title: Assessing the adequacy of endoscopically tied knots: a functional approach.
abstract: OBJECTIVE
  Endoscopic intracorporeal knots have potentially enormous applications in endoscopic surgery. We describe a method for testing the security of various types of endoscopically tied knots using a vessel perfusion manometer system.
  
  
  METHODS
  A 4-cm segment of porcine splenic artery was placed on the mucosal surface of a pig stomach. The two ends of the vessel were brought out through the gastric wall and connected to a two-way manometer. One end was also joined to a pressure infusion bag. The stomach was mounted in an Erlangen training model. A long 3/0 nylon thread, previously introduced into the submucosal layer of the stomach and encircling the vessel, was brought out from the mouth. Three-throw square knots, Mayo knots, "surgeon's" knots and five-throw square knots were tied and pushed into place using a cap attached to a gastroscope. The pressure at the two ends of the artery was compared. If the pressure could be increased to over 200 mm Hg at one end without a change in the other, the knot was considered secure.
  
  
  RESULTS
  Each type of knot was tested 12 times under endoscopic vision. The range for mean knotting time was 3.4 - 4.5 minutes. Five-throw knots took significantly longer to tie than three-throw knots (P < 0.005). There was one loose knot in each of the three-throw and Mayo groups, and three each in the "surgeon's" and five-throw groups (P > 0.05).
  
  
  CONCLUSIONS
  This system is a reliable model for testing intracorporeal knots tied endoscopically. A three-half-hitches square knot with 3/0 nylon, tied using a flexible endoscope and knot-tightening cap, can withstand pressure up to 200 mm Hg.
authors.affiliation: Endoscopy Center, Prince of Wales Hospital, The Chinese University of Hong Kong, China.
authors.forename: B
authors.initials: B
authors.lastname: Hu
authors.forename: L C
authors.initials: LC
authors.lastname: Sun
authors.forename: M
authors.initials: M
authors.lastname: Karmakar
authors.forename: P B
authors.initials: PB
authors.lastname: Cotton
authors.forename: C J
authors.initials: CJ
authors.lastname: Gostout
authors.forename: R H
authors.initials: RH
authors.lastname: Hawes
authors.forename: A N
authors.initials: AN
authors.lastname: Kalloo
authors.forename: S V
authors.initials: SV
authors.lastname: Kantsevoy
authors.forename: P J
authors.initials: PJ
authors.lastname: Pasricha
authors.forename: S C
authors.initials: SC
authors.lastname: Chung
mesh_terms: D000818:Animals; D004724:Endoscopy; D006801:Humans; D066298:In Vitro Techniques; D008348:Manikins; D008365:Manometry; D010477:Perfusion; D015203:Reproducibility of Results; D033081:Shear Strength; D013157:Splenic Artery / Q000601:surgery*; D013270:Stomach / Q000601:surgery*; D013536:Suture Techniques; D013552:Swine; D013718:Tensile Strength