title: Ultrasound-guided lumbar plexus block in volunteers; a randomized controlled trial.
abstract: The currently best-established ultrasound-guided lumbar plexus block (LPB) techniques use a paravertebral location of the probe, such as the lumbar ultrasound trident (LUT). However, paravertebral ultrasound scanning can provide inadequate sonographic visibility of the lumbar plexus in some patients. The ultrasound-guided shamrock LPB technique allows real-time sonographic viewing of the lumbar plexus, various anatomical landmarks, advancement of the needle, and spread of local anaesthetic injectate in most patients. We aimed to compare block procedure outcomes, effectiveness, and safety of the shamrock vs LUT.
  
  
  
  Twenty healthy men underwent ultrasound-guided shamrock and LUT LPBs (2% lidocaine–adrenaline 20 ml, with 1 ml diluted contrast added) in a blinded randomized crossover study. The primary outcome was block procedure time. Secondary outcomes were procedural discomfort, number of needle insertions, injectate spread assessed with magnetic resonance imaging, sensorimotor effects, and lidocaine pharmacokinetics.
  
  
  
  The shamrock LPB procedure was faster than LUT (238 [sd 74] vs 334 [156] s; P=0.009), more comfortable {numeric rating scale 0–10: 3 [interquartile range (IQR) 2–4] vs 4 [3–6]; P=0.03}, and required fewer needle insertions (2 [IQR 1–3] vs 6 [2–12]; P=0.003). Perineural injectate spread seen with magnetic resonance imaging was similar between the groups and consistent with motor and sensory mapping. Zero/20 (0%) and 1/19 (5%) subjects had epidural spread after shamrock and LUT (P=1.00), respectively. The lidocaine pharmacokinetics were similar between the groups.
  
  
  
  Shamrock was faster, more comfortable, and equally effective compared with LUT.
  
  
  
  NCT02255591
authors.affiliation: Department of Anaesthesiology and Intensive Care, Aarhus University Hospital, Nørrebrogade 44, Aarhus C, DK-8000, Denmark.
authors.forename: J M C
authors.initials: JMC
authors.lastname: Strid
authors.affiliation: Department of Research and Development, Division of Emergencies and Critical Care, Oslo University Hospital, Kirkeveien 166, Oslo, N-0450, Norway.|Department of Anaesthesiology and Pain Medicine, Inselspital, Bern University Hospital, University of Bern, Freiburgstrasse 8, Bern, CH-3010, Switzerland.
authors.forename: A R
authors.initials: AR
authors.lastname: Sauter
authors.affiliation: Department of Anaesthesiology, Oslo University Hospital Rikshospitalet, Sognsvannsveien 20, Oslo, N-0372, Norway.
authors.forename: K
authors.initials: K
authors.lastname: Ullensvang
authors.affiliation: Department of Biomedicine, Faculty of Health, Aarhus University, Vennelyst Blvd. 4, Aarhus C, DK-8000, Denmark.
authors.forename: M N
authors.initials: MN
authors.lastname: Andersen
authors.affiliation: Department of Anaesthesiology and Intensive Care, Aarhus University Hospital, Nørrebrogade 44, Aarhus C, DK-8000, Denmark.
authors.forename: M
authors.initials: M
authors.lastname: Daugaard
authors.affiliation: Department of Biomedicine, Faculty of Health, Aarhus University, Vennelyst Blvd. 4, Aarhus C, DK-8000, Denmark.
authors.forename: M A F
authors.initials: MAF
authors.lastname: Bendtsen
authors.affiliation: Department of Orthopaedic Surgery, Aarhus University Hospital, Tage-Hansens Gade 2, Aarhus C, DK-8000, Denmark.
authors.forename: K
authors.initials: K
authors.lastname: Søballe
authors.affiliation: Department of Radiology, Aarhus University Hospital, Nørrebrogade 44, Aarhus C, DK-8000, Denmark.
authors.forename: E M
authors.initials: EM
authors.lastname: Pedersen
authors.affiliation: Department of Anaesthesiology and Intensive Care Medicine, Zealand University Hospital, University of Copenhagen, Sygehusvej 10, Roskilde, DK-4000, Denmark.
authors.forename: J
authors.initials: J
authors.lastname: Børglum
authors.affiliation: Department of Anaesthesiology and Intensive Care, Aarhus University Hospital, Nørrebrogade 44, Aarhus C, DK-8000, Denmark.
authors.forename: T F
authors.initials: TF
authors.lastname: Bendtsen
mesh_terms: D000328:Adult; D000779:Anesthetics, Local / Q000008:administration & dosage*; D018592:Cross-Over Studies; D006801:Humans; D008012:Lidocaine / Q000008:administration & dosage*; D008160:Lumbosacral Plexus / Q000000981:diagnostic imaging / Q000187:drug effects*; D008297:Male; D009407:Nerve Block / Q000379:methods*; D012016:Reference Values; D016037:Single-Blind Method; D013997:Time Factors; D018084:Ultrasonography, Interventional / Q000379:methods*; D055815:Young Adult
chemical_list: D000779:Anesthetics, Local; D008012:Lidocaine