Method and systems for buffering anesthetic cartridges with buffering solutions

Abstract

An anesthetic cartridge is adapted to receive a volume of buffer by displacing a plunger in one end of the anesthetic cartridge inwardly so that addition of the buffer volume will not displace the plunger excessively beyond the end of the cartridge body. By properly determining the amount of buffer volume required to raise the pH of the anesthetic to a target value, the degree of inward displacement of the plunger can be determined and the cartridge can be used with a system for delivering a precise amount of buffer solution having a known pH into the cartridge to raise its pH, just before the anesthetic is delivered to the patient.

1 . A method for buffering an anesthetic in a cartridge having a septum at one end and a plunger at the other end, said method comprising:
 determining a volume of buffer needed to adjust the pH of a volume of the anesthetic to a target value;   providing an anesthetic cartridge containing the volume of anesthetic wherein the plunger is set back from an end of the cartridge by a distance sufficient to allow the cartridge to receive the volume of buffer without displacing the plunger beyond the end of the cartridge; and   introducing the volume of buffer into the cartridge.   
     
     
         2 . A method as in  claim 1 , wherein the cartridge is prepared at a central manufacturing facility and the cartridges are distributed to a plurality of local users, wherein the users inject the buffer. 
     
     
         3 . A method as in  claim 2 , wherein the users inject the buffer prior to a procedure, in order to produce buffered anesthetic for use in the procedure. 
     
     
         4 . A method as in  claim 3 , wherein at least a portion of the buffered anesthetic is injected into a patient within 2 minutes of introducing the buffer. 
     
     
         5 . A method as in  claim 1 , wherein the anesthetic originally has a pH below 6.0 and the volume of buffer raises the pH of the buffered anesthetic to at least 7.0. 
     
     
         6 . A method as in  claim 5 , wherein the volume of buffer increases the pH to at least 7.3. 
     
     
         7 . A method as in  claim 1 , wherein the local anesthetic is an amide local anesthetic. 
     
     
         8 . A method as in  claim 1 , wherein the local anesthetic is an amine local anesthetic. 
     
     
         9 . A method as in  claim 1 , wherein the local anesthetic is lidocaine. 
     
     
         10 . A method as in  claim 1 , wherein the local anesthetic is articaine. 
     
     
         11 . A method as in  claim 1 , wherein the local anesthetic contains a vasoconstrictor. 
     
     
         12 . A method as in  claim 11 , wherein the vasoconstrictor is epinephrine. 
     
     
         13 . A method as in  claim 1 , wherein an internal volume of the anesthetic cartridge is in the range from 1.45 ml to 2.3 ml, the anesthetic volume is in the range from 1.15 ml to 2.2 ml, and the buffer volume is in the range from 0.1 ml to 0.35 ml. 
     
     
         14 . A system for preparing a buffered anesthetic, said system comprising:
 an anesthetic cartridge having a septum at one end and a plunger at the other end, wherein said cartridge is filled with a volume of anesthetic; and   a buffer container holding a volume of buffer selected to raise the pH of the anesthetic to a target pH;   wherein the buffer container is adapted to transfer the buffer volume to the anesthetic cartridge and wherein the plunger is set back from an end of the anesthetic cartridge by a distance sufficient to allow the cartridge to receive the buffer volume without displacing the plunger beyond the end of the cartridge.   
     
     
         15 . A system as in  claim 13 , wherein the anesthetic cartridge has an internal volume in the range from 1.45 ml to 2.3 ml, the anesthetic volume within the cartridge is in the range from 1.1 ml to 2.2 ml, and the buffer volume is in the range from 0.10 ml to 0.35 ml. 
     
     
         16 . A system as in  claim 15 , wherein the buffer comprises a sodium bicarbonate solution having a nominal pH and an actual pH which is with ±0.1 of the nominal pH. 
     
     
         17 . An inventory of anesthetic cartridges comprising:
 a plurality of identical containers each having a plunger at one end, a septum at other end, and being partially filled with an anesthetic solution;   wherein the plunger in each container is spaced away from the plunger end of the cartridge by a distance of at least 10% of the container length.