Postoperative pain after different doses of remifentanil infusion during anaesthesia: a meta-analysis

BACKGROUND

This meta-analysis aimed to explore the correlation between the different doses of remifentanil-based anaesthesia and postoperative pain in randomised trials.

METHODS

The electronic databases including PubMed, Cochrane, clinical trial registries, and Google Scholar were searched up to November 2022 for randomised controlled trials (RCTs) that assessed the dose dependent efficacy of remifentanil for postoperative pain intensity and hyperalgesia.

RESULTS

31 studies involving 2019 patients were included for analysis. Compared with the high remifentanil dose administration, patients in low doses showed less postoperative pain intensity at 1-2 h (weighted mean differences (WMD): 0.60, 95% CI, 0.05 to 1.15), 3-8 h (WMD: 0.38, 95% CI, 0.00 to 0.75), 24 h (WMD: 0.26, 95% CI, 0.04 to 0.48) and 48 h (WMD: 0.32, 95% CI, 0.09 to 0.55). Remifentanil-free regimen failed to decrease the pain score at 24 h (WMD: 0.10, 95% CI, -0.10 to 0.30) and 48 h (WMD: 0.15, 95% CI, -0.22 to 0.52) in comparison with remifentanil-based anaesthesia. After excluding trials with high heterogeneity, the dose of the remifentanil regimen was closely correlated with the postoperative pain score (P=0.03). In addition, the dose of the remifentanil regimen was not associated with the incidence of postoperative nausea and vomiting (PONV) (P=0.37).

CONCLUSIONS

Our meta-analysis reveals that the low dose of remifentanil infusion is recommendable for general anaesthesia maintenance. No evidence suggests that remifentanil-free regimen has superiority in reducing postoperative pain. Moreover, remifentanil doesn't have a dose dependent effect in initiating PONV.

TRIAL REGISTRATION

The protocol of present study was registered with PROSPERO (CRD42022378360).

Ketamine for postoperative pain treatment in spinal surgery: Systematic review with meta-analysis and trial sequential analysis

AIM

We aimed to assess the beneficial and harmful effects of perioperative pain treatment with ketamine in patients undergoing spinal surgery.

METHODS

We searched Medline, Embase, and CENTRAL from inception until 15 February 2023 for randomised clinical trials comparing ketamine with placebo or no intervention in patients undergoing spinal surgery. The primary outcomes were cumulative opioid consumption at 24 h postoperatively and serious adverse events. We adhered to recommendations of the Cochrane Collaboration and performed meta-analysis, Trial Sequential Analysis (TSA) to assess the risks of random errors, risk of bias assessment to evaluate the risks of systematic errors, and used the Grading of Recommendations Assessment, Development and Evaluation (GRADE).

RESULTS

We included a total of 28 randomised clinical trials enrolling 2110 participants providing data for our pre-defined outcomes. Twenty-three trials enrolled adult participants and 5 trials enrolled paediatric participants. Three trials were at low risk of bias. Meta-analysis and TSA of trials including adults showed that ketamine versus placebo or no intervention seemed to reduce the cumulative 24-h opioid consumption (mean difference -17.57 mg; TSA-adjusted 95% confidence interval, -24.22 to -10.92; p < .01; low certainty of evidence), and there was no evidence of a difference of ketamine versus placebo or no intervention on the risk of serious adverse events (risk ratio 2.16; 96.7% confidence interval, 0.35 to 13.17; p = .36; very low certainty of evidence).

CONCLUSION

In adults undergoing spinal surgery, ketamine may reduce cumulative 24-h opioid consumption. Ketamine may increase the occurrence of serious adverse events, but the evidence was very uncertain.

Perioperative Low-Dose Ketamine for Postoperative Pain Management in Spine Surgery: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Objective

Although low-dose ketamine has been shown to be generally beneficial in terms of pain control in a variety of major surgery, there is no consensus regarding the effectiveness of supplemental ketamine analgesic use exclusively in spine surgery. The objective of this systematic review and meta-analysis of randomized controlled trials (RCTs) was to assess the efficacy and safety of perioperative low-dose ketamine for pain management and analgesic consumption in patients undergoing spine surgery.

Methods

A comprehensive literature search was performed for relevant studies using PubMed, EMBASE, Web of Science, and Cochrane Library. Patients who received perioperative low-dose ketamine were compared to the control group in terms of postoperative pain intensity, opioid consumption, and adverse events. Patients were further categorized by ages and administration times for subgroup analysis.

Results

A total of 30 RCTs comprising 1,865 patients undergoing elective spine surgery were included. Significantly lower pain intensity and less opioid consumption at 12 h, 24 h, and 48 h postoperatively and lower incidence of postoperative nausea and vomiting (PONV) were observed in the ketamine group (all P < 0.05). There was no significant difference of central nervous system (CNS) adverse events between groups. However, different efficacy of low-dose ketamine was detected when patients were categorized by ages and administration times.

Conclusion

Perioperative low-dose ketamine demonstrated analgesic and morphine-sparing effect with no increased adverse events after spine surgery. However, this effect was not significant in pediatric patients. Only postoperative or intraoperative and postoperative administration could prolong the analgesic time up to 48 h postoperatively. Further studies should focus on the optimal protocol of ketamine administration and its effect on old age participants.

Effects of Ketamine on Postoperative Pain After Remifentanil-Based Anesthesia for Major and Minor Surgery in Adults: A Systematic Review and Meta-Analysis

Ketamine, an N-methyl-D-aspartate (NMDA) receptor antagonist, has been postulated as an adjuvant analgesic for preventing remifentanil-induced hyperalgesia after surgery. This systematic review and meta-analysis aims to assess the effectiveness of ketamine [racemic mixture and S-(+)-ketamine] in reducing morphine consumption and pain intensity scores after remifentanil-based general anesthesia. We performed a literature search of the PubMed, Web of Science, Scopus, Cochrane, and EMBASE databases in June 2017 and selected randomized controlled trials using predefined inclusion and exclusion criteria. To minimize confounding and heterogeneity, studies of NMDA receptor antagonists other than ketamine were excluded and the selected studies were grouped into those assessing minor or major surgery. Methodological quality was evaluated with the PEDro and JADA scales. The data were extracted and meta-analyses were performed where possible. Twelve RCTs involving 156 adults who underwent minor surgery and 413 adults who underwent major surgery were included in the meta-analysis. When used as an adjuvant to morphine, ketamine reduced postoperative morphine consumption in the first 24 h and postoperative pain intensity in the first 2 h in the minor and major surgery groups. It was also associated with significantly reduced pain intensity in the first 24 h in the minor surgery group. Time to the first rescue analgesia was longer in patients who received ketamine and underwent major surgery. No significant differences in the incidence of ketamine-related adverse effects were observed among patients in the intervention group and controls. This systematic review and meta-analysis show that low-dose (≤0.5 mg/kg for iv bolus or ≤5 μg/kg/min for iv perfusion) of ketamine reduces postoperative morphine consumption and pain intensity without increasing the incidence of adverse effects.