title: Ultrasound compared with nerve stimulation guidance for peripheral nerve catheter placement: a meta-analysis of randomized controlled trials.
abstract: BACKGROUND
  The aim of this meta-analysis was to compare the efficacy and safety of ultrasound (US) vs nerve stimulation (NS) guidance for peripheral nerve catheter placement.
  
  
  METHODS
  This meta-analysis was performed according to the PRISMA statement and the recommendations of the Cochrane Collaboration. For dichotomous outcomes relative risks [RRs; 95% confidence intervals (CIs)] were calculated, while for continuous outcomes, mean differences (MDs; 95% CI) were calculated. All statistical analyses were performed using the Revman® statistical software (Version 5.1).
  
  
  RESULTS
  Fifteen randomized controlled trials including 977 patients satisfied the inclusion criteria. Peripheral nerve catheters placed under US guidance showed a higher RR of 1.14 (95% CI: 1.02-1.27; P=0.02) for an overall successful block in comparison with NS. However, postoperative pain scales at movement (numeric rating scale: 0-10) were comparable between US- vs NS-guided peripheral nerve catheters 24 (MD: 0.08; 95% CI: -0.77 to 0.94; P=0.85) and 48 (MD: 1.0; 95% CI: -0.3 to 2.3; P=0.13) h after surgery. Patients receiving a US-guided peripheral nerve catheter had a lower RR of 0.13 (95% CI: 0.04-0.38; P=0.0002) for an accidental vascular puncture.
  
  
  CONCLUSIONS
  There is evidence that US-guided peripheral nerve catheters show a higher success rate and a lower risk for an accidental vascular puncture compared with NS guidance. However, this difference resulted only in marginally lower postoperative pain scores at rest. Nevertheless, these results were influenced by heterogeneity and should be interpreted with caution.
authors.affiliation: Department of Anaesthesiology, Intensive Care and Pain Medicine, University Hospital of Muenster, Albert-Schweitzer-Campus 1 (Building A1), 48149 Muenster, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Schnabel
authors.forename: C H
authors.initials: CH
authors.lastname: Meyer-Frießem
authors.forename: P K
authors.initials: PK
authors.lastname: Zahn
authors.forename: E M
authors.initials: EM
authors.lastname: Pogatzki-Zahn
mesh_terms: D002406:Catheterization, Peripheral / Q000009:adverse effects / Q000379:methods; D004558:Electric Stimulation / Q000379:methods; D006801:Humans; D009407:Nerve Block / Q000009:adverse effects / Q000379:methods*; D010149:Postoperative Pain / Q000517:prevention & control; D010525:Peripheral Nerves / Q000000981:diagnostic imaging*; D016032:Randomized Controlled Trials as Topic; D018084:Ultrasonography, Interventional / Q000379:methods*
keywords: acute pain, regional techniques; anaesthetic techniques, regional; regional anaesthesia