A trocar houses a pneumo-needle, the cutting tip of which emerges eccentrically from the tip of said trocar. An obturator, in turn, is housed within said pneumo-needle and is controlled at the distal end of the pneumo-needle by a spring release button. A latch attached to the trocar permits the pneumo-needle...http://www.google.de/patents/US5312351?utm_source=gb-gplus-sharePatent US5312351 - Combined pneumo-needle and trocar apparatus
