Effect of distribution and membrane structure of alkalinized lidocaine across an endotracheal tube cuff

Abstract

Lidocaine hydrochloride and alkalinized lidocaine hydrochloride solutions were filled in en­ dotracheal tube cuffs to determine the rate of diffusion of lidocaine across the cuffs, and assess the usefulness of these cuffs as a drug delivery system. Mallinckrodt^TM Oral RAE^® tracheal tubes were filled with three different lidocaine solutions, i.e., mixtures of 4% lido­ caine hydrochloride solution and distilled water, 4% lidocaine hydrochloride solution an 8.4% sodium bicarbonate solution (LSB­Gr), and 4% lidocaine hydrochloride solution and dipotassium phosphate solution (LDP­Gr). Cuffs filled with the relevant lidocaine solution were placed in beakers filled with distilled water. A 100 μL sample of the water in the vessel was taken from each beaker every 30 minutes for 360 minutes to determine the concentra­ tion of lidocaine diffused across the cuff using fluorescence polarization immunoassay.The cuff surface was observed after 60, 180, and 360 minutes of exposure for changes in the structure of the material. Lidocaine in LSB­Gr and LDP­Gr diffused across the cuffs at 30 minutes of exposure and thereafter. The lidocaine concentration in water in the vessel was 133.8 μg/mL for LSB­Gr, and 119.0 μg/mL for LDP­Gr. Although the cuffs did not rup­ ture during exposure, the cuff material deteriorated over time. The results indicate that alka­ linization of intracuff lidocaine increases the rate of diffusion of lidocaine across the en­ dotracheal tube cuff and affects the cuff material, which increases the risk of complications due to cuff rupture. (J Osaka Dent Univ 2016 ;50 : 1−6)