Methods and apparatus for buffering parenteral solutions

1. A device for transferring a volume of a solution from a first cartridge having a septum to another solution in a second cartridge having a septum, said device comprising:

a cartridge holder having a proximal end, a distal end, and a chamber for removably holding the first cartridge;

a plunger driver removably attachable to the proximal end of the cartridge holder and having a piston rod which engages a plunger on the first cartridge; and

a cartridge connector having a proximal end attachable to the distal end of the cartridge holder, a distal end adapted to engage a septum end of the second cartridge, said cartridge connector including a transfer needle and an exhaust needle which extend distally to penetrate the septum end of the second cartridge, wherein the transfer needle extends proximally to penetrate the septum of the first cartridge and the exhaust needle terminates in the sealed interior waste chamber;

wherein after use, the plunger driver may be removed from the cartridge holder, the first cartridge removed, and the cartridge holder and plunger cleaned for re-use.

2. A device as in claim 1 , wherein the cartridge connector has an interior waste chamber which is configured to receive waste solution from the second cartridge which is displaced from the second cartridge as fluid from the first cartridge is transferred.

3. A device as in claim 1 , wherein the cartridge holder has a cylindrical body with a window to allow visual observation of the contents of the first cartridge in the cartridge holder.

4. A device as in claim 3 , wherein a distal region of the cylindrical body is enlarged to removably receive the cartridge connector.

5. A device as in claim 1 , wherein the plunger driver is adjustable so that the length of travel of the piston rod can be selected prior to advancement of said piston rod.

6. A device as in claim 4 , wherein the cartridge connector comprises a cylindrical body that is removably received within the enlarged distal region of the cartridge holder.

7. A device as in claim 2 , wherein the sealed interior walls waste chamber is defined between spaced-apart walls in the cylindrical body of the cartridge connector.

8. A device as in claim 3 , wherein a first end of the cylindrical body forms a cylindrical sleeve which surrounds the exposed ends of the exhaust cylindrical needle and the transfer needle, wherein said cylindrical sleeve is adapted to receive the septum end of a cartridge.

9. A device as in claim 8 , wherein a first end of the transfer needle is axially spaced-apart from the first end of the exhaust needle.

10. A device as in claim 9 , wherein the transfer needle passes axially through the sealed interior waste chamber.

11. A device as in claim 10 , wherein an exposed second end of the transfer needle is free of surrounding structure, said connector further including a removable cap for placing over the exposed second end of the transfer needle.

12. A method for buffering an anesthetic cartridge, said method comprising:

(a) removably inserting a first buffer cartridge having a septum and a plunger into a chamber of a cartridge holder;

(b) attaching a plunger driver to a proximal end of the cartridge holder:

(c) attaching one end of a cartridge connector to a distal end of the cartridge holder so that a transfer needle penetrates the septum of the buffer cartridge;

(d) attaching a first anesthetic cartridge to another end of the cartridge connector so that the transfer needle and an exhaust needle penetrate the septum of the first anesthetic cartridge;

(e) advancing a plunger on the plunger driver to engage the plunger on the buffer cartridge to transfer a volume of buffer from the first buffer cartridge into the first anesthetic cartridge and exhaust a volume of anesthetic from the first anesthetic cartridge;

(f) removing the first anesthetic cartridge from the cartridge connector for use;

(g) optionally connecting another anesthetic cartridge to the cartridge connector and repeating step (e) one or more times; and

(h) when done with the first buffer cartridge, removing the plunger driver and the first buffer cartridge and cleaning the cartridge holder and plunger driver for re-use.

13. A method as in claim 12 , further comprising disposing of the cartridge connector.

14. A method as in claim 13 , wherein the cartridge connector contains the exhausted anesthetic.

15. A method as in claim 12 , wherein additional anesthetic cartridges are sequentially replaced on the cartridge connector and volumes of buffer transferred to said additional anesthetic cartridges until the buffer cartridge is empty.

16. A method as in claim 15 , further comprising visually observing the buffer cartridge to determine when said buffer cartridge is empty.

17. A method as in claim 16 , wherein the cartridge holder has a window that allows visual observation of the contents of the buffer cartridge.