Plasma lignocaine concentrations following topical laryngeal application.

Lignocaine 4%, 4 mg/kg, was sprayed onto the larynx and subglottic area of 96 children aged from 2 weeks to 12 years and plasma lignocaine concentrations were measured. While the majority were well within the accepted safe range (4.5 micrograms/ml) occasional concentrations over 8 micrograms/ml appeared in all groups. Simultaneous arterial and venous sampling showed a small but significant difference in the first 10 minutes.