Lidocaine has been used in neonates as an effective drug in controlling neonatal seizures not responding to traditional anticonvulsant therapy. Little is known about the effect of lidocaine on heart rate or occurrence of cardiac arrhythmias in neonates. The purpose of the present study was to assess the incidence of cardiac arrhythmias associated with lidocaine use for neonatal seizures. A retrospective review was performed in 207 neonates who received lidocaine for treatment of neonatal seizures. All were given a loading dose of 2 mg/kg in 10 min followed by a continuous infusion of 6 mg/kg per h, tailed off over the next 48 h. A total of ten (4,8%) infants developed cardiac arrhythmias during lidocaine infusion. In five infants a bradycardia developed, associated with a prolonged QRS complex in one. In one infant a tachycardia was seen following the bolus administration. In the other four an irregular heart rate was noted. In eight infants the arrhythmias disappeared immediately following discontinuation of lidocaine. In two infants, with severe encephalopathy, who died, the association was not so clear.
Conclusion: The present study demonstrates that continuous cardiac monitoring of neonates who receive lidocaine for neonatal seizures is indicated, as there is a risk to develop cardiac arrhythmias. Lidocaine should be discontinued immediately when a cardiac arrhythmia occurs. Lidocaine should not be given to patients with a congenital heart disease and to infants who have already been treated with diphantoine.