In this systematic review and meta-analysis, OFA decreased pain scores in patients within 0–2 hours after surgery in comparison to OA. At 24 hours following the operation, there was no noteworthy difference in the pain score between the two groups. These results correspond with prior research[23, 37, 38].
This meta-analysis found that OFA resulted in a lower overall consumption of postoperative analgesics, both within 0–2 hours after the surgery and in the postoperative period, compared to OA. These results indicate that patients who receive OFA require fewer postoperative analgesics for pain management compared to those who receive OA, who require higher amounts of postoperative analgesics. This finding suggests that OFA provides an advantage in reducing the need for analgesics after surgery, which could potentially improve a patient's postoperative recovery by mitigating side effects. A meta-analysis conducted by Alexander Olausson et al.[38]supports these findings by indicating that the opioid group experienced more pain and required higher opioid doses 24 hours post-surgery.
The study results exhibited heterogeneity, which can be attributed to variances in design and anesthetic application amongst included studies. However, the limited number of studies prevented further subgroup analysis. Furthermore, the current evidence primarily pertains to short-term follow-up studies and requires confirmation from long-term follow-up data. Further research with extended follow-up durations is required to compare the effects of OFA with opioids in regulating postoperative pain and opioid consumption. These studies can provide comprehensive information, allowing for a more reliable basis for clinical practice and decision-making.
It should be noted that there was heterogeneity in the study results. This may be attributed to differences in the design and anesthetic application of the included studies. However, the number of included studies limited further subgroup analysis. Additionally, the current evidence mainly pertains to short-term follow-up studies and lacks confirmation from long-term follow-up data. Further studies with medium- to long-term follow-up are necessary to compare the effects of OFA with those of opioids on postoperative pain control and opioid consumption. These studies can offer more comprehensive information, providing a more reliable basis for clinical practice and decision-making.
Moreover, the use of an OFA approach was found to effectively decrease the occurrence of PONV, particularly in laparoscopic surgeries. The benefit of OFA can be attributed to its avoidance of the common side effects associated with opioids, leading to a more positive impact on patients' well-being. The medications utilized in OFA, such as dexmedetomidine, propofol, ketamine, lidocaine, and magnesium, demonstrate potential in reducing PONV. This is in line with the fourth edition of the consensus guidelines for preventing and treating PONV, which recommend the implementation of multimodal analgesic approaches to minimize the reliance on opioids during the perioperative period of laparoscopic procedures[9].
The postoperative prophylactic use of an antiemetic regimen is not clear to us, and some studies have used ondansetron and/or dexamethasone as prophylaxis, which may also reduce the occurrence of postoperative nausea and vomiting and the use of antiemetic drugs. However, Ziemann-Gimmel[39] found a significant reduction in PONV in the OFA group, even with triple PONV prophylaxis for both groups. Thus, OFA can significantly reduce the risk of postoperative nausea and vomiting, thus effectively reducing the use of antiemetics. This is consistent with previous study findings[23].
In terms of PACU discharge time, no significant difference was observed between the two groups, which is consistent with previous studies[23, 38]. Although PACU recovery time can indirectly reflect the effectiveness of anesthetic modalities, it cannot be used alone to judge the superiority of OFA versus opioid anesthesia. For PACU lag time, other factors, such as the type of surgery and patient characteristics, need to be considered.
For the analysis of postoperative quality of recovery, our meta-analysis showed no statistically significant difference between opioid-free multimodal anesthesia and opioid anesthesia in terms of QoR40 quality of recovery scores. However, in each of the original studies, we observed higher scores in the opioid-free multimodal anesthesia group than in the opioid anesthesia group. We must point out the lack of bias in our findings because we only presented objective results obtained in the original studies.
In summary, OFA is a widely studied technique globally, continually undergoing refinement and improvement in clinical practice. Nevertheless, compared to opioids, there is less experience and knowledge regarding the specific drugs and their combinations in OFA[15]. Several controversies persist, warranting further research to optimize its therapeutic effectiveness and safety in anesthesia practice. The meta-analysis provides new evidence and best practices for pain management and adverse events in opioid-free multimodal anesthesia in laparoscopic surgery. However, due to the small number of literature included in the study, there is still a limited understanding of the advantages and disadvantages of opioid-free multimodal anesthesia in surgery. Therefore, randomized trials with larger sample sizes are urgently needed to further support our conclusions, as well as to further investigate aspects such as long-term postoperative effects, quality of recovery, and patient satisfaction.