This prospective randomized trial compared ultrasound-guided single-injection (SI) and triple-injection (TI) subparaneural popliteal sciatic nerve block. We hypothesized that multiple injections are not required when local anesthetic (LA) is deposited under the paraneurium because the latter entraps LA molecules, ensuring circumferential spread around the nerve. Therefore, in addition to comparable success rates, we also expected similar total anesthesia-related times (sum of performance and onset times) and designed this study as an equivalency trial. Ultrasound-guided subparaneural posterior popliteal sciatic nerve block was carried out in 100 patients. In the SI group, LA was deposited at a single location between the tibial and peroneal nerves. In the TI group, LA was injected between the tibial and peroneal divisions, medial to the tibial nerve, and lateral to the common peroneal nerve. The total LA volume (15 mL) and mixture (lidocaine 1%–bupivacaine 0.25%–epinephrine 5 μg/mL) were identical in all subjects. The performance time, number of needle passes, and adverse events (paresthesia, neural edema) were recorded by the (nonblinded) investigator supervising the block. A blinded observer evaluated the success rate (sensorimotor composite score ≥6/8 points at 30 minutes) as well as the onset time and contacted patients 7 days after the surgery to inquire about persistent numbness or motor deficit. Both techniques provided comparable success rates (92%) and total anesthesia-related times (17.1–19.7 minutes). Expectedly, the SI group required fewer needle passes (1 vs 3; P < 0.001) and a shorter needling time (3.0 ± 2.3 minutes vs 4.0 ± 2.3 minutes; P = 0.025). The TI group displayed a shorter onset time (12.5 ± 7.9 minutes vs 15.8 ± 7.9 minutes; P = 0.027). The performance time, procedural discomfort, and incidence of paresthesia (14%–20%) were similar between the 2 groups. Sonographic neural swelling was detected in 2 subjects in the SI group. In both cases, the needle was carefully withdrawn and the injection was completed uneventfully. Follow-up of the 100 subjects 1 week after surgery revealed no residual numbness or motor deficit. Ultrasound-guided SI and TI subparaneural popliteal sciatic nerve blocks result in comparable success rates and total anesthesia-related times. Expectedly, the SI technique requires fewer needle passes.

This dose-finding study aimed to determine the minimum effective volume in 90% of patients (MEV90) of lidocaine 1.5% with epinephrine 5 μg/mL for ultrasound-guided costoclavicular block. Using an in-plane technique and a lateral-to-medial direction, the block needle was positioned in the middle of the 3 cords of the brachial plexus in the costoclavicular space. The entire volume of lidocaine was deposited in this location. Dose assignment was carried out using a biased-coin-design up-and-down sequential method, where the total volume of local anesthetic administered to each patient depended on the response of the previous one. In case of failure, the next subject received a higher volume (defined as the previous volume with an increment of 2.5 mL). If the previous patient had a successful block, the next subject was randomized to a lower volume (defined as the previous volume with a decrement of 2.5 mL), with a probability of b = 0.11, or the same volume, with a probability of 1 − b = 0.89. Success was defined, at 30 minutes, as a minimal score of 14 of 16 points using a sensorimotor composite scale. Patients undergoing surgery of the elbow, forearm, wrist, or hand were prospectively enrolled until 45 successful blocks were obtained. This clinical trial was registered with ClinicalTrials.gov (ID NCT02932670). Fifty-seven patients were included in the study. Using isotonic regression and bootstrap confidence interval, the MEV90 for ultrasound-guided costoclavicular block was estimated to be 34.0 mL (95% confidence interval, 33.4–34.4 mL). All patients with a minimal composite score of 14 points at 30 minutes achieved surgical anesthesia intraoperatively. For ultrasound-guided costoclavicular block, the MEV90 of lidocaine 1.5% with epinephrine 5 μg/mL is 34 mL. Further dose-finding studies are required for other concentrations of lidocaine, other local anesthetic agents, and multiple-injection techniques.

This multicenter, randomized trial compared intravenous (IV) and perineural (PN) dexamethasone for ultrasound (US)-guided infraclavicular brachial plexus block. Our research hypothesis was both modalities would result in similar durations of motor block. One hundred fifty patients undergoing upper limb surgery with US-guided infraclavicular block were randomly allocated to receive IV or PN dexamethasone (5 mg). The local anesthetic agent (35 mL of lidocaine 1%-bupivacaine 0.25% with epinephrine 5 μg/mL) was identical in all subjects. Patients and operators were blinded to the nature of IV and PN injectates. During the performance of the block, the performance time, number of needle passes, procedural pain, and complications (vascular puncture, paresthesia) were recorded.Subsequently, a blinded observer assessed the success rate (defined as a minimal sensorimotor composite score of 14 of 16 points at 30 minutes), onset time as well as the incidence of surgical anesthesia (defined as the ability to complete surgery without local infiltration, supplemental blocks, IV opioids, or general anesthesia). Postoperatively (at 24 hours), the blinded observer contacted patients with successful blocks to enquire about the duration of motor block, sensory block, and postoperative analgesia. The main outcome variable was the duration of motor block. No intergroup differences were observed in terms of technical execution (performance time/number of needle passes/procedural pain/complications), onset time, success rate, and surgical anesthesia. However, compared to its IV counterpart, PN dexamethasone provided 19% to 22% longer durations for motor block (15.7 ± 6.2 vs 12.9 ± 5.5 hours; P = 0.009), sensory block (16.8 ± 4.4 vs 13.9 ± 5.4 hours; P = 0.002), and postoperative analgesia (22.1 ± 8.5 vs 18.6 ± 6.7 hours; P = 0.014). Compared with its IV counterpart, PN dexamethasone (5 mg) provides a longer duration of motor block, sensory block, and postoperative analgesia for US-guided infraclavicular block. Future dose-finding studies are required to elucidate the optimal dose of dexamethasone.