Tissue pad degradation of ultrasonic device may enhance thermal injury and impair its sealing performance in liver surgery

BACKGROUND: Ultrasonic devices are widely used in many surgical fields, including hepatectomy; however, the negative effects of tissue pad degradation of ultrasonic devices, including those in liver surgery, remain unknown. The Harmonic(®) 1100 (H-1100) scalpel has advanced heat control technology than previous models, such as the Harmonic(®) HD1000i (H-HD1000i). We hypothesized that, because of its advanced temperature-control technology, the H-1100 scalpel would show less tissue pad degradation, resulting in superior sealing performance, compared to that with the H-HD1000i scalpel. AIM: To elucidate ultrasonic device tissue pad degradation effects on instrument temperature and sealing performance using ex vivo porcine liver/vessel models. METHODS: Two different harmonic scalpels were used and compared: A newer model, the H-1100 scalpel, and an older model, the H-HD1000i scalpel. Using ex vivo porcine livers, each instrument was activated until the liver parenchyma was dissected. The device temperature (passive jaw temperature) was measured after every 10 consecutive activations, until 300 transections of the porcine liver were performed. Tissue pad degradation was evaluated after 300 activations. Sealing performance was evaluated using excised porcine carotid vessels; vessel sealing speed and frequency of vessel burst pressure below 700 mmHg were determined after 300 transections of porcine liver parenchyma. RESULTS: The temperature of the H-HD1000i scalpel was approximately 10°C higher than that of the H-1100 scalpel, and gradually increased as the number of activations increased. The median passive jaw temperature of the H-HD1000i scalpel was significantly higher than that of the H-1100 scalpel (73.4°C vs 65.1°C; P < 0.001). After 300 transections of porcine liver parenchyma, less tissue pad degradation was observed with the H-1100 scalpel than with the H-HD1000i scalpel (0.08 mm vs 0.51 mm). The H-1100 scalpel demonstrated faster vessel-sealing speed (4.9 sec. vs 5.1 sec.) and less frequent vessel burst pressure < 700 mmHg (0% vs 40%) after 300 activations than the H-HD1000i scalpel; however, the difference did not reach statistical significance (P = 0.21 and P = 0.09, respectively). CONCLUSION: In an ex vivo porcine hepatectomy model, the H-1100 scalpel shows lower passive jaw temperature and maintains its sealing performance by avoiding tissue pad degradation compared to that with the H-HD1000i.