Investigation of the thermal tissue effects of the argon plasma coagulation modes “pulsed” and “precise” on the porcine esophagus, ex vivo and in vivo

BackgroundArgon plasma coagulation (APC) is a monopolar, noncontact, thermal procedure that is widely used in therapeutic endoscopy. Systematic investigations of the tissue damage ex vivo and in vivo with the new, second-generation APC modes are lacking.ObjectiveThe aim of this study is to compare the tissue effects of the pulsed effect 2 and precise APC modes.Design and SettingEx vivo and in vivo animal model.SubjectsThis study involved 3 explanted porcine esophagi and 8 pigs under general anesthesia.InterventionAPC application on 3 explanted esophagi and during esophagoscopy.Main Outcome MeasurementsThe tissue effect was subjected to histological and statistical investigation.ResultsIn vivo, a well known type of superficial tissue damage (type A) of the tunica mucosa and a new injury pattern (type B) limited to the tunica muscularis, were found. Ex vivo, only type A injuries were seen. Thermal injury of the tunica muscularis was significantly lower with precise APC compared with pulsed APC in vivo. The pulsed effect 2 shows a positive correlation between the penetration depth and the power (r = 0.38, P < .0002) or application time for the highest power setting used (40 W, r = 0.77, P < .0001). This correlation could not be detected with precise APC because of its very superficial tissue effect.LimitationsThis was an animal study. The distance of the APC probe to the esophagus may have varied between applications in vivo.ConclusionThermal damage by APC of the esophageal tunica muscularis seems to be underestimated ex vivo. The extent of tissue injury was significantly lower with precise APC than with pulsed APC, indicating that precise APC may be suitable for the treatment of particularly thermosensitive, thin-wall anatomy.