Blood gas syringe

• US 4,159,713 A
• Filed: 06/02/1977
• Issued: 07/03/1979
• Est. Priority Date: 06/02/1977
• Status: Expired due to Term

• Current Assignee: Becton, Dickinson & Co
• Original Assignee: Becton, Dickinson & Co
• Inventors: Prais, Alois G.
• Primary Examiner(s): Yasko, John D.
• Application Number:
  US05/802,786
• Time in Patent Office: 761 Days
• Field of Search: 128/218 P, 128/218 R, 128/234, 128/2 F
• US Class Current: 600/578
• CPC Class Codes: A61B 5/15003 for venous or arterial blood
• CPC Class Codes: A61B 5/150099 by negative pressure, other than vacuum extraction into a syringe by pulling on the piston rod or into pre-evacuated tubes
• CPC Class Codes: A61B 5/150236 Pistons, i.e. cylindrical bodies that sit inside the syringe barrel, typically with an air tight seal, and slide in the barrel to create a vacuum or to expel blood
• CPC Class Codes: A61B 5/150244 Rods for actuating or driving the piston, i.e. the cylindrical body that sits inside the syringe barrel, typically with an air tight seal, and slides in the barrel to create a vacuum or to expel blood
• CPC Class Codes: A61B 5/150389 Hollow piercing elements, e.g. canulas, needles, for piercing the skin
• CPC Class Codes: A61B 5/150519 Details of construction of hub, i.e. element used to attach the single-ended needle to a piercing device or sampling device
• CPC Class Codes: A61B 5/153 Devices specially adapted for taking samples of venous or arterial blood, e.g. with syringes

Abstract

The disclosure is of an improved blood gas syringe, particularly a self-filling arterial blood gas syringe. In one embodiment, the improved syringe comprises a conventional syringe barrel, a plunger rod and an elastomeric piston at the bottom of the plunger rod. The plunger rod is connected to the piston by a flexible coupling permitting the plunger rod to flex out of alignment with the piston component of the plunger without axially displacing the piston, thereby assuring that a seal is maintained between piston and syringe barrel. The syringe has several advantages over prior art blood gas syringes, such as the obviation of inadvertently drawing air into the syringe when the plunger is not kept in axial alignment therewith when being drawn back.

Claims

1. A blood gas syringe, which comprises;

a barrel having a first open end for receiving a slidable plunger, a second open end adapted to mount a needle on the opening thereof and a bore communicating between said ends; and

a plunger slidably mounted in the bore of said barrel, said plunger being at least partially withdrawable from said barrel through said first open end, said plunger comprising;

(a) an elastomeric piston having an upper end and a lower end, a body joining said upper and lower ends, said body having a diameter less than the diameter of said bore, and a sealing flange radially disposed about the outer periphery of said body between the upper and lower ends, said flange forming a light sliding seal with the inner walls of said barrel;

(b) a plunger rod having a first end extending out of the first open end of said barrel and a second end within the bore of said barrel; and

(c) means for coupling without a rigid connection, said second end of said rod to the lower end of said piston, said means permitting the displacement of the first end of said rod out of axial alignment with said piston, without moving said piston out of said alignment, said means also permitting free rotation and axial movement of the rod without moving the piston, and

wherein said means comprises a stud mounted in said piston and an opening in the second end of said rod, said stud including a spacing bar component extending distally from the connection with the piston and a stud cap at the terminal end of the spacing bar, said stud spacing bar being inserted in and retained in said opening by engagement of the stud cap with the portions of said rod defining said opening, said spacing bar being of a dimension permitting the rod to float thereon without a rigid connection between rod and piston, said rod being rotatable and axially displaceable upon the spacing bar.

2. The syringe of claim 1 having a finger grasping flange at the first open end of said barrel.

3. The syringe of claim 1 wherein said sealing flange is the only contacting surface between the piston and said barrel.

4. The syringe of claim 1 which further comprises a means for stopping the plunger assembly from complete withdrawal from the first end of said barrel.

5. The syringe of claim 4 wherein said means for stopping comprises a rib circumscribing the outer periphery of said plunger rod and a rib circumscribing the inner walls of said barrel at a point adjacent to said first open end.