What Ingredients are Essential for the Recipe of a Study?

This article refers to:

The Effect of Pre-emptive Dexketoprofen Administration on Postoperative Pain Management in Patients with Ultrasound Guided Interscalene Block in Arthroscopic Shoulder Surgery

In this investigation [1], the authors evaluated among other objectives, the analgesic efficacy and the duration of analgesia from a cohort of 60 patients for arthroscopic shoulder surgery. The group 2 was treated prior to surgery with iv dexketoprofen (Dx) and an ultrasound-guided interscalene block (ISB) under general anesthesia and performed as ambulatory procedure [2]. Another objective of the study was the duration of motor and sensitive blocks. There were no significant differences in terms of motor block duration (min) and were significant differences in terms of sensory block duration (min) between the Dx group 210.66 ± 74.55 and control group 168.00 ± 80.31 (p < 0.05). The differences between the duration of both blocks could be explained both by the regression of nervous block, the last one to recover is the sensitive one, both by the volume (20 mL) and the concentration of bupivacaine (0.25%) and lidocaine (1%) administered, as well as by the anti-inflammatory effect of iv Dx. Local anesthetics (LA) act in different ways, none of which have been proven, which would also be interesting to elucidate. LA may cause local vasoconstriction limiting systemic uptake or may have direct effects on peripheral nerves. In addition, they may also act systemically by anti-inflammatory effects. Falçao et al. have shown that a minimum volume of 2.34 mL of 0.5% bupivacaine with epinephrine in single-injection ISB provide complete absence of pain and no use of analgesics for 6 h [3]. Numerous randomized controlled trials and meta-analyses have revised the pros and cons of the use of various individual adjuvants [4]. Adrenaline is one of the different adjuvants that extend nerve block [3]. Dexamethasone improves the quality and duration of peripheral nerve block (PNB) over LA alone. This is thought to be mediated by attenuating the release of inflammatory mediators, reducing ectopic neuronal discharge, and inhibiting potassium channel-mediated discharge of nociceptive C-fibres [5]. The addition of those two adjuvants may provide patients who are otherwise not eligible for extended, continuous perineural techniques, to experience an extended period of analgesia compared with LA PNB alone. Cummings et al. reported that when 8 mg of dexamethasone was added to bupivacaine for ISB, the duration of analgesia extended approximately from 14 to 24 hours [6]. Tandoc et al. found similar results with 4 mg (21.6 hours) and 8 mg (25.2 hours) of dexamethasone [7]. However, there are no systematic reviews or meta-analyses estimating the effect of dexamethasone on PNB duration and the incidence of complications. Also, dexamethasone is not approved for perineural administration by any regulatory body (EU, FDA, and HC) [8]. It is necessary to propose clinical trials to demonstrate one or more mechanisms of action of dexamethasone and the minimum effective and safe dose. Another goal of the study was fentanyl requirements during the immediate postoperative period which were significantly lower in the DX group (p < 0.05) and the incidence of nausea, with no significant differences in both groups (p > 0.05). This can be justified by the small sample size, so it would be interesting to continue this study with more patients and to observe whether the administration of fentanyl associates or does not associate a significant incidence of nausea. We must reduce opioids, condition that must be met to perform outpatient surgery [9, 10]. I would recommend using volumes between 10 and 15 mL of a single LA, preferably of intermediate-long action and avoid mixing it with a short-acting LA to prolong the effect. In both groups it was necessary to administer a major opioid, therefore the LA concentrations used seem to be low; a volume higher than 20 mL in the ISB is not recommended due to the associated risks. The option to reduce the LA volume and avoid the opioid may be to use a LA with adrenaline or with dexamethasone, so studies will be necessary.

This study provides us more information about the importance of managing regional techniques associated with general anesthesia in outpatient surgery. This type of procedure allows reducing or avoiding the perioperative use of opioids and neuromuscular relaxants, which makes it suitable for this type of surgery. In the same line is the use of NSAIDs prior to tissue damage, which aims to also reduce the dose of opioids. The result is an awakening without pain and without nausea and home discharge, which reduces health costs. I suggest that a larger study would be beneficial with the following methodological modifications. Firstly, to describe the method used to generate the randomization and to describe the masking method. As well it would be useful to continue including patients in such a way that this pilot study could be published in the future as a clinical trial.

Declaration of Interest

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.