A cannula is described that includes a diverter mechanism in the form of a blast plate deployable from within the lumen of the cannula and retractable from the lumen of the cannula. The blast plate may take the form of a planar surface, a curved surface, a membrane mounted on a wire ring, or a conical...http://www.google.com.au/patents/US6508826?utm_source=gb-gplus-sharePatent US6508826 - Cannula with flow diversion mechanism and methods of use
