Reduced systemic absorption of intrabronchial lidocaine by high-frequency nebulization

Serum lidocaine concentrations were measured in a series of patients during and after topical administration of lidocaine used to anesthetize the nasal mucosa, pharynx, and larynx for diagnostic fiberoptic bronchoscopy. In one group of patients (N = 9) the trachea and bronchi were sprayed with a 2% lidocaine solution administered in 2 mL volumes. Another group (N = 14) received a 2% lidocaine solution which was administered by inhalation of lidocaine dispensed by a high-frequency nebulizer. Multiple serum samples drawn over a 1-hour period were analyzed by gas chromatography with nitrogen-phosphorous detection. In the spray group versus the inhalation group, there were no differences in mean age (54 vs 55 years), total lidocaine dose (572 vs 525 mg), or time of peak serum lidocaine concentration (43 vs 41 minutes after dose). However, the peak serum lidocaine concentrations were significantly lower in the inhalation group vs the spray group (1.40 vs 3.63 micrograms/mL). Thus, administration of lidocaine via inhalation by ultrasonic nebulization results in lower peak serum concentrations, and a reduction in the likelihood of toxicity, than when administered by conventional topical spray.