Lidocaine blood concentrations during fiberoptic bronchoscopy.

Blood lidocaine concentrations were measured in 21 patients during routine fiberoptic bronchoscopy. In one patient, concentrations were in the toxic range. Measureable, but generally safe, concentrations were observed in the remaining patients. Cardiac and central nervous system toxicity may result from lidocaine adsorption, particularly in the seriously ill patient, although none was observed during the course of these studies.