Increased success rate with infraclavicular brachial plexus block using a dual-injection technique

STUDY OBJECTIVE: To test the hypothesis that dual injection of the local anesthetic in coracoid infraclavicular brachial plexus block might enhance both sensory and motor block for anesthesia of the upper limb when compared with a single-injection technique. DESIGN: Comparative, prospective, randomized, investigator-blinded study. SETTING: University-affiliated hospital. PATIENTS: 60 patients scheduled for surgery of the hand, forearm, or elbow. INTERVENTIONS: Patients were randomly assigned to receive either a coracoid infraclavicular block guided by nerve stimulator with a single injection technique (Group 1) or a dual-injection technique (Group 2). Injection of 40 mL 1.5% mepivacaine was made after eliciting one evoked motor response in the upper limb with a nerve stimulator for coracoid infraclavicular block in Group 1 and injection of two separate doses of 20 mL 1.5% mepivacaine after elicitation of two motor responses in Group 2. MEASUREMENTS: Assessment of sensory and motor block in the upper limb 5 and 20 minutes after the end of the injection of the local anesthetic. The time needed to elicit the second response and to inject the second dose of local anesthetic was also recorded. MAIN RESULTS: Significantly higher rates of sensory block to pinprick on the distributions of axillary, musculocutaneous, radial, ulnar, and medial cutaneous of the forearm nerves were found in Group 2 at 20 minutes. Significantly higher rates of motor block for arm, wrist, and hand movements were found in Group 2 at 20 minutes. CONCLUSIONS: Dual injection of local anesthetic guided by nerve stimulator increases the efficacy of coracoid block when compared with a single injection of the same dose of local anesthetic.     

Restricted infraclavicular distribution of the local anesthetic solution after infraclavicular brachial plexus block

BACKGROUND AND OBJECTIVES: The distribution of local anesthetic after different approaches for brachial plexus anesthesia could be responsible for the varying rates of side effects, such as phrenic block, hoarseness, and Horner's syndrome associated with each approach. We compared the distribution of local anesthetic within the neurovascular space in infraclavicular block with that of interscalene and supraclavicular block. METHODS: In a prospective analysis using fluoroscopy, we studied the distribution of a solution of local anesthetic containing radiologic contrast medium in 18 patients. Six patients received an interscalene block, another 6 patients received a perpendicular supraclavicular block, and another 6 patients, a perpendicular coracoid block. RESULTS: Distribution of the anesthetic solution in the interscalene and supraclavicular groups extended to both supraclavicular and infraclavicular spaces in all patients. This distribution was significantly different (P <.05) compared with that of the infraclavicular group. In this group, the solution remained below the clavicle in every patient. CONCLUSIONS: Spread of the local anesthetic from the infraclavicular space after infraclavicular coracoid block appears to be limited to below the level of the clavicle. Conversely, local anesthetic solution passes below the clavicle in all patients given interscalene or supraclavicular blocks.     

Single-stimulation, low-volume infraclavicular plexus block: influence of the evoked distal motor response on success rate

BACKGROUND AND OBJECTIVES: We compared the success rate of single-injection infraclavicular plexus block by using electrically evoked radial, ulnar, or median nerve-type distal motor response to guide the injection of local anesthetic. METHODS: Consecutive patients requiring surgery distal to the upper arm were prospectively included in this study over a 6-month period. No search for predetermined distal motor responses was performed. The first qualifying distal motor response evoked for a stimulating current intensity of <0.5 mA distributed patients into 3 groups of patients. The study was continued until 3 groups of 60 patients were fulfilled. Twenty to 25 minutes after the injection of 30 mL of 1.5% mepivacaine, blinded evaluation of block quality was performed. A successful block was defined by the presence of a complete sensory block of the 5 major nerve distal distributions of the arm. RESULTS: Five hundred patients were included. The first evoked distal motor response was of radial, median, and ulnar nerve type in 46% (n = 230), 42% (n = 210), and 12% (n = 60) cases, respectively. The success rate of the infraclavicular plexus block was significantly higher when the injection was performed on a radial nerve-type response (90%) as compared with the median (74%) or ulnar (68%) nerve distal motor response. Intraoperative sedation and general anesthesia were not needed. None of the patients experienced specific complications. CONCLUSION: We showed that evoked distal motor response influenced the success rate of single-injection infraclavicular plexus block. The highest success rate was obtained when injection was performed after radial nerve-type motor response.     

Efficacy of vertical infraclavicular plexus block vs. modified axillary plexus block: a prospective, randomized, observer-blinded study

BACKGROUND: Despite containing severe risks, infraclavicular approaches to the brachial plexus gained increasing popularity. Likewise, the vertical infraclavicular plexus block improved anesthesia compared to the standard axillary approach but contains the risk of pneumothorax. Therefore we modified the standard axillary technique by inserting a proximal directed catheter, referred to as a high axillary plexus block. We prospectively compared quality and onset of neural blockade after vertical infraclavicular plexus block (VIP) and high axillary plexus block (HAP) in two randomized groups (30 patients in each). METHODS: In group VIP the insulated needle was inserted midway between the ventral process of the acromion and the jugular notch. In group HAP, first an axillary needle was placed. Through this a stimulating catheter was inserted in a proximal direction (10-15 cm); correct placement was confirmed by nerve stimulation. All patients received 40 ml ropivacaine 0.75% (300 mg). Discriminating between analgesia and anesthesia, a blinded observer assessed progression of neural blockade every 5 min for 60 min by pin prick. Incomplete blocks were supplemented 60 min after initial injection. RESULTS: All patients in both groups demonstrated sufficient surgical anesthesia. No patient needed systemic supplementation or general anesthesia. However, vertical infraclavicular plexus block indicated superior anesthesia compared to high axillary plexus block, regarding musculocutaneous, axillary and radial nerve, which were completely blocked with a higher success rate and in a shorter time interval (P < 0.05). CONCLUSIONS: While both techniques provide sufficient surgical anesthesia, vertical infraclavicular plexus block demonstrated a partially higher success rate and a faster onset than high axillary plexus block.     

Brachial plexus block with a new local anaesthetic: 0.5 percent ropivacaine

A new local anaesthetic, ropivacaine hydrochloride, was used in a concentration of 0.5 per cent in 32 patients receiving a subclavian perivascular block for upper extremity surgery. One group (n = 15) received 0.5 per cent ropivacaine without epinephrine and a second group (n = 17) received 0.5 per cent ropivacaine with epinephrine in a concentration of 1:200,000. Anaesthesia was achieved in 87 per cent of the patients in both groups in all of the C5 through T1 brachial plexus dermatomes. Motor block was profound with 100 per cent of patients in both groups developing paresis at both the shoulder and hand and 100 per cent developing paralysis at the shoulder. There was a rapid initial onset of sensory block (a mean of less than four minutes for analgesia) with a prolonged duration (a mean of greater than 13 hr of analgesia). The addition of epinephrine did not significantly affect the quality or onset of sensory or motor block. The duration of sensory block was reduced by epinephrine at T1 for analgesia and at C7, C8, and T1 for anaesthesia. The duration of sensory block in the remaining brachial plexus dermatomes as well as the duration of motor block was not effected by epinephrine. There was no evidence of cardiovascular or central nervous system toxicity in either group with a mean dose of 2.5-2.6 mg.kg-1 ropivacaine.     

Does local anaesthetic affect the success rate of intravenous cannulation?

We aimed to assess whether subcutaneous lignocaine affects the success rate of intravenous cannulation using a randomized clinical trial. Pre-prepared cannulation packs, 50% containing local anaesthetic, were used to cannulate consecutive consenting patients presenting to the Emergency Department who required cannulation as part of their routine treatment. Doctors with less than four years postgraduate experience randomly selected a pack to perform cannulation and completed a data collection form after each cannulation. Eighty-seven patients received lignocaine with 73 (83.9%) successfully cannulated on the first attempt, 79 patients were cannulated without lignocaine with 64 (81%) successfully cannulated on the first attempt. Subcutaneous lignocaine did not significantly affect the success rate of intravenous cannulation on the first attempt (P = 0.5). Subcutaneous lignocaine has been shown to significantly reduce the pain of intravenous cannulation. This study supports the use of local anaesthesia for all routine venous cannulation.     

Analgesic efficacy of local anaesthetic wound administration in knee arthroplasty: volume vs concentration

Wound administration of local anaesthetic may be effective for postoperative pain management in knee arthroplasty, but the analgesic efficacy of local anaesthetic in relation to volume vs concentration has not been determined. In a double‐blinded trial, 48 patients scheduled for total knee arthroplasty were randomly assigned to receive either a high volume/low concentration solution of ropivacaine (20 ml, 0.5%) or a low volume/high concentration solution of ropivacaine (10 ml, 1%), 6 and 24 h postoperatively through an intracapsular catheter. Pain was assessed for 2 h after administration. Pain was reduced in both groups with ropivacaine administration 24 h postoperatively (p < 0.02), but with no difference in analgesia between groups at all time intervals. No reduction in pain scores was observed with ropivacaine injection 6 h postoperatively. The median (IQR [range]) dose of oxycodone administered was 12.5 (10–19 [0–35]) mg in the high volume/low concentration group, and 20 mg (16–40 [0–65]) mg in the low volume/high concentration group (p = 0.005). In conclusion, intracapsular administration of local anaesthetic may have limited analgesic efficacy with no volume vs concentration relationship after total knee arthroplasty.     

Ultrasound guidance improves the success rate of a perivascular axillary plexus block

BACKGROUND: Traditional approaches to performing brachial plexus blocks via the axillary approach have varying success rates. The main objective of this study was to evaluate if a specific technique of ultrasound guidance could improve the success of axillary blocks in comparison to a two injection transarterial technique. METHODS: Fifty-six ASA physical status I-III patients presenting for elective hand surgery were prospectively randomized to receive an axillary block performed by either a transarterial technique (Group TA) or an ultrasound-guided perivascular approach (Group US). Both groups received a total of 30 ml of 1.5% lidocaine (225 mg) with 5 microg/ml epinephrine. Patients were then evaluated for block onset in specific nerve distributions and whether or not the block acted as a surgical anesthetic. RESULTS: Group TA sustained more failures defined as conversion to general anesthesia or the inability to localize the artery [Group TA eight patients (29%) vs. Group US in which 0 patients required conversion to general anesthesia (0%) P < 0.01]. Group US demonstrated a reduction in performance times vs. Group TA (7.9 +/- 3.9 min vs. 11.1 +/- 5.7 min, P < 0.05). By 30 min post-injection, there were no significant differences between groups TA and US in terms of the proportion of patients demonstrating a complete motor or sensory loss. CONCLUSION: Ultrasonographic guidance improves the overall success rate of axillary blocks in comparison to a transarterial technique.     

Vertical infraclavicular block of the brachial plexus: effects on hemidiaphragmatic movement and ventilatory function

BACKGROUND AND OBJECTIVES: Several case reports have suggested that block of the brachial plexus by the vertical infraclavicular approach influences hemidiaphragmatic movement and ventilatory function. These effects have not been evaluated in a prospective study. METHODS: Thirty-five consecutive patients scheduled for elective surgery under brachial plexus anesthesia were included. A vertical infraclavicular block was performed with ropivacaine 0.75%, 0.5 mL/kg. Ipsilateral hemidiaphragmatic movement was measured by ultrasonography at maximal forced inspiration and sniff. Forced vital capacity (FVC) and forced expiratory volume (FEV(1)) were measured by a portable vitalograph. All measurements were performed before the block procedure and at 5, 10, 30, and 60 minutes after the block. RESULTS: The block was successful in 34 of 35 patients. In 9 patients (26%), a change in hemidiaphragmatic movement (reduced or paradoxical) was observed. A significant decrease in ventilatory function was found in 8 of these 9 patients between baseline and at 60 minutes: FVC = -0.8 +/- 0.4 L and FEV(1) = -0.7 +/- 0.3 L, mean +/- SD (relative decrease: FVC = 30 +/- 14% and FEV(1) = 32 +/- 13%, mean +/- SD). Horner's syndrome was seen in 4 patients (12%), and in all, a change in hemidiaphragmatic movement was observed. No clinical signs of ventilatory dysfunction were noticed. CONCLUSION: The vertical infraclavicular block can result in a change in ipsilateral hemidiaphragmatic movement, with a decrease of ventilatory function. Although a correlation between the presence of Horner's syndrome and hemidiaphragmatic dysfunction was observed, hemidiaphragmatic dysfunction also occurred independently.     

Phrenic nerve block caused by interscalene brachial plexus block: effects of digital pressure and a low volume of local anesthetic.

BACKGROUND AND OBJECTIVES: Interscalene brachial plexus block (ISB) is associated with phrenic block and diaphragmatic paralysis when high volumes (40-50 mL) of local anesthetic are injected. The goal of our study was to test if a low volume of local anesthetic administered while maintaining proximal digital pressure might more selectively block the brachial plexus and decrease the frequency of phrenic nerve block. METHODS: Twenty healthy patients undergoing ISB for orthopedic surgery of the upper extremity were randomly allocated to receive either 20 mL 1.5% mepivacaine while proximal digital pressure to the site of puncture was performed, or 40 mL 1.5% mepivacaine without digital pressure. Spirometry and clinical data were evaluated at baseline, 10, and 90 minutes after accomplishing the block and after the motor and sensory block resolved. Diaphragmatic excursion during deep inspiration was also evaluated 90 minutes after the block was performed, with the patient in the sitting position. RESULTS: Interscalene brachial plexus block produced diaphragmatic paralysis in all patients included in the study, as demonstrated by the pulmonary function testing and the chest radiograph. No significant differences were found in any of the parameters studied. At 10 minutes, baseline functional residual capacity had diminished by 34 +/- 10% in the 40 mL group and 37 +/- 13% in the 20 mL group. Maximum cephalad sensory dermatome level was also similar in both groups, being C 3 or above in all patients. Ipsilateral hemidiaphragmatic motion was similar in both groups (3.2 +/- 2.3 cm in the 40 mL group and 2.6 +/- 1.7 cm in the 20 mL group). However, in no case was dyspnea manifested. CONCLUSIONS: Decreasing the volume of local anesthetic and applying proximal digital pressure to the site of injection is not effective in reducing the cervical block spread and the frequency or intensity of diaphragmatic paralysis during interscalene ISB.     

超声引导锁骨上与锁骨下入路臂丛阻滞效果的比较

目的 比较超声引导锁骨上入路和锁骨下入路臂丛阻滞的效果.方法 择期上肢手术患者120例,性别不限,年龄18～80岁,ASA分级Ⅰ-Ⅲ级,采用随机数字表法,将患者随机分为2组(n=60):锁骨上入路组(SCB组)和锁骨下入路组(ICB组).局麻药采用0.375％罗哌卡因与1％利多卡因混合液(含1∶200000肾上腺素)分别行锁骨上或锁骨下臂丛阻滞,0.5 ml/kgo分别记录阻滞操作时间、麻醉维持时间及麻醉成功情况,注药完毕后每5 min测定腋神经、桡神经、正中神经、尺神经、肌皮神经、前臂内侧和臂内侧皮神经的阻滞情况及不良反应、并发症的发生情况,直至30 min.结果 与SCB组比较,ICB组麻醉成功率、尺神经、前臂内侧皮神经和臂内侧皮神经阻滞有效率升高,穿刺过程中异感发生率降低,阻滞操作时间延长(P＜0.05).两组均无严重并发症发生.结论 超声引导锁骨下入路臂丛阻滞的效果优于锁骨上入路.     

Frontal slab composite magnetic resonance neurography of the brachial plexus: implications for infraclavicular block approaches

BACKGROUND: Magnetic resonance neurography (MRN) is an imaging method by which nerves can be selectively highlighted. Using commercial software, the authors explored a variety of approaches to develop a three-dimensional volume-rendered MRN image of the entire brachial plexus and used it to evaluate the accuracy of infraclavicular block approaches. METHODS: With institutional review board approval, MRN of the brachial plexus was performed in 10 volunteer subjects. MRN imaging was performed on a GE 1.5-tesla magnetic resonance scanner (General Electric Healthcare Technologies, Waukesha, WI) using a phased array torso coil. Coronal STIR and T1 oblique sagittal sequences of the brachial plexus were obtained. Multiple software programs were explored for enhanced display and manipulation of the composite magnetic resonance images. The authors developed a frontal slab composite approach that allows single-frame reconstruction of a three-dimensional volume-rendered image of the entire brachial plexus. Automatic segmentation was supplemented by manual segmentation in nearly all cases. For each of three infraclavicular approaches (posteriorly directed needle below midclavicle, infracoracoid, or caudomedial to coracoid), the targeting error was measured as the distance from the MRN plexus midpoint to the approach-targeted site. RESULTS: Composite frontal slabs (coronal views), which are single-frame three-dimensional volume renderings from image-enhanced two-dimensional frontal view projections of the underlying coronal slices, were created. The targeting errors (mean +/- SD) for the approaches-midclavicle, infracoracoid, caudomedial to coracoid-were 0.43 +/- 0.67, 0.99 +/- 1.22, and 0.65 +/- 1.14 cm, respectively. CONCLUSION: Image-processed three-dimensional volume-rendered MNR scans, which allow visualization of the entire brachial plexus within a single composite image, have educational value in illustrating the complexity and individual variation of the plexus. Suggestions for improved guidance during infraclavicular block procedures are presented.     

A comparison of single versus multiple injections on the extent of anesthesia with coracoid infraclavicular brachial plexus block

Single-injection coracoid infraclavicular brachial plexus block produces inconsistent anesthesia of the upper limb. In this study, we sought to determine the number of injections needed to provide a reasonably complete anesthesia of the upper limb with this approach. Seventy-five patients were randomly assigned to receive a coracoid block guided by nerve stimulator with 42 mL of 1.5% mepivacaine with a single-injection (Group 1), dual-injection (Group 2), or triple-injection (Group 3) technique. No search for a specific motor response was performed in any group. Sensory and motor block was assessed 5 and 20 min after the end of the injection of local anesthetic. Significantly less complete anesthesia to pinprick in the distributions of the axillary, musculocutaneous, radial, ulnar, and medial cutaneous forearm nerves was found in Group 1 at 20 min. Significantly less complete paralysis for arm, wrist, and hand movements was found in Group 1 at 20 min. No significant difference was found between Groups 2 and 3. We conclude that dual and triple injection of local anesthetic guided by nerve stimulator increases the efficacy of coracoid block when compared with a single-injection technique.     

The use of a vertical infraclavicular brachial plexus block in a patient with myasthenia gravis: effects on lung function

A patient who was suffering an exacerbation of myasthenia gravis dislocated her elbow. She underwent closed reduction of the dislocation under vertical infraclavicular brachial plexus blockade. The technique was successful but was associated with a 29% decrease in forced vital capacity, from 1.7 l to 1.2 l. The patient did not show any symptoms of ventilatory failure. Her recovery was uncomplicated.     

Comparative evaluation of ultrasound-guided continuous infraclavicular brachial plexus block with stimulating catheter and traditional technique: a prospective-randomized trial

Background: Secondary catheter failure has been reported in up to 40% of patients with continuous peripheral nerve blocks resulting in failure to provide pain relief after the initial block wears off. Introduction of stimulating catheters as well as ultrasound for regional anaesthesia has facilitated correct placement of catheter tip, closer to the plexus. This randomized study was conducted to compare the efficacy of continuous infraclavicular brachial plexus blocks using non-stimulating catheter, stimulating catheter and ultrasound-guided catheter placement with nerve stimulation assistance.
Methods: Patients undergoing elective hand surgery were randomly allocated to receive continuous infraclavicular brachial plexus block using non-stimulating catheter [group traditional nerve stimulation (TR)], stimulating catheter [group stimulating catheter (ST)] or ultrasound-guided catheter placement with nerve stimulation assistance [group ultrasound guidance with nerve stimulation assistance (US)]. Motor and sensory blocks were assessed every 5 min and primary block success was determined at 30 min. After resolution of the primary block, threshold stimulating current and resulting response, spread of drug on re-injection as seen ultrasonographically and the capacity to re-establish block was documented. Complications and need for supplement was noted.
Results: The primary block success was significantly higher in the US group [96% US, 58% ST, 59% TR ( P =0.0005)]. Secondary catheter failure was significantly lower in the US group [9% US, 17% ST, 86% TR ( P <0.0001)]. Axillary nerve was blocked more predictably in the US group (100% US, 79% ST, 50% TR ( P =0.0003).
Conclusion: In this study, ultrasound guidance with nerve stimulation assistance significantly improved primary success and reduced secondary catheter failure in continuous infraclavicular brachial plexus blocks.