A surgical instrument includes a movable member having a proximal portion, the movable member defining an opening at the proximal portion. The instrument includes a stationary member defining an aperture. The stationary member is arranged relative to the movable member with a close fit between the stationary...http://www.google.es/patents/US7766844?utm_source=gb-gplus-sharePatente US7766844 - Surgical instrument aspiration valve
