Topical lidocaine during fiberoptic bronchoscopy (FOB) improves patient comfort. The maximum dose tolerable without toxicity isn’t clearly established. A maximum dose of < 8.2 mg/kg is advocated. Review of our institution’s lidocaine use revealed a mean of 12.1 mg/kg. We prospectively evaluated the safety of topical lidocaine during FOB.
Our institutional FOB preparation includes 5-10 ml 4% nebulized lidocaine, 5-10 ml 2% viscous lidocaine (nasal mucosa), 10-20 ml 2% aqueous lidocaine (vocal cords), as needed 1% aqueous lidocaine (tracheobronchial tree), and conscious sedation with cardiac monitoring. Post-procedure data was collected from FOB patients, including total lidocaine, symptoms of toxicity, potential drug interactions, and procedure indication. Serum lidocaine and blood methemoglobin levels were obtained 45 minutes post-procedure. Statistical interpretation included t-tests and ANOVA. FOB operators were blinded. The study was approved by the Institutional Review Board.
Of 170 consecutive FOBs, data was available for 135 patients with mean age 64.7 years (range 20-89), 84 (62.2%) male, and 43 (31.9%) receiving beta-blockade. The most common indication (58.5%) was mass/adenopathy. None had significant hepatic disease. Symptoms of euphoria or dizziness were reported in 84 (62.2%) post-procedure. No abnormalities on cardiac monitoring were noted. Total mean lidocaine usage was 15.2 ± 4.4 mg/kg. Usage in females was significantly more than males (17.1 ± 4.5 versus 14.0 ± 3.8 mg/kg, p= < 0.0001). There was no difference in usage based on age, indication, beta-blockade, or presence of symptoms. Mean post-procedure lidocaine level (normal 1.2 –5.0 mcg/ml) was 1.6 ± 0.7 (range 0.8 –5.1) mcg/ml. Mean methemoglobin level (normal 0.4 –1.2 percent) was 0.7 ± 0.3 (range 0.1 –1.9) percent. There was no difference based on sex, age, indication, beta-blockade, or presence of symptoms.
Our use of lidocaine in FOB is higher than commonly recommended. This does not translate into significantly elevated patient serum lidocaine or methemoglobin levels.
Higher doses of lidocaine than are currently recommended may be safely used in FOB.
W.C. Frey, None.