Safety of high dose lidocaine in flexible bronchoscopy

BACKGROUND: The maximum safe dose for topical lidocaine during flexible bronchoscopy (FB) without toxicity is not established; recent guidelines advocate a dose <8.2 mg/kg. Noting our routine use of lidocaine above 12 mg/kg, we prospectively evaluated the safety of high dose topical lidocaine. METHODS: The standard institution FB preparation included 4% nebulized lidocaine, 2% nasal viscous lidocaine, 2% aqueous lidocaine for the vocal cords, and 1% aqueous lidocaine for the tracheobronchial tree. Procedure data were collected to include FB indication and duration, lidocaine use, and postprocedure symptoms. Serum lidocaine and blood methemoglobin levels were obtained 45 minutes postlidocaine administration. RESULTS: Consecutive data were collected for 154 patients with a mean age of 64.7 years. The most common FB indication (60%) was evaluation of a lung mass or mediastinal adenopathy. No arrhythmias or seizures were noted. Symptoms of euphoria or dizziness were reported in 84 patients (62.2%). Mean lidocaine usage was 15.4±4.5 mg/kg (1.17±0.20 gm). Lidocaine dose for females was significantly higher than males (16.9±4.9 mg/kg vs. 14.3±3.8 mg/kg, P=0.0003). There was no significant difference in dose on the basis of age, indication for FB, or presence of symptoms. Mean serum lidocaine level was 1.6±0.7 μg/mL and mean blood methemoglobin level was 0.7±0.3%. There were no significant differences shown. CONCLUSIONS: Our routine use of lidocaine in FB is higher than recommended. There were not significantly elevated serum lidocaine or blood methemoglobin levels, or clinical evidence of toxicity.