Dose:  Administered dose should not exceed 5 to 7 mg/kg (tips to minimize discomfort with parenteral use )

Comments: For local or regional anesthesia, the total dose administered should not exceed 5 to 7 mg/kg (Yaster et al. J Pediatr 1994; 124:166). Lidocaine is extremely useful for providing anesthesia for infants and children of all ages. The overall safety record of its use as a local anesthetic has been good; in the majority of cases in which a toxic reaction occurred, the drug was either inadvertently injected intravascularly or the dose administered was excessive (Berde. J Pediatr 1993; 122:S19). Local anesthetic administration must be strictly limited by a total dose that must not be exceeded. Davidson and Boom (Brit Med J 1992;305:617) reported that warming lidocaine reduced pain of administration to most adult volunteers. The vial of lidocaine was warmed to 43^o C and drawn into a syringe. If administered within 30 seconds, the final temperature of the drug was 37^o C.

Toxicity:  Mild side effects include visual and auditory disturbances, restlessness, and muscle twitching. More severe effects include seizures, coma, arrhythmias (bradycardia), respiratory arrest, and cardiovascular collapse. Using the above recommended dose should ensure that toxic serum concentrations of the drug do not develop. However, if lidocaine is injected directly into an artery or vein, even small fractions of the dose can produce systemic toxicity.  See adverse effects associated with lidocaine.

Preparation:
Lidocaine (Xylocaine) 1% is available in a 2 ml ampule pirated from the LP trays or from the manufacturer in 2 ml single dose vials. The drug may be diluted with normal saline or sterile water for injection to decrease the concentration to 0.5% or 0.25%.  

Lidocaine 2% jelly that can be used to anesthetize mucosal linings such as the nares prior to a nasotracheal intubation. The volume used can be controlled by expressing the lidocaine jelly into a syringe before administration (don't exceed 0.25 to 0.3 ml).

Lidocaine 4% (either as AneCream or LMX) is a topical anesthetic that contains 40 mg lidocaine per gram of liposomal cream. It is currently being substituted for EMLA. It's onset of action is 30 minutes. It contains no prilocaine so there is no risk of methemoglobineia. It is currently not labeled for use in < 37 weeks. There can be concerns about excessive systemic absorption, particularly in preterm infants, so the "dose of lidocaine" should not exceed 5 to 7 mg/kg.