2.1 Patient enrollment and study design
After obtaining approval from the Ethics Committee of the Affiliated Hospital of Jiaxing University ((Identifier: LS2020-307). The study protocol was registered in the Chinese Clinical Trial Registry (ChiCTR2000038376). The Chinese Clinical Trial Registration date is September 21, 2020 (21/09/2020 ), and the date of patient enrollment is September 23, 2020 (23/09/2020). This experimental study obtained the consent of all the participants and signed a written informed consent form. The age of the patient is between 18 and 80 years old, with American Society of Anesthesiologists (ASA) grade 1-2, and preparing to undergo modified radical mastectomy in our hospital. The exclusion criteria included patients with shock or coma, abnormal blood coagulation, infection in the planned block area, severe nerve injury on the side of the limb; patients with history of chronic pain and taking analgesic; patients with psychiatric diseases; patents on radiotherapy and/or chemotherapy; patients allergic to local anesthetics (e.g. lidocaine and ropivacaine) and to general anesthetics; patients and/or their families that refused surgical anesthesia; Previous history of breast surgery or other chest surgery; body mass index (BMI) ≥35 kg/m2.