Cannula and stylet system

• US 5,250,035 A
• Filed: 04/20/1992
• Issued: 10/05/1993
• Est. Priority Date: 04/20/1992
• Status: Expired due to Fees

• Current Assignee: Abbott Laboratories Incorporated
• Original Assignee: Abbott Laboratories Incorporated
• Inventors: Patrick, Donald H., Smith, Gary N.
• Primary Examiner(s): Yasko, John D.
• Assistant Examiner(s): Gutowski, Anthony
• Application Number:
  US07/871,559
• Time in Patent Office: 533 Days
• Field of Search: 604/491, 604/51, 604/53, 604/158, 604/164, 604/165, 604/166, 604/168, 604/170, 604/174, 604/274, 604/900, 606/185, 128/753, 128/754
• US Class Current: 604/168.01
• CPC Class Codes: A61B 17/3401 Puncturing needles for the peridural or subarachnoid space or the plexus, e.g. for anaesthesia local anaesthesia A61M19/00
• CPC Class Codes: A61M 25/0606 "Over-the-needle" catheter assemblies, e.g. I.V. catheters
• CPC Class Codes: Y10S 604/90 Telltale showing entry of blood into body inserted conduit

Abstract

A needle system including a plastic cannula and a stylet, and a procedure utilizing the needle system for positioning the end of a spinal catheter within the subarachnoid space surrounding a patient'"'"'s spinal cord for continuous administration of anesthetics and/or analgesic medications. The stylet has a pencil-point sharpened end for forming a minimal size opening in the dura defining the subarachnoid space to minimize the loss of cerebrospinal fluid therefrom during this procedure. The cannula has a hub formed of glass-clear plastic, which is provided with viewing recesses.

Claims

1. A needle system for introducing a spinal catheter into the subarachnoid space surrounding a spinal cord with a minimal loss of cerebrospinal fluid, said system comprising, a plastic cannula having a centrally bored hub provided at one end thereof, an elongated stylet having a cone-shaped pencil-point end and a handle at its opposite end, which stylet is insertable into said cannula through said hub, the relative lengths of said cannula and said stylet being such that, when said stylet handle abuts against said cannula hub upon full assembly thereof, said pencil-point end of said stylet projects beyond the end of said cannula whereby a minimal opening is formed in the dura by said pencil-point end of said stylet to minimize the loss of cerebrospinal fluid therethrough during removal of said stylet and insertion of a spinal catheter into the subarachnoid space through said cannula wherein said stylet is formed of stainless steel, and said cannula hub is formed of glass-clear plastic and is provided with indicator means.

2. A needle system for introducing a spinal catheter into the subarachnoid space surrounding a spinal cord with a minimal loss of cerebrospinal fluid, said system comprising, a non-pointed but beveled cannula having a hub provided at one end thereof, a bore extending through said hub in axial alignment with a bore of said cannula, an elongated stylet having a cone-shaped pointed end and a handle at its opposite end, which stylet is insertable into said cannula through said hub, the relative lengths of said cannula and said stylet being such that, when said stylet handle abuts against said cannula hub upon full assembly thereof, said cone-shaped pointed end of said stylet projects beyond the end of said non-pointed but beveled cannula whereby, when said fully assembled cannula and stylet are inserted into a previously formed elongated puncture in a patient'"'"'s back, said cone-shaped pointed end of said stylet and said beveled end of said cannula pierce the dura just enough to form a minimal opening into the subarachnoid space within the dura, whereupon removal of said stylet from said cannula permits introduction of a spinal catheter through said cannula and into said subarachnoid space with a minimal loss of cerebrospinal fluid therefrom wherein said stylet is formed of stainless steel, said handle is formed of plastic, said hub is formed of glass-clear plastic and is provided with one or more viewing-window depressions.