Heat production during pulmonary artery sealing with energy vessel-sealing devices in a swine model

OBJECTIVES Energy vessel-sealing devices are being increasingly utilized to seal pulmonary artery (PA) branches during lobectomy. Heat from these devices can potentially injure surrounding tissues. We evaluated heat production from devices in a live animal model. METHODS PA branches were sealed in pigs with 4 energy vessel-sealing devices: 2 ultrasonic (US), 1 advanced bipolar or 1 mixed US and bipolar (mixed) device. Thermocouples were implanted in tissue surrounding the PA branch being sealed to measure tissue temperature. A thermal camera measured the sealing site and the temperatures of the instruments. Pathological analysis was performed on PA stumps to identify thermal damage. RESULTS A total of 37 PA branches were sealed in 4 pigs. Maximum tissue heat measured by the thermocouples for the 2 US, advanced bipolar and mixed devices was 42, 39, 42 and 46°C, respectively. The mean tissue temperatures at the site of the sealing measured with the thermal camera were 78, 75, 70 and 82°C (P = 0.834) and the mean instrument blade temperatures were 224, 195, 83 and 170°C (P = 0.5) for the 2 US, advanced bipolar and mixed devices, respectively. The mean diameter of the region with tissue reaching 60°C or more measured with the thermal camera was between 4 and 6 mm for the 4 devices (P = 0.941). On pathological analysis, PA stumps had either thermal damage on the adventitia and external media (26/37) or transmural damage (11/37) at 1 mm from sealed site. CONCLUSIONS A 3-mm safety margin between the instrument blades and vital structures is recommended. Instrument blades can reach high temperatures that may cause tissue damage.