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Journal of Biomedical Optics

Optical, thermal, and electrical monitoring of radio-frequency tissue modification
Author(s): Timmy Floume; Richard R. A. Syms; Ara W. Darzi; George B. Hanna
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Paper Abstract

Radio-frequency (rf) tissue fusion involves the sealing of tissue between two electrodes delivering rf currents. Applications include small bowel fusion following anastomosis. The mechanism of adhesion is poorly understood, but one hypothesis is that rf modification is correlated to thermal damage and dehydration. A multimodal monitoring system capable of acquiring tissue temperature, electrical impedance, and optical transmittance at 1325-nm wavelength during rf delivery by a modified LigasureTM fusion tool is presented. Measurements carried out on single layers of ex vivo porcine small bowel tissue heated at ≈500-kHz frequency are correlated with observation of water evaporation and histological studies on full seals. It is shown that the induced current generates a rapid quasilinear rise of temperature until the boiling point of water, that changes in tissue transmittance occur before impedance control is possible, and that a decrease in transmission occurs at typical denaturation temperatures. Experimental results are compared with a biophysical model for tissue temperature and a rate equation model for thermal damage.

Paper Details

Date Published: 1 January 2010
PDF: 10 pages
J. Biomed. Opt. 15(1) 018003 doi: 10.1117/1.3323089
Published in: Journal of Biomedical Optics Volume 15, Issue 1
Show Author Affiliations
Timmy Floume, Imperial College London (United Kingdom)
Richard R. A. Syms, Imperial College London (United Kingdom)
Ara W. Darzi, Imperial College London (United Kingdom)
George B. Hanna, Imperial College London (United Kingdom)

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