Histologic characteristics of laparoscopic argon beam coagulation

Study Objectives. To describe histologic effects of laparoscopic argon beam coagulation and determine the extent of tissue necrosis at various power settings and exposure times. Design. Prospective experimental analysis (Canadian Task Force classification II-1). Setting. University animal laboratory. Subjects. Adult female domestic pigs. Interventions. Various power settings (40, 60, 80 W) at increasing exposure times (1, 3, 5 sec) were used during laparoscopic application of argon beam coagulation to different tissues (uterine horn, bladder, ureter, kidney, bowel, liver). Animals were sacrificed within 1 hour of coagulation for histologic tissue preparation. Measurements and Main Results. Histologic measurements of both depth and lateral extent of electrosurgical tissue effects (mm +/- SD) were ascertained and evaluated statistically by one-way repeated measures analysis of variance. Depth of tissue necrosis was confined to I mm or less in uterine horn, bladder, and ureter. Even at highest power settings, bowel had tissue necrosis no greater than 2 mm. Both liver and kidney shelved a deeper histologic effect (4-5 mm). The lateral extent of tissue necrosis ranged from 2 mm (ureter) to 15 mm (liver). Conclusion. Laparoscopic argon beam coagulation results in tissue effects that are dependent on both low power setting and duration of application, as well as on electrical and physical characteristics of target tissue. Thermal tissue penetration can be expected to be less than 2 mm in bowel, bladder, and ureter, and less than 5 mm in kidney and liver, even at 5 seconds of exposure time and at a power setting as high as 80 W. As with all thermal modalities used for hemostasis and tissue coagulation, laparoscopic argon beam coagulation can be performed safely as long as the potential for inadvertent thermal injury is understood.