One of the options in our armamentarium prior to inserting an NG tube or performing a non-emergent nasotracheal intubation is nebulized lidocaine. However, the total dose is always a concern with this anesthetic agent before we have to worry about toxicity such as lightheadedness, tremors, hallucinations, seizures, and cardiac arrest. Here are some points to remember:
- Maximum IV dose is 3 mg/kg when used as an antiarryhthmic in ACLS.
- Maximum subcutaneous/intradermal dose is 4.5 mg/kg. When used in combination with epinephrine, this value is increased to 7 mg/kg.
- One study evaluated lidocaine plasma levels after nebulized administration and found that a dose of 400 mg (5.7 mg/kg in a 70 kg patient) produced a peak of 1.1 mcg/ml, far below the 5 mcg/ml level associated with toxicity.
- Application to real-life: Using 4% topical lidocaine in a 5-mL nebulizer will give a total dose of 200 mg. This is within the range of safe, studied doses, and will provide the anesthetic effect you (and the patient) desires.
References
- Chinn WM, Zavala DC, Ambre J. Plasma levels of lidocaine following nebulized aerosol administration. Chest 1977;71(3):346-8.
- Wu FL, Razzaghi A, Souney PF. Seizure after lidocaine for bronchoscopy: case report and review of the use of lidocaine in airway anesthesia. Pharmacotherapy 1993;13:72-8.