• Miao Zhu, Ju-Jun Liu, Yan-Ping Shen, Zheng-Bin Pan, Chang-Cheng Lv, Wen-Din Chen, and Xiaowei Qian.
• Department of Anesthesiology, Women's Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China.
• Reg Anesth Pain Med. 2023 Oct 30.

IntroductionPreviously, we demonstrated that patients with full-term singletons and preterm twins require similar dose of intrathecal hyperbaric ropivacaine. However, these findings may be attributable to enrolled patients with preterm twin pregnancies. In this study, we aimed to determine the intrathecal dose requirements of hyperbaric ropivacaine for twins and singletons at equal gestational ages.MethodsWe enrolled 75 patients with preterm singletons and 75 patients with preterm twins scheduled for cesarean delivery under combined spinal-epidural anesthesia in this two-arm parallel, randomized, double-blind, dose-response study. Patients with singletons and twins were randomly assigned to receive one of five different doses of hyperbaric ropivacaine: 10, 12, 14, 16, or 18 mg. A probit regression model was used to determine the dose effective in 50% of patients (ED50) and dose effective in 90% of patients (ED90) values. The relative median potency was calculated to compare the ED50 between patients with twins and singletons.ResultsIntrathecal ropivacaine ED50 and ED90 (with 95% CI) in patients with preterm singletons were 9.9 (7.2 to 11.5) mg and 16.8 (14.5 to 22.9) mg, respectively. In patients with preterm twins, these values were 9.2 (95% CI 6.4 to 10.8) mg and 15.6 (95% CI 13.6 to 20.6) mg. Between patients with preterm twins and preterm singletons, the relative potency (ED50 ratios) was 0.933 (95% CI 0.72 to 1.15).ConclusionsDuring preterm gestation, intrathecal hyperbaric ropivacaine dose requirements for scheduled cesarean delivery were not different between patients with twins and singletons.Trial Registration NumberChiCTR2100051382.© American Society of Regional Anesthesia & Pain Medicine 2023. Re-use permitted under CC BY-NC. No commercial re-use. Published by BMJ.

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