Experimental comparison of mesenteric vessel sealing and thermal damage between one bipolar and two ultrasonic shears devices

Background: Several instruments are available for open and laparoscopic dissection, including electrothermal bipolar vessel sealers and ultrasonically coagulating shears. The vessel sealing ability of three devices in colorectal specimens was compared in an experimental study. Methods: Surgical specimens from patients scheduled for elective open or laparoscopic colorectal resection were allocated to one of the three devices. After removal of the surgical specimen, up to eight mesenteric vessels were dissected ex vivo and sealed using the allocated instrument. The vessel seal was tested for the maximum pressure at which it leaked and then assessed by a pathologist for depth of thermal tissue damage. Results: A total of 93 vessels from 18 patients were assessed ex vivo (LOTUS (TM) n = 33; Harmonic Ace (R) n = 30; LigaSure (TM) n = 30), a median of 6 (range 1-8) vessels per surgical specimen with a mean(s.d.) diameter of 1.06(0.70) mm and wall thickness of 0.29(0.19) mm. Mean(s.d.) bursting pressures were 1170(440), 1470(670) and 1510(740) mmHg with LOTUS (TM), Harmonic Ace (R) and LigaSure (TM) respectively. ANCOVA showed no difference in bursting pressure between the instruments (P = 0.058). The depth of thermal damage was significantly greater with LigaSure (TM) (3.37(1.44) mm) than with LOTUS (TM) (2.18(0.99) mm; P < 0.001) or Harmonic Ace (R) (1.95(0.92) mm; P < 0.001). Conclusion: All three instruments were equally good at sealing blood vessels, with bursting pressures well above physiological blood pressure levels. Registration number: NCT01121614 (http://www.clinicaltrials.gov).