Diaphragm-Sparing Nerve Blocks for Shoulder Surgery.

Shoulder surgery can result in significant postoperative pain. Interscalene brachial plexus blocks (ISBs) constitute the current criterion standard for analgesia but may be contraindicated in patients with pulmonary pathology due to the inherent risk of phrenic nerve block and symptomatic hemidiaphragmatic paralysis. Although ultrasound-guided ISB with small volumes (5 mL), dilute local anesthetic (LA) concentrations, and LA injection 4 mm lateral to the brachial plexus have been shown to reduce the risk of phrenic nerve block, no single intervention can decrease its incidence below 20%. Ultrasound-guided supraclavicular blocks with LA injection posterolateral to the brachial plexus may anesthetize the shoulder without incidental diaphragmatic dysfunction, but further confirmatory trials are required. Ultrasound-guided C7 root blocks also seem to offer an attractive, diaphragm-sparing alternative to ISB. However, additional large-scale studies are needed to confirm their efficacy and to quantify the risk of periforaminal vascular breach. Combined axillary-suprascapular nerve blocks may provide adequate postoperative analgesia for minor shoulder surgery but do not compare favorably to ISB for major surgical procedures. One intriguing solution lies in the combined use of infraclavicular brachial plexus blocks and suprascapular nerve blocks. Theoretically, the infraclavicular approach targets the posterior and lateral cords, thus anesthetizing the axillary nerve (which supplies the anterior and posterior shoulder joint), as well as the subscapular and lateral pectoral nerves (both of which supply the anterior shoulder joint), whereas the suprascapular nerve block anesthetizes the posterior shoulder. Future randomized trials are required to validate the efficacy of combined infraclavicular-suprascapular blocks for shoulder surgery.

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.

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.