CO2-, argon, and Nd:YAG lasers are being used. The effect of laser is primarily thermal.23 Photonic energy is converted into thermal energy at the tissue level. The CO2-laser is the most commonly used laser. It works with a non-contact-technique. The CO2-laser beam is almost completely absorbed in water. This limits its depth of penetration to a fraction of a millimetre, which leads to a minimal tissue trauma. The Nd:YAG laser is different. It has a much lower absorption in water, leading to thermic coagulation in deeper tissue-layers and enabling haemostatic coagulation of bigger vessels. Argon-lasers act with a combination of coagulation and vapourisation. Up to now, lasers have barely been used in laparoscopic surgery, but clinical trials about laparoscopic cholecystectomy are in progress.8
In order to complete the devices used in laparoscopic surgery to achieve haemostasis, CUSA® and HYDRO-JET® have to be described.25--27 These devices are primarily used to dissect parenchy-matous organs or to perform the total mesorectal excision.28,29 They help to identify vessels and bile ducts that can be closed by clips or ligature.
CUSA® is an ultrasonic-dissection system that works with mechanical energy. A continuous suction system is integrated, which keeps the tissue close to the oscillating tip of the instrument to increase the efficiency and to clean the operating area. It works with a frequency of 23 or 36 kHz depending on the handpiece. Special laparoscopic tips with a diameter of 2.54 mm are available.
HYDRO-JET® uses a fine, on its surface drilled, laminar jet of water that leads to a highly differentiated mode of application and tissue selection. The pressure is adjustable from 1 to 150 bar. The integrated suction is adjustable from 0 and 800 mm Hg. There are reports on laparoscopic liver resection and nephrectomy as well as on total mesorectal excision.6,25,28 The application of both systems has been rare in laparoscopic surgery.
Laparoscopic vascular staplers are available with a diameter of 12 mm and different lengths of magazines. They rotate 360° and can be deflect to both sides up to 45°. They are used for closing large vessels like the splenic artery and the splenic vein within the hilus, during splenectomy or for dissecting the mesocolon, including the inferior mesenteric artery and vein. Compared with other haemostatic devices, vascular staplers are rather expensive.
Harold and co-workers performed an experimental study to compare the bursting pressure of arteries sealed with ultrasonic coagulation shears, electrothermal bipolar vessel sealer, titanium laparoscopic clips, and plastic laparoscopic clips.21 The authors used arteries from pigs with three different size groups (2 to 3, 4 to 5 and 6 to 7 mm).21 They found that electrothermal bipolar vessel sealer can be used in vessels up to 7 mm in diameter. In vessels ranging from 4 to 7 mm, it has mean bursting pressures well above physiologic systolic blood pressure. The ultrasonic coagulation shears is effective for vessels in the 2 or 3 mm range. Both titanium and plastic clips achieve substantial bursting pressures for all vessel sizes.21
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