Có một số loại trocar: sắc nhọn hình kim tự tháp, sắc nét, hình nón, lập dị và thẳng thừng hình nón (Hình ). Trocar sắc nhọn hình kim tự tháp cổ điển là hoàn toàn chấn thương, đặc biệt là khi được đưa vào điều chỉnh các cách. Kết quả là, rò rỉ khí và dislodgment xảy ra một cách dễ dàng. | Instrumentation 17 2 Figure . Disposable 5 mm cannula and trocar. The cannula is transparent. The trocar has a conical end with a narrow retractable blade at the tip. There are several trocar types sharp pyramidal sharp conical eccentric and blunt conical Fig. . The classic sharp pyramidal trocar is quite traumatic especially when inserted in screwing way. As a result leakage of gas and dislodgment occur easily. The sharp conical trocar is less traumatic as it dilates the tissues. Leakage of gas and dislodgment of the cannula is less likely to occur but the insertion requires substantially more force to pierce the body wall. Eccentric trocars make a slit-like hole and require less force to be inserted. Blunt conical trocars are ideal when a cannula is inserted using an open technique. Due to its conical form the opening in the body wall can be somewhat smaller then the diameter of the cannula which allows for fixation through dilatation. Even when inserted in an open way it is advisable to insert the cannula together with a trocar which in this circumstance should be blunt. This will not only prevent damage of tissues caused by the edge of the cannula but allows a smaller hole for insertion. The trocar not only has a smaller diameter than the inside diameter of the cannula but also has a conical tip. Cannulae without Trocar A new nondisposable cannula with a screw winding on its outer surface and blunt starting point has been developed for insertion without a trocar Fig. . A small fascial incision is made after which the cannula is screwed in clockwise direction. This process can be supervised by using a telescope inside the cannula at the same time. By doing so the tissues are not cut but pouched away. The cannula is removed by screwing in counter clock direction. 18 Pediatric Laparoscopy 2 Figure . Different trocars upper sharp conical middle sharp pyramidal lower blunt conical. Cannula Insertion First Cannula For the introduction of the first .
