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.

Perineural dexamethasone has gained popularity in regional anaesthesia to prolong the duration of analgesia, but its advantage over systemic administration is disputed. The objective of this meta-analysis was to compare the analgesic efficacy of both routes of administration during peripheral nerve block. The methodology followed the PRISMA statement guidelines. The primary outcome was the duration of analgesia analysed according to the type of local anaesthetic administered (bupivacaine or ropivacaine). Secondary outcomes included cumulative opioid consumption in morphine i.v. equivalents, pain scores, and complication rates (neurological complications, infection, or hyperglycaemia). Eleven controlled trials, including 914 patients, were identified. The duration of analgesia was significantly increased with perineural dexamethasone vs systemic dexamethasone by a mean difference of 3 h [95% confidence interval (CI): 1.4, 4.5 h; P=0.0001]. Subgroup analysis revealed that the duration of analgesia was increased by 21% with bupivacaine (mean difference: 4.0 h; 95% CI: 2.8, 5.2 h; P<0.00001) and 12% with ropivacaine (mean difference: 2.0 h; 95% CI: -0.5, 4.5 h; P=0.11). The quality of evidence for our primary outcome was moderate according to the GRADE system. There were no significant differences in other secondary outcomes. No neurological complications or infections were reported. Glucose concentrations were not increased when dexamethasone was injected systemically, but this outcome was reported by only two trials. There is, therefore, moderate evidence that perineural dexamethasone combined with bupivacaine, but not ropivacaine, slightly prolongs the duration of analgesia, without an impact on other pain-related outcomes, when compared with systemic dexamethasone. Injection of perineural dexamethasone should be cautiously balanced in light of the off-label indication for this route of administration.

Many consider femoral nerve block the gold standard in pain management following knee arthroplasty. Local infiltration analgesia is an alternate approach that applies the concept of surgical wound infiltration with local anaesthetics. This meta-analysis aims to compare both analgesic treatments for analgesia and functional outcomes after total knee arthroplasty. This meta-analysis was performed according to the PRISMA statement guidelines. The primary outcomes were cumulative i.v. morphine consumption, pain scores at rest and on movement on postoperative day one (analogue scale,0-10). Secondary outcomes included range of motion, quadriceps muscle strength, length of stay and rates of complications (neurologic events, cardiovascular events, falls and knee infections). Fourteen trials, including 1122 adult patients were identified. There was no difference in i.v. morphine consumption (mean difference: -2.0 mg; 95% CI: -4.9, 0.9 mg; I(2)=69%; P=0.19), pain scores at rest (mean difference: -0.1; 95% CI: -0.4, 0.3; I(2)=72%; P=0.80) and pain scores on movement (mean difference: 0.2; 95% CI: -0.5, 0.8; I(2)=80%; P=0.64) on postoperative day one (a negative mean difference favours local infiltration analgesia). The qualities of evidence for our primary outcomes were moderate according to the GRADE system. There were no clinical differences in functional outcomes or rates of complications. Complication rates were captured by three trials or fewer with exception of knee infection, which was sought by eight trials. Local infiltration analgesia provides similar postoperative analgesia after total knee arthroplasty to femoral nerve block. Although this meta-analysis did not capture any difference in rates of complications, the low number of trials that specifically sought these outcomes dictates caution.

There is currently very low quality evidence that 4 mg of perineural dexamethasone represents a ceiling dose that prolongs analgesia duration by a mean period of 6 and 8 hours when combined with short-/intermediate- or long-acting local anesthetics, respectively. Additional data are needed to explore the threshold for this effect, particularly with doses below 4 mg. The risk of neurologic complications is probably not increased (very low evidence).

BACKGROUND: Both dexamethasone and dexmedetomidine are effective peripheral nerve block (PNB) perineural adjuncts that prolong block duration. However, each is associated with side effects. With paucity of head-to-head comparisons of these adjuncts, the question of the best adjunct to mix with local anesthetics (LA) for PNB is unanswered. This meta-analysis aims to inform current practice and future research by identifying the superior adjunct by comparing dexamethasone and dexmedetomidine. METHODS: Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, trials comparing the combination of perineural dexamethasone or dexmedetomidine with LA to LA alone for PNB were sought. The Cochrane Risk of Bias Tool was used to assess the methodological quality of trials, and indirect or network meta-analyses using random-effects modeling were planned. We designated duration of analgesia as a primary outcome. Secondary outcomes included sensory and motor block durations, sensory and motor block onset times, and the risks of hypotension, sedation, and neurological symptoms. RESULTS: Fifty trials were identified, including only 1 direct comparison, precluding a network meta-analysis. Indirect meta-analysis of 49 trials (3019 patients) was performed. Compared to dexmedetomidine, dexamethasone prolonged the duration of analgesia by a mean difference (95% confidence interval [CI]) of 148 minutes (37–259 minutes) (P = .003), without prolonging sensory/motor blockade. Dexmedetomidine increased rates of hypotension (risk ratio [95% CI], 6.3 [1.5–27.5]; P = .01) and sedation (risk ratio [95% CI], 15.8 [3.9–64.6]; P = .0001). Overall risk of bias was moderate, and publication bias was noted, resulting in downgrading evidence strength. CONCLUSIONS: There is low-quality evidence that both adjuncts similarly prolong sensory/motor blockade. However, dexamethasone may be a superior adjunct; it improves the duration of analgesia by a statistically significant increase, albeit clinically modest, equivalent to 2.5 hours more than dexmedetomidine, without the risks of hypotension or sedation. Future direct comparisons are encouraged.