{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,23]],"date-time":"2026-10-23T20:48:53Z","timestamp":1792788533922,"version":"4.5.0"},"reference-count":39,"publisher":"Public Library of Science (PLoS)","issue":"9","license":[{"start":{"date-parts":[[2021,9,17]],"date-time":"2021-09-17T00:00:00Z","timestamp":1631836800000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["Grant No. 81900064"],"award-info":[{"award-number":["Grant No. 81900064"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]},{"name":"Science and Technology Support Project of Sichuan Province","award":["2020YJ0050"],"award-info":[{"award-number":["2020YJ0050"]}]},{"name":"Science and Technology Support Project of Sichuan Province","award":["No. 2018SZ0113"],"award-info":[{"award-number":["No. 2018SZ0113"]}]}],"content-domain":{"domain":["www.plosone.org"],"crossmark-restriction":false},"short-container-title":["PLoS ONE"],"abstract":"<jats:sec id=\"sec001\">\n                    <jats:title>Background<\/jats:title>\n                    <jats:p>\n                      Caudal epidural block (CEB) provides reliable anesthesia for adults undergoing anorectal surgery. Despite the widely utilization, the minimum effective concentration for 90% patients (MEC\n                      <jats:sub>90<\/jats:sub>\n                      ) of ropivacaine for CEB remains unknown.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec id=\"sec002\">\n                    <jats:title>Objective<\/jats:title>\n                    <jats:p>To estimate MEC of ropivacaine for CEB in anorectal surgery.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec id=\"sec003\">\n                    <jats:title>Design<\/jats:title>\n                    <jats:p>A prospective dose-finding study using biased coin design up-and-down sequential method.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec id=\"sec004\">\n                    <jats:title>Setting<\/jats:title>\n                    <jats:p>Operating room and postoperative recovery area of Chengdu Shangjin Nanfu Hospital, from October 2019 to January 2020.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec id=\"sec005\">\n                    <jats:title>Patients<\/jats:title>\n                    <jats:p>50 males and 51 females scheduled for anorectal surgery.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec id=\"sec006\">\n                    <jats:title>Interventions<\/jats:title>\n                    <jats:p>We conducted two independent biased coin design up-and down trials by genders. The concentration of ropivacaine administered to the first patient of male and female were 0.25% with fixed volume of 14ml for male and 12ml for female patients based on our previous study. In case of failure, the concentration was increased by 0.05% in the next subject. Otherwise, the next subject was randomized to a concentration 0.05% less with a probability of 0.11, or the same concentration with a probability of 0.89. Success was defined as complete sensory blockade of perineal area 15 min after the block evidenced by the presence of a lax anal sphincter and pain-free surgery.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec id=\"sec007\">\n                    <jats:title>Main outcome measures<\/jats:title>\n                    <jats:p>\n                      The MEC of ropivacaine to achieve a successful CEB in 90%(MEC\n                      <jats:sub>90<\/jats:sub>\n                      ) of the patients.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec id=\"sec008\">\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>\n                      The MEC\n                      <jats:sub>90<\/jats:sub>\n                      of ropivacaine for CEB were estimated to be 0.35% (95% CI 0.29 to 0.4%) for male and 0.353% (95%CI 0.22 to 0.4%) for female. By extrapolation to MEC in 99% of subjects (MEC99) and pooled adjacent violators algorithm (PAVA) adjusted responses, it would be optimal to choose 0.4% ropivacaine with a volume of 14ml for male and 12ml for female.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec id=\"sec009\">\n                    <jats:title>Conclusions<\/jats:title>\n                    <jats:p>A concentration of 0.35% ropivacaine with a volume of 14ml provided a successful CEB in 90% of the male patients, while 0.353% ropivacaine with a volume of 12ml provided a successful CEB in 90% of the female patients. A concentration of 0.4% and a volume of 14ml for male and 12 ml for female would be successful in 99% of the patients.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec id=\"sec010\">\n                    <jats:title>Trial registration<\/jats:title>\n                    <jats:p>\n                      <jats:ext-link xmlns:xlink=\"http:\/\/www.w3.org\/1999\/xlink\" ext-link-type=\"uri\" xlink:href=\"http:\/\/www.chictr.org.cn\/\" xlink:type=\"simple\">Chictr.org.cn<\/jats:ext-link>\n                      identifier: No. ChiCTR 1900024315.\n                    <\/jats:p>\n                  <\/jats:sec>","DOI":"10.1371\/journal.pone.0257283","type":"journal-article","created":{"date-parts":[[2021,9,17]],"date-time":"2021-09-17T13:34:37Z","timestamp":1631885677000},"page":"e0257283","update-policy":"https:\/\/doi.org\/10.1371\/journal.pone.corrections_policy","source":"Crossref","is-referenced-by-count":11,"title":["The minimum effective concentration (MEC90) of ropivacaine for ultrasound-guided caudal block in anorectal surgery. A dose finding study"],"prefix":"10.1371","volume":"16","author":[{"given":"Xuehan","family":"Li","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jun","family":"Li","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Pei","family":"Zhang","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Huifei","family":"Deng","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Mingan","family":"Yang","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Hongbo","family":"He","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9213-3104","authenticated-orcid":true,"given":"Rurong","family":"Wang","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"340","published-online":{"date-parts":[[2021,9,17]]},"reference":[{"issue":"18","key":"pone.0257283.ref001","doi-asserted-by":"crossref","first-page":"2675","DOI":"10.2165\/00003495-200565180-00013","article-title":"Ropivacaine: a review of its use in regional anaesthesia and acute pain management","volume":"65","author":"D Simpson","year":"2005","journal-title":"Drugs"},{"issue":"e-Supplement 58","key":"pone.0257283.ref002","first-page":"7","article-title":"Rurong Wang. 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