Opioid-sparing and opioid-free anaesthesia: concepts, rationale, evidence, and practical implications

Opioids have long been central to perioperative analgesia, but their well-recognised adverse effects, including postoperative nausea and vomiting, respiratory depression, ileus, and the risk of persistent postoperative use, have increased interest in strategies that reduce perioperative opioid exposure. This narrative review examines two such strategies, opioid-sparing anaesthesia and opioid-free anaesthesia (OFA), and presents them as related points along a continuum of opioid minimisation rather than as opposing approaches. We define each strategy, outline the rationale for opioid reduction, including opioid-induced hyperalgesia, and review the multimodal and regional anaesthesia techniques that support both. Current evidence from mixed surgical populations and procedure-specific analyses, including cardiac, thoracic, orthopaedic, bariatric, and breast surgery, suggests that the most consistent benefit of opioid minimisation is improved tolerability, particularly reduced postoperative nausea and vomiting, rather than a major reduction in postoperative pain intensity. OFA may also shift the adverse-effect profile towards haemodynamic events such as bradycardia and hypotension. We also discuss the practical challenges of implementation, including training requirements, monitoring issues, and the important but often overlooked distinction between opioid-free anaesthesia and opioid-free analgesia. Finally, we consider the main limitations of the current literature, especially inconsistent definitions, a focus on short-term outcomes and the near-exclusive enrolment of opioid-naive patients. We conclude that clinically meaningful outcomes depend more on the quality of the perioperative pathway than on whether intraoperative opioids are reduced or completely avoided.