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Safety trocar instrument having a retractable trocar actuated by relief of pressure on the trocar point

  • US 5,158,552 A
  • Filed: 11/04/1991
  • Issued: 10/27/1992
  • Est. Priority Date: 11/04/1991
  • Status: Expired due to Term
First Claim
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1. A safety trocar instrument for piercing the wall of an anatomical cavity to provide communication with the inside of the cavity, said trocar instrument comprising:

  • (a) a tubular cannula;

    (b) an elongate trocar, having a sharp piercing point, mounted for axial reciprocal movement within said cannula between a withdrawn rest position in which said point is received within and shielded by the distal end of said cannula, a fully extended position in which said point is exposed beyond the distal end of said cannula, and an intermediate position retracted toward the rest position from the fully extended position in which said point is also exposed beyond the distal end of said cannula;

    (c) means for biasing said trocar to its withdrawn position;

    (d) latch means for latching said trocar, in opposition to said biasing means, for reciprocal movement between the fully extended position and the intermediate position; and

    (e) trip means coupling said trocar to said latch means when said trocar moves from the fully extended position to the intermediate position, and tripping said latch means when said trocar returns toward said fully extended position to unlatch said trocar and thereby permit said trocar to be moved to the withdrawn rest position by said biasing means.

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