Experimental studies of thermal therapy for severe nonvariceal bleeding indogs

Background: There are several methods of achieving endoscopic hemostasis fo r nonvariceal hemorrhage, including use of a hearer probe, bipolar electroc oagulation, use of a Gold probe, and injection therapy with epinephrine or ethyl alcohol. However, due to clinical variations, clinical studies compar ing thermal with injection therapy have yielded conflicting results. Theref ore, we used a canine model of acute bleeding from gastric serosal vessels to examine the efficacy of the heater probe and the Gold probe in achieving hemostasis and to compare the injurious effects of these methods with inje ction therapy. Methods: Seven mongrel dogs were used in the study. Four were assigned to a cute experiments in which transected blood vessels were allowed to bleed pr ofusely. Two dogs of this group were treated with either a large or small G old probe, while the other two were treated with either a large or small he arer probe. In the other three dogs, we tested the chronic effects of the h eater probe, the Gold probe, and injection therapy with dilute epinephrine. Results: Complete hemostasis was achieved for all four dogs in the acute ex periments. Dogs treated with either a large or small heater probe had coagu lation necrosis that extended to the serosa and muscularis but not to the m ucosa. The large Gold probe had similar results, but the small Gold probe c aused tissue damage to the serosa, muscularis, submucosa, and mucose at sev eral of the application sites. Both probes caused scarring of the gastric w all. In the chronic experiments, we found that the Gold probe caused larger mucosal ulcers than the heater probe. All ulcers healed in 3 weeks. The ep inephrine injection caused localized swelling and discoloration, but after 1 week the tissue returned to normal. Conclusions: Both the heater probe and the Gold probe are effective in achi eving hemostasis in a canine model of nonvariceal hemorrhage, and both meth ods are superior to injection therapy. For active bleeding ulcers, we curre ntly recommend a combination therapy, using first injection therapy and the n a heater or Gold probe. However, clinicians should be aware of the potent ial for tissue damage.