Serum lidocaine concentrations in asthmatics undergoing research bronchoscopy.

STUDY OBJECTIVES

To determine how often serum lidocaine concentrations (SLC) fall into the potentially toxic range (> 5 mg/L) in asthmatics undergoing research bronchoscopy, and to determine whether subject or procedure characteristics are associated with higher SLC.

DESIGN

Prospective, observational study.

SETTING

Academic research center.

PARTICIPANTS

Fifty-one volunteers with mild to moderate asthma enrolled in three separate bronchoscopy protocols to study airway inflammation in asthma.

INTERVENTIONS

Lidocaine was administered topically to the upper airway and tracheobronchial tree to achieve local anesthesia for bronchoscopy. Venous blood was sampled during bronchoscopy, 30 min after upper airway anesthesia was completed (time 1), and 30 min after bronchoscopy was completed (time 2).

MEASUREMENTS AND RESULTS

The mean total amount of lidocaine administered was 600 +/- 122 mg (8.2 +/- 2.0 mg/kg). No signs or symptoms of lidocaine toxicity were observed in any of the subjects. SLC ranged between 0.10 and 2.90 mg/L at time 1 and 0.50 and 3.20 mg/L at time 2. SLC was significantly correlated with the total amount of lidocaine (milligrams/kilogram) administered at both points (time 1, r = 0.33, p = 0.021; time 2, r = 0.33, p = 0.023). No statistically significant relationship was observed between SLC and subject age, sex, weight, baseline FEV(1), procedure length, or study protocol. No statistically significant relationship was found between subject FEV(1) and either total lidocaine dose or procedure length.

CONCLUSIONS

An average total dose of 600 mg (8.2 mg/kg) of lidocaine appears to be safe in mild to moderate asthmatics undergoing research bronchoscopy.