title: How much work is required to puncture dura with Tuohy needles?
abstract: The effects of needle bevel orientation and cerebrospinal fluid (CSF) pressure on dural displacement and force required to penetrate cadaveric dura were studied using 40 samples. A constant hydrostatic pressure was applied to the subdural surface, either high or low, simulating the sitting and lateral positions. A 17-gauge Tuohy needle was advanced through the dura with the bevel oriented parallel or perpendicular to dural fibres. Travel distance and peak force at which dural penetration occurred were measured under both pressure conditions. The work required to produce dural penetration was calculated. Greater force and work were required to penetrate dura in the perpendicular orientation (P < 0.05), regardless of the subdural pressure exerted. Dural displacement was similar under both pressure conditions.
authors.affiliation: Department of Anesthesiology, Veterans Affairs Medical Center, Miami, FL 33125, USA.
authors.forename: M C
authors.initials: MC
authors.lastname: Lewis
authors.forename: J P
authors.initials: JP
authors.lastname: Lafferty
authors.forename: M S
authors.initials: MS
authors.lastname: Sacks
authors.forename: V S
authors.initials: VS
authors.lastname: Pallares
authors.forename: M
authors.initials: M
authors.lastname: TerRiet
mesh_terms: D000328:Adult; D000368:Aged; D002102:Cadaver; D015170:Cerebrospinal Fluid Pressure / Q000502:physiology*; D004388:Dura Mater / Q000033:anatomy & histology*; D006801:Humans; D006874:Hydrostatic Pressure; D007268:Injections, Epidural / Q000379:methods; D008875:Middle Aged; D009339:Needles; D011187:Posture; D013129:Spinal Puncture / Q000295:instrumentation*