title: [Sciatic nerve block "out-of-plane" distal to the bifurcation: effective and safe].
abstract: BACKGROUND
  Ultrasound guided distal sciatic nerve block (DSB) at bifurcation level shows fast onset and provides excellent success rates. However, its safe performance might be difficult for the unexperienced physician. Just slightly distal to the bifurcation, the tibial nerve (TN) and common fibular nerve (CFN) can be shown clearly separated from each other. Therefore, we investigated if a block done here would provide similar quality results compared to the DSB proximally to the division, with a potentially lower risk of nerve damage.
  
  
  METHODS
  In this randomized, prospective trial, 56 patients per group received either a DSB distal to the bifurcation "out-of-plane" (dist.) or proximally "in-plane" (prox.) with 30 ml of Mepivacaine 1% each. Success was tested by a blinded examiner after 15 and 30 min respectively (sensory and motor block of TN and CFN: 0 = none, 2 = complete, change of skin temperature). Videos of the blocks were inspected by an independent expert retrospectively with regard to the spread of the local anesthetic (LA) and accidental intraneural injection.
  
  
  RESULTS
  Cumulative single nerve measurements and temperature changes revealed significant shorter onset and better efficacy (dist/prox: 15 min: 3.13 ± 1.86/1.82 ± 1.62; 30 min: 5.73 ± 1.92/3.21 ± 1.88; T15 min: 30.3 ± 3.48/28.0 ± 3.67, T30 min. 33.0 ± 2.46/30.6 ± 3.86; MV/SD; ANOVA; p < 0.01) combined with a higher rate of subparaneural spread in the dist. group (41/51 vs.12/53; χ2; p < 0,01). Procedure times were similar. There were no complications in either group.
  
  
  CONCLUSIONS
  The subparaneural spread of the LA turned out to be crucial for better results in the distal group. The steep angle using the out-of-plane approach favors needle penetration through the paraneural sheath. The distance between the branches allows the safe application of the LA, so an effective block can be done with just one injection.
  
  
  CONCLUSIONS
  DSB slightly distal to the bifurcation, in an out-of-plane technique between the TN and CFN, can be done fast, effectively and safe.
authors.affiliation: Abteilung für Anästhesiologie und Intensivmedizin, Berufsgenossenschaftliche Unfallklinik Murnau, Murnau am Staffelsee, Deutschland. geiser@bgu-murnau.de.
authors.forename: T
authors.initials: T
authors.lastname: Geiser
authors.affiliation: Klinik für Anästhesiologie, Intensiv-, Rettungs- und Schmerzmedizin, Kantonsspital St.Gallen, St. Gallen, Schweiz.
authors.forename: J
authors.initials: J
authors.lastname: Apel
authors.affiliation: Klinik und Poliklinik für Anästhesiologie und Intensivtherapie, Universitätsklinikum Carl Gustav Carus, Technische Universität, Dresden, Deutschland.
authors.forename: O
authors.initials: O
authors.lastname: Vicent
authors.affiliation: Abteilung für Anästhesiologie und Intensivmedizin, Berufsgenossenschaftliche Unfallklinik Murnau, Murnau am Staffelsee, Deutschland.
authors.forename: J
authors.initials: J
authors.lastname: Büttner
mesh_terms: D000328:Adult; D000779:Anesthetics, Local; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D008297:Male; D019300:Medical Errors; D008619:Mepivacaine; D008875:Middle Aged; D009407:Nerve Block / Q000379:methods*; D010543:Peroneal Nerve / Q000000981:diagnostic imaging / Q000293:injuries; D011446:Prospective Studies; D012584:Sciatic Nerve / Q000000981:diagnostic imaging*; D013979:Tibial Nerve / Q000000981:diagnostic imaging / Q000293:injuries; D018084:Ultrasonography, Interventional
chemical_list: D000779:Anesthetics, Local; D008619:Mepivacaine
keywords: Nerve damage; Out-of-plane; Paraneural sheath; Sciatic nerve block; Ultrasound