How can we safely use ultrasonic laparoscopic coagulating shears?

Purpose: To investigate changes in temperature of the tissue pad (contrary to active blade) of ultrasonic laparoscopic coagulation shears (LCS) and histological changes of tissue surrounding the pad during activation. Methods: Three types of ultrasonic LCS were assessed: SonoSurg (SSg) (Olympus, Tokyo, Japan), AutoSonix (AS) (Tyco, Pembroke, Bermuda) and Harmonic Scalpel (HS) (Johnson & Johnson, Cincinnati, OH, USA). Vibration amplitudes were 70%/100% (SSg), Level 3/Level 5 (AS) and Level 5 (HS). Durations of vibration were 5 s, 10 s, 15 s and 20 s. Changes in temperature of the tissue pad were evaluated by cutting chicken parts extracorporeally with the three types of LCS. Histological changes around the tissue pad of the SSg were evaluated in a laparoscopic porcine model. Results: At intermediate power (70% or Level 3), the SSg tissue pad temperatures were 33 degrees C, 42 degrees C, 55 degrees C and 70 degrees C, whereas the AS tissue pad temperatures were 45 degrees C, 72 degrees C, 80 degrees C and 100 degrees C. At maximum power, the temperatures of the SSg tissue pad were 38 degrees C, 45 degrees C, 70 degrees C and 95 degrees C, those of the AS were 50 degrees C, 65 degrees C, 70 degrees C and 90 degrees C and those of the HS were 49 degrees C, 65 degrees C, 75 degrees C and 90 degrees C. Histological changes occurred at 10 s, 15 s and 20 s. Conclusion: Surgeons should be aware that the temperature of the tissue pad also becomes elevated when using ultrasonic LCS. Thus, they should be concerned with surrounding tissues and organs around both the tissue pad and the active blade during activation. Regardless of the LCS type and power, a short activation time within 5 s is a safe method for using the instrument.