Plasma lignocaine concentration following nebulization for awake intubation

Nebulization of lignocaine is a common technique for preparing the airway prior to awake intubation. The aim of the study was to assay the serum levels of lignocaine. Ten ASA I volunteers had 6 mg/kg of 10% lignocaine solution nebulized via facemask. Blood assays for peak levels were performed. Mean peak serum lignocaine level was 0.29 mg/l with a highest measurement of 0.45 mg/l. This peak occurred 30 minutes following commencing nebulization. No subject developed symptoms or signs of lignocaine toxicity. Peak plasma lignocaine levels were an order of magnitude below the accepted toxic threshold of 5 mg/l. This indicates that supplemental doses of lignocaine via the bronchoscope can be given with safety.