Critically Appraised Topic: Does ultrasound-guided nerve block or procedural sedation provide better pain control for shoulder reduction?
Summary of methods:
Study #1: This was a randomized controlled trial of patients presenting to the emergency department with a shoulder dislocation. Patients were eligible if they were at least 18 years of age and required reduction of shoulder dislocation in the ED. Exclusion criteria included known allergy to local anesthetic agents, hemodynamic instability, respiratory distress, or were unable to give consent because of altered mental status. The primary objective of the study was to compare length of stay in patients randomized to US-guided interscalene nerve block (NB) or procedural sedation (PS) using etomidate to facilitate reduction of shoulder dislocation. Secondary objectives included pain experienced by the patient during reduction. Patients receiving NB were injected 20 to 30 mL of lidocaine with epinephrine (concentration not specified) until the anesthetic was dispersed around the nerve roots, visualized in real time using US. Patients were judged ready for reduction after complete absence of pain with gentle shoulder palpation and movement. Patients randomized to PS received etomidate as the sole agent (dosing not specified). 42 patients were enrolled, with 21 patients in each group. None of the subjects receiving NB required additional analgesia or sedation while performing shoulder reduction. After the procedure, patients were asked to rate their associated pain and followed until discharge. Median pain levels of both groups was 0 (PS range 0 to 4, NB range 0 to 3, p = 0.80).
Study #2: This was also a randomized controlled trial of adult patients presenting to the ED with an anterior shoulder dislocation. Exclusion criteria were defined as any contraindication to the medications used in each group, underlying medical conditions such as severe heart disease, presence of neurovascular compromise or concomitant fractures related to the dislocation, or patient refusal. The primary outcomes were ED length of stay and pain score during reduction in patients randomized to US-guided interscalene NB or PS using propofol and fentanyl. Patients receiving NB were injected 15 to 25 mL of 1% lidocaine with 0.1 mg of 1:100,000 concentration epinephrine until the nerve fascicles were expanded apart. Sensory examinations were performed until the patient reported complete analgesia in the shoulder region. PS was done with a starting dose of 2 μg/kg of fentanyl and 1 mg/kg of propofol titrated to the desired sedation. 60 patients were enrolled, with 30 patients randomized into each group. Patients receiving PS had a Mean (SD) pain score of 0.38 (0.5) and those receiving NB had a pain score of 3.43 (1.6) for a significant difference of p < 0.001.
Conclusions: In my review of the literature, I can conclude that there is no evidence supporting US-guided NB as better pain control as compared to procedural sedation for shoulder reduction. Interscalene NB causes at best similar – possibly more – patient pain. Further studies with primary objectives on comparisons in patient pain should be conducted using other types of NB.