Background 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. Objective To estimate MEC of ropivacaine for CEB in anorectal surgery. Design A prospective dose-finding study using biased coin design up-and-down sequential method. Setting Operating room and postoperative recovery area of Chengdu Shangjin Nanfu Hospital, from October 2019 to January 2020. Patients 50 males and 51 females scheduled for anorectal surgery. Interventions 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. Main outcome measures The MEC of ropivacaine to achieve a successful CEB in 90%(MEC90) of the patients. Results 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. Conclusions 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. Trial registration Chictr.org.cn identifier: No. ChiCTR 1900024315.

Myocardial ischemia-reperfusion (I/R) injury is a leading cause of heart disease and death. Decreasing the detrimental effect of I/R remains an urgent issue in clinical practice. The present study examined the interaction of the anesthetics (sevoflurane and propofol), ADAM8, and microRNA (miR)-221-5p in myocardial tissue protection in the hypoxia-reoxygenation (H/R) model. H9C2 cells were cultured and subjected to H/R stimulation for further verifications in vitro . Reverse transcription-quantitative PCR or western blotting was performed to evaluate mRNA or protein expression levels. Cell Counting Kit-8, BrdU, and caspase-3 activity assays were performed to investigate cell viability, proliferation and apoptosis. A dual-luciferase reporter assay was performed to verify the association between miR-221-5p and ADAM8. Sevoflurane had greater protective effects on the life of cardiomyocytes with H/R injury compared with propofol by promoting cell viability, proliferation and inhibiting apoptosis. Concurrently, compared with propofol-treated H/R injured cardiomyocytes, the expression level of ADAM8 in sevoflurane-treated H/R injured cardiomyocytes was higher. In addition, overexpression of ADAM8 promoted the cell viability and proliferation of sevoflurane-treated cardiomyocytes with H/R injury but inhibited cell apoptosis, while the downregulation of miR-221-5p showed an opposite trend to that of ADAM8 overexpression. The present data provide evidence that sevoflurane can mediate the miR-221-5p/ADAM8 axis, playing a better protective role compared with propofol in cardiomyocytes with H/R injury.

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