In Reply:–

Drs. Shroff and Mayhew are concerned that the epidural loading dose of 3% 2-chloroprocaine was too large because plasma cholinesterase concentrations are reduced in neonates and infants.1However, the half-life of 2-chloroprocaine is of such short duration that increasing the dose has no significant clinical impact on complications. In our case report, we reported the half-life of chloroprocaine to be 1–4.5 min.2However, others have reported the plasma half-life to be less than 60 s.3,4Plasma chloroprocaine concentrations have been measured in pediatric patients receiving continuous epidural infusions. Former preterm infants undergoing inguinal hernia repair received loading doses of 1 ml/kg 2-chloroprocaine, 3% (30 mg/kg), via  an indwelling caudally placed epidural catheter and were then given infusions at a minimum rate of 30 mg · kg−1· h−1.5The mean cumulative dose of 2-chloroprocaine infused over 95 ± 35 min was 84 ± 30 mg · kg−1· h−1. The plasma chloroprocaine concentrations were 0 mg/ml in four patients and 0.5 mg/ml in one patient, and there was no evidence of neurotoxicity or cardiovascular toxicity.5Suggested loading doses of epidurally administered 2-chloroprocaine in the pediatric regional literature have ranged from 30 to 60 mg/kg.3,4 

Based on the above data, the loading dose of 30 mg/kg was clearly appropriate. However, as we highlighted in our case report, pediatric epidurals should be tested before administration of a loading dose of local anesthetic to minimize the risk of unintentional intravascular injections and subsequent toxicity.

* University of Pittsburgh School of Medicine, The Children’s Hospital of Pittsburgh, Pittsburgh, Pennsylvania. cladfp@anes.upmc.edu

References

References
1.
Zsigmond EK, Downs JR: Plasma cholinesterase activity in newborns and infants. Can Anaesth Soc J 1971; 18:278–85
2.
Kuhnert BR, Kuhnert PM, Philipson EH, Syracuse CD, Kaine CJ, Yun CH: The half-life of 2-chloroprocaine. Anesth Analg 1986; 65:273–8
3.
Tobias JD, Sandra L, O’Dell N, Pietsch JB, Neblett WW: Continuous regional anaesthesia in infants. Can J Anaesth 1993; 40:1065–8
4.
Gunter JB: Benefit and risks of local anesthetics in infants and children. Pediatr Drugs 2002; 4:649–72
5.
Henderson K, Sethna NF, Berde CB: Continuous caudal anesthesia for inguinal hernia repair in former preterm infants. J Clinical Anesthesia 5:129–33