To examine whether lidocaine diffusion across an endotracheal tube cuff affects tracheostomy tube discomfort. Two tracheostomy tube cuffs were inflated with 5 ml lidocaine 4% solution and air at 20 cmH2O, and then placed in 20 ml distilled water at 37 degrees C. After vigorous stirring, 100 microl of this water was then sampled immediately then 1, 2, 4, 8, 24 hr later to measure lidocaine concentration by high-performance liquid chromatography. Sixteen patients undergoing tracheostomy following oral cancer resection were randomly assigned to two groups: lidocaine (n=8) and placebo (n=8). A tracheostomy tube cuff was inflated with 5 ml lidocaine 4% or saline 0.9% and air to a cuff pressure of 20 cmH2O, in the lidocaine and placebo groups respectively. Tube discomfort was evaluated using a visual analogue scale at 0, 0.5, 1, 2 and 4 hr after lidocaine or saline administration. Neither analgesics nor sedatives was given during the evaluation period. Lidocaine time-dependently diffused across the tracheostomy tube cuff. Thirty and 60 min after cuff inflation lidocaine concentrations in the water bath reached approximately 8 and 17 microg x ml(-1) representing 160 and 340 microg in 20 ml of water, respectively. The VAS decreased from 53.5 +/- 10.6 to 25.1 +/- 9.8 mm (P < 0.01) 0.5 hr following lidocaine administration which continued until the end of evaluation period. In the placebo group, VAS did not change. Lidocaine diffusion across the tracheostomy tube cuff reduces tube discomfort.
