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Preliminary results of ultrasound-guided interscalene block for dislocated shoulder:
Background Traditionally, patients with a dislocated shoulder joint will be subjected to general anesthesia for closed reduction, if this procedure cannot be managed with light intravenous sedation and opioid analgesia. Successful interscalene blockade of the brachial plexus allows painfree reduction of the dislocated shoulder. However, the interscalene blockade for a dislocated shoulder is usually performed in the emergency room and to optimize patient safety it is desirable to minimize the dose of local anesthetic using ultrasound-guidance. The objective of this cohort study was to determine the clinical feasibility of ultrasound-guided interscalene brachial plexus blockade using a safe dose of just 10 mL of lidocaine 1% in producing sufficient and effective muscle relaxation, allowing painfree reduction of a dislocated glenohumeral joint.
Methods We performed ultrasound-guided interscalene brachial plexus blockade with 10 mL of lidocaine 1% in a cohort of 10 patients with dislocated glenohumeral joints presenting in the emergency room, where the shoulder could not be reduced following intravenous sedation and analgesia. Results The success rate of closed reduction of the dislocated shoulders was 100% with complete pain control and muscle relaxation during the reducting procedure. Median patient satisfaction (VAS, Visual Analogue Scale 0-10) after completion of the procedure was 10 (range 8-10). Conclusion Ultrasound-guided interscalene brachial plexus blockade using merely 10 mL of lidocaine 1% effectively produces muscle relaxation allowing pain free reduction of the dislocated glenohumeral joint with a success rate of 100% and high patient satisfaction.
Keywords dislocation, shoulder, glenohumeral joint, ultrasound
Dislocation of the gleno-humeral joint is associated with severe pain and is frequently presented in the emergency room (ER). Reduction of a shoulderdislocationrequiresalleviation of the pain and musclerelaxation. Traditionally, this is obtained using general anesthesia (GA) with rapid sequence induction, when initial attempts of reduction using light oral and/or intravenous sedation and opioid analgesia are not successful. However, GA is associated with the risk of aspiration and requires an anesthetist, access to the operating theatre and postoperative observation in the Post Anesthesia Care Unit (PACU). Interscalene blockade (ISB) of the brachial plexus (BP) will achieve the desired effect of muscle relaxation and pain alleviation and eliminates the risks of GA cost-effectively. ISB of the BP usingelicitation of paresthesia to locate the target nerves wasemployedalready in 1973 to obtainanalgesia and musclerelaxationallowingreduction of a dislocatedshoulder joint 1. ISB of the BP using electrical nerve stimulation to allow reduction of a dislocated shoulder joint was later reported 2, 3. However, the motor response due to the electrical stimulation can be very painful in patients with dislocated shoulder joints. Some authors have reported location of the BP using ultrasound-guided regional anesthesia instead of electrical nerve stimulation 4, 5. Blaivas and Lyon (2006) used in-plane (IP) approach and 30 mL of either lidocaine 1% or bupivacaine 0.25%. The success rate of pain free joint reduction was 100% in four patients. Bhoi et al. (2010) used out-of-plane approach and 6-15 mLlidocaine 2% and had a success rate of a 100% in three patients. The current report describes an ultrasound-guided approach to ISB of the BP using IP approach and 10 mL of lidocaine 1% for reduction of the gleno-humeral joint in a preliminary cohort of patients with dislocated shoulder where reduction in the ER had been attempted with light sedation and analgesia without success.
The requirement for approval of the protocol and for written informed consent, was waived by the Central Denmark Regional Committees on Biomedical Research Ethics,due to the fact that the ultrasound-guided ISB of the BP for reduction of dislocated shoulders is an established method in our departments. Following informed consent 10 consecutive patients scheduled for reduction of dislocated gleno-humeral joint were included in the study (Table 1). We have only included patients with dislocation of the gleno-humeral joint where reduction has been attempted in the ER without success. Following establishment of venous access, the patient was placed in the supine position with the head turned contralateral to the side to be blocked. Vital signs monitoring was opted out during the procedure in the ER provided that all of the following criteria were fulfilled: (1) the block was performed by a consultant anesthetist who performs ultrasound guided peripheral nerve blocks on a daily basis and (2) the block was performed with uninterrupted, direct real time visualization of the needle tip during the entire procedure and (3) using parasagittal from-posterior-to-anterior IP approach and (4) with visualization of the spread of a 1 mL test dose of saline alongside the nerve roots of C5-C6 prior to injection of lidocaine and (5) real time visualization of the spread of lidocaine during the entire injection and (6) no supplementary lidocaine in addition to 100 mg was injected (7) in a fully awake and alert patient. If the above criteria 1-7 were not fulfilled, then the procedure was aborted immediately and not resumed until full vital signs monitorering had been applied. . Needle path and injection of local anesthetics Using an aseptic technique the needle was inserted from the posterior end of the ultrasound transducer and thereafter advanced IP in an anterior direction until the needle tip was seen in close proximity to the C5 and C6 nerve roots (Fig. 1). Hydrolocation was performed with 1 mL of saline confirming the appropriate location of the needle tip and the spread of the injectate prior to injection of local anesthetic (10 mL of lidocaine 1%). The endpoint of the injection manoeuvre was to observe that the local anesthetic spread alongside the C5 and C6 nerve roots as assessed by real-time ultrasound. The dose of lidocaine was injected incrementally with intermittent aspiration. If the spread of local anesthetic was deemed inadequate the needle tip was repositioned as necessary with direct real time visualization using solely ultrasonographic guidance. Equipment The ultrasound scanning was performed with an M-Turbo ultrasound machine (Sonosite, Bothell, WA) using a 6-13 MHz linear transducer (HFL38, Sonosite®, Bothell, WA, USA) covered by a sterile sleeve. Definition of successful ISB Successful ISB was defined as reduction of the dislocated shoulder joint with no need for conversion to general anesthesia.
Study design and data collection The study was planned as a prospective cohort study to determine the clinical feasibility of the low-dose IP ISB to allow reduction of a dislocated shoulder joint . Thus, no formal power analysis or statistical test analysis was performed.
A total of 10 patients were enrolled. Nine patients had an anterior dislocation of the gleno-humeral joint and one had a posterior dislocation. Demographic data are presented in table 1. The success rate of reduction of the dislocated shoulders was 100% with complete pain control and muscle relaxation during the reducting procedure. Median patient satisfaction (VAS, Visual Analogue Scale 0-10) after completion of the procedure was 10 (range 8-10). Median time from completed block performance to shoulder reduction was five minutes (range 3-10 minutes). The median pain VAS score immediately prior to the performance of the interscalene block was 10 (range 7-10), and all patients were awake and fully alert during the procedure. All procedures were completed in accordance with the criteria 1-7 (see Methods). Outcome data are presented in table 2.
Our preliminary data demonstrate that a dislocated shoulder can be reduced effectively without pain, and with good muscle relaxation using ultrasound-guided interscalene brachial plexus blockade with a small dose of lidocaine. By application of this technique, deep sedation and opioids and/or general anesthesia with fast track induction is avoided in a population of typically non-fasting patients. Ultrasound-guided ISB of the BP is applicable also in patients with severe cardiac co-morbidity, where GA would not be attractive. Ultrasound-guided ISB of the BP is also a simple and low-cost technique compared to general anesthesia and does not occupy the capacity of the surgical ward or the PACU. Application of a safe and innocuous dose of a local anesthetic with a broad therapeutic range is critically important, when peripheral nerve blocks are performed in the ER outside the primary venue of anesthesia. The standard dose of 100 mg lidocaine optimizes patient safety, as accidental intravenous injection of this magnitude of lidocaine would be virtually harmless. However, intravenous injection using ultrasound-guidance is practically impossible when appropriately performed in accordance with the criteria listed in the Methods section. The theoretical risk of an accidental intraarterial or intraspinal injection is considered non-existent obeying the above mentioned criteria 1-7. Resuscitation equipment is readily accessible in the settings of the ER. However, any dose of any local anesthetic employed for peripheral nerve blocks without full vital signs monitoring remains a controversial issue. If the reader cannot honour all the criteria 1-7, the advice of the authors is to apply full vital signs monitoring during and after the performance of the nerve block – even when using a small dose of a local anesthetic with a broad therapeutic range. Our preliminary data suggest that the patients experience maximum satisfaction with this technique (median VAS score 10). We have no data to compare patient satisfaction to nerve stimulation guidance for interscalene blockade or general anesthesia. There are some important limitations to our study. First, the study is non-randomized, un-blinded and it does not include a control group. Second, the sensory and motor quality of the interscalene blocks was not tested and the effect was just documented by clinical success. Third, lidocaine pharmacokinetics was not calculated and serum-lidocaine was not measured. Fourth, the choice of dose of local anesthetic was arbitrary and not based on titration. Fifth, the study included only a small sample of patients. However, the clinical success rate of reduction was 100% and the patient satisfaction very high despite the fact that our data were sampled in a population of patients where the primary attempt for a closed reduction of the dislocated shoulder supported by sedatives and opioids failed.
This strongly indicates the feasibility of the described technique and reduced dosing of local anesthetic.
Future randomized controlled trials have to clarify the usefulness of a broader indication for ultrasound guided interscalene nerve blockade for patients with dislocated shoulders.
This preliminary cohort study demonstrates that ultrasound guided interscalene BP blockade using merely 10 mL of lidocaine 1% effectively produces muscle relaxation allowing pain free reduction of the dislocated glenohumeral joint with a success rate of 100% and maximum patient satisfaction.
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