Carta Acesso aberto Revisado por pares

Opioid-free anaesthesia: should we all adopt it? An overview of current evidence

2023; Lippincott Williams & Wilkins; Volume: 40; Issue: 8 Linguagem: Inglês

10.1097/eja.0000000000001775

ISSN

1365-2346

Autores

Patrice Forget, Marc Van de Velde, Esther Pogatzki‐Zahn,

Tópico(s)

Anesthesia and Sedative Agents

Resumo

Multimodal analgesia or opioid-sparing techniques? Opioid-free anaesthesia (OFA) is a term covering a variety of techniques and substances, generally based on the concept of using opioid-sparing techniques and multimodal analgesia. These techniques allow the anaesthesiologist to spare opioids (up to no opioids) during the procedure.1 There is an abundant literature documenting the feasibility of OFA, in routine practice, including cohorts of more than 20 000 patients.2 However, while current guidelines emphasise multimodal analgesia and opioid-sparing techniques, they do not explicitly discuss arguments for or against OFA, even if referencing OFA.3,4 These recommendations are supported by data suggesting that the use of high doses of opioids during surgery, particularly remifentanil, may, on its own, worsen the quality of postoperative pain management.5,6 This supports the use of multimodal analgesia alongside reduction of intraoperative opioid administration.7 Additionally, there are situations where practitioners may need to opt for OFA, such as during a time of limited opioid access, because of a shortage, or in resource-limited settings.8,9 It is clear that some of these techniques facilitate the management of certain patients, such as those taking opioids before surgery.10 However, like any technique, combining opioid-sparing techniques to the point of no longer needing opioids during surgery requires learning and training, because the drugs and techniques that can spare the use of opioids are not without risk either.10 So, to what extent are these techniques transferable, and is it worth considering for all patients or just for specific groups of patients? A large, pragmatic, multicentre trial In this issue, Zhou et al.11 describes the largest randomized controlled trial of OFA versus an opioid-based technique in endoscopic nasal surgery. They convincingly show that while the quality of recovery (assessed using the QoR-40 questionnaire) is not different, sub-scores, such as pain scores, were improved in the OFA group. In line with the lack of difference regarding the primary endpoint (QoR-40), it is important to emphasise that OFA cannot solve everything. In terms of safety and adverse events, collected as secondary endpoints, their incidence and severity appeared to be higher in the opioid-based group.11 However, most importantly, Zhou et al. have shown that the technique is transferable. They adopted a relatively low dose of dexmedetomidine (bolus and infusion of 0.5 μg kg−1 and 0.5 μg kg−1 h−1) and a pragmatic design, respecting routine practices as much as possible (use of vasoactive agents, e.g.). The absence of ketamine in their study illustrates that different OFA techniques may be adequate, depending on the patient and type of surgery. In other surgical procedures where postsurgical opioid requirements are greater, required for longer, or in patients with preoperative opioid use, ketamine might be more useful.12 Thus, OFA is feasible, implementable, transferable and supported by high-quality evidence in terms of noninferiority (in quality of recovery) and potential superiority in some aspects (certainly nausea and vomiting, less certainly for QoR). This poses the question: where is OFA needed and (when) should it be implemented in clinical practice? An overview of meta-analyses on opioid-free anaesthesia Transferable does not necessarily mean generalisable. The generalisablilty can be, at least indirectly and in part, assessed by the convergence of the literature. In other words, when looking at how appropriate a technique is, it is important to look at the results of other studies. These can be confirmatory or not, with similar results or not. They inform us about sources of potential divergence and help us to explore them. In August 2022, three meta-analyses, focusing specifically on OFA in any type of surgery were available on PubMed/MEDLINE.13–15 The first, published in 2019 by Frauenknecht et al., 13 concluded that, supported by 'strong evidence', anaesthesiologists should reconsider their intraoperative opioid choices on a case-by-case basis. This was based on the fact that postoperative pain management is not improved by the use of opioids during surgery, and that the incidence of nausea and vomiting is increased. In 2021, Salomé et al. concluded that there was no clinical benefit with OFA, except for the risk of nausea and vomiting.14 They insisted, despite the negative reviews, that more safety data be collected. On the other hand, shortly after Salomé et al., Olausson et al.15 concluded that OFA can improve outcomes in several surgical settings without evidence of adverse effects. So which evidence converges and which does not? Specific techniques exist to assess confidence in meta-analyses. We have chosen the AMSTAR 2 tool to assess their quality (https://amstar.ca/). The overall quality rating ranges from high to critically low (Table 1). Considering all three meta-analyses, the evidence consistently converges to allow us to conclude that OFA helps prevent nausea and vomiting in a wide range of populations, which is confirmed by Zhou et al.11 in this issue of EJA. Evidence also converges that pain scores and opioid consumption are decreased or neutrally affected by OFA, possibly depending on the type of patients, setting and surgery. Finally, the quantitative evidence converges to say that no safety signal appears in general,13–15 although this cannot be excluded in particular cases, according to the opinion of Salomé et al.14 However, their plea for the need for more safety data may have been, at least partially, met by Zhou et al., including transferability of the technique, with adequate training. Zhou et al. describe the training as having 'conducted a series of lectures' and 'trained all the participants until they were able to conduct this technique independently and were approved by the project leader'. This training is likely a critical aspect with the adoption of any new technique and may reconcile the apparent discrepancies between quantitative evidence and authors' opinion.Table 1: AMSTAR 2 (https://amstar.ca/) scores for meta-analyses on opioid-free anaesthesiaFinally, what really matters? The National Institute for Health and Care Excellence (NICE) considers that 'critical outcomes for decision-making are health-related quality of life, pain reduction, amount of additional medications used and adverse events related to treatment'.3 OFA reduces the amount of medications (opioids) and can modify some of these outcomes (nausea and vomiting, for instance). Certain aspects of quality of life (recovery) are improved, but not all and not for everyone. Considering that many of these goals can be achieved using opioid-sparing strategies (i.e. avoiding high doses of opioids first, rather than eliminating them entirely), this means that alongside different tools (OFA being one of them), a patient-centred approach is essential and is the priority. Taking into account, the current guidelines and limited training, perhaps the better goal would be to prioritise opioid-sparing strategies (and to reduce opioid use for anaesthesia, rather than focussing too much on OFA). It is also important to remember that OFA is not the same as giving no opioids in the postoperative phase. This leaves room for different techniques and different drugs. In short, whatever technique we offer to patients, listening and learning from them, reassessing the quality of care, collecting data and constantly improving our techniques, remains the cornerstone of perioperative medicine. In the future, we need more evidence about risk–benefit of different drug combinations, who will benefit from which drug is best, and what outcomes identified as the most important are affected.16

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