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 In both cases, the needle was carefully withdrawn and the injection was completed uneventfully.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 infraclavicular block and targeted intracluster injection supraclavicular block.

BACKGROUND AND OBJECTIVES: This prospective, randomized trial compared ultrasound-guided targeted intracluster injection (TII) supraclavicular brachial plexus block (SCB) and infraclavicular brachial plexus block (ICB). METHODS: Sixty-four patients were randomly allocated to receive an ultrasound-guided TII SCB (n = 32) or ICB (n = 32). The local anesthetic agent (lidocaine 1.5% with epinephrine 5 µg/mL) was identical in all subjects. In the TII SCB group, half the volume (16 mL) was injected inside the largest neural cluster (confluence of trunks and divisions of the brachial plexus). Subsequently, the remaining half (16 mL) was divided into equal aliquots and injected inside every single satellite cluster. In the ICB group, the entire volume (35 mL) was injected dorsal to the axillary artery. 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 onset time, incidence of Horner syndrome, and success rate (surgical anesthesia). The main outcome variable was the total anesthesia-related time (sum of performance and onset times). RESULTS: Due to a quicker onset [8.9 (5.6) vs 17.6 (5.3) minutes; P < 0.001], the total anesthesia-related time was shorter with TII SCB [18.2 (6.1) vs 22.8 (5.3) minutes; P < 0.001]. However no differences were observed between the 2 groups in terms of success rate (93.7%-96.9%), block-related pain scores, and adverse events such as vascular puncture and paresthesia. Expectedly, the ICB group required fewer needle passes (2 vs 6; P < 0.001) as well as shorter needling [4.8 (2.3) vs 9.0 (2.9) minutes; P < 0.001] and performance [5.6 (2.3) vs 9.5 (2.9) minutes; P < 0.001] times. Moreover, the ICB approach was associated with a decreased incidence of Horner syndrome (3.1% vs 53.1%; P < 0.001). CONCLUSIONS: Ultrasound-guided TII SCB and ICB provide comparable success rates. Due to its quick onset, TII SCB results in a shorter total anesthesia-related time.