Prehospital ultrasound-guided nerve blocks improve reduction-feasibility of dislocated extremity injuries compared to systemic analgesia. A randomized controlled trial

PLoS One. 2018 Jul 2;13(7):e0199776. doi: 10.1371/journal.pone.0199776. eCollection 2018.


Background: Out-of-hospital analgosedation in trauma patients is challenging for emergency physicians due to associated complications. We compared peripheral nerve block (PNB) with analgosedation (AS) as an analgetic approach for patients with isolated extremity injury, assuming that prehospital required medical interventions (e.g. reduction, splinting of dislocation injury) using PNB are less painful and more feasible compared to AS.

Methods: Thirty patients (aged 18 or older) were randomized to receive either ultrasound-guided PNB (10 mL prilocaine 1%, 10 mL ropivacaine 0.2%) or analgosedation (midazolam combined with s-ketamine or with fentanyl). Reduction-feasibility was classified (easy, intermediate, impossible) and pain scores were assessed using numeric rating scales (NRS 0-10).

Results: Eighteen patients were included in the PNB-group and twelve in the AS-group; 15 and 9 patients, respectively, suffered dislocation injury. In the PNB-group, reduction was more feasible (easy: 80.0%, impossible: 20.0%) compared to the AS-group (easy: 22.2%, intermediate: 22.2%, impossible: 55.6%; p = 0.01). During medical interventions, 5.6% [1/18] of the PNB-patients and 58.3% [7/12] of the AS-patients experienced pain (p<0.01). Recorded pain scores were significantly lower in the PNB-group during prehospital medical intervention (median[IQR] NRS PNB: 0[0-0]) compared to the AS-group (6[0-8]; p<0.001) as well as on first day post presentation (NRS PNB: 1[0-5], AS: 5[5-7]; p = 0.050). All patients of the PNB-group would recommend their analgesic technique (AS: 50.0%, p<0.01).

Conclusions: Prehospital ultrasound-guided PNB is rapidly performed in extremity injuries with high success. Compared to the commonly used AS in trauma patients, PNB significantly reduces pain intensity and severity.

Publication types

  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Analgesia / methods*
  • Anesthetics, Local / administration & dosage*
  • Extremities / diagnostic imaging
  • Extremities / injuries*
  • Feasibility Studies
  • Female
  • Humans
  • Joint Dislocations / complications*
  • Joint Dislocations / diagnostic imaging
  • Joint Dislocations / physiopathology
  • Male
  • Middle Aged
  • Nerve Block / methods*
  • Pain Management
  • Pain, Postoperative / etiology
  • Pain, Postoperative / prevention & control*
  • Prospective Studies
  • Ultrasonography / methods*


  • Anesthetics, Local

Grants and funding

This work was supported by departmental funding sources. BB received funding from the research program of the University Medical Center Goettingen, University of Goettingen [Ref: Forschungsförderungprogramm_UMG_2015; URL:]. This funding was provided after trial registration at the DRKS. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.