title: Opening Injection Pressure Is Higher in Intraneural Compared With Perineural Injections During Simulated Nerve Blocks of the Lower Limb in Fresh Human Cadavers.
abstract: OBJECTIVE
  Needle-induced nerve trauma and intraneural injection can lead to neurologic injury during peripheral nerve blocks. In this study, we assessed the utility of opening injection pressure (OIP), time to OIP, and rate of rise to OIP in detecting needle-nerve contact and intraneural injection.
  
  
  METHODS
  Five common ultrasound-guided blocks of the femoral, saphenous, subgluteal sciatic, tibial, and common peroneal nerves were simulated in 10 fresh cadavers. Opening injection pressure was defined as peak psi in the 60-second interval during which the injection is initiated. Pressure-time curves were constructed separately for intraneural and perineural injections for each of the 5 nerves studied.
  
  
  RESULTS
  Opening injection pressure was higher for intraneural than for perineural injections (P < 0.001), ranging from 21.5 psi (1111.9 mm Hg) to 25.8 psi (1334.2 mm Hg) for intraneural injections and from 3.8 psi (196.5 mm Hg) to 6.1 psi (315.5 mm Hg) for perineural injections. Time to OIP tended to be shorter for intraneural than for perineural injections, particularly for the subgluteal sciatic, tibial, and common peroneal nerves. Curves of intraneural injections had steep slopes with high peaks; curves of perineural injections had low slopes followed by plateaus. Rise to OIP was greater for intraneural than for perineural injections.
  
  
  CONCLUSIONS
  In our fresh human cadaver model, OIP detected intraneural needle placement. Monitoring of OIP could be useful in detecting and/or preventing intraneural injection during nerve blocks in the clinical setting.
authors.affiliation: From the *Department of Anaesthesia, AZ Turnhout, Turnhout; †Department of Anaesthesia, University Hospital Antwerp, Antwerp; and ‡Department of Development and Regeneration, Jan Palfijn Anatomy Lab, University of Leuven Campus Kulak, Kortrijk, Belgium; §Department of Anaesthesia and Intensive Care, Philipps-University Hospital, Marburg, Germany; ∥Pain Centre, Department of Anesthesiology, University Medical Centre Groningen, University of Groningen, Groningen, the Netherlands; and #Anesthesiology ZOL, Genk; and **Department of Cardiovascular Sciences, KU Leuven and Department of Anaesthesiology, UZ Leuven, Leuven, Belgium.
authors.forename: Kris
authors.initials: K
authors.lastname: Vermeylen
authors.forename: Marlies
authors.initials: M
authors.lastname: Hermans
authors.forename: Filiep
authors.initials: F
authors.lastname: Soetens
authors.forename: Evie
authors.initials: E
authors.lastname: Vereecke
authors.forename: Thorsten
authors.initials: T
authors.lastname: Steinfeldt
authors.forename: Gerbrand
authors.initials: G
authors.lastname: Groen
authors.forename: Admir
authors.initials: A
authors.lastname: Hadzic
authors.forename: Marc
authors.initials: M
authors.lastname: Van de Velde
mesh_terms: D000328:Adult; D002102:Cadaver; D005260:Female; D005267:Femoral Nerve / Q000000981:diagnostic imaging / Q000502:physiology; D006801:Humans; D007267:Injections / Q000295:instrumentation* / Q000379:methods; D035002:Lower Extremity / Q000000981:diagnostic imaging* / Q000294:innervation* / Q000502:physiology; D008297:Male; D009339:Needles; D009407:Nerve Block / Q000295:instrumentation* / Q000379:methods; D010543:Peroneal Nerve / Q000000981:diagnostic imaging / Q000502:physiology; D011312:Pressure; D012584:Sciatic Nerve / Q000000981:diagnostic imaging / Q000502:physiology; D013979:Tibial Nerve / Q000000981:diagnostic imaging / Q000502:physiology