Lidocaine infiltration means injection of the skin, subcutaneous tissue, mucosal or submucosal tissues with lidocaine for purpose of anesthesia.
Lidocaine is a local anesthetic commonly marketed in the Philippines as Xylocaine.
Nowadays, Xylocaine preparation for infiltration in the Philippine market comes as a 2% solution in 5 ml polyamp duofit.
Xylocaine 2% – 2 gm / 100 ml = 2000 mg / 100 ml = 20 mg / ml.
Maximum dosage in an adult is 4.5 mg / kg or 300 mg or 3 ampules of Xylocaine 2% (100 mg / ampule which contains 5 ml) or 15 ml of Xylocaine 2%.
To use more volume of Xylocaine with reduced concentration, say 1%, add 5 ml of NSS to an ampule of 5 ml Xylocaine 2%. One can now give a maximum of 30ml of Xylocaine 1%.
The duration of action of lidocaine without epinephrine is about one hour. The duration of action of lidocaine with epinephrine is about 2 hours.
The maximum dose for lidocaine with epinephrine is 600 mg.
To prepare a 1:200,000 solution of epinephrine in 1% Xylocaine, add 0.1 ml of 1:1000 epinephrine to 19.1 ml of Xylocaine 1%. (http://www.frca.co.uk/article.aspx?articleid=100816)
To reduce pain of anesthetic infiltration,
- Use small gauge and long needle say G-25 or G27.
- Infiltrate the looser layer (subcutaneous) rather than the tighter layer (dermis) or the former first before the latter (if both have to be done).
- Distract the patient while infiltrating.
- Consider the use of EMLA (topic Xylocaine) but this needs to be done 90 minutes before infiltration and with occlusion.