Syringe with adjustable two piece plunger rod

1. A medical device comprising:

a syringe barrel having a side wall with an inside surface defining a chamber for retaining fluid, an open proximal end and a distal end including a distal wall having a passageway therethrough in fluid communication with the chamber, the open proximal end including a peripheral flange; and

an elongate plunger rod disposed within the barrel, the plunger rod comprising a distal portion, a proximal portion, and a stopper disposed on a distal end of the distal portion, the stopper having a distal face and a proximal end, the proximal portion of the plunger rod slidably mounted to the distal portion so that the overall length of the plunger rod is reversibly adjustable to a plurality of different locked lengths between a compressed locked length and a fully extended length, thereby permitting varying amounts of fluid to be expelled from the barrel corresponding to the plurality of locked lengths,

wherein one of the distal portion or proximal portion slidably receives the other of the distal portion or proximal portion,

wherein the one or the other of the distal portion or proximal portion is hollow and the other of the distal portion or proximal portion is sized to be inserted into the hollow portion, and

wherein the distal portion is hollow and the proximal portion includes a plurality of depressions spaced axially along the proximal portion that cooperate with a tab disposed on the distal portion to provide a plurality of locked positions and to provide a plunger rod that can have a plurality of locked lengths.

2. The medical device of claim 1 , wherein each depression comprises a notch having a ramped surface and a stop face which engages the tab when the plunger rod is in a locked position.

3. The medical device of claim 2 , further comprising indicia on the plunger rod that indicates the amount of fluid to be dispensed from the syringe when the plunger rod is advanced distally.

4. A medical device comprising:

a syringe barrel having a side wall with an inside surface defining a chamber for retaining fluid, an open proximal end and a distal end including a distal wall having a passageway therethrough in fluid communication with the chamber, the open proximal end including a peripheral flange; and

an elongate plunger rod disposed within the barrel, the plunger rod comprising a distal portion, a proximal portion, and a stopper disposed on a distal end of the distal portion, the stopper having a distal face and a proximal end, the proximal portion of the plunger rod slidably mounted to the distal portion so that the overall length of the plunger rod is reversibly adjustable to a plurality of different locked lengths between a compressed locked length and a fully extended length, thereby permitting varying amounts of fluid to be expelled from the barrel corresponding to the plurality of locked lengths,

wherein the plunger rod further comprises a proximal end including a thumbpress and a thumbpress cap covering the thumbpress.

5. The medical device of claim 4 , wherein the thumbpress cap is adapted to lock the thumbpress with the peripheral flange.

6. A medical device comprising:

a syringe barrel having a side wall with an inside surface defining a chamber for retaining fluid, an open proximal end and a distal end including a distal wall having a passageway therethrough in fluid communication with the chamber, the open proximal end including a peripheral flange; and

an elongate plunger rod disposed within the barrel, the plunger rod comprising a distal portion and proximal portion disposed in a slidable, nested arrangement, the proximal portion having a thumb press, one of the distal portion or the proximal portion having a projecting tab and the other of the distal portion or proximal portion having a plurality of grooves that cooperate with the tab so that the overall length of the plunger rod is adjustable between a plurality of different locked lengths ranging from a compressed locked length to a fully-extended length so as to permit varying amounts of fluid to be expelled from the syringe barrel based on the adjustable length of the plunger rod,

wherein the distal portion and proximal portion can be rotated with respect to each other, wherein in a first rotation position, the distal portion and proximal portion can be moved axially with respect to each other, and in a second rotation position, the distal portion and proximal portion can be locked to prevent relative axial movement of the distal portion and proximal portion.

7. The medical device of claim 6 , wherein the grooves are spaced axially along the proximal portion and the tab is associated with the distal portion.

8. The medical device of claim 7 , further comprising indicia associated with each groove to indicate an amount of fluid that will be expelled from the syringe when the thumb press is advanced toward the barrel and prevented from further distal movement.

9. The device of claim 7 , wherein the tab comprises a radially-inward projection which fits into at least one of the grooves to prevent relative axial movement of the distal portion and the proximal portion.

10. The device of claim 9 , wherein the proximal portion includes an axially extending narrowed portion which permits the tab to slide along the proximal portion and allow the distal portion and proximal portion to be fully extended and compressed with respect to each other, and upon rotation of the proximal portion with respect to the distal portion, to permit the tab to engage at least one of the grooves.

11. The device of claim 6 , wherein the device is enclosed within a package.

12. The device of claim 6 , wherein the chamber is pre-filled with a fluid selected from a flush solution and a medication.

13. The device of claim 6 , further comprising a thumbpress cap covering the thumbpress.

14. The device of claim 13 , wherein the thumbpress cap is adapted to form a seal with the peripheral flange.

15. A medical device comprising:

a syringe barrel having a side wall with an inside surface defining a chamber for retaining fluid, an open proximal end and a distal end including a distal wall having a passageway therethrough in fluid communication with the chamber, the open proximal end including a peripheral flange; and

an elongate plunger rod disposed within the barrel, the plunger rod comprising a distal portion and proximal portion being slidable with respect to each other and including means for regulating the overall length of the plunger rod between a compressed locked length and a fully-extended length to permit variable amounts of fluid to be expelled from the syringe,

wherein the distal portion and proximal portion can be rotated with respect to each other, wherein in a first rotation position, the distal portion and proximal portion can be moved axially with respect to each other, and in a second rotation position, the distal portion and proximal portion can be locked to prevent relative axial movement of the distal portion and proximal portion, and

wherein the plunger rod further comprises a proximal end including a thumbpress and a thumbpress cap covering the thumbpress.

16. The medical device of claim 15 , wherein the thumbpress cap is adapted to lock the thumbpress with the peripheral flange.

17. A medical device comprising:

a syringe barrel having a side wall with an inside surface defining a chamber for retaining fluid, an open proximal end and a distal end including a distal wall having a passageway therethrough in fluid communication with the chamber, the open proximal end including a peripheral flange; and

an elongate plunger rod disposed within the barrel, the plunger rod comprising a distal portion, a proximal portion, and a stopper disposed on a distal end of the distal portion, the stopper having a distal face and a proximal end, the proximal portion of the plunger rod slidably mounted to the distal portion so that the overall length of the plunger rod is reversibly adjustable to a plurality of different locked lengths between a compressed locked length and a fully extended length, thereby permitting varying amounts of fluid to be expelled from the barrel corresponding to the plurality of locked lengths,

wherein a length of axial motion of the plunger rod through the barrel corresponds to a locked position of the plunger rod between a compressed locked length and a fully extended length, and wherein the amount of fluid to be expelled from the barrel corresponds to the length of axial motion of the plunger rod,

wherein the length of axial motion of the plunger rod through the barrel is limited by the proximal portion of the plunger rod interfering with a portion of the barrel adjacent the open proximal end thereof, and

wherein the proximal portion of the plunger rod comprises a thumbpress for interference contact with the peripheral flange of the barrel.

18. The medical device of claim 6 , wherein a length of axial motion of the plunger rod through the barrel is determined by the position of the projecting tab with respect to one of the plurality of grooves, and wherein the amount of fluid to be expelled from the barrel corresponds to the length of axial motion of the plunger rod.