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 sphincterotomy of bile ducts in the livers of pigs, ampullae of humans post mortem, and during clinical sphincterotomy. The effect of waveform on hemostasis was studied in experiments on canine mesenteric arteries.
Results: Electrosurgical waveforms (CUT, COAG, BLEND) were measured. Halving wire contact length halved energy needed to initiate cutting. The CUT waveform rarely initiated cutting at lower power settings than the BLEND waveform. With CUT, BLEND, and COAG waveforms, approximately the same energy initiated cutting. Efficiency of cutting increased linearly with power. The COAG waveform required higher power settings than BLEND or CUT to initiate cutting (p < 0.05). Force and wire diameter influenced cutting. BLEND was more effectively hemostatic than CUT (p < 0.05). COAG was significantly more hemostatic than BLEND and CUT. Cutting efficiency during clinical sphincterotomy was poor.
Conclusions: This work has practical implications. Shortening wire contact length was effective in starting a cut at suboptimal settings, whereas changing 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.