Butorphanol decreased the median effective concentration of ropivacaine in ultrasound-guided interscalene brachial plexus block

• Hang Su ,

  Roles Conceptualization, Formal analysis, Writing – review & editing

  ¶☯ Hang Su and Juan Li contributed equally to this work.

  Affiliation Department of Anesthesiology, Affiliated Hospital of North Sichuan Medical College, Nanchong, People’s Republic of China

  ⨯
• Juan Li ,

  Roles Conceptualization, Data curation, Writing – original draft, Writing – review & editing

  ¶☯ Hang Su and Juan Li contributed equally to this work.

  Affiliation Department of Anesthesiology, Bazhong Central Hospital, Bazhong, People’s Republic of China

  ⨯
• Jiping Zhang,

  Roles Conceptualization, Data curation, Writing – review & editing

  Affiliation Department of Anesthesiology, Bazhong Central Hospital, Bazhong, People’s Republic of China

  ⨯
• Yiran Zhang,

  Roles Conceptualization, Formal analysis, Writing – review & editing

  Affiliation Department of Anesthesiology, Affiliated Hospital of North Sichuan Medical College, Nanchong, People’s Republic of China

  ⨯
• Faping Tu

  Roles Conceptualization, Writing – review & editing

  * E-mail: tfpnc@163.com

  Affiliation Department of Anesthesiology, Affiliated Hospital of North Sichuan Medical College, Nanchong, People’s Republic of China

  https://orcid.org/0000-0003-0994-4852

  ⨯