A meta-analysis of the effects of opioid-free anesthesia on postoperative analgesia and recovery after various types of surgery

Background: Opioids are widely used to manage stress responses during surgery and postoperative pain. However, opioids have both short-term and long-term side effects, The feasibility of opioid-free anesthesia is controversial. This meta-analysis aims to collect the current evidence on opioid-free anesthesia and analyze whether opioid-free anesthesia is feasible. Method: We searched Cochrane-Library, Pubmed database and EMBASE. Included were randomized controlled trials published between January 2000 and March 2023 in which at least one opioid-free study group was not using opioids before surgery, during induction of anesthesia, and before recovery from anesthesia. The Primary outcome was postoperative pain score (2h and 24h) , the Secondary outcomes were extubation time, discharge time from the post-anesthesia care unit, incidence of nausea and vomiting, opioid consumption, and Postoperative recovery quality score between strict opioid-free and opioid-based general anesthesia. Result: 37 RCTs were eventually included, involving a total of 2723 patients. Meta-analysis showed that in a comprehensive analysis of all included studies, opioid-free anesthesia (OFA) had no clinically significant effects on postoperative extubation time, PACU discharge time, postoperative pain score at 2h, and postoperative recovery quality score. However, it is clinically significant that the incidence of nausea and vomiting after opioid-free anesthesia (OFA) (MD=0.32,955CI: [0.22,0.45], I 2 = 43%,P<0.00001), pain score at 24h after surgery (MD=-0.72, 95%CI: [-0.90, -0.53], I 2 = 60%,P=0.007,and opioid consumption after surgery (MD=-2.07, 95%CI: [-2.65,-1.50], I 2 = 60%,P<0.00001) are reduced. Through subgroup analysis of opioid-free anesthesia for different types of surgery, we found that opioid-free anesthesia has different effects on patients with different types of surgery.