title: Experimental evaluation of the optimal in-vitro conditions for bipolar electrocoagulation in the bile duct.
abstract: OBJECTIVE
  Although there have been many reports concerning the therapeutic use and potential of laser and monopolar electrocoagulation therapy, little has been published on the effects of bipolar electrocoagulation on biliary tissue. Although it has been reported that endoscopic recanalization of malignant stent obstruction using bipolar electrocoagulation is an advantageous form of treatment, the optimal parameters for this type of treatment have not yet been determined. The purpose of this prospective study was therefore to evaluate, under in-vitro conditions, the maximum applicable energy required; the influence of probe angle and duration time on the extent of the coagulation achieved; and whether multiple intermittent short pulses show any significant differences in the extent of coagulation achieved, in comparison with the use of a single continuous pulse.
  
  
  METHODS
  In this in-vitro study, experiments were carried out in 84 common bile ducts from freshly slaughtered swine. The extension of tissue injury after electrocoagulation treatment was measured at 60 combinations of varying levels of power output, probe angles, duration times, and pulse patterns. All of the results were correlated with the diameter of the untreated and normal bile duct walls under in-vitro conditions.
  
  
  RESULTS
  When energy was applied at levels up to a maximum of 16 J, the extension of tissue coagulation was about 58% of the untreated bile duct wall diameter. Energy settings exceeding 16 J involved the whole wall diameter in most cases, often including the periductal fatty tissue. Additional energy applications higher than 16 J, 32 J, and 100 J, showed undesirable tissue changes, such as an increasing diameter in the treated bile duct walls of up to 56.8% of the wall diameter of control specimens.
  
  
  CONCLUSIONS
  The study evaluated the standard settings in an in-vitro model. The results indicate that protective and effective use of bipolar electrocoagulation on normal porcine bile duct tissue requires: the use of a low power setting (less than 16 J); the use of continuous short pulse patterns; placement of the probe tip at an obtuse angle (0 degree); and the use of short application times.
authors.affiliation: Dept. of Otorhinolaryngology, Head and Neck Surgery, University of Dresden, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Offergeld
authors.forename: C
authors.initials: C
authors.lastname: Tschöpe
authors.forename: H J
authors.initials: HJ
authors.lastname: Brambs
mesh_terms: D000818:Animals; D001652:Bile Ducts / Q000601:surgery*; D004564:Electrocoagulation / Q000379:methods; D011446:Prospective Studies; D013552:Swine