Ultrasound-Guided Single-Injection Infraclavicular Block Versus Ultrasound-Guided Double-Injection Axillary Block: A Noninferiority Randomized Controlled Trial.

BACKGROUND: Single-injection ultrasound-guided infraclavicular block is a simple, reliable, and effective technique. A simplified double-injection ultrasound-guided axillary block technique with a high success rate recently has been described. It has the advantage of being performed in a superficial and compressible location, with a potentially improved safety profile. However, its effectiveness in comparison with single-injection infraclavicular block has not been established. We hypothesized that the double-injection ultrasound-guided axillary block would show rates of complete sensory block at 30 minutes noninferior to the single-injection ultrasound-guided infraclavicular block. METHODS: After approval by our research ethics committee and written informed consent, adults undergoing distal upper arm surgery were randomized to either group I, ultrasound-guided single-injection infraclavicular block, or group A, ultrasound-guided double-injection axillary block. In group I, 30 mL of 1.5% mepivacaine was injected posterior to the axillary artery. In group A, 25 mL of 1.5% mepivacaine was injected posteromedial to the axillary artery, after which 5 mL was injected around the musculocutaneous nerve. Primary outcome was the rate of complete sensory block at 30 minutes. Secondary outcomes were the onset of sensory and motor blocks, surgical success rates, performance times, and incidence of complications. All outcomes were assessed by a blinded investigator. The noninferiority of the double-injection ultrasound-guided axillary block was considered if the limits of the 90% confidence intervals (CIs) were within a 10% margin of the rate of complete sensory block of the infraclavicular block. RESULTS: At 30 minutes, the rate of complete sensory block was 79% in group A (90% CI, 71%-85%) compared with 91% in group I (90% CI, 85%-95%); the upper limit of CI of group A is thus included in the established noninferiority margin of 10%. The rate of complete sensory block was lower in group A (proportion difference of 12% [95% CI, 2-22]; P = 0.0091), as was surgical success rate (82% [95% CI, 74%-89%] vs 93% [95% CI, 86%-97%]; proportion difference of 11% [95% CI 1-20]; P = 0.0153). Sensory block onset also was slower in group A (log rank test P = 0.0020). Performance times were faster in group I (231 seconds [95% CI, 213-250]) than in group A (358 seconds [95% CI, 332-387]; P < 0.0001). No statistically significant difference was observed for vascular puncture, paresthesia during block performance, or procedure-related pain. No neurologic complication was noted at follow-up. CONCLUSIONS: We failed to demonstrate that the rate of complete sensory block of the double-injection axillary block is noninferior to the single-injection infraclavicular block. However, the rate of complete sensory block at 30 minutes is statistically significantly lower with the axillary block. The ultrasound-guided single-injection infraclavicular block thus seems to be the preferred technique over the axillary for upper arm anesthesia.

Ultrasound-guided regional anesthesia for upper limb surgery.

PURPOSE: The purpose of this module is to review the main ultrasound-guided approaches used for regional anesthesia of the upper limb. PRINCIPAL FINDINGS: The anatomical configuration of the upper limb, with nerves often bundled around an artery, makes regional anesthesia of the arm both accessible and reliable. In-depth knowledge of upper limb anatomy is required to match the blocked territory with the surgical area. The interscalene block is the approach most commonly used for shoulder surgery. Supraclavicular, infraclavicular, and axillary blocks are indicated for elbow and forearm surgery. Puncture techniques have evolved dramatically with ultrasound guidance. Instead of targeting the nerves directly, it is now recommended to look for diffusion areas. Typically, local anesthetics are deposited around vessels, often as a single injection. Phrenic nerve block can occur with the interscalene and supraclavicular approaches. Ulnar nerve blockade is almost never achieved with the interscalene approach and not always present with a supraclavicular block. If ultrasound guidance is used, the risk for pneumothorax with a supraclavicular approach is reduced significantly. Nerve damage and vascular puncture are possible with all approaches. If an axillary approach is chosen, the consequences of vascular puncture can be minimized because this site is compressible. CONCLUSIONS: Upper limb regional anesthesia has gained in popularity because of its effectiveness and the safety profile associated with ultrasound-guided techniques.

Complications of single-injection ultrasound-guided infraclavicular block: a cohort study.

INTRODUCTION: In recent studies on ultrasound-guided infraclavicular block (ICB), the authors have favoured a single injection posterior to the axillary artery rather than multiple injections; however, procedural complications and success rates associated with single-injection ultrasound-guided ICB are not well known. We undertook an observational study to evaluate the success rates of experienced and non-experienced operators performing ICBs and to identify the complications associated with ultrasound-guided single-injection ICB. METHODS: We conducted an observational cohort study of all ultrasound-guided single-injection ICBs performed over a two-year period (2008-2010). We identified the subjects for our study using a local database and excluded patients younger than 18 yr and those who received a continuous ICB. Complications (non-neurological and neurological) and ICB success rates were the primary and secondary end points, respectively. We collected the following data from patients' charts: patient demographics, types of complications and their respective frequencies, and the experience of the clinician performing the ICBs, and we identified potential late complications by telephone interview. Using a seven-point Likert scale, two experts in regional anesthesia evaluated the likelihood of a relationship between the identified neurological signs or symptoms and the ICB. A neurologist then evaluated the complications identified as being potentially related to the ICB. Summary data were collated, and 95% confidence intervals (CI) were calculated. RESULTS: We reviewed 627 ICB procedures, and 496 (79%) patients received telephone interviews. Most patients were males who had undergone either plastic or orthopedic surgery. Mepivacaine 1.5% was used in 96% of cases with a median volume of 30 mL [interquartile range 30-38]. We identified 131 cases of neurological signs or symptoms. Four cases were retained as possible links to the ICB, but they underwent complete resolution of symptoms at the time of evaluation. Two possible cases of local anesthetic toxicity were observed. There was a 93% success rate (95% CI 91 to 95) and the results were comparable between the experienced and the non-experienced operators (94% vs 93%, respectively). DISCUSSION: We observed few complications associated with a single-injection ultrasound-guided ICB and a high success rate regardless of the operator's expertise. The technique appears to be reliable, easy to perform, and safe.

Comparison of a single- or double-injection technique for ultrasound-guided supraclavicular block: a prospective, randomized, blinded controlled study.

BACKGROUND: Despite good success rates reported with ultrasound-guided supraclavicular block using 1 or multiple injections, no consensus exists on the best technique to use. We designed this study to test the hypothesis that a double-injection technique would hasten the onset of sensory block. METHODS: Adult patients undergoing hand, wrist, or elbow surgery were enrolled in this prospective double-blind randomized study. Blocks were performed under ultrasound guidance. In group S (single injection), 30 mL of mepivacaine 1.5% was injected at the junction of the subclavian artery and the first rib. In group D (double injection), 15 mL of the same solution was injected at the site described above, then 15 mL was injected in the most superficial portion of the lateral aspect of the cluster formed by the brachial plexus trunks and divisions. The primary end point was the rate of complete sensory block at 15 mins. Secondary end points were the rates of sensory, motor, and surgical blocks and procedure time. RESULTS: Fifty-one patients were randomized to each group. The rate of complete sensory block was similar at 15 mins (group S: 49% [95% confidence interval, 36%-62%], group D: 53% [95% confidence interval, 40%-66%]; P = 0.80) and at each time interval. The rates of complete motor block and surgical block success were similar between groups. The procedure time was shorter in group S (179 ± 104 vs 275 ± 137 secs; P < 0.01). CONCLUSIONS: The double-injection technique offers no benefit over a single injection for the performance of an ultrasound-guided supraclavicular block.

Brief reports: a comparison of an injection cephalad or caudad to the division of the sciatic nerve for ultrasound-guided popliteal block: a prospective randomized study.

BACKGROUND: The optimal site for local anesthetic injection during ultrasound-guided sciatic popliteal block remains controversial. METHODS: Patients were randomized to receive 25 mL ropivacaine 0.75% around the sciatic nerve cephalad to the peroneal-tibial division in group A (n = 51) or caudad to the division in group B (n = 51). The sensory and motor blocks were evaluated every 5 minutes up to 30 minutes. RESULTS: Rates of complete sensory block and surgical anesthesia were superior in group B (P < 0.0001). CONCLUSION: The caudad technique provided better surgical anesthesia.

Symptomatic axillary hematoma after ultrasound-guided infraclavicular block in a patient with undiagnosed upper extremity mycotic aneurysms.

We present a case of axillary hematoma complicating an ultrasound-guided infraclavicular block in a patient with undiagnosed mycotic aneurysms of the peripheral arteries. Mycotic aneurysm is a rare medical condition with well-identified risk factors. When performing regional anesthesia in patients with these risk factors, clinicians should have a high degree of suspicion about the possible existence of vascular anomalies. A preprocedure Doppler study of the block area and real-time guidance of the needle using ultrasound may be useful.

A comparison of a single or triple injection technique for ultrasound-guided infraclavicular block: a prospective randomized controlled study.

BACKGROUND: Good success rates have been reported with ultrasound-guided infraclavicular block using one or multiple injections of local anesthetic. We hypothesized that a separate injection of local anesthetics on each cord enhances the onset of complete sensory block. We designed this prospective randomized study to compare the rate of complete sensory block using one or three injections of local anesthetic. METHODS: Patients scheduled for hand, wrist, or elbow surgery were included in this study. All blocks were performed under ultrasound guidance. In Group S (single injection), 30 mL of mepivacaine 1.5% was injected posterior to the axillary artery. In Group T (triple injections), 10 mL of mepivacaine 1.5% was injected on the posterior, medial, and lateral aspects of the axillary artery. Sensory block was evaluated every 3 min up to 30 min. The primary end point was the rate of complete sensory block at 15 min. RESULTS: Forty-nine and 51 patients were randomized in Groups S and T, respectively. The rate of complete sensory block was comparable at 15 min (Group S: 84%, Group T: 78%, P = 0.61) and at each time interval up to 30 min. There was no statistically significant difference in the rate of complications between the two groups. CONCLUSIONS: The success rate and the onset of complete sensory block after ultrasound-guided infraclavicular block are not enhanced by a triple injection of local anesthetic compared with a single injection posterior to the axillary artery.

Comparison of 3 intensities of stimulation threshold for brachial plexus blocks at the midhumeral level: a prospective, double-blind, randomized study.

BACKGROUND: We conducted this prospective randomized study to compare the success rate and the onset time between 3 intensities of stimulation threshold (<0.5, 0.5-0.64, and 0.65-0.8 mA) when using a peripheral nerve stimulation at the midhumeral level. METHODS: Sixty-nine adult patients undergoing elective hand surgery were studied. Blocks were performed using conventional nerve stimulation technique. Needle advance began at 2 mA (1 Hz, 0.1 millisecond). When motor response (MR) occurred at less than 0.5 mA, needle position was fixed for "group <0.5 mA." For "group 0.5-0.64 mA," the needle was withdrawn until MR occurred at greater than 0.5 mA and disappeared at less than 0.5 mA. For "group >0.65 mA," the needle was withdrawn until MR occurred at greater than 0.65 mA and disappeared at less than 0.65 mA. For each group, patients received 8 mL of ropivacaine 7.5 mg/mL on the 4 nerves (radial, median, ulnar, and musculocutaneous). Primary end point was the number of failed radial nerve sensory blocks at 30 mins. RESULTS: The time to perform the block was not different between the 3 groups (17 mins [SD, 7 mins] vs 13 mins [SD, 8 mins] and 13 mins [SD, 4 mins], respectively). The time required to obtain a complete sensory block was shorter for the 4 nerves in group <0.5 mA, with a statistical significance for radial and musculocutaneous nerves in group <0.5 mA versus group 0.5-0.64 mA and group >0.65 mA. Patients in group <0.5 mA had a greater success rate for complete sensory radial nerve compared with those of group 0.5-0.64 mA and group >0.65 mA at any interval times between 5 and 30 mins (P = 0.0001). Supplemental local anesthesia was provided for the 3 groups more frequently for the median nerve, with no difference between groups. Group >0.65 mA required 5 general anesthesias (20%) as compared with 1 (4%) in group <0.5 mA (P < 0.05). No adverse event (dysesthesia) occurred after 48 hrs and 45 days. CONCLUSION: We conclude that intensity of stimulation influenced onset time and success rate.