A multicenter, randomized comparison between 2, 5, and 8 mg of perineural dexamethasone for ultrasound-guided infraclavicular block.

BACKGROUND AND OBJECTIVES: This multicenter, randomized trial compared 2, 5, and 8 mg of perineural dexamethasone for ultrasound-guided infraclavicular brachial plexus block. Our research hypothesis was that all three doses of dexamethasone would result in equivalent durations of motor block (equivalence margin=3.0 hours). METHODS: Three hundred and sixty patients undergoing upper limb surgery with ultrasound-guided infraclavicular block were randomly allocated to receive 2, 5, or 8 mg of preservative-free perineural dexamethasone. 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 dose of dexamethasone. 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 out of 16 points at 30 min), onset time as well as the incidence of surgical anesthesia (defined as the ability to complete surgery without local infiltration, supplemental blocks, intravenous opioids, or general anesthesia). Postoperatively, the blinded observer contacted patients with successful blocks to inquire about the duration of motor block, sensory block, and postoperative analgesia. The main outcome variable was the duration of motor block. RESULTS: 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. Furthermore, all three doses of dexamethasone provided similar durations of motor block (14.9-16.1 hours) and sensory block. Although 5 mg provided a longer analgesic duration than 2 mg, the difference (2.7 hours) fell within our pre-established equivalence margin (3.0 hours). CONCLUSIONS: 2, 5, and 8 mg of dexamethasone provide clinically equivalent sensorimotor and analgesic durations for ultrasound-guided infraclavicular block. Further trials are required to compare low (ie, 2 mg) and ultra-low (eg, 0.5-1 mg) doses of perineural dexamethasone for brachial plexus blocks. TRIAL REGISTRATION NUMBER: TCTR20150624001.

Minimum Effective Volume of Lidocaine for Ultrasound-Guided Costoclavicular Block.

BACKGROUND AND OBJECTIVES: 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. METHODS: 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). RESULTS: 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. CONCLUSIONS: 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.

A randomized comparison between costoclavicular and paracoracoid ultrasound-guided infraclavicular block for upper limb surgery.

BACKGROUND: This two-centre randomized trial compared costoclavicular and paracoracoid ultrasound-guided infraclavicular brachial plexus block in patients undergoing upper limb surgery. We hypothesized that both techniques would result in similar onset times and designed the study as an equivalence trial. METHODS: Ninety patients undergoing upper limb surgery at or distal to the elbow were randomly allocated to receive a costoclavicular (n = 45) or paracoracoid (n = 45) ultrasound-guided infraclavicular brachial plexus block. Both groups received a 35-mL mixture of 1% lidocaine-0.25% bupivacaine with epinephrine 5 µg·mL-1. In the costoclavicular group, local anesthetic was injected into the costoclavicular space in the middle of the three cords of the brachial plexus. In the paracoracoid group, local anesthetic was deposited dorsal to the axillary artery in the lateral infraclavicular fossa. A blinded observer recorded the block onset time (primary endpoint), success rate (i.e., surgical anesthesia), block-related pain scores, as well as the incidence of hemidiaphragmatic paralysis. Performance time and the number of needle passes were also recorded during the performance of the block. The total anesthesia-related time was defined as the sum of the performance and onset times. RESULTS: The mean (SD) onset times were comparable between the costoclavicular and paracoracoid groups [16.0 (7.5) min vs 16.8 (6.2) min, respectively; mean difference, 0.8; 95% confidence interval, -2.3 to 3.8; P = 0.61]. Furthermore, no intergroup differences were found in terms of performance time (P = 0.09), total anesthesia-related time (P = 0.90), surgical anesthesia (P > 0.99), and hemidiaphragmatic paralysis (P > 0.99). The paracoracoid technique required marginally fewer median [interquartile range] needle passes than the costoclavicular technique (2 [1-4] vs 2 [1-6], respectively; P = 0.048); however, procedural pain was comparable between the two study groups. CONCLUSION: Costoclavicular and paracoracoid ultrasound-guided infraclavicular blocks resulted in similar onset times. Furthermore, no intergroup differences were found in terms of performance times and success rates. Future dose-finding trials are required to elucidate the minimum effective volume of local anesthetic for costoclavicular infraclavicular blocks. This trial was registered at www.clinicaltrials.in.th (Study ID: TCTR20160525001).

A randomized comparison between intravenous and perineural dexamethasone for ultrasound-guided axillary block.

BACKGROUND: This randomized double-blinded trial compared the effect of intravenous and perineural dexamethasone (8 mg) on the duration of motor block for ultrasound (US)-guided axillary brachial plexus block (AXB). METHODS: Patients undergoing upper limb surgery with US-guided AXB were randomly allocated to receive preservative-free dexamethasone (8 mg) via intravenous (n = 75) or perineural (n = 75) administration. The local anesthetic agent, 1% lidocaine -0.25% bupivacaine (30 mL) with epinephrine 5 µg·mL-1, was identical in all subjects. Operators and patients were blinded to the nature of the intravenous and perineural injectate. A blinded observer assessed the block success rate (i.e., a minimal sensorimotor composite score of 14 out of 16 points at 30 min), block onset time, as well as the presence of surgical anesthesia. Postoperatively, the blinded observer contacted all patients with successful blocks to record the duration of motor block (primary outcome), sensory block, and postoperative analgesia. RESULTS: No intergroup differences were observed in terms of success rate, surgical anesthesia, and block onset time. Compared to intravenous administration, perineural dexamethasone provided longer mean (SD) durations for motor block [17.5 (4.6) hr vs 12.8 (4.5) hr; mean difference, 4.6 hr; 95% confidence interval [CI], -6.21 to -3.08; P < 0.001], sensory block [17.7 (5.1) hr vs 13.7 (5.0) hr; mean difference, 4.0 hr; 95% CI, -5.77 to -2.27; P < 0.001], and postoperative analgesia [21.1 (4.6) hr vs 17.1 (4.6) hr; mean difference, 4.0 hr; 95% CI, -5.70 to -2.30; P < 0.001]. CONCLUSION: Compared to intravenous dosing, perineural dexamethasone (8 mg) results in longer durations of sensorimotor block and postoperative analgesia for ultrasound-guided axillary block. This trial was registered at www.clinicaltrials.gov number, NCT02629835.