Schnittwirkung des Holmium-Lasers in der magen- und darmschleimhaut des schweines - Eine in vitro studie

Endoscopic treatment of colorectal polyps is usually performed by electrocautery snare. For large sessile polyps mostly «piecemeal» resection is required, which frequently leads to complications (bleeding, transmural burning, perforation). Due to it's transmissability by flexible glass fibers and good cutting and haemostatic qualities, the Holmium-laser 〈λ = 2.12 μm〉 was tested in several endoscopic methods of working for some years. In this study we have examined the cutting qualities of a Holmium-Laser in regard to it's use as an alternative to snare resection. In fresh porcine stomach- and colon tissue we examined single and multiple cuttings, applicated directly to the tissue by a flexible glass fiber (Ø = 318 μm). The following parameters were varried: power (1-7 W), cutting speed (0,3-0,6 mm/s), cutting angle (10°-80°). The zones of defect and necrosis were measured histomorphometrically. In the colon, the mucosa usually was cut through by a single cut with 3-4 W average power (repetition rate: 10 Hz, speed: 0.3 mm/s, angle: 40°). Using this adjustment perforation of the colon was seen if cuttings were repeated 4 to 5 times. However, even after 6 cuttings with 3 W aveage power, there was no visible perforation in stomach. The most favourable cutting angles were between 30° and 40°. In all experiments the cuts were surrounded by a damage zone range from 200 to 700 μm. In our investigations, the Holmium-Laser proved to be a suitable instrument for cutting tissue in a precise and controlled way. Continuing studies have to prove if cutting parameters we optimized in vitro are transferable to endoscopic methods of working and if risky adjustments (steep angle, low cutting speed) are avoidable.