Opioid-Free Versus Opioid-Based Anesthesia in Modified Radical Mastectomy

Overview

This randomized controlled trial compares opioid-free anesthesia combined with pectoral nerve block (PECS I and II) with opioid-based anesthesia in patients undergoing modified radical mastectomy. The study evaluates postoperative CD4+ T-cell counts as a marker of cellular immune response, as well as postoperative pain intensity and nausea and vomiting. Twenty-eight patients were randomly assigned to receive either opioid-free anesthesia with PECS I and II block or opioid-based anesthesia with fentanyl. CD4+ T-cell counts were assessed before and 24 hours after surgery, while postoperative pain was assessed at 2, 6, 12, and 24 hours after surgery.

This randomized controlled trial was conducted in patients undergoing modified radical mastectomy at Wahidin Sudirohusodo General Hospital and affiliated teaching hospitals in Makassar, Indonesia. The study compared opioid-free anesthesia combined with pectoral nerve block (PECS I and II) with opioid-based anesthesia. Twenty-eight patients were randomly allocated in a 1:1 ratio to two groups. The opioid-free anesthesia group received ultrasound-guided PECS I and II blocks before induction, followed by a dexmedetomidine-based anesthetic regimen. The opioid-based anesthesia group received a fentanyl-based anesthetic regimen. General anesthesia was maintained with sevoflurane in both groups. Randomization was performed using a computer-generated random sequence with allocation concealment using sealed, opaque envelopes. Participants and outcome assessors were blinded to group allocation. The primary immunological outcome was the absolute CD4+ T-cell count. Venous blood samples were collected 24 hours before surgery and 24 hours after surgery, and CD4+ T-cell counts were measured using the Pima™ Alere CD4 Analyzer. Postoperative pain intensity was assessed using a 0-10 visual analogue scale at 2, 6, 12, and 24 hours after surgery, both at rest and during movement. Postoperative nausea and vomiting were assessed during the first 24 postoperative hours. Rescue analgesia with intravenous fentanyl was administered when the visual analogue scale score was 4 or higher. The study included women aged 18-65 years undergoing modified radical mastectomy with American Society of Anesthesiologists Physical Status I-II and a body mass index greater than 18 and less than 30 kg/m². Patients with major cardiovascular, cerebrovascular, hepatic, or renal disease, uncontrolled systemic disease, previous chemotherapy or radiotherapy, long-term opioid use, allergy to local anesthetics or opioids, infection at the injection site, coagulation disorders, bilateral breast surgery, or refusal to participate were excluded. The study was conducted from May to July 2026 and was approved by the Biomedical Research Ethics Committee, Faculty of Medicine, Hasanuddin University (approval number 979/UN4.6.4.5.31/PP36/2026). Written informed consent was obtained from all participants before participation.