title: Lack of Sex Difference in Minimum Local Analgesic Concentration of Ropivacaine for Ultrasound-Guided Supraclavicular Brachial Plexus Block.
abstract: BACKGROUND
  Sex differences, which may be an important variable for determining anesthetic requirements, have not been well investigated in the aspect of local anesthetic. This investigation aimed to compare the minimum local analgesic concentration (MLAC) of ropivacaine for ultrasound-guided supraclavicular brachial plexus block (US-SCB) between men and women.
  
  
  METHODS
  Patients aged 18-45 years undergoing elective forearm, wrist, or hand surgeries under US-SCB were divided into 2 groups according to sex. The initial concentration was 0.375% ropivacaine 20 mL and the concentration for the next patient was determined by the up-down technique at 0.025% intervals. Success was defined as the absence of any pain in response to a pinprick in the region of all 4 terminal nerves and the skin incision within 45 min. The primary outcome was the MLAC of ropivacaine, which was estimated by the Dixon and Massey method. The analgesia duration, which was defined as the time from the end of the US-SCB injection to the time of feeling discomfort and need for additional analgesics, was observed for each patient.
  
  
  RESULTS
  The MLAC of ropivacaine 20 mL for US-SCB was 0.2675% (95% confidence interval [CI], 0.2512-0.2838%) in men and 0.2675% (95% CI, 0.2524-0.2826%) in women. There was no significant difference in MLAC or the analgesia duration between the 2 groups (P>0.05).
  
  
  CONCLUSIONS
  We found no significant sex-related differences in MLAC or analgesia duration of ropivacaine for US-SCB.
authors.affiliation: Department of Anesthesiology and Pain Medicine, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China (mainland).
authors.forename: Qingqing
authors.initials: Q
authors.lastname: Pei
authors.affiliation: Department of Anesthesiology and Pain Medicine, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China (mainland).
authors.forename: Yanqing
authors.initials: Y
authors.lastname: Yang
authors.affiliation: Department of Anesthesiology and Pain Medicine, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China (mainland).
authors.forename: Qin
authors.initials: Q
authors.lastname: Liu
authors.affiliation: Department of Anesthesiology and Pain Medicine, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China (mainland).
authors.forename: Zhiyou
authors.initials: Z
authors.lastname: Peng
authors.affiliation: Department of Anesthesiology and Pain Medicine, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China (mainland).
authors.forename: Zhiying
authors.initials: Z
authors.lastname: Feng
mesh_terms: D000293:Adolescent; D000328:Adult; D000577:Amides / Q000494:pharmacology / Q000627:therapeutic use*; D000700:Analgesics / Q000494:pharmacology / Q000627:therapeutic use*; D000779:Anesthetics, Local / Q000008:administration & dosage; D065527:Brachial Plexus Block / Q000379:methods*; D005260:Female; D005542:Forearm / Q000601:surgery; D006225:Hand / Q000601:surgery; D006801:Humans; D008297:Male; D008875:Middle Aged; D010149:Postoperative Pain / Q000517:prevention & control; D000077212:Ropivacaine; D012737:Sex Factors; D014463:Ultrasonography; D014953:Wrist / Q000601:surgery
chemical_list: D000577:Amides; D000700:Analgesics; D000779:Anesthetics, Local; D000077212:Ropivacaine