title: Differences in penetration force of intravenous catheters: effect of grinding methods on inner needles of intravenous catheters.
abstract: OBJECTIVE
  To compare penetration forces of intravenous catheters based on two grinding methods used for the inner needle tip.
  
  
  METHODS
  Forty intravenous catheters were divided into two groups according to two inner needle grinding methods: Lancet and Backcut. To compare the characteristics of inner needles, 18 gauge Surflo outer catheters, were attached to all inner needles. We measured penetration forces by attaching a "Push-Pull-Gauge" to the chamber of intravenous catheters, then we penetrated intravenous catheters through a 0.04-mm thick polyethylene film. The penetration velocity was 3.3 mm/sec. we measured penetration forces at 30- and 45-degree penetration angles.
  
  
  RESULTS
  There was no significant difference in the penetration forces of inner needle and outer catheter between the two groups at the 45-degree penetration angle. Penetration forces of the inner needle and the outer catheter in the Backcut group was significantly lower than those of the Lancet group at the 30-degree penetration angle. The penetration force of the outer catheter was reduced from 0.3 N to 0.18 N, a 40 % reduction at 30-degree penetration angle. Computerized measurements of penetration holes indicate that the Y-shaped incision mark of the Backcut leaves larger incision hole than the actual puncture size. We hypothesize that the Y-shaped incision mark creates more efficient path for the outer catheter to advance. Therefore, lower penetration force was indicated compared to the other group.
  
  
  CONCLUSIONS
  Backcut shows less penetration force of inner needles of peripheral intravenous catheters than lancet.
authors.affiliation: Department of Anesthesiology, Tokai University School of Medicine, Bohseidai, Isehara, Kanagawa 259-1193, Japan.
authors.forename: Toshiyasu
authors.initials: T
authors.lastname: Suzuki
authors.forename: Akira
authors.initials: A
authors.lastname: Tanaka
authors.forename: Haruo
authors.initials: H
authors.lastname: Fukuyama
authors.forename: Junichi
authors.initials: J
authors.lastname: Nishiyama
authors.forename: Masahiro
authors.initials: M
authors.lastname: Kanazawa
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Oda
authors.forename: Miwa
authors.initials: M
authors.lastname: Takahashi
mesh_terms: D002404:Catheterization / Q000295:instrumentation*; D007275:Injections, Intravenous; D009339:Needles; D013314:Stress, Mechanical