To Örebro University

BACKGROUND:  Opioid-based treatment is used to manage stress responses during surgery and postoperative pain. However, opioids have both acute and long-term side-effects, calling for opioid-free anaesthetic strategies. This meta-analysis compares adverse events, postoperative recovery, discharge time from post-anaesthesia care unit, and postoperative pain, nausea, vomiting, and opioid consumption between strict opioid-free with opioid-based general anaesthesia.

METHODS:  We conducted a systematic review and meta-analysis. We searched PubMed, Embase, Cinahl, Cochrane Library, selected reference lists, and Google Scholar. We included randomised controlled trials (RCTs) published between January 2000 and February 2021 with at least one opioid-free study arm, i.e. no opioids administered preoperatively, during anaesthesia induction, before skin closure, or before emergence from anaesthesia.

RESULTS:  The study comprised 1934 patients from 26 RCTs. Common interventions included laparoscopic gynaecological surgery, upper gastrointestinal surgery, and breast surgery. There is firm evidence that opioid-free anaesthesia significantly reduced adverse post-operative events (OR 0.32, 95% CI 0.22 to 0.46, I² =56%, p<0.00001), mainly driven by decreased nausea (OR 0.27, (0.17 to 0.42), p<0,00001) and vomiting (OR 0.22 (0.11 to 0.41), p<0.00001). Postoperative opioid consumption was significantly lower in the opioid-free group (-6.00 mg (-8.52 to -3.48), p<0.00001). There was no significant difference in length of post-anaesthesia care unit stay and overall postoperative pain between groups.

CONCLUSIONS:  Opioid-free anaesthesia can improve postoperative outcomes in several surgical settings without evidence of adverse effects on patient safety and pain management. There is a need for more evidence-based non-opioid anaesthetic protocols for different types of surgery as well as postoperative phases.