Motor-sparing nerve blocks for total knee replacement: A scoping review.

STUDY OBJECTIVE: This scoping review investigates the optimal combination of motor-sparing analgesic interventions for patients undergoing total knee replacement (TKR). DESIGN: Scoping review. INTERVENTION: MEDLINE, EMBASE and CINAHL databases were searched (inception-last week of May 2020). Only trials including motor-sparing interventions were included. Randomized controlled trials lacking prospective registration and blinded assessment were excluded. MAIN RESULTS: The cumulative evidence suggests that femoral triangle blocks outperform placebo and periarticular infiltration. When combined with the latter, femoral triangle blocks are associated with improved pain control, higher patient satisfaction and decreased opioid consumption. Continuous femoral triangle blocks provide superior postoperative analgesia compared with their single-injection counterparts. However, these benefits seem less pronounced when perineural adjuvants are used. Combined femoral triangle-obturator blocks result in improved analgesia and swifter discharge compared with femoral triangle blocks alone. CONCLUSIONS: The optimal analgesic strategy for TKR may include a combination of different analgesic modalities (periarticular infiltration, femoral triangle blocks, obturator nerve block). Future trials are required to investigate the incremental benefits provided by local anesthetic infiltration between the popliteal artery and the capsule of the knee (IPACK), popliteal plexus block and genicular nerve block.

Erector spinae plane block: A narrative review with systematic analysis of the evidence pertaining to clinical indications and alternative truncal blocks.

STUDY OBJECTIVE: This narrative review discusses the anatomy, mechanism of action, techniques, pharmacology, indications, complications and substitutes for erector spinae plane (ESP) blocks. INTERVENTIONS: The Medline, Embase and Google Scholar databases (inception-last week of April 2020) were searched. For indications and alternative blocks, a systematic analysis of the available evidence was carried out. In order to highlight the best evidence available, only randomized trials with prospective registration, blinded assessment and sample size justification were retained for analysis. MAIN RESULTS: The collective body of anatomical studies suggests that ESP block may work through a combination of different mechanisms (e.g., local anesthetic spread to the thoracic paravertebral space, epidural space, and dorsal ramus). Compared to control, the available evidence suggests that ESP block results in decreased postoperative pain and opioid requirement for a wide array of thoracic and abdominal surgical interventions. Erector spinae plane blocks and thoracic paravertebral blocks seem to provide comparable benefits for thoracoscopic and breast cancer surgery when performed with a similar number of injections. Currently, ESP blocks should be favored over intercostal blocks since, at best, the latter provide similar analgesia to ESP blocks despite requiring multiple-level injections. CONCLUSIONS: In recent years, ESP blocks have become the topic of considerable clinical interest. Future trials are required to investigate their optimal technique, dose of local anesthetic and perineural adjuvants. Moreover, additional investigation should compare ESP blocks with robust multimodal analgesic regimens as well as truncal blocks such as thoracic epidural block, midpoint transverse process to pleura block, PECS block, quadratus lumborum block, and transversus abdominis plane block.

Randomized comparison between epidural waveform analysis through the needle versus the catheter for thoracic epidural blocks.

BACKGROUND: Epidural waveform analysis (EWA) provides a simple confirmatory adjunct for loss of resistance (LOR): when the needle/catheter tip is correctly positioned inside the epidural space, pressure measurement results in a pulsatile waveform. Epidural waveform analysis can be carried out through the tip of the needle (EWA-N) or the catheter (EWA-C). In this randomized trial, we compared the two methods. We hypothesized that, compared with EWA-C, EWA-N would result in a shorter performance time. METHODS: One hundred and twenty patients undergoing thoracic epidural blocks for thoracic or abdominal surgery were randomized to EWA-N or EWA-C. In the EWA-N group, LOR was confirmed by connecting the epidural needle to a pressure transducer. After obtaining a satisfactory waveform, the epidural catheter was advanced 5 cm beyond the needle tip. In the EWA-C group, the epidural catheter was first advanced 5 cm beyond the needle tip after the occurrence of LOR. Subsequently, the catheter was connected to the pressure transducer to detect the presence of waveforms. In both study groups, the block procedure was repeated at different intervertebral levels until positive waveforms could be obtained (through the needle or catheter as per the allocation) or until a predefined maximum of three intervertebral levels had been reached. Subsequently, the operator administered a 4 mL test dose of lidocaine 2% with epinephrine 5 µg/mL through the catheter. An investigator present during the performance of the block recorded the performance time (defined as the temporal interval between skin infiltration and local anesthetic administration through the epidural catheter). Fifteen minutes after the test dose, a blinded investigator assessed the patient for sensory block to ice. Success was defined as a bilateral block in at least two dermatomes. Furthermore, postoperative pain scores, local anesthetic consumption, and breakthrough analgesic consumption were recorded. RESULTS: No intergroup differences were found in terms of performance time, success rate, postoperative pain, local anesthetic requirement, and breakthrough analgesic consumption. CONCLUSION: EWA can be carried out through the needle or through the catheter with similar efficiency (performance time) and efficacy (success rate, postoperative analgesia). TRIAL REGISTRATION NUMBER: NCT03603574.