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
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.
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
FEV1, procedure length, or study protocol. No statistically
significant relationship was found between subject FEV1 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.