title: Effect of spinal needle characteristics on measurement of spinal canal opening pressure.
abstract: OBJECTIVE
  A wide variety of spinal needles are used in clinical practice. Little is currently known regarding the impact of needle length, gauge, and tip type on the needle's ability to measure spinal canal opening pressure. This study aimed to investigate the relationship between these factors and the opening-pressure measurement or time to obtain an opening pressure.
  
  
  METHODS
  Thirteen distinct spinal needles, chosen to isolate the effects of length, gauge, and needle-point type, were prospectively tested on a lumbar puncture simulator. The key outcomes were the opening-pressure measurement and the time required to obtain that measure. Pressures were recorded at 10-s intervals until 3 consecutive, identical readings were observed.
  
  
  RESULTS
  Time to measure opening pressure increased with increasing spinal needle length, increasing gauge, and the Quincke-type (cutting) point (P<0.001 for all). The time to measurement ranged from 30s to 530s, yet all needle types were able to obtain a consistent opening pressure measure.
  
  
  CONCLUSIONS
  Although opening pressure estimates are unlikely to vary markedly by needle type, the time required to obtain the measurement increased with increasing needle length and gauge and with Quincke-type needles.
authors.affiliation: Department of Emergency Medicine, Mayo Clinic, Rochester, MN, United States. Electronic address: bellamkonda.venkatesh@mayo.edu.
authors.forename: Venkatesh R
authors.initials: VR
authors.lastname: Bellamkonda
authors.affiliation: Department of Emergency Medicine, University of New Mexico, Albuquerque, NM, United States.
authors.forename: Thomas C
authors.initials: TC
authors.lastname: Wright
authors.affiliation: Division of Biomedical Statistics and Informatics, Mayo Clinic, Rochester, MN, United States.
authors.forename: Christine M
authors.initials: CM
authors.lastname: Lohse
authors.affiliation: Department of Emergency Medicine, Trinity Health, Minot, ND, United States.
authors.forename: Virginia R
authors.initials: VR
authors.lastname: Keaveny
authors.affiliation: Department of Emergency Medicine, Mayo Clinic, Rochester, MN, United States.
authors.forename: Eric C
authors.initials: EC
authors.lastname: Funk
authors.affiliation: Department of Otorhinolaryngology-Head and Neck Surgery, Mayo Clinic, Rochester, MN, United States.
authors.forename: Michael D
authors.initials: MD
authors.lastname: Olson
authors.affiliation: Department of Emergency Medicine, Mayo Clinic, Rochester, MN, United States.
authors.forename: Torrey A
authors.initials: TA
authors.lastname: Laack
mesh_terms: D015170:Cerebrospinal Fluid Pressure; D006801:Humans; D008348:Manikins; D013129:Spinal Puncture / Q000295:instrumentation*
keywords: Headache; Intracranial hypertension; Needles; Process improvement; Spinal puncture; Throughput