The minimum effective concentration (MEC90) of ropivacaine for ultrasound-guided caudal block in anorectal surgery. A dose finding study.
<h4>Background</h4>Caudal epidural block (CEB) provides reliable anesthesia for adults undergoing anorectal surgery. Despite the widely utilization, the minimum effective concentration for 90% patients (MEC90) of ropivacaine for CEB remains unknown.<h4>Objective</h4>To estima...
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| Autores principales: | , , , , , , |
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| Formato: | article |
| Lenguaje: | EN |
| Publicado: |
Public Library of Science (PLoS)
2021
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| Materias: | |
| Acceso en línea: | https://doaj.org/article/23dafdb8fef842f9b8486a01368b999a |
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| Sumario: | <h4>Background</h4>Caudal epidural block (CEB) provides reliable anesthesia for adults undergoing anorectal surgery. Despite the widely utilization, the minimum effective concentration for 90% patients (MEC90) of ropivacaine for CEB remains unknown.<h4>Objective</h4>To estimate MEC of ropivacaine for CEB in anorectal surgery.<h4>Design</h4>A prospective dose-finding study using biased coin design up-and-down sequential method.<h4>Setting</h4>Operating room and postoperative recovery area of Chengdu Shangjin Nanfu Hospital, from October 2019 to January 2020.<h4>Patients</h4>50 males and 51 females scheduled for anorectal surgery.<h4>Interventions</h4>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.<h4>Main outcome measures</h4>The MEC of ropivacaine to achieve a successful CEB in 90%(MEC90) of the patients.<h4>Results</h4>The MEC90 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.<h4>Conclusions</h4>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.<h4>Trial registration</h4>Chictr.org.cn identifier: No. ChiCTR 1900024315. |
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