title: In vitro study of safety and co-efficiency of the transbronchial coagulation techniques.
abstract: BACKGROUND
  The usual transbronchial coagulation techniques include microwave, argon plasma coagulation (APC), electrocautery and cryotherapy. However, there are serious clinical problems in the safety of each. By analyzing the experimental data and clinical observations, we observed the variable effects of different coagulation techniques via bronchofibroscopy, to look for an optimal interventional management of luminal bronchus diseases, and evaluate the safety and the equivalent point.
  
  
  METHODS
  Four kinds of coagulation techniques under bronchoscopy were performed on the fresh bronchus of healthy sheep, and the pathologic changes in all groups were observed under the microscope. The different treatment parameters were as follows: microwave 60 W×1 second, 3 seconds, 5 seconds and 40 W×1 second, 3 seconds, 5 seconds; APC 40 W×1 second, 3 seconds, 5 seconds; electrocautery 40 W×1 second, 3 seconds, 5 seconds; cryotherapy 100 Ω×60 seconds, 120 seconds.
  
  
  RESULTS
  After treatment, ovine bronchial mucosa in all groups showed pathologic changes such as local necrosis and amotio of the mucosa lining epithelium, local submucosa coagulative necrosis or tissue defects, while inflammation in the surrounding tissue was not obvious. Under the same output power and action time, different methods had different outcomes. The damage by APC was the most superficial, microwave was the second, and electrocautery caused the worst damage. The study also found that effects of electrocautery at 40 W×3 seconds, microwave at 40 W×5 seconds or 60 W×3 seconds, APC at 40 W×5 seconds and cryotherapy at 100 Ω×120 seconds were the equivalent point conditions. The appearance included mucosa absence, partial submucosa absence, and collagen fiber coagulation in treatment areas.
  
  
  CONCLUSIONS
  Each coagulation technique has its own characteristic. It is very important to choose the appropriate power and action time of the suitable method according to the therapy requirement.
authors.affiliation: Department of Respiratory Medicine, Changhai Hospital, Second Military Medical University, Shanghai 200433, China. bc7878@sohu.com
authors.forename: Chong
authors.initials: C
authors.lastname: Bai
authors.forename: Yu-chao
authors.initials: YC
authors.lastname: Dong
authors.forename: Xiao-lian
authors.initials: XL
authors.lastname: Song
authors.forename: Yi
authors.initials: Y
authors.lastname: Huang
authors.forename: Hui
authors.initials: H
authors.lastname: Shi
authors.forename: Zhen-li
authors.initials: ZL
authors.lastname: Hu
authors.forename: Qiang
authors.initials: Q
authors.lastname: Li
mesh_terms: D000818:Animals; D057908:Argon Plasma Coagulation / Q000009:adverse effects*; D001982:Bronchial Diseases / Q000473:pathology / Q000628:therapy*; D001999:Bronchoscopy; D017679:Cryotherapy / Q000009:adverse effects*; D004564:Electrocoagulation / Q000009:adverse effects*; D008872:Microwaves / Q000009:adverse effects*; D012756:Sheep