A 2-month-old boy was brought from the operation theatre with generalized tonic clonic convulsions since 10 minutes. Baby had undergone circumcision few minutes earlier and lignocaine was the local anaesthetic agent used. On examination, he was convulsing and was able to maintain his airway. Immediately oxygen and intravenous diazepam 1 mg was given slowly under monitoring. Baby was still convulsing, another dose of diazepam 1 mg was given slowly. Baby went into respiratory depression with HR>100/min, intubated immediately and assisted ventilation was given for 3 minutes. Extubation was done after baby started having spontaneous respiration. On examination, baby was afebrile, respiratory rate 38/min, heart rate 160/min, capillary refilling time of 2 seconds, oxygen saturation of 96% at room air with normal pupillary reaction to light. Baby was drowsy, with no focal deficits and other system examination was unremarkable. He was started on intravenous fluids, cefotaxime and injection phenobarbitone. His blood counts, blood sugar, serum calcium, phosphorous, serum electrolyes, blood urea, serum creatinine, CRP and chest X-ray were within normal limits. ECG showed tachycardia with heart rate of 160/minute. After 20 hours, baby was conscious, active and was started on breast feeds. Baby was given maintenance dose of phenobarbitone for 48 hours and discharged after 2 days.

Lignocaine toxicity has been reported after subcutaneous administration, oral administration, and intravascular injection [1,2]. Even though toxicity due to local anesthetics is extremely rare in infants and children; seizures, dysrhythmias, cardiovascular collapse, and transient neuropathic symptoms have been reported [3-5]. Infants have a much higher free serum concentration of local anaesthetics than older children and adults, therefore they are more prone to the deleterious effects of local anesthetics [3,4]. Children have been reported to have convulsions even with serum lignocaine concentrations within the therapeutic range of 1-5 microgram/mL [2]. However, we could not estimate the serum concentration of lignocaine in our child. The maximum safe dose of lignocaine is 3 mg/kg [1]. On questioning, we got information that about 1mL of 2% lignocaine (20mg) had been used as local anesthetic for circumcision. Our baby weight was 5.2 kg and the maximum safe dose was 15.6 mg, but he had received 20 mg. Using Naranjo scale to ascribe the side-effect of lignocaine, it was Probable adverse drug reaction.

The treatment of local anesthetic toxicity is essentially supportive. The symptoms of toxicity persist as long as the plasma concentration remains above the therapeutic index [1]. Despite apparent safety of lignocaine, extra care should be taken in young children as it is easy to overestimate the dose-to-weight ratio [1].

1. Donald MJ, Derbyshire S. Lignocaine toxicity; a complication of local anesthesia administered in the community. Emerg Med J. 2004;21:249-50.

2. Smith M, Wolfram W, Rose R. Toxicity seizures in an infant caused by (or related to) oral viscous lidocaine use. J Emerg Med. 1992;10:587-90.

3. Gunter JB. Benefit and risks of local anesthetics in infants and children. Paediatr Drugs. 2002;4:649-72.

4. Dalens BJ, Mazoit JX. Adverse effects of regional anaesthesia in children. Drug Safe. 1998;19:251-68.