Minimizing Resistance to Catheter Advancement During Vascular Cannulation

Abstract

A hypodermic needle minimizing resistance to catheter advancement during vascular cannulation includes a needle shaft and a needle tip including an open needle bevel extending along middle and proximal portions of the open bevel until a distal end of the needle shaft, wherein a most distal portion of the open bevel is filled to prevent flashback. The hypodermic needle also includes a catheter overlying the needle shaft in the resting position.

1 . A hypodermic needle minimizing resistance to catheter advancement during vascular cannulation, comprising:
 a needle shaft having a needle tip;   the needle tip extending to a distal point in alignment with a longitudinal axis extending along a wall of the needle shaft, the needle tip including an open needle bevel extending diametrically across a full extent of the needle, the open portion of the open needle bevel extending along middle and proximal portions of the open needle bevel until a distal end of the needle shaft, wherein a most distal portion of the open needle bevel is filled so that contact of the open portion of the open needle bevel with a vessel is delayed until a predetermined portion of the needle tip is in the vessel to delay flashback from the open portion of the open needle bevel, the open needle bevel being filled as dead space to ensure that flashback cannot occur until a region of the open needle bevel with greater than a prescribed width has passed through an anterior vessel wall;   a catheter having a constant diameter along its length, the catheter overlying the needle shaft in the resting position;   wherein a distance from the catheter to a distal tip of the open needle bevel is greater than a distance from the catheter to a most distant point of flashback via the open portion of the open needle bevel, thereby delaying flashback until a predetermined portion of the needle tip is in the vessel to ensure an adequate size path is formed in a vessel wall so as to minimize resistance to advancement of the catheter during vascular cannulation.   
     
     
         2 - 6 . (canceled) 
     
     
         7 . The needle according to  claim 1 , wherein the dead space is positioned adjacent the distal tip. 
     
     
         8 . The needle according to  claim 1 , wherein the dead space extends from the distal tip to the middle portion of the open needle bevel. 
     
     
         9 . A method for needle insertion, comprising:
 providing a needle having a needle shaft with a needle tip, the needle tip extending to a distal point in alignment with a longitudinal axis extending along a wall of the needle shaft, the needle tip including an open needle bevel extending diametrically across a full extent of the needle, an open portion of the open needle bevel extending along middle and proximal portions of the open needle bevel until a distal end of the needle shaft, wherein a most distal portion of the open needle bevel is filled as dead space to ensure that flashback cannot occur until a region of the open needle bevel with greater than a prescribed width has passed through an anterior vessel wall;   entering a vessel by puncturing a vessel wall of the vessel with the needle tip of the needle as per use of a standard open-bevel needle;   further entering the vessel with die needle tip of the needle until flashback is achieved.   
     
     
         10 . The method according to  claim 9 , wherein the step of providing includes providing a catheter overlying the needle shaft in a resting position. 
     
     
         11 . The method according to  claim 10 , further including the step of engaging the catheter in the vessel at or prior to flashback after the step of entering a vessel. 
     
     
         12 . The method according to  claim 11 , wherein the step of further entering the vessel includes further entering with the needle tip of the needle until a circumference of the portion of the needle tip within a vessel wall closely approaches that of the catheter to facilitate catheter advancement into the vessel. 
     
     
         13 . The method according to  claim 12 , further including, after the step of further entering the vessel, threading the catheter over the needle and into the vessel. 
     
     
         14 . The method according to  claim 13 , wherein a distance from the catheter to a distal tip of the open needle bevel which enters the vessel is greater than a distance from the catheter to a most distant point of flashback via the open portion of the open needle bevel 
     
     
         15 . The method according to  claim 10 , wherein the step of further entering the vessel includes further entering with the needle tip of the needle until a circumference of the portion of the needle tip within a vessel wall closely approaches that of the catheter to facilitate catheter advancement into the vessel. 
     
     
         16 . The method according to  claim 15 , further including, after the step of further entering the vessel, threading the catheter over the needle and into the vessel. 
     
     
         17 . The method according to  claim 16 , wherein a distance from the catheter to a distal tip of the open needle bevel which enters the vessel is greater than a distance from the catheter to a most distant point of flashback via the open portion of the open needle bevel. 
     
     
         18 . The method according to  claim 9 , wherein there distal tip of the needle is inserted such that 50-100% of the diameter of the needle shaft is within the vessel at the time of flashback.