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Abstract
Introduction: Two common ways of providing anesthesia for shoulder dislocation reductions in the emergency department (ED) are intra-articular lidocaine (IAL) injections and procedural sedation (PS). We sought to compare PS with propofol or etomidate to IAL for shoulder dislocation reductions in the ED. Methods: This was an open-label, randomized controlled trial of patients aged 18–70 years with anterior shoulder dislocations who presented to a single ED. We randomized patients to either PS or IAL for their shoulder dislocation reduction. The primary outcome measure was ED length of stay (LOS). Secondarily, we assessed patient satisfaction and the number of attempts required for successful reduction. Results: We identified 60 patients who met the criteria for enrollment, and were able to enroll 43. We randomized 23 patients to IAL and 20 to PS. In the IAL group, the mean ED LOS was 133 min as compared to 124 min for the PS group (difference 9 min [95% confidence interval (CI)-22–41], P = 0.54). Patients in the IAL group required an average of 1.9 reduction attempts as compared to 1.2 in the PS group (difference of 0.7 [95% CI 0.2–1.2]). The mean patient satisfaction scores were similar at 9.7 and 9.8 for the IAL and PS groups, respectively. Conclusions: This study lacked a sufficient sample size to detect small differences but found no statistically significant difference in mean ED LOS or patient satisfaction for patients who received IAL as compared to PS. Patients in the PS group required fewer attempts for successful reduction.
Keywords: Intra-articular injection, procedural sedation, shoulder dislocation
How to cite this article: Introduction 
Shoulder dislocations are the most common dislocations presenting to emergency departments (EDs).[1] The best means of providing anesthesia for a shoulder dislocation reduction is not certain. A number of previous studies have evaluated different means of pain management for shoulder dislocation reductions including various intravenous (IV) analgesics and sedatives,[2],[3],[4],[5] interscalene blocks,[6],[7] and intra-articular lidocaine (IAL) injections.[8],[9],[10]
Studies evaluating interscalene blocks have found this technique to be very successful, and patients who get interscalene blocks tend to have shorter ED stays.[6],[7] However, the blocks for those studies were done by physicians with special training for those procedures, and the vast majority of emergency physicians (EPs) are not trained to do interscalene blocks.
More commonly used anesthetic techniques in the ED for shoulder dislocation reductions are IAL and IV sedation, which we will refer to as procedural sedation (PS). Prior data have suggested the use of IAL results in shorter hospital length of stay (LOS)[8],[9],[11],[12] and may be safer[11],[12] than PS for shoulder dislocation reductions. However, those data come from studies that used medications that have fallen out of favor for PS, namely opioids and benzodiazepines. Thus, it is possible that using shorter-acting medications such as propofol or etomidate may eliminate the benefit of having a shorter LOS seen with IAL in previous studies, and may make PS safer and more effective.
To determine if the use of PS with propofol or etomidate is superior to IAL for anterior shoulder dislocation reductions, we performed a randomized study comparing the two techniques for ED patients with anterior shoulder dislocations.
Methods Study design and setting
We performed a prospective, open-label, randomized controlled trial on patients presenting to the ED with anterior shoulder dislocations and no other acute medical issues. We enrolled patients at a single ED in Miami, Florida that receives approximately 80,000 visits per year and is part of a level 1 trauma center. This ED is staffed by emergency medicine residents 24 h/day, and those residents performed all the procedures in this study. We obtained approval from the Miami, Florida institutional review board (Protocol Number 2018-233), and we prospectively registered this trial on clinicaltrials.gov (NCT03625076). This research received no specific grant from any funding agency in the public, commercial or not-for-profit sectors. This study was conducted in accordance with the Helsinki Declaration.
Selection of participants
We sought to enroll patients in the ED who had an anterior shoulder dislocation and were between the ages of 18 and 70 years. We excluded patients who had a shoulder fracture (other than a Hill-Sachs), who had multiple traumatic injuries, who required diagnostic testing for a medical issue other than a shoulder dislocation, who were pregnant or breastfeeding, who were prisoners, who had altered mental status, who had a known allergy to one of the study drugs, or whom the attending physician excluded for safety concerns (if they thought one method of anesthesia was unsafe for that particular patient).
For patients meeting the inclusion criteria and none of the exclusion criteria above, we attempted to obtain written, informed consent.
Interventions
After obtaining informed consent, we allocated each patient to either PS or IAL as follows. Before the enrollment of the first patient, a system involving the use of a random number generator was developed to randomly assign all potential study subjects to either PS or IAL in a 1:1 ratio. One research volunteer not involved in data collection assembled a concealed, opaque envelope containing the group assignment for each potential study patient. After the patient provided informed consent, the treating physician opened the envelope to reveal the group allocation.
In this study, we allowed treating physicians to choose between either propofol or etomidate for PS. We did not specify the use of one of these medications as there was disagreement within our department about the optimal agent for PS. Although ketamine is also a reasonable choice for PS, the recovery time after sedation with ketamine is longer, so its use was not optimal for this study (which focuses on LOS). The dose of PS medications was left up to the treating clinician as there is some variability in the response to these medications, depending on the patient.
Patients who were randomized to the IAL group were to receive 20 mL of 1% lidocaine injected into the glenohumeral joint using a lateral approach. During the study, there was a shortage of 1% lidocaine, so we also allowed 10 mL of 2% lidocaine to be used for 8 patients. Treating physicians were instructed to wait 10 min after injection before attempting reduction. Preprocedural analgesia while awaiting X-ray results or while setting up for IAL or PS were left to the treating clinician.
We allowed treating physicians to use whatever reduction technique they preferred.
If a patient was initially randomized to IAL, and the physician was unable to reduce the shoulder with IAL, the physician could utilize PS if they felt that would allow successful reduction.
Methods of measurement
For each enrolled patient, we recorded their age, sex, and race. After the reduction, the treating physician logged the number of reduction attempts and the reduction technique (s) used. After the procedure, the treating physician also recorded any adverse events associated with IAL or PS. For adverse events related to PS, physicians specifically tracked myoclonus, oxygen desaturation <92%, hypotension, and interventions performed. More generally, adverse events related to PS tracking were guided by the International Sedation Task Force guidelines.[13] Just before ED discharge, the patient reported their satisfaction with the procedure on a scale from 0 to 10. The ED LOS and the medications administered to the patient in the ED were abstracted from the chart by one of the study investigators approximately 1 month after their visit. At that time, the investigator also assessed for return visits to the ED that might be related to the IAL (for example, for septic arthritis or cellulitis near the shoulder).
Outcome measures
The primary outcome measure was the difference in ED LOS between the PS and IAL groups. Secondarily, we compared the two groups with regard to the number of attempts required to reduce the shoulder and patient satisfaction.
Data analysis
Thirty-five patients would be needed in each group to find a 60 min difference between the group mean LOS, with a power of 0.80, an alpha of 0.05, and a standard deviation of 90 min. Thus, we hoped to enroll 70 patients.
We entered de-identified data into Microsoft Excel (Version 16, Microsoft, Redmond, WA) and analyzed it in a statistical program called R. We compared means using independent samples t-tests for normally distributed data and using the Mann–Whitney U-test for nonnormal data.
Results From August 12, 2018, to April 23, 2020, we enrolled a total of 43 patients – 23 were randomized to the IAL group and 20 to the PS group. As shown in [Figure 1], over a quarter of eligible patients were not enrolled because either the treating physician or the patient wanted to choose their method of anesthesia (They did not want randomization to choose for them). As a result of this issue and the difficulties encountered related to the COVID-19 pandemic, enrollment was slow, and we stopped the study before reaching our goal of 70 patients.
Figure 1: Demonstrates patient flow of ED patients with anterior shoulder dislocationsPatients ranged in age from 18 to 70 years old with a median age of 31 years. Patients were predominantly male (86%) and Caucasian Hispanic (84%). [Table 1] shows a comparison of baseline characteristics and outcomes between the groups. Notably, regarding the primary outcome, patients randomized to IAL had a mean ED LOS of 133 min as compared to 124 min for the PS group. The between groups difference of 9 min (95% confidence interval [CI]-22–41) is not statistically significant (P = 0.54).
Table 1: Baseline characteristics and outcomes for ED shoulder dislocation patients randomized to either intra-articular lidocaine (IAL) or procedural sedation (PS) for their reduction attemptSecondarily, patients randomized to the IAL group required a higher average number of reduction attempts at 1.9 as compared to 1.2 for those randomized to PS (difference of 0.7 [95% CI 0.2–1.2]). The mean patient satisfaction scores were similar at 9.7 and 9.8 for the IAL and PS groups, respectively (difference of 0.1 [95% CI-0.3–0.4]).
Among the 23 patients randomized to IAL, three patients ended up having PS performed after IAL because the physician was unable to reduce the shoulder. These patients had a mean ED LOS of 184 min, while the mean for patients whose shoulder was successfully reduced after IAL alone was 126 min.
There were no serious adverse events in either group. In those randomized to PS, there were two brief episodes of apnea that resolved without intervention. Both of these occurred in patients who received propofol. There were no adverse events identified for patients randomized to IAL.
Discussion This study provides evidence that the use of IAL may not shorten a shoulder dislocation patient's ED LOS as compared to PS when using short-acting sedatives such as propofol or etomidate. Undoubtedly, there are many factors that contribute to a patient's ED LOS, and the speed at which IAL or PS can be performed will vary at different facilities. However, the prior publications expressing that IAL reduces ED LOS compared to PS were based on the use of sedative medications such as opioids and benzodiazepines[8],[9] that are no longer first-line medications for PS.
There is only one prior small study that compares IAL to PS, in which the majority of patients in the PS group received propofol.[10] Our results were consistent with that study in that there was no difference in ED LOS between groups, and there were lower rates of successful reductions in the IAL group.[10] We are unaware of any prior studies that have compared PS with etomidate to IAL, but one prior study comparing sedation with etomidate to interscalene nerve blocks found shorter LOS with the nerve blocks.[6]
Our study's finding that patients randomized to IAL had a higher mean number of reduction attempts than those randomized to PS is consistent with prior data[10] and is intuitive. Properly performed PS completely relaxes the patient's muscles, which should allow for the optimal conditions to reduce the shoulder. However, the need for occasional extra reduction attempts if IAL is tried before PS does not necessarily result in any harm to the patient, and our study found no difference in patient satisfaction between the two groups.
This study was not powered to compare IAL and PS with regard to safety, but no serious adverse events were identified in either group. Just two clinically insignificant episodes of apnea occurred for patients randomized to PS, but patients who were at high risk for serious adverse events from PS were not included in this study (as either the physicians or the patients themselves excluded them). For such high-risk patients, PS should not be utilized, if possible. Injections of IAL are a low-risk procedure with a theoretical risk for septic arthritis, but no documented cases.[14]
In the end, both IAL and PS seem to be effective means of anesthesia for shoulder dislocation reductions that produce high patient satisfaction and few serious adverse events. In some cases, the patient may require no anesthesia at all. However, if a physician elects to forgo anesthesia or use IAL, they may occasionally have to proceed to PS to successfully reduce the shoulder. Optimally, an emergency physician knows multiple techniques for shoulder dislocation reduction and can employ a method of anesthesia that works best for that individual patient.
When considering the results of this study, there are several limitations to consider. Most notably, this study was underenrolled, and the small sample size prevents us from being able to draw precise conclusions. A big reason for the low enrollment was that in many cases, either the physician or the patient had a strong preference for either IAL or PS such that they did not want to proceed with the study protocol and leave the method of anesthesia to chance. This in itself suggests that the decision about IAL versus PS versus some other anesthetic strategy should be tailored to the individual patient and physician preferences. Along these same lines, the high percentage of patients who did not want to participate may have created groups with artificially increased satisfaction.
Another limitation to consider is the fact that this study was performed at a single, academic ED where EM residents performed all procedures. Therefore, our data are most relevant to academic facilities and may not be otherwise generalizable.
Finally, due to a shortage of 1% lidocaine, we allowed physicians to use 10 mL of 2% lidocaine for 8 patients (until 1% lidocaine was again available). It is possible that injecting 10 mL of 2% lidocaine is less effective than 20 mL of 1% lidocaine, making IAL, overall, seem less effective. However, ED LOS and mean number of reduction attempts are similar for patients who received IAL with 1% lidocaine compared to those who received 2% lidocaine.
Conclusions This study lacked a sufficient sample size to detect small differences between groups, but we found no statistically significant differences between patients randomized to IAL versus PS for shoulder dislocation reduction with regard to ED LOS or patient satisfaction. However, patients randomized to PS had a lower mean number of reduction attempts needed for successful reduction. The initial use of either PS or IAL may be warranted depending on the individual patient.
Research quality and ethics statement
This study was approved by the Miami, Florida Institutional Review Board (IRB# 2081-233) The authors followed applicable EQUATOR Network (http://www.equator-network.org/) guidelines during the conduct of this research project.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
References 
Correspondence Address:
Tony Zitek
4300 Alton Rd, Miami Beach, Florida 33140
USA
Source of Support: None, Conflict of Interest: None
CheckDOI: 10.4103/jets.jets_49_22
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