A combination of infraclavicular and suprascapular nerve blocks for total shoulder arthroplasty: A case series.

BACKGROUND: Shoulder arthroplasty is associated with significant post-operative pain. Interscalene plexus block is the gold standard for pain management in patients undergoing this surgery, however, alternatives are currently being developed. We hypothesized that a combination of anterior suprascapular nerve block and lateral sagittal infraclavicular block would provide effective post-operative analgesia. Primary aims for this study were to document numeric rating scale (NRS) pain score and use of oral morphine equivalents (OMEq) during the first 24 hours after surgery. Secondary aim was to determine the incidence of hemidiaphragmatic paralysis. METHODS: Twenty patients (ASA physical status I-III) scheduled for shoulder arthroplasty were studied. Four mL ropivacaine 0.5% was administered for the suprascapular nerve block and 15 mL ropivacaine 0.75% for the infraclavicular block. Surgery was performed under general anaesthesia. Paracetamol and prolonged-release oxycodone were prescribed as post-operative analgesics. Morphine and oxycodone were prescribed as rescue pain medication. Diaphragm status was assessed by ultrasound. RESULTS: Median NRS (0-10) at 1, 3, 6, 8 and 24 hours post-operatively were 1, 0, 0, 0 and 3, respectively. NRS at rest during the first 24 post-operative hours was 4 (2.5-4.5 [0-5]), median (IQR [range]). Maximum NRS was 6.5 (5-8 [0-10]) median (IQR [range]). Total OMEq during the first 24 post-operative hours was 52.5 mg (30-60 [26.4-121.5]) median (IQR [range]). Hemidiaphragmatic paralysis was diagnosed in one patient (5%). CONCLUSIONS: The combination of suprascapular and infraclavicular nerve block shows an encouraging post-operative analgesic profile and a low risk for hemidiaphragmatic paralysis after total shoulder arthroplasty.

Brachial plexus block of the posterior and the lateral cord using ropivacaine 7.5 mg/mL.

BACKGROUND: We recently showed that the novel combination of a superficial cervical plexus block, a suprascapular nerve block, and the lateral sagittal infraclavicular brachial plexus block (LSIB) provides an alternative anaesthetic method for arthroscopic shoulder surgery. In this study, we hypothesised that the LSIB dose for this shoulder block could be significantly reduced by injecting only towards the shoulder relevant posterior and lateral cords. Our aim was to determine the minimum effective volume in 50% of the patients (MEV50 ) and to estimate the MEV95, when using ropivacaine 7.5 mg/mL to block these cords. METHODS: Twenty-three adult patients scheduled for hand surgery participated in the study. Considering the artery as a clock face with 12 o'clock ventral, the designated volume was injected immediately outside the arterial wall and between 8 and 9 o´clock. The in-plane technique was used. Block success was assessed 30 minutes after withdrawal of the needle. Successful posterior cord block was defined as anaesthesia or analgesia of the axillary nerve. Successful lateral cord block was defined as either anaesthesia or analgesia, or >50% motor block of the musculocutaneous nerve. MEV50 was determined by the staircase up-and-down method. Logistic regression and probit transformation were applied to estimate MEV95 . RESULTS: MEV50 and MEV95 were 7.8 mL [95% confidence interval (CI), 7.3-8.4] and 9.0 mL (95% CI, 7.8-10.3), respectively. CONCLUSION: For single-deposit infraclavicular posterior and lateral cord block, the MEV95 of ropivacaine 7.5 mg/mL was estimated to 9.0 mL.

MRI of axillary brachial plexus blocks: a randomised controlled study.

BACKGROUND: Axillary plexus blocks are usually guided by ultrasound, but alternative methods may be used when ultrasound equipment is lacking. For a nonultrasound-guided axillary block, the need for three injections has been questioned. OBJECTIVES: Could differences in block success between single, double and triple deposits methods be explained by differences in local anaesthetic distribution as observed by MRI? DESIGN: A blinded and randomised controlled study. SETTING: Conducted at Oslo University Hospital, Rikshospitalet, Norway from 2009 to 2011. PATIENTS: Forty-five ASA 1 to 2 patients scheduled for surgery were randomised to three equally sized groups. All patients completed the study. INTERVENTIONS: Patients in the single-deposit group had an injection through a catheter parallel to the median nerve. In the double-deposit group the patients received a transarterial block. In the triple-deposit group the injections of the two other groups were combined. Upon completion of local anaesthetic injection the patients were scanned by MRI, before clinical block assessment. The distribution of local anaesthetic was scored by its closeness to terminal nerves and cords of the brachial plexus, as seen by MRI. The clinical effect was scored by the degree of sensory block in terminal nerve innervation areas. MAIN OUTCOME MEASURES: Sensory block effect and MRI distribution pattern. RESULTS: The triple-deposit method had a higher success rate (100%) than the single-deposit method (67%) and the double-deposit method (67%) in blocking all cutaneous nerves distal to the elbow (P = 0.04). The patients in the triple-deposit group most often had the best MRI scores. For any nerve or cord, at least one of the single-deposit or double-deposit groups had a similarly high MRI score as the triple-deposit group. CONCLUSION: Distal to the elbow, the triple-deposit method had the highest sensory block success rate. This could be explained to some extent by analysis of the magnetic resonance images. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT01033006.

Brachial plexus block with or without ultrasound guidance.

PURPOSE OF REVIEW: Should ultrasound or nerve stimulation be used for brachial plexus blocks? We investigated last year's literature to help answer this question. RECENT FINDINGS: Many of the reports concluded that ultrasound guidance may provide a higher success rate for brachial plexus blocks than guidance by nerve stimulator. However, the studies were not large enough to conclude that ultrasound will reduce the risk of nerve injury, local anesthetic toxicity or pneumothorax. Ultrasound may reveal anatomical variations of importance for performing brachial plexus blocks. For postoperative analgesia, 5 ml of ropivacaine 0.5% has been sufficient for an ultrasound-guided interscalene block. For peroperative anesthesia, as much as 42 ml of a local anesthetic mixture was calculated to be appropriate for an ultrasound-guided supraclavicular method. For the future, we notice that three-dimensional and four-dimensional ultrasound technology may facilitate visualizing the needle, the nerves and the local anesthetic distribution. Impedance measurements may be helpful for nerve blocks not guided by ultrasound. SUMMARY: We think that the literature gives a sufficient basis to recommend the use of ultrasound for guidance of brachial plexus blocks. The potential for ultrasound to improve efficacy and reduce complications of brachial plexus blocks requires larger scaled studies.

Current threshold for nerve stimulation depends on electrical impedance of the tissue: a study of ultrasound-guided electrical nerve stimulation of the median nerve.

BACKGROUND: Understanding the mechanisms causing variation in current thresholds for electrical nerve stimulation may improve the safety and success rate of peripheral nerve blocks. Electrical impedance of the tissue surrounding a nerve may affect the response to nerve stimulation. In this volunteer study, we investigated the relationship between impedance and current threshold needed to obtain a neuromuscular response. METHODS: Electrical nerve stimulation and impedance measurements were performed for the median nerve in the axilla and at the elbow in 29 volunteers. The needletip was positioned at a distance of 5, 2.5, and 0 mm from the nerve as judged by ultrasound. Impulse widths of 0.1 and 0.3 ms were used for nerve stimulation. RESULTS: A significant inverse relationship between impedance and current threshold was found at the elbow, at nerve-to-needle distances of 5 and 2.5 mm (P = 0.001 and P = 0.036). Impedance values were significantly lower in the axilla (mean 21.1, sd 9.7 kohm) than at the elbow (mean 36.6, sd 13.4 kohm) (P < 0.001). Conversely, current thresholds for nerve stimulation were significantly higher in the axilla than at the elbow (P < 0.001, P < 0.001, P = 0.024). A mean ratio of 1.82 was found for the measurements of current thresholds with 0.1 versus 0.3 ms impulse duration. CONCLUSIONS: Our results demonstrate an inverse relationship between impedance measurements and current thresholds and suggest that current settings used for nerve stimulation may require adjustment based on the tissue type. Further studies should be performed to investigate the clinical impact of our findings.

Electrical nerve stimulation or ultrasound guidance for lateral sagittal infraclavicular blocks: a randomized, controlled, observer-blinded, comparative study.

BACKGROUND: Ultrasound guidance is frequently used to perform infraclavicular brachial plexus blocks. In this study, we compared electrical nerve stimulation and ultrasound guidance for the lateral sagittal infraclavicular block. METHODS: Eighty patients, ASA 1-2, were randomized for either nerve stimulation (group NS) or ultrasound-guided blocks (group US). The brachial plexus was anesthetized with 0.6 mL/kg mepivacaine (15 mg/mL) with epinephrine (2.5 microg/mL) in both groups. For ultrasound-guided blocks, local anesthetic was injected cranioposterior to the axillary artery. An observer who was blinded for the method assessed the blocks and questioned the patients. Successful block was defined as analgesia or anesthesia of all five nerves distal to the elbow. The main outcome variables were the time until readiness for surgery, quantified discomfort during the block, and pain related to tourniquet ischemia on a numeric rating scale (0-10). RESULTS: Block performance time was 4.3 min (sd 1.3) and 4.1 min (sd 1.3) (P = 0.64) in group NS and group US, respectively. Onset time for sensory block was 13.7 min (sd 6.6) and 13.9 min (sd 5.8), (P = 0.99). The time until readiness for surgery was 18.1 min in both groups (sd 6.6 and 6.0) (P = 0.99). Median discomfort related to the block procedure was 1 in both groups (P = 0.92), and median tourniquet pain was 0.5 in group NS and 1 in group US (P = 32). Differences in success rates, between 85% in group NS and 95% in group US, were not significant (P = 0.26). CONCLUSIONS: We conclude that favorable results can be obtained when either nerve stimulation or ultrasound guidance is used for lateral sagittal infraclavicular block. Using ultrasound, local anesthetic injection cranioposterior to the artery appears feasible.

Use of magnetic resonance imaging to define the anatomical location closest to all three cords of the infraclavicular brachial plexus.

Infraclavicular techniques are often used to perform brachial plexus blocks. In our volunteer study we used magnetic resonance imaging to identify the brachial plexus and axillary vessels in a sagittal plane corresponding to the lateral sagittal infraclavicular block. In 20 volunteers, all cords were positioned within 2 cm from the artery approximately within 2/3 of a circle. We derived an injection site that was closest to all cords, cranio-posterior and adjacent to the axillary artery. We conclude that this knowledge may be useful for the performance of infraclavicular blocks aided by ultrasound. However, our proposals should be tested by clinical studies.

The vertical infraclavicular brachial plexus block: a simulation study using magnetic resonance imaging.

The recommended needle trajectory for the vertical infraclavicular brachial plexus block is anteroposterior, caudad to the middle of the clavicle. We studied the risk of pneumothorax and subclavian vessel puncture and the precision of this method by using magnetic resonance imaging in 20 adult volunteers. The trajectory aimed at the lung in six subjects, five of whom were women. However, pleural contact could be avoided in all subjects by halting needle advancement after contact with the subclavian vessels, plexus, or first rib. The subclavian vein was reached by the trajectory in three and the subclavian artery in five subjects. The trajectory had a median distance to the plexus (closest aspect) of 1 mm (range, 0-9 mm) and contacted the nerves in 9 subjects. In conclusion, there is a small probability that the needle may reach the pleura when a vertical infraclavicular brachial plexus block is performed, particularly in women, and a high probability that it will contact the subclavian vein or artery. Although the trajectory is close to the plexus, any medial deviation carries the risk of pleural or subclavian vessel contact at other depths. Clinical accuracy in defining the insertion point is critical.

A novel infraclavicular brachial plexus block: the lateral and sagittal technique, developed by magnetic resonance imaging studies.

UNLABELLED: A new infraclavicular brachial plexus block method has the patient supine with an adducted arm. The target is any of the three cords behind the pectoralis minor muscle. The point of needle insertion is the intersection between the clavicle and the coracoid process. The needle is advanced 0 degrees -30 degrees posterior, always strictly in the sagittal plane next to the coracoid process while abutting the antero-inferior edge of the clavicle. We tested the new method using magnetic resonance imaging (MRI) in 20 adult volunteers, without inserting a needle. Combining 2 simulated needle directions by 15 degrees posterior and 0 degrees in the images of the volunteers, at least one cord in 19 of 20 volunteers was contacted. This occurred within a needle depth of 6.5 cm. In the sagittal plane of the method the shortest depth to the pleura among all volunteers was 7.5 cm. The MRI study indicates that the new infraclavicular technique may be efficient in reaching a cord of the brachial plexus, often not demanding more than two needle directions. The risk of pneumothorax should be minimal because the needle is inserted no deeper than 6.5 cm. However, this needs to be confirmed by a clinical study. IMPLICATIONS: A new infraclavicular brachial plexus block method was investigated using magnetic resonance imaging without inserting needles in the volunteers. The study suggests two needle directions for performance of the block and that the risk of lung injury should be minimal. Expectations need to be confirmed by a clinical study.

An evaluation of the supraclavicular plumb-bob technique for brachial plexus block by magnetic resonance imaging.

UNLABELLED: Partly based on magnetic resonance imaging studies, the "plumb-bob" approach for brachial plexus block was designed to minimize the risk of pneumothorax. Nevertheless, the risk of pneumothorax has remained a concern. We analyzed magnetic resonance images from 10 volunteers to determine whether the risk of pneumothorax was decreased with this method. The recommended initial needle direction is anteroposterior through the junction between the lateral-most part of the sternocleidomastoid muscle and the superior edge of the clavicle. If the initial placement is not successful, the brachial plexus may be sought in sectors 20 degrees -30 degrees cephalad or caudad to the anteroposterior line in a sagittal plane through the insertion point. We found that the anteroposterior line reached the pleura in 6 of 10 volunteers without prior contact with the subclavian artery or the brachial plexus, but always with contact with the subclavian vein. To reach the middle of the brachial plexus, a mean cephalad redirection of the simulated needle by 21 degrees was required (range from 41 degrees cephalad to 15 degrees caudad in one case). We conclude that the risk of contacting the pleura and the subclavian vessels may be reduced by initially directing the needle 45 degrees cephalad instead of anteroposterior. If the brachial plexus is not contacted, the angle should be gradually reduced. IMPLICATIONS: In magnetic resonance images of volunteers, simulated needle passes with the "plumb-bob" approach to the supraclavicular brachial plexus block were analyzed for precision and risk profile. To avoid needle contact with the lung, the subclavian vein, and the subclavian artery, our results suggest a change in the method's initial needle direction.

Distribution of local anesthetic in axillary brachial plexus block: a clinical and magnetic resonance imaging study.

BACKGROUND: There is an unsettled discussion about whether the distribution of local anesthetic is free or inhibited when performing brachial plexus blocks. This is the first study to use magnetic resonance imaging (MRI) to help answer this question. METHODS: Thirteen patients received axillary block by a catheter-nerve stimulator technique. After locating the median nerve, a total dose of 50 ml local anesthetic was injected via the catheter in four divided doses of 1, 4, 15, and 30 ml. Results of sensory and motor testing were compared with the spread of local anesthetic as seen by MRI scans taken after each dose. The distribution of local anesthetic was described with reference to a 20-mm diameter circle around the artery. RESULTS: Thirty minutes after the last dose, only two patients demonstrated analgesia or anesthesia in the areas of the radial, median, and ulnar nerve. At that time, eight of the patients had incomplete spread of local anesthetic around the artery, as seen by MRI. Their blocks were significantly poorer than those of the five patients with complete filling of the circle, although incomplete blocks were also present in the latter group. CONCLUSION: This study demonstrated that MRI is useful in examining local anesthetic distribution in axillary blocks because it can show the correlation between MRI distribution pattern and clinical effect. The cross-sectional spread of fluid around the brachial-axillary artery was often incomplete-inhibited, and the clinical effect often inadequate.