Lidocaine blood levels following aerosolization and intravenous administration.

STUDY OBJECTIVE

To determine whether, following aerosolization of lidocaine for topical airway anesthesia, intravenous (IV) lidocaine produces toxic lidocaine blood concentrations.

DESIGN

Randomized, double-blind study.

SETTING

University-affiliated hospital.

PATIENTS

Forty healthy patients scheduled for outpatient surgery.

INTERVENTIONS

The patients received in a randomized, double-blind manner aerosolized lidocaine or placebo followed 10 minutes later by IV lidocaine or placebo.

MEASUREMENTS AND MAIN RESULTS

After completion of lidocaine or placebo aerosolization and 2 minutes following IV administration of either lidocaine or the placebo, venous blood samples were obtained. Lidocaine concentration was measured using a homogenous enzyme assay. The group receiving both aerosolized and IV placebo and the group receiving aerosolized lidocaine and an IV placebo had undetectable (less than 0.05 micrograms/ml) serum lidocaine levels. The groups that received either an aerosolized placebo or aerosolized lidocaine and IV lidocaine had similar serum lidocaine concentrations [3.34 +/- 0.46 vs. 3.24 +/- 0.55 micrograms/ml (mean +/- SEM); p greater than 0.05 by Mann-Whitney U test].

CONCLUSION

IV lidocaine can be safely administered following aerosolization of lidocaine in spontaneously breathing patients without producing toxic blood lidocaine concentrations.