729-42b8-859f-f4c6451388d4","order_by":1,"name":"Kateryna Bielka","email":"","orcid":"","institution":"Bogomolets National Medical University","correspondingAuthor":false,"prefix":"","firstName":"Kateryna","middleName":"","lastName":"Bielka","suffix":""},{"id":560711115,"identity":"5bfbe2c6-3c1b-436a-9453-fc27e91b4b8b","order_by":2,"name":"Roman Nimkovych","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA4klEQVRIiWNgGAWjYDACZiAEAQP2/ocPgDQPH/FaeM4wG4C0sBFlD1iLRA6bBIhBUIs5O3eywce2w/LmErnHKr/m2MmwMTA/fHQDjxbLZt7NiTPbDhvu7HmXdlt2WzLQYWzGxjl4tBgc5t18mOfM4QSD4wlmtyW3MQO18LBJE6flQIJZseS2euK0JPNUALWcyDFj/LjtMHFaDGdUpBtuOHMsWZpx23EeNmZCfjl/drPEBwNreYPjzQc//txWbc/P3vzwMT4tUNAMJpl5wCRh5SBQByYZfxCnehSMglEwCkYYAACmFEhBBwyqIgAAAABJRU5ErkJggg==","orcid":"","institution":"Kyiv Perinatal Center","correspondingAuthor":true,"prefix":"","firstName":"Roman","middleName":"","lastName":"Nimkovych","suffix":""},{"id":560711116,"identity":"5cbef344-8607-4e17-9180-b14f02fdaf66","order_by":3,"name":"Ihor Sirenko","email":"","orcid":"","institution":"Bogomolets National Medical University","correspondingAuthor":false,"prefix":"","firstName":"Ihor","middleName":"","lastName":"Sirenko","suffix":""}],"badges":[],"createdAt":"2025-10-13 09:53:21","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-7847370/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-7847370/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1186/s12871-026-03813-z","type":"published","date":"2026-04-07T15:57:00+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":98438987,"identity":"0b1a5e3c-ef30-4d02-ba81-86303ca7e937","added_by":"auto","created_at":"2025-12-17 17:00:39","extension":"docx","order_by":0,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":663066,"visible":true,"origin":"","legend":"","description":"","filename":"SACSManuscriptBMCrevised5.docx","url":"https://assets-eu.researchsquare.com/files/rs-7847370/v1/bcbf0ef5e6325c04e24972d7.docx"},{"id":98334047,"identity":"d5f845a7-0311-4433-a93d-9a1f1bc6faca","added_by":"auto","created_at":"2025-12-16 15:55:35","extension":"json","order_by":1,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":7542,"visible":true,"origin":"","legend":"","description":"","filename":"b194b44d1b58405499477b6c57f6bd99.json","url":"https://assets-eu.researchsquare.com/files/rs-7847370/v1/4d60e944c5f9e7ed2cbb4c01.json"},{"id":98334045,"identity":"cc7139cc-8221-4c48-8bfd-f100087c00ee","added_by":"auto","created_at":"2025-12-16 15:55:35","extension":"pdf","order_by":2,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":472419,"visible":true,"origin":"","legend":"","description":"","filename":"CONSORT2025checklistNimkovych.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7847370/v1/1282d73e06aec054abebaadd.pdf"},{"id":98334058,"identity":"f6073171-2eec-40ad-a3c5-846598061d12","added_by":"auto","created_at":"2025-12-16 15:55:36","extension":"pdf","order_by":3,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":342071,"visible":true,"origin":"","legend":"","description":"","filename":"CONSORT2025flowdiagramNimkovych.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7847370/v1/c6aad9cf357aa500a1162ea7.pdf"},{"id":98438553,"identity":"5a15f2ac-96da-470a-a579-69061fdd3c76","added_by":"auto","created_at":"2025-12-17 16:59:31","extension":"xml","order_by":4,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":90866,"visible":true,"origin":"","legend":"","description":"","filename":"b194b44d1b58405499477b6c57f6bd991enriched.xml","url":"https://assets-eu.researchsquare.com/files/rs-7847370/v1/a9cba2d7ab079c5b57eb0823.xml"},{"id":98334050,"identity":"72211349-367b-4e72-a952-341b50c11d58","added_by":"auto","created_at":"2025-12-16 15:55:35","extension":"png","order_by":5,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":76240,"visible":true,"origin":"","legend":"","description":"","filename":"floatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-7847370/v1/401c58bd97f721055e2f0af2.png"},{"id":98437552,"identity":"ea9d313d-ede8-4bc4-9a1d-942305c267f7","added_by":"auto","created_at":"2025-12-17 16:57:27","extension":"png","order_by":6,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":158530,"visible":true,"origin":"","legend":"","description":"","filename":"floatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-7847370/v1/ee047465a90ff573e015388f.png"},{"id":98436935,"identity":"2ca2c8bc-9e1a-4cc7-80d9-71c3e799611d","added_by":"auto","created_at":"2025-12-17 16:56:28","extension":"png","order_by":7,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":74232,"visible":true,"origin":"","legend":"","description":"","filename":"floatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-7847370/v1/a50fd9198a43dfcf82ce65eb.png"},{"id":98438668,"identity":"64365c22-80fa-4c43-ac47-5ee6b1ba7963","added_by":"auto","created_at":"2025-12-17 16:59:45","extension":"png","order_by":8,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":171981,"visible":true,"origin":"","legend":"","description":"","filename":"floatimage4.png","url":"https://assets-eu.researchsquare.com/files/rs-7847370/v1/be11cb073dde5a893658d70e.png"},{"id":98436940,"identity":"0af66c27-a863-4302-ab01-2d8ebad77752","added_by":"auto","created_at":"2025-12-17 16:56:28","extension":"png","order_by":9,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":60325,"visible":true,"origin":"","legend":"","description":"","filename":"floatimage5.png","url":"https://assets-eu.researchsquare.com/files/rs-7847370/v1/e66de5921a0327ba76d82aa8.png"},{"id":98437354,"identity":"3daf82f9-3b16-4735-b523-343d9de8d7fc","added_by":"auto","created_at":"2025-12-17 16:57:14","extension":"png","order_by":10,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":119883,"visible":true,"origin":"","legend":"","description":"","filename":"floatimage6.png","url":"https://assets-eu.researchsquare.com/files/rs-7847370/v1/3b26836b81850b65b7c5f83b.png"},{"id":98438999,"identity":"723677ad-0819-4343-852b-c0bec1fa565f","added_by":"auto","created_at":"2025-12-17 17:00:41","extension":"png","order_by":11,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":115837,"visible":true,"origin":"","legend":"","description":"","filename":"floatimage7.png","url":"https://assets-eu.researchsquare.com/files/rs-7847370/v1/64f5005332e23d56e9d9f876.png"},{"id":98334066,"identity":"08903582-abf9-4086-918e-c43659c6cd81","added_by":"auto","created_at":"2025-12-16 15:55:36","extension":"png","order_by":12,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":15761,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-7847370/v1/181686c6fe34e8763fd5d555.png"},{"id":98334062,"identity":"2ff28c4a-0f55-413a-aa4c-a98f5760bf06","added_by":"auto","created_at":"2025-12-16 15:55:36","extension":"png","order_by":13,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":50474,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-7847370/v1/951182bfe5c4dbcda9b2e620.png"},{"id":98334054,"identity":"3ee03380-54d6-44cb-8012-dc1e7e1dfda6","added_by":"auto","created_at":"2025-12-16 15:55:36","extension":"png","order_by":14,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":25802,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-7847370/v1/b0d440f1cb9b783907538aba.png"},{"id":98437445,"identity":"f40071f2-2c5a-49bb-b275-30255f393341","added_by":"auto","created_at":"2025-12-17 16:57:20","extension":"png","order_by":15,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":53283,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage4.png","url":"https://assets-eu.researchsquare.com/files/rs-7847370/v1/facfa3a1cd4f5cd357031c55.png"},{"id":98438069,"identity":"ac3e7d24-e8db-4ef6-8861-3e44f71b1db4","added_by":"auto","created_at":"2025-12-17 16:58:37","extension":"png","order_by":16,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":17417,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage5.png","url":"https://assets-eu.researchsquare.com/files/rs-7847370/v1/f1b59c0b821d77f0c7ff0671.png"},{"id":98437439,"identity":"047cd2f6-da57-4f8a-9b80-25cdca588886","added_by":"auto","created_at":"2025-12-17 16:57:19","extension":"png","order_by":17,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":48030,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage6.png","url":"https://assets-eu.researchsquare.com/files/rs-7847370/v1/7f3ee46453b868631dbb783f.png"},{"id":98438342,"identity":"265565eb-9e5a-45e8-b5bc-fe2144b60949","added_by":"auto","created_at":"2025-12-17 16:59:02","extension":"png","order_by":18,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":46184,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage7.png","url":"https://assets-eu.researchsquare.com/files/rs-7847370/v1/d4410a333ff0b0f8eaabdce8.png"},{"id":98334065,"identity":"a1520fee-3859-426b-9a99-e9ba90531aeb","added_by":"auto","created_at":"2025-12-16 15:55:36","extension":"xml","order_by":19,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":85201,"visible":true,"origin":"","legend":"","description":"","filename":"b194b44d1b58405499477b6c57f6bd991structuring.xml","url":"https://assets-eu.researchsquare.com/files/rs-7847370/v1/be14b895773aac39b350edbc.xml"},{"id":98334064,"identity":"60e6c5b0-7140-4f24-8638-283e1be231b2","added_by":"auto","created_at":"2025-12-16 15:55:36","extension":"html","order_by":20,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":99329,"visible":true,"origin":"","legend":"","description":"","filename":"earlyproof.html","url":"https://assets-eu.researchsquare.com/files/rs-7847370/v1/262a7cc40989adc97b9ea717.html"},{"id":106808738,"identity":"2e9774af-999f-4393-8df9-81351d4156a1","added_by":"auto","created_at":"2026-04-13 15:59:49","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":878779,"visible":true,"origin":"","legend":"","description":"","filename":"SACSManuscriptBMCrevised5.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7847370/v1_covered_894ef573-147f-43de-99d6-9a7c69b67b34.pdf"},{"id":98334041,"identity":"60b148f6-3d96-42d8-9ae9-cd5075d34d98","added_by":"auto","created_at":"2025-12-16 15:55:35","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"supplement","size":342071,"visible":true,"origin":"","legend":"","description":"","filename":"CONSORT2025flowdiagramNimkovych.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7847370/v1/4485f566731d9df1cdda243c.pdf"},{"id":98437383,"identity":"8707cecf-c137-4234-84f6-e9c3dce390bb","added_by":"auto","created_at":"2025-12-17 16:57:15","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":472419,"visible":true,"origin":"","legend":"","description":"","filename":"CONSORT2025checklistNimkovych.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7847370/v1/c6676e9815b445451b38dfb7.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"\u003cp\u003eComparison of Fractionated Versus Bolus Administration of Different Doses of Hyperbaric Bupivacaine Combined With Opioids in Spinal Anesthesia for Caesarean Section – A Prospective, Randomized, Single Blind Clinical Trial\u003c/p\u003e","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":true,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":true,"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":"Spinal Anesthesia, Cesarean Section, Fractionated Dose, Bolus Dose, Bupivacaine, Hemodynamic Stability, Hypotension","lastPublishedDoi":"10.21203/rs.3.rs-7847370/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7847370/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e \u003cp\u003eSpinal anesthesia with hyperbaric bupivacaine and neuraxial opioids is the preferred technique for cesarean section, but maternal hypotension remains a common complication. Fractionated administration of local anesthetic may provide hemodynamic stability while maintaining effective anesthesia. This study aimed to compare the efficacy and safety of fractionated versus bolus administration of different doses of hyperbaric bupivacaine combined with opioids in spinal anesthesia for cesarean section.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e \u003cp\u003eThis prospective, randomized, single-blind clinical trial included 99 pregnant women (ASA II-III) scheduled for cesarean section. Patients were randomized into three groups (n\u0026thinsp;=\u0026thinsp;33 each): Group B received a bolus injection of bupivacaine (0.07 mg/cm height); Group F7 received the same total dose but fractionated (i.e. divided into two injections separated by an interval); and Group F6 received a lower fractionated dose (0.06 mg/cm height). All patients also received 10 \u0026micro;g fentanyl and 100 \u0026micro;g morphine intrathecally. The primary outcome was hemodynamic stability, assessed by arterial pressure changes, incidence of hypotension and bradycardia, and vasopressor requirements. Secondary outcomes included block characteristics, duration of analgesia, and perioperative side effects.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eThe three groups were comparable in demographic characteristics (age, height, BMI). The incidence of hypotension did not differ significantly: 24.2% in Group B, 27.3% in Group F7, and 27.3% in Group F6 (p\u0026thinsp;\u0026gt;\u0026thinsp;0.05). Mean phenylephrine requirements were numerically lower in the fractionated groups (Group F6: 1325.2\u0026thinsp;\u0026plusmn;\u0026thinsp;909.83 \u0026micro;g, Group F7: 1462.1\u0026thinsp;\u0026plusmn;\u0026thinsp;1070.56 \u0026micro;g) than in the bolus group (Group B: 1616.7\u0026thinsp;\u0026plusmn;\u0026thinsp;1182.2 \u0026micro;g), but the differences were not statistically significant (p\u0026thinsp;\u0026gt;\u0026thinsp;0.05). The duration of analgesia was comparable between groups (Group B: 216\u0026thinsp;\u0026plusmn;\u0026thinsp;49 min, Group F7: 212\u0026thinsp;\u0026plusmn;\u0026thinsp;56 min, Group F6: 207\u0026thinsp;\u0026plusmn;\u0026thinsp;57 min, p\u0026thinsp;=\u0026thinsp;0.79). The duration of motor block showed a trend towards being shorter in the reduced-dose fractionated group (Group B: 178\u0026thinsp;\u0026plusmn;\u0026thinsp;43 min, Group F7: 169\u0026thinsp;\u0026plusmn;\u0026thinsp;53 min, Group F6: 155\u0026thinsp;\u0026plusmn;\u0026thinsp;33 min, p\u0026thinsp;=\u0026thinsp;0.12), though this difference did not reach statistical significance.\u003c/p\u003e\u003ch2\u003eConclusions\u003c/h2\u003e \u003cp\u003eFractionated administration of hyperbaric bupivacaine combined with opioids in our study did not significantly reduce hypotension incidence compared to bolus administration. However, the lower dose (0.06 mg/cm) fractionated technique showed a trend toward reduced vasopressor requirements and shorter duration of motor block. Moreover, both fractionated techniques provided effective postoperative analgesia, suggesting that fractionated spinal anesthesia may be a reasonable alternative for cesarean section.\u003c/p\u003e\u003ch2\u003eTrial Registration:\u003c/h2\u003e \u003cp\u003eTrial Registration Number on ClinicalTrials.gov: NCT07249814. The trial was registered retrospectively at ClinicalTrials.gov on November 25, 2025.\u003c/p\u003e","manuscriptTitle":"Comparison of Fractionated Versus Bolus Administration of Different Doses of Hyperbaric Bupivacaine Combined With Opioids in Spinal Anesthesia for Caesarean Section – A Prospective, Randomized, Single Blind Clinical Trial","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-12-16 15:55:30","doi":"10.21203/rs.3.rs-7847370/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2026-01-05T18:39:53+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-01-01T19:59:06+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-12-19T19:32:02+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"265205851362190167299815747179111458585","date":"2025-12-18T09:41:56+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"225891548702531167943619487565611239616","date":"2025-12-13T20:55:58+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-12-11T04:03:39+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-12-11T04:00:52+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2025-11-27T11:08:47+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-11-26T13:04:04+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Anesthesiology","date":"2025-11-26T12:58:38+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":"a4ac5bde-d912-4424-a09e-265a96848de2","owner":[],"postedDate":"December 16th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2026-04-13T15:59:39+00:00","versionOfRecord":{"articleIdentity":"rs-7847370","link":"https://doi.org/10.1186/s12871-026-03813-z","journal":{"identity":"bmc-anesthesiology","isVorOnly":false,"title":"BMC Anesthesiology"},"publishedOn":"2026-04-07 15:57:00","publishedOnDateReadable":"April 7th, 2026"},"versionCreatedAt":"2025-12-16 15:55:30","video":"","vorDoi":"10.1186/s12871-026-03813-z","vorDoiUrl":"https://doi.org/10.1186/s12871-026-03813-z","workflowStages":[]},"version":"v1","identity":"rs-7847370","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7847370","identity":"rs-7847370","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}