A Randomized Comparison Between Single- and Triple-Injection Subparaneural Popliteal Sciatic Nerve Block.

BACKGROUND AND OBJECTIVES: 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. METHODS: 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. RESULTS: 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 In both cases, the needle was carefully withdrawn and the injection was completed uneventfully.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. CONCLUSIONS: 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.

A randomized comparison between double-injection and targeted intracluster-injection ultrasound-guided supraclavicular brachial plexus block.

BACKGROUND: In this prospective, randomized, observer-blinded study, we compared double-injection (DI) ultrasound-guided supraclavicular block to a novel targeted intracluster-injection (TII) technique, whereby local anesthetic is injected inside the main and satellite neural clusters (confluences of trunks and divisions of the brachial plexus). METHODS: Ninety patients were randomly allocated to receive a DI (n = 45) or TII (n = 45) technique for ultrasound-guided supraclavicular block. The local anesthetic drug (lidocaine 1.5% with epinephrine 5 µg/mL) and total volume (32 mL) were identical in all subjects. In both groups, half the volume (16 mL) was injected inside the main neural cluster. For the DI technique, the second half (16 mL) was deposited at the "corner pocket" (intersection of the first rib and subclavian artery). In contrast, for the TII technique, the remaining half was divided into equal aliquots and injected inside every single satellite cluster. The main outcome variable was the total anesthesia-related time (sum of performance and onset times). RESULTS: Due to a quicker onset (mean ± standard deviation (SD): 10.1 ± 6.4 vs 18.5 ± 8.3 minutes; P < 0.0001), the total anesthesia-related time was shorter with the TII technique (21.2 ± 7.7 vs 27.7 ± 9.0 minutes; P = 0.001; 95% confidence interval for the difference of the means: 2.90-10.08 minutes). There were 0 (of 45) and 3 (of 45) surgical failures for the TII and DI group, respectively. Thus, the 2 methods achieved comparable rates of surgical anesthesia (93.3%-100.0%; 95% confidence interval for the difference of the success rates: -2.3% to 17.9%). No intergroup differences were observed in block-related pain scores and adverse events. The DI group required fewer needle passes (median ± interquartile range: 4 ± 2 vs 7 ± 3; P < 0.0001) as well as shorter needling (8.4 ± 2.9 vs 10.7 ± 2.7 minutes; P < 0.0001) and performance (9.0 ± 3.2 vs 11.2 ± 3.0 minutes; P = 0.001) times. CONCLUSION: Although DI and TII ultrasound-guided supraclavicular blocks seem to provide comparable success rates, we cannot exclude the possibility that an intergroup difference of 17.9% might have gone undetected. Due to its quick onset, the TII technique results in a shorter total anesthesia-related time.

Minimum effective volume of combined lidocaine-bupivacaine for analgesic subparaneural popliteal sciatic nerve block.

BACKGROUND AND OBJECTIVES: The aim of this study was to determine the minimum effective volume (MEV) of combined lidocaine 1.0%-bupivacaine 0.25% with epinephrine 5 µg/mL in 90% of patients (MEV90) for ultrasound-guided subparaneural popliteal sciatic nerve block. METHODS: All subjects received an ultrasound-guided subparaneural popliteal sciatic nerve block (at the neural bifurcation) with combined lidocaine 1.0%-bupivacaine 0.25% and epinephrine 5 µg/mL. Using an out-of-plane technique, a 17-gauge, 8-cm Tuohy needle was advanced until its tip was positioned between the tibial and peroneal nerves inside the paraneural sheath. Volume assignment was carried out using a biased coin design, up-and-down sequential method, where the 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 3.0 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 3.0 mL), with a probability of b = 0.11, or the same volume, with a probability of 1 - b = 0.89. Using a composite scale encompassing sensory and motor block, success was defined, at 30 minutes, as a minimal score of 6 points (out of 8 points). The 6-point score was intended to mirror successful postoperative analgesia. Patients undergoing surgery of the leg, ankle, or foot were prospectively enrolled until 45 successful blocks were obtained. RESULTS: Fifty-two patients were recruited for this study. Using isotonic regression and bootstrap confidence interval, the MEV90 of combined lidocaine 1.0%-bupivacaine 0.25% with epinephrine 5 µg/mL was estimated to be 13.3 mL (95% confidence interval, 10.2-16.4 mL). CONCLUSIONS: For ultrasound-guided subparaneural (analgesic) popliteal sciatic nerve block, the MEV90 of combined lidocaine 1.0%-bupivacaine 0.25% with epinephrine 5 µg/mL is 13.3 mL (95% confidence interval, 10.2-16.4 mL).

Analgesia for clavicular fracture and surgery: a call for evidence.

The sensory innervation of the clavicle remains controversial. The supraclavicular, subclavian, and long thoracic/suprascapular nerves, alone or together, may be responsible for pain transmission after clavicular fracture and surgery. Peripheral nerve blocks used to anesthetize the clavicle include superficial cervical plexus blocks, interscalene blocks, and combined superficial cervical plexus-interscalene blocks. Future (randomized) trials are required to determine which constitutes the best option for emergency department (fracture) and operating room (surgical fixation) settings.

A randomized comparison between 3 combinations of volume and concentration of lidocaine for ultrasound-guided infraclavicular block.

BACKGROUND: This prospective, randomized, observer-blinded study compared 3 combinations of volume and concentration using the same total dose of lidocaine for ultrasound-guided infraclavicular block. METHODS: Ninety patients were randomized to 1 of 3 combinations of volume and concentration for lidocaine: (1) 52.5 mL of lidocaine 1%, (2) 35 mL of lidocaine 1.5%, and (3) 26.25 mL of lidocaine 2%. In all 3 groups, the total dose administered (525 mg) was the same. In addition, epinephrine 5 fg/mL was used in all subjects. The main outcome variable was onset time. The performance time, number of needle passes, block-related pain scores, success rate (surgical anesthesia), and the incidence of vascular puncture and paresthesia were also recorded. The total anesthesia-related time was defined as the sum of the performance and onset times. RESULTS: The onset times, which were 18.8 ± 5.6 minutes (95% confidence interval [CI], 16.4-21.1 minutes), 20.7 ± 7.0 minutes (95% CI, 18.0-23.5 minutes), and 21.7 ± 6.0 minutes (95% CI, 19.1-24.2 minutes) for the 1%, 1.5%, and 2% groups, respectively, were not statistically different.Furthermore, the performance times (4.4-4.7 minutes), total anesthesia-related times (23.7-26.3 minutes), and rates of surgical anesthesia (90.0%-96.7%) were comparable among the 3 groups. The number of needle passes and procedural discomfort, as well as the incidence of paresthesia and vascular puncture, were also similar. There were minor differences in the patterns of block for individual nerves. In terms of sensory block, compared with the 2% group, more patients in the 1.5% group displayed a complete block of the ulnar and radial nerves at 10 and 20 minutes, respectively. In terms of motor block, the 2% group yielded the lowest of rate of complete block of the musculocutaneous nerve from 15 minutes onward. CONCLUSIONS: Using an identical dose (525 mg) of adrenalized lidocaine for ultrasound-guided infraclavicular block, we found no differences in onset time among 3 commonly used concentrations (1%, 1.5%, and 2%). Further studies are required to determine the optimal combination of volume and concentration of lidocaine for other ultrasound-guided approaches to the brachial plexus.

A randomized comparison between bifurcation and prebifurcation subparaneural popliteal sciatic nerve blocks.

BACKGROUND: In this prospective, randomized, observer-blinded trial, we compared ultrasound-guided subparaneural popliteal sciatic nerve blocks performed either at or proximal to the neural bifurcation (B). We hypothesized that the total anesthesia-related time (sum of performance and onset times) would be decreased with the prebifurcation (PB) technique. METHODS: Ultrasound-guided posterior popliteal sciatic nerve block was performed in 68 patients. All subjects received an identical volume (30 mL) and mix of local anesthetic agent (1% lidocaine-0.25% bupivacaine-5 µg/mL epinephrine). In the PB group, the local anesthetic solution was deposited at the level of the common sciatic trunk, just distal to the intersection between its circular and elliptical sonographic appearances, inside the paraneural sheath. In the B group, the injection was performed inside the sheath between the tibial and peroneal divisions. A blinded observer recorded the success rate (complete tibial and peroneal sensory block at 30 minutes) and onset time. The performance time, number of needle passes, and adverse events (paresthesia, neural edema) were also recorded. All subjects were contacted 7 days after the surgery to inquire about the presence of persistent numbness or motor deficit. RESULTS: Both techniques resulted in comparable success rates (85%-88%; 95% confidence interval [CI] of the intergroup difference, -14% to 19%) and required similar performance times (8.1 minutes; 95% CI of the difference, -1.65 to 1.71 minutes), onset times (15.0-17.7 minutes; 95% CI of the difference, -7.65 to 2.31 minutes), and total anesthesia-related times (23.4-26.0 minutes; 95% CI of the difference, -7.83 to 2.74 minutes). The number of needle passes and incidence of paresthesia (25%-34%) were also similar between the 2 groups. Sonographic neural swelling was detected in 2 and 3 subjects in the PB and B groups, respectively. In all 5 cases, the needle was carefully withdrawn and the injection completed uneventfully. Patient follow-up 1 week after the surgery revealed 2 patients with residual numbness. In both instances, the latter had resolved by 1 month. CONCLUSION: When local anesthetic is injected inside the paraneural sheath, B and PB posterior popliteal sciatic nerve blocks result in comparable success and total anesthesia-related times. However, in light of the 95% CIs, we cannot exclude the possibility that an intergroup difference of 19% and 7.83 minutes might have gone undetected for success rate and total time, respectively.

Minimum effective volume of lidocaine for double-injection ultrasound-guided axillary block.

BACKGROUND: The aim of this study was to determine the minimum effective volume of lidocaine 1.5% with epinephrine 5 µg/mL in 90% of patients (MEV90) for double-injection ultrasound-guided axillary block (AXB). METHODS: All subjects received a double-injection ultrasound-guided AXB with lidocaine 1.5% and epinephrine 5 µg/mL. A 17-gauge, 8-cm Tuohy needle was initially advanced until its tip was positioned next to the musculocutaneous nerve. Volume assignment was carried out using a biased coin design up-and-down sequential method, where the 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 1.0 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 1.0 mL), with a probability of b = 0.11, or the same volume, with a probability of 1 - b = 0.89. After injection of the musculocutaneous nerve, the needle was redirected toward the dorsal aspect of the axillary artery. For this second injection, volume assignment was carried out in a similar fashion; however, volume increments/decrements were 3.0 instead of 1.0 mL. Using a composite scale encompassing sensory and motor block, success was defined, at 30 minutes, as a composite score of 4 points (out of 4 points), and 10 points (out of 12 points) for the musculocutaneous and perivascular injection, respectively. Patients undergoing surgery of the forearm, wrist, or hand were prospectively enrolled until 45 successful musculocutaneous blocks or 45 successful perivascular injections were obtained. RESULTS: Fifty patients were included in the study. Using isotonic regression and bootstrap confidence interval (CI), the MEV90 was estimated to be 5.5 mL (95% CI, 3.0-6.7 mL) and 23.5 mL (95% CI, 23.1-23.9 mL) for the musculocutaneous and perivascular injection, respectively. CONCLUSIONS: For double-injection ultrasound-guided AXB, the MEV90 of lidocaine 1.5% with epinephrine 5 µg/mL is 5.5 and 23.5 mL for the musculocutaneous nerve and perivascular injection, respectively. Further dose-finding studies are required for other concentrations of lidocaine, other local anesthetic agents, and other techniques for ultrasound-guided AXB.

A prospective, randomized comparison between perivascular and perineural ultrasound-guided axillary brachial plexus block.

BACKGROUND: This prospective, randomized, observer-blinded study compared perivascular (PV) and perineural (PN) ultrasound-guided axillary brachial plexus block (AXB) for upper extremity surgery. METHODS: Fifty patients were randomly allocated to receive a PV (n = 25) or PN (n = 25) ultrasound-guided AXB. The local anesthetic agent (lidocaine 1.5% with epinephrine 5 µg/mL) and total volume (32 mL) were identical in all subjects. For both groups, the musculocutaneous nerve was first located and then anesthetized using 8 mL. Subsequently, in the PV group, 24 mL was deposited dorsal to the axillary artery (6-o'clock position). In contrast, for the PN group, the median, ulnar, and radial nerves were individually anesthetized with volumes of 8 mL. During the performance of the block, the performance time, number of needle passes, and complications (vascular puncture, paresthesia) were recorded. Subsequently, a blinded observer assessed the onset time, block-related pain scores, and success rate (surgical anesthesia). The main outcome variable was the total anesthesia-related time (sum of performance and onset times). RESULTS: No differences were observed between the 2 groups in terms of success rate (92%-96%), total anesthesia-related time (27.1-29.0 min), and block-related pain scores. However, the PV technique required fewer needle passes (3.5 [SD, 1.0] vs 8.2 [SD, 2.2]; P = 0.000) as well as a shorter performance time (8.2 [SD, 2.3] vs 15.7 [SD, 3.2] min; P = 0.000) and was associated with a lower incidence of paresthesia (8 vs 52%; P = 0.001). In contrast, the PN technique resulted in a quicker onset time (13.8 [SD, 7.0] vs 18.9 [SD, 7.0] min; P = 0.021) and a decreased incidence of vascular puncture (0 vs 24%; P = 0.01). CONCLUSIONS: Perivascular and PN ultrasound-guided AXBs result in comparable success rates and total anesthesia-related times. Because of fewer needle passes and a shorter performance time, the PV technique provides a simple alternative for ultrasound-guided AXB.