Plasma concentration of lidocaine after endotracheal spray

The rate of absorption and plasma concentrations of lidocaine were determined in 15 supine patients under general anesthesia following either endotracheal spray of 200 mg. (average 3.3 mg./kg.) of 4 percent lidocaine hydrochloride solution with a special cannula (LTA Kit, Abbott) (N = 6) or 1 mg./kg. of 2 percent lidocaine solution as an intravenous bolus injection (N = 9). In the 6 patients after endotracheal spray, peak plasma lidocaine levels were reached at 15 to 20 minutes (mean 3.54 plus or minus 0.76 S.E. mug./ml. at 20 minutes). In the 9 patients given 1 mg./kg. intravenously, dose peak concentrations were reached within 2 minutes (mean 5.63 plus or minus 0.18 S.E. mug./ml. at 2 minutes). Plasma concentrations of lidocaine in both groups were within nontoxic ranges.