A Prospective Comparison of Procedural Sedation and Ultrasound-guided Interscalene Nerve Block for Shoulder Reduction in the Emergency Department

Alina Mitina, DO
Published March 1, 2022

Probetrotters | Medical Education

Study Design

This study was a prospective, randomized study that compared procedural sedation and interscalene nerve block for patients presenting with shoulder dislocations.


The primary objective of the study was to compare the length of stay in patients randomized to ultrasound (US)  guided interscalene block or procedural sedation to facilitate the reduction of shoulder dislocation in the emergency department (ED). The secondary objectives were to compare one on one health care provider time, pain experienced by the patient during reduction, and post-procedural patient satisfaction between the two groups.


  • Patients 18 and older were randomized to procedural sedation or interscalene traditional nerve block groups. 
  • Ultrasound-guided nerve blocks were performed by emergency physicians who were trained in bedside US examinations and had at least 2 years of US experience in the ED. US physicians also received a 2-hour didactic course in interscalene blocks and had performed 10 prior to the study. 
  • Physicians acquired standard images of the brachial plexus of the interscalene position in the short axis. Lidocaine with epinephrine was injected into the brachial plexus and visualized real-time using US. Once anesthesia was present reduction was done. 
  • Procedural sedation was performed using etomidate and all patients were monitored with blood pressure, cardiac, and pulse oximetry after for hemodynamic instability.

Figure 2. Interscalene cervical block  using doppler flow to identify the cervical artery.

Figure 3. Interscalene block using hydrodissection. The hypoechoic area is considered the “hydrodissection” where normal saline is injected into the area of interest, followed by a local anesthetic.

What are some possible flaws in the methods used?

Flaws that I see with this study are not standardizing the type of shoulder reduction technique that was used and the provider doing the reduction or procedural sedation. Additionally, there was no post-procedural home follow-up on symptoms and recovery in the nerve block and procedural sedation groups. This study is difficult to generalize to all emergency departments because we do not know the workflow and logistics of this specific emergency department, there is no breakdown of the timeline post procedures to discharge.


Reduction accomplished with nerve block vs. procedural sedation was 100%. However, the length of stay (LOS) was significantly higher in the procedural sedation group versus the nerve block group (177.3 ± 37.9 minutes and 100.3 ± 28.2 minutes; p < 0.0001). The one-on-one health care provider time was 47.1 (±9.8) minutes on average for the sedation group and 5 (±0.7) minutes for the US-guided interscalene block group (p < 0.0001).

Patient satisfaction, self-reported pain, and post procedure complications (nerve blocks versus medication related side effects post procedure) were not significantly different between the two groups.


ED’s are becoming more crowded with limited nursing staff across the United States. Procedural sedation requires a nurse to constantly observe the patient until they are back to a normal mental status, which may take over 2 hours. This increases the length of stay of patients and takes away nursing staff from other patients. Due to the lack of nerve stimulation equipment emergency physicians have been unable to perform nerve blocks on patients. However, now with the availability of US emergency physicians can utilize this tool. This study showed that US-guided nerve blocks can significantly decrease the LOS for patients. Procedural sedation involves pre and post sedation monitoring which varies for different people especially with those which have significant comorbidities. Training and experience can make nerve blocks a useful alternative to procedural sedation for patients who have cardiac risk factor or airway disease.

Take Home Points

        • The length of stay in the ED is much higher in the procedural sedation group than in the nerve block group but did not make a difference in post-procedure patient satisfaction, pain, and complications.  

        • The length of stay is a valuable metric in the ED as a shorter stay increases patient satisfaction and decreases the number of resources utilized during the patient visit. 

        • With short-staffing, a shorter length of stay allows nurses to tend to their other patients. 

        • It is also beneficial to have two different modalities for treating patients who need shoulder reductions as some patients, like those with respiratory or cardiac comorbidities, may be better candidates for a nerve block.

Study Limitations

  • One of the limitations of the study was that ED physicians were not blinded to the interventions that they were performing.
  • The reduction technique, time of achieving reduction, and exact time from the beginning of nerve block or procedural sedation were not kept track of.
  • The post procedure time frame with both procedural sedation and nerve blocks are both important as different hospitals have different protocols on how they observe and discharge patients after procedures.
  • Interscalene nerve block was not compared to other types of nerve blocks, such as intra-articular nerve block.
  • There was no good follow-up with patients on both techniques, so no clear post-procedural complications are known.
  • Lastly, the small sample size makes the final conclusion reached not generalizable. Additionally, interscalene blocks must be used with caution in patient’s with COPD, lung malignancy, or ones that have poor reserve as the block can lead to phrenic nerve paralysis. This is dangerous because phrenic nerve injury can lead to diaphragmatic paralysis, which can negatively impact the patient.

Does this study influence your practice?

This study influences my practice by showing me the power that ultrasound has in expediting patient care. Decreasing the length of stay for ED patients can be accomplished by being able to become independent of a variety of factors that influence your medical decision-making. Through the incorporation of ultrasound, this study shows how one can use it to understand human anatomy and directly ease pain in a way that uses fewer resources and staff. By using ultrasound more often in the ED physicians will be able to use fewer resources and have more time to expedite patient care. Although there are limitations of doing interscalene nerve blocks such as difficulty accessing the brachial plexus secondary to a patient’s body habitus, complications with lidocaine toxicity, infection, bleeding, and puncture of vasculature. I still believe that in the hands of a trained provider it is a great modality as compared to the resources and prolonged length of stay created by procedural sedation.

[1] A Prospective Comparison of Procedural Sedation and Ultrasound-guided Interscalene Nerve Block for Shoulder Reduction in the Emergency Department. Michael Blaivas, MD, Srikar Adhikari, MD, RDMS, and Lina Lander, ScD