Electrophysical factors influencing endoscopic sphincterotomy

Background: Analog computer techniques were used to measure electrosurgical power during sphincterotomy in experimental models and patients. Methods: Total energy and transient changes in power were measured during s phincterotomy of bile ducts in the livers of pigs, ampullae of humans post mortem, and during clinical sphincterotomy. The effect of waveform on hemos tasis was studied in experiments on canine mesenteric arteries. Results: Electrosurgical waveforms (CUT, COAG, BLEND) were measured. Halvin g wire contact length halved energy needed to initiate cutting. The CUT wav eform rarely initiated cutting at lower power settings than the BLEND wavef orm. With CUT, BLEND, and COAG waveforms, approximately the same energy ini tiated cutting. Efficiency of cutting increased linearly with power. The CO AG waveform required higher power settings than BLEND or CUT to initiate cu tting (p < 0.05). Force and wire diameter influenced cutting. BLEND was mor e effectively hemostatic than CUT (p < 0.05). COAG was significantly more h emostatic than BLEND and CUT. Cutting efficiency during clinical sphinctero tomy was poor. Conclusions: This work has practical implications. Shortening wire contact length was effective in starting a cut at suboptimal settings, whereas chan ging from BLEND to CUT made little difference. Increasing power setting may help if cutting does not start. BLEND stops bleeding better than CUT. COAG stops bleeding better than BLEND but cuts poorly. Cutting during clinical sphincterotomy is inefficient and can be improved.