title: Comparison of torsional and linear mode ultrasonic coagulating shears for sealing veins.
abstract: BACKGROUND
  Torsional mode ultrasonic coagulating shears are an alternative device to linear mode shears for hemostatic cutting. The aim of this study was to compare the vessel-sealing quality of torsional and linear mode ultrasonic coagulating shears on human veins.
  
  
  METHODS
  Veins were harvested from 15 patients during varicose vein surgery. Each vessel was sealed and cut by both devices at different sites. The seals were either tested for burst pressure or examined microscopically to compare mural thickness, seal length, and extent of coagulation and lateral thermal effect.
  
  
  RESULTS
  For veins 2.0-3.0 mm in diameter, the median burst pressure was higher on seals made with torsional mode shears (245, IQR 161-360 mm Hg vs. 133, IQR 101-165 mm Hg; P = 0.001). Similarly, for veins 3.5-4.5 mm in diameter, the median burst pressure was higher with torsional mode shears (149, IQR 118-212 mm Hg vs. 94, IQR 82-126 mm Hg; P = 0.001). There was no significant difference in the median burst pressure for veins 5.0-6.0 mm in diameter (82, IQR 61-132 mm Hg vs. 76, IQR 40-114 mm Hg; P = 0.268). Seals made with torsional mode shears showed significantly greater seal length (517 +/- 300 microm vs. 316 +/- 147 microm; P = 0.016), more tissue coagulation (467 +/- 197 microm vs. 335 +/- 128 microm; P = 0.015), and greater lateral thermal effect (1479 +/- 340 microm vs. 1116 +/- 253 mum; P < 0.001).
  
  
  CONCLUSIONS
  Torsional mode ultrasonic shears produced more secure seals on veins up to 4.5 mm in diameter. This can be explained by the greater seal length produced by torsional mode shears.
authors.affiliation: Academic Unit of Surgery, The General Infirmary at Leeds, Leeds, United Kingdom. ching_ss@hotmail.com
authors.forename: Siok Siong
authors.initials: SS
authors.lastname: Ching
authors.forename: Caroline S
authors.initials: CS
authors.lastname: Verbeke
authors.forename: Shervanthi
authors.initials: S
authors.lastname: Homer-Vanniasinkam
authors.forename: Michael J
authors.initials: MJ
authors.lastname: McMahon
mesh_terms: D016009:Chi-Square Distribution; D004564:Electrocoagulation / Q000295:instrumentation*; D004867:Equipment Design; D004869:Equipment Safety; D016558:Hemostasis, Endoscopic / Q000295:instrumentation*; D006801:Humans; D018709:Statistics, Nonparametric; D013525:Surgical Instruments; D013718:Tensile Strength; D014464:Ultrasonic Therapy / Q000295:instrumentation*; D014648:Varicose Veins / Q000601:surgery*; D014656:Vascular Surgical Procedures / Q000295:instrumentation