title: A randomized comparative trial of OTSC and Padlock for upper GI hemostasis in a standardized experimental setting.
abstract: BACKGROUND
  Upper gastrointestinal bleeding (UGIB) is the key emergency situation in clinical endoscopy and is traditionally treated with injection, thermal or through the scope clipping therapy. Mortality rates are in the range of 8-10% and demand new treatment approaches. The Over-The-Scope Clip (OTSC®) has been described as a very effective hemostatic device in UGIB. We compared OTSC with the Padlock™ device in an established pre-clinical setting.
  
  
  METHODS
  Our test-bed consisted of the biohybrid EASIE model using soft silicone tubes, tunneled into the gastric wall and surfacing at a mucosa defect, representing the bleeding site. After successful deployment of the OTSC and Padlock devices on the spurting ulcer bleed (Forrest Ia) the vessel tubes were pressurized with a manometer to 120 mmHg. Tight closure at this pressure was defined as successful hemostasis (primary endpoint). N = 11 procedures were done with each device. Statistical testing was done using Fisher's exact test. Sample size was adjusted to an assumed α-error of 5% (two-sided test) and a power of 80%.
  
  
  RESULTS
  Technically correct placement of the respective hemostatic device was achieved in all procedures. A statistically significant difference was found in the primary endpoint. In OTSC the success proportion was 100%; 11/11 (95% KI 74.1% to 100%); in Padlock it was 0%; 0/11 (95% KI 0%-25.8%). This means that no bleeding was stopped by Padlock. The mean value of perfusion pressure resistance was 300 mmHg (cut-off) for OTSC and 9.2 ± 8.4 mmHg for Padlock.
  
  
  CONCLUSIONS
  Our data on hemostatic function of OTSC coincide with the clinical literature and earlier pre-clinical studies in the EASIE model, which is widely accepted as a realistic and effective simulation system for clinical conditions. The inability of Padlock to stop hemorrhage may be due to design differences and, thus, its limitation in providing tight sealing of the clipped tissue.
  
  
  CONCLUSIONS
  Different types of endoscope-tip mounted clips have different performances. OTSC consistently stops simulated spurting bleeding, Padlock fails to do so. These differences are statistically significant.
authors.affiliation: a St. Anna-Klinik, Proctological Institute , Stuttgart , Germany.
authors.forename: Ruediger L
authors.initials: RL
authors.lastname: Prosst
authors.affiliation: b Department of Internal Medicine , Spital am Limmat, Gastroenterology , Schlieren , Switzerland.
authors.forename: Thomas
authors.initials: T
authors.lastname: Kratt
mesh_terms: D016099:Endoscopy, Gastrointestinal / Q000295:instrumentation / Q000379:methods*; D004867:Equipment Design; D006471:Gastrointestinal Hemorrhage / Q000401:mortality / Q000628:therapy*; D016558:Hemostasis, Endoscopic / Q000295:instrumentation / Q000379:methods*; D006801:Humans
keywords: GI; OTSC; Padlock; bleeding; endoscopy