Quantifying electrosurgery-induced thermal effects and damage to human tissue: an exploratory study with the fallopian tube as a novel in-vivo in-situ model.

OBJECTIVE: To develop a human in vivo in situ model for analyzing the extent and the basic mechanisms of thermal spread and thermal tissue damage. DESIGN: Prospective, open, uncontrolled, nonrandomized, single-center exploratory study. SETTING: University hospital. PATIENTS: Eighteen adult patients undergoing open abdominal hysterectomy for benign disease. INTERVENTIONS: Unilateral fallopian tube tissue desiccation (10 seconds) with a laparoscopic bipolar clamp at routine settings. MAIN OUTCOME MEASURES: Deep tissue temperature (thermal probe), tissue surface temperature (thermal camera), and gross and histologic assessments of lesions with a newly developed composite scoring system. RESULTS: Fifteen specimens from 18 patients were evaluated. Lateral thermal damage (LTD; determined by lactate dehydrogenase staining), was strongly correlated with maximum desiccation temperature. Deep tissue LTD and surface LTD were linearly related. Histologic and macroscopic criteria for thermal effects and damage and the corresponding scores proved functional and strongly correlated with LTD. Measurement of deep tissue and tissue surface temperatures consistently yielded complete temporal and spatial temperature distributions that were describable by the heat equation. CONCLUSIONS: Our novel in vivo in situ model allows standardized, reproducible, quantitative assessment of electrosurgery-induced thermal effects and damage in human tissue. It will likely provide further insight into the underlying biothermomechanics and may prove useful in the development of safety guidelines for laparoscopic electrosurgery.