Seizure after lidocaine for bronchoscopy: case report and review of the use of lidocaine in airway anesthesia.

Lidocaine-induced seizures have been reported after topical administration. A 30-year-old, 48-kg women with acquired immunodeficiency syndrome, chronic end-stage renal failure, anemia, congestive heart failure (CHF), cardiomyopathy, and increased liver function tests was admitted to the hospital with fever, chills, and dry cough. Bronchoscopy was performed to rule out Pneumocystis carinii pneumonitis; the patient experienced seizure activity after administration of a total dose of topical lidocaine 300 mg. Plasma drug concentration measured shortly after seizure, and at 4 and 22 hours after seizure were 12.0, 7.6, and 1.4 mg/L, respectively. A direct correlation exists between clinical symptoms and blood level of lidocaine; as the level increases to 8-12 mg/L the probability of seizure increases. The extent of absorption and bioavailability after airway administration depends on tissue vascularity, sites and techniques of application, patient's disease state, and, most important, the dose/unit body weight. The lidocaine dose should be titrated slowly and patients monitored for altered mental status. The dose often has to be decreased empirically in patients with liver disease or CHF. Efforts should be made to deliver minimum amounts of the drug to the lower respiratory tract, since its pharmacokinetics at that site are similar to those with intravenous administration.