A controllable sheath for optimizing the control of surgical instruments at the operation site includes a flexible sheath surrounding an endoscope and including a lumen extending along the walls of the sheath and adjacent to the endoscope. The lumen permits the passage of surgical instruments from the...http://www.google.co.uk/patents/US7070559?utm_source=gb-gplus-sharePatent US7070559 - Controllable endoscopic sheath apparatus and related method of use
