Radiofrequency energy-induced heating of bovine capsular tissue: Temperature changes produced by bipolar versus monopolar electrodes.
OBJECTIVE
To determine temperature changes associated with radiofrequency (RF) energy-induced heating of bovine capsular tissue using a bipolar RF electrode versus a temperature-controlled, monopolar RF electrode.


METHODS
In vitro laboratory investigation using bovine capsular tissue.


METHODS
Samples of bovine tissue were placed in a saline bath (37 degrees C) and RF energy was applied using bipolar and monopolar RF electrodes at manufacturer-recommended settings for tissue shrinkage. Fluoroptic thermometry was used to record temperatures on the tissue surface and at depths of 1 mm and 2 mm during continuous delivery of RF energy at 1, 2, 3, 4, 5, and 10 second time increments.


RESULTS
The highest mean temperatures were recorded on the tissue surface, as follows (mean +/- SD; *P <.05, value compared with baseline): 1 sec 2 sec 3 sec 4 sec 5 sec 10 sec Bipolar 40.1 +/- 1.0* 48.2 +/- 4.7* 62.8 +/- 6.9* 76.0 +/- 7.6* 84.7 +/- 5.7* 94.7 +/- 1.9* Monopolar 39.0 +/- 0.7* 48.2 +/- 4.3* 67.7 +/- 7.0* 86.6 +/- 6.1* 93.8 +/- 2.7* 59.5 +/- 2.6* For the bipolar RF electrode, there was a strong linear relationship (R =.926) between mean surface temperatures versus time. The temperature-controlled, monopolar RF electrode did not appear to properly regulate the delivery of RF energy to maintain tissue temperatures at the selected level (i.e., 65 degrees C). The bipolar RF electrode produced a smaller temperature gradient (average difference, 9.2 degrees C) at the 1-mm tissue depth compared with the monopolar RF electrode (average difference, 14.6 degrees C). Temperature profiles at the 2-mm tissue depth were comparable for both types of RF electrodes.


CONCLUSIONS
These data provide basic information pertaining to the temperature profiles produced by bipolar and monopolar RF electrodes applied to collagen-based tissue.
Shellock
F G
FG
Department of Radiology, School of Medicine, The University of Southern California, Los Angeles, California, U.S.A. Frank.Shellock@gte.net
D000818:Animals; D002417:Cattle; D017097:Electric Impedance; D004566:Electrodes / Q000145:classification*; D004598:Electrosurgery / Q000295:instrumentation*; D004867:Equipment Design; D006358:Hot Temperature / Q000627:therapeutic use; D066298:In Vitro Techniques; D017746:Joint Capsule / Q000473:pathology / Q000528:radiation effects*; D011846:Radio Waves; D013499:Surface Properties