title: Gas flow during bronchoscopic ablation therapy causes gas emboli to the heart: a comparative animal study.
abstract: BACKGROUND
  Thermal ablation is one of the most commonly used modalities to treat central airway obstruction. Both laser and argon plasma coagulation (APC) have been reported to cause gas emboli and cardiac arrest. We sought to determine whether bronchoscopic ablation therapy can result in systemic gas emboli, correlate their presence with the rate of gas flow, and establish whether a zero-flow (ZF) modality would result in the significant reduction or elimination of emboli.
  
  
  METHODS
  CO(2) laser delivered through a photonic bandgap fiber (PBF) and APC were applied in the trachea and mainstem bronchi of six anesthetized sheep at varying dosages and gas flow rates. Direct epicardial echocardiography was used to obtain a four-chamber view and detect gas emboli.
  
  
  RESULTS
  The presence of gas flow accompanying APC and the CO(2) laser with forward flow correlated significantly with the appearance of gas bubbles in the atria. A definite dose response was observed between the gas flow rate and the number of bubbles seen. When the CO(2) laser was delivered through a PBF with ZF to the trachea or bronchi, no bubbles were observed.
  
  
  CONCLUSIONS
  Bronchoscopic thermal ablation therapy using gas flow is associated with gas emboli in a dose-dependent fashion. The use of the flexible PBF with ZF is not associated with the development of gas emboli. Further study is required to determine whether a clinically safe threshold of gas emboli exists, and the relationships among the pathologic depth of tissue destruction, gas flow, pulse duration, and the development of gas emboli.
authors.affiliation: Department of Interventional Pulmonology, Johns Hopkins Hospital, Baltimore, MD 21205, USA. dfellerk@jhmi.edu
authors.forename: David
authors.initials: D
authors.lastname: Feller-Kopman
authors.forename: Jeanne M
authors.initials: JM
authors.lastname: Lukanich
authors.forename: Gil
authors.initials: G
authors.lastname: Shapira
authors.forename: Uri
authors.initials: U
authors.lastname: Kolodny
authors.forename: Baruch
authors.initials: B
authors.lastname: Schori
authors.forename: Heather
authors.initials: H
authors.lastname: Edenfield
authors.forename: Burak
authors.initials: B
authors.lastname: Temelkuran
authors.forename: Armin
authors.initials: A
authors.lastname: Ernst
authors.forename: Yair
authors.initials: Y
authors.lastname: Schindel
authors.forename: Yoel
authors.initials: Y
authors.lastname: Fink
authors.forename: Jon
authors.initials: J
authors.lastname: Fox
authors.forename: Raphael
authors.initials: R
authors.lastname: Bueno
mesh_terms: D000402:Airway Obstruction / Q000601:surgery; D000818:Animals; D001980:Bronchi / Q000000981:diagnostic imaging; D001999:Bronchoscopy / Q000379:methods*; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D004562:Electrocardiography; D004618:Embolism, Air / Q000150:complications* / Q000209:etiology*; D006323:Heart Arrest / Q000209:etiology*; D053685:Laser Therapy / Q000009:adverse effects*; D054020:Lasers, Gas / Q000009:adverse effects* / Q000627:therapeutic use; D012756:Sheep; D014132:Trachea / Q000000981:diagnostic imaging; D014463:Ultrasonography