Serum lidocaine concentrations in children during bronchoscopy with topical anesthesia

To evaluate the safety of topical lidocaine anesthesia in children undergoing bronchoscopy, we determined SLC in 15 children aged 3 months to 9.5 years during flexible fiberoptic bronchoscopy. A total lidocaine dose of 3.2 to 8.5 (mean +/- SEM = 5.7 +/- 0.5) mg/kg was administered to nose, larynx and bronchial tree over 9 to 45 (mean +/- SEM = 20 +/- 2.7) minutes. No complication occurred during the procedure. Peak SLC were 1-3.5 (mean +/- SEM = 2.5 +/- 0.2) micrograms/ml. The Vd beta was 1.79 +/- 0.19 L/kg, the t1/2 beta was 109 +/- 12 minutes, and the total body clearance 12.2 +/- 1.1 ml/min/kg. Peak SLC correlated well with the dose expressed as mg/kg (r = 0.59, p less than 0.025), and even better when related to body surface area (r = 0.63, p less than 0.01). Lidocaine doses up to 8.5 mg/kg proved safe and resulted in therapeutic SLC in our patients. Lidocaine dose up to 7 mg/kg appears to be safe provided that it does not exceed an upper limit of 175 mg/m2 and is gradually administered over a minimum of 15 minutes. Doses of 7-8.5 mg/kg appear to be safe when administered over longer periods.