Ultrasonic, bipolar, and integrated energy devices: comparing heat spread in collateral tissues

Integrated devices incorporating ultrasonic and bipolar technology have been used in laparoscopic surgery, however, are not yet incorporated into open operations. Here, we compare thermal spread and recurrent laryngeal nerve (RLN) functional data of the integrated THUNDERBEAT Open Fine Jaw device, the bipolar Ligasure Small Jaw, and the ultrasonic Harmonic Focus for open thyroidectomy.

The three energy devices were compared in a live porcine model using three tissue types including liver, muscle, and thyroid. The devices were fired three times on each energy setting, and the thermal spread was measured by thermocouples that were inserted in surrounding tissues at 1-mm intervals. To determine RLN injury, devices were fired at successive 1-mm increments from the RLN until the monitor signal was lost.

When comparing heat generated across these devices at 1 mm, the peak temperature (Celsius) reached in liver tissue was observed with the ultrasonic device (115.4 ± 86.7), in muscle tissue with the integrated device (104.2 ± 82.1), and in thyroid with the bipolar device (81.4 ± 41.3). Temperatures generated at individual settings on each device were similar (P = 0.11-0.81). RLN injury occurred after firing on manually approximated tissue 1-mm away from the RLN for all devices; however, there was no signal loss at ≥2 mm.

Heat transfer was similar among all devices with the exception of the ultrasonic device when used in the liver, which showed higher temperatures. Liver tissue showed the most consistent results. RLN injury did not occur if the devices were fired on manually approximated tissue ≥2 mm from the nerve.