Regional Anesthesia & Pain Medicine | 2021
Keep it simple and cheap, enhancing the quality of regional analgesia
Abstract
To the Editor The finite duration of singleinjection techniques is a limitation of regional anesthesia in acute postoperative pain management. There are three main methods to prolong the span of regional anesthetic techniques. The first is to include local anesthetic adjuncts, but the expected prolongation usually is no more than 8 hours. The second is continuous catheter techniques, but it is more complex to perform and requires an organized followup to decrease infection and migration risk. The last is using a sustainedrelease local anesthetic, such as liposomal bupivacaine. One of the main issues with the latter is the cost. A recent systematic review and metaanalysis by Hussain et al showed no difference between periarticular liposomal and plain bupivacaine in postoperative pain scores, analgesic consumption, opioidrelated side effects, length of stay and safety or functional outcomes in knee arthroplasty. This group is well known for showing highquality evidence not supporting the use of liposomal bupivacaine over nonliposomal bupivacaine for peripheral nerve blocks. They also exposed an industrysponsored trial in which financial and commercial conflict was not disclosed. In addition to the lack of evidence, liposomal bupivacaine is not available in all countries due to economic or policy issues. That encourages us to, rather than seeking new and expensive methods to prolong blocks, looking at inexpensive solutions such as adding triamcinolone to lower extremity blocks for total knee arthroplasty. Although triamcinolone’s physical and chemical compatibility with common local anesthetics has been described, it is usually reserved for chronic pain procedures. It has been safely added for perineural, intraarticular and epidural administration, but little is known about its effectiveness in acute postoperative pain management. According to the latest recommendations of the World Institute of Pain, its perineural administration reduces the spontaneous ectopic discharges that arise in experimental nerve end neuromas and prevent further development of ectopic impulses in freshly severed nerves. They also state that particulate corticosteroids may only be (transforaminally) injected at level L3 or lower. Thus, we recommend using triamcinolone for lower extremity blocks. Our findings suggest that using perineural triamcinolone as a local anesthetic adjunct could be a valuable opioidsparing option. It is cheaper than liposomal bupivacaine and easier to perform than continuous catheter techniques. We have seen the efficacy of this underutilized drug. In our case series, we performed a singleshot infiltration between the popliteal artery and capsule of the knee and adductor canal block using 20 mL of 0.25% bupivacaine with 20 mg of triamcinolone acetonide for fasttrack knee replacement. Most patients benefit from longlasting pain relief up to 72 hours, and we did not find any complications. Nowadays, we also recommend warming bupivacaine with an incubator fluid warmer at 37°C, as previously reported in a randomized controlled trial by Makharita et al. The proposed mechanism is the reduction of local anesthetic pKa, increasing the nonionized part and membrane permeability, accelerating its onset. Once the nonionized parts pass through the nerve membrane and gain access to the axoplasm, they equilibrate into ionized parts that bind to Na channels in a high concentration leading to a longerlasting block. Relying on a single method to improve regional anesthesia is not the best option; as always, the best approach must be multimodal. None of the methods to date fulfill all the criteria of the ideal regional anesthetic technique. Maybe it is time to think about a better use for the things we already have. We suggest physicians to use available and cheaper means such as adding triamcinolone and warming local anesthetics. Simple things can make a difference.