Efficacité analgésique d'une anesthésie avec opioïdes versus sans opioïdes : une revue systématique de la littérature avec méta-analyses [Analgesic impact of intra-operative opioids versus opioid free anesthesia: a systematic review and meta-analysis] Les opioïdes sont administrés durant l'intervention afin de contrôler la réponse sympathique à un stimulus chirurgical, mais aussi pour soulager la douleur postopératoire. Récemment, l'utilisation des opioïdes durant la chirurgie a été remise en question en raison de l'absence probable de bénéfice dans la phase postopératoire immédiat, mais aussi en raison des effets secondaires, tels que les nausées et vomissements postopératoires. Le but de cette méta-analyse est d'investiguer si l'utilisation d'opioïde intraopératoire comparée à une stratégie sans opioïde permet de diminuer les douleurs postopératoires sans augmenter le taux de nausées et vomissements postopératoires. Nous avons inclus des essais cliniques randomisés et contrôlés effectués chez des patients adultes pour tout type de chirurgie qui ont étudié l'efficacité analgésique postopératoire d'une administration intraopératoire d'opioïde avec soit l'administration d'un placebo, soit l'absence d'administration. L'analyse des 23 études identifiées avec plus de 1300 patients inclus a démontré que les scores de douleurs au repos (échelle de 0 à 10, 0 étant aucune douleur et 10 la pire douleur imaginable) à 2h postopératoire étaient équivalents dans les deux groupes, avec une différence moyenne (IC 95%) de 0,2 point (-0,2 à 0,5), p=0,38. Les taux de nausées et vomissements postopératoires étaient de 24% dans le groupe avec opioïde et 19% dans le groupe sans ce qui représente un risque relatif (IC 95%) de 0,77 (0,61 à 0,97), p=0,03. En conclusion, l'utilisation d'opioïde intraopératoire ne diminue pas les douleurs postopératoires, mais est associée à une augmentation des nausées et vomissements postopératoire.

Intra-operative remifentanil is associated with increased postoperative analgesic requirements and opioid consumption. Dexmedetomidine has characteristics suggesting it may substitute for intra-operative remifentanil during general anaesthesia, but existing literature has reported conflicting results. We undertook this meta-analysis to investigate whether general anaesthesia including dexmedetomidine would result in less postoperative pain than general anaesthesia including remifentanil. The MEDLINE and PubMed electronic databases were searched up to October 2018. Only randomised trials including patients receiving general anaesthesia and comparing dexmedetomidine with remifentanil administration were included. Meta-analyses were performed mostly employing a random effects model. The primary outcome was pain score at rest (visual analogue scale, 0-10) at two postoperative hours. The secondary outcomes included: pain score at rest at 24 postoperative hours; opioid consumption at 2 and 24 postoperative hours; and rates of hypotension, bradycardia, shivering and postoperative nausea and vomiting. Twenty-one randomised trials, including 1309 patients, were identified. Pain scores at rest at two postoperative hours were lower in the dexmedetomidine group, with a mean difference (95%CI) of À0.7 (À1.2 to À0.2), I 2 = 85%, p = 0.004, and a moderate quality of evidence. Secondary pain outcomes were also significantly better in the dexmedetomidine group. Rates of hypotension, shivering and postoperative nausea and vomiting were at least twice as frequent in patients who received remifentanil. Time to analgesia request was longer, and use of postoperative morphine and rescue analgesia were less, with dexmedetomidine, whereas episodes of bradycardia were similar between groups. There is moderate evidence that intra-operative dexmedetomidine during general anaesthesia improves pain outcomes during the first 24 postoperative hours, when compared with remifentanil, with fewer side effects.

Background Opioid‐induced hyperalgesia is a state of nociceptive sensitisation secondary to opioid administration. The objective of this meta‐analysis was to test the hypothesis that high‐dose intraoperative opioids contribute to increased post‐operative pain and hyperalgesia when compared with a low‐dose regimen in patients under general anaesthesia. Methods We followed the Preferred Reporting Items for Systematic Reviews and Meta‐Analyses statement guidelines and rated the certainty of evidence with the Grading of Recommendations, Assessment, Development and Evaluation system. Only trials investigating pain outcomes and comparing two different dosages of the same intraoperative opioid in patients under general anaesthesia were included. The primary outcome was pain score (analogue scale, 0‐10) at 24 post‐operative hours. Secondary outcomes included pain score and cumulative intravenous morphine equivalents (mg) consumed at 2 post‐operative hours, together with mechanical pain threshold (g·mm−2). Results Twenty‐seven randomised controlled trials, including 1630 patients, were identified. Pain score at rest at 24 post‐operative hours was increased in the high‐dose group (mean difference [95% CI]: −0.2 [−0.4, −0.1]; trial sequential analysis‐adjusted CI: −0.4, −0.02; low certainty of evidence). Similarly, at 2 post‐operative hours, both pain score (mean difference [95% CI]: −0.4 [−0.6, −0.2]; low certainty of evidence) and cumulative intravenous morphine equivalents consumed (mean difference [95% CI]: −1.6 mg [−2.6, −0.7]; low certainty of evidence) were significantly higher in the high‐dose group. Finally, the threshold for mechanical pain was significantly lower in the high‐dose group (mean difference to pressure [95% CI]: 3.8 g·mm−2 [1.8, 5.8]; low certainty of evidence). Conclusions There is low certainty of evidence that high‐dose intraoperative opioid administration increases pain scores in the post‐operative period, when compared with a low‐dose regimen.