Lidocaine-eluting endotracheal tube effectively attenuates intubation related airway response

BACKGROUND: Lidocaine (LDC) is a local anesthetic widely used to relieve intubation-related airway responses. However, low drug concentration and short effective duration of LDC is inadequate to provide a satisfactory anesthetic effect on the surface of the airway. The present study sought to develop a LDC-delivery endotracheal tube (ETT) to achieve high local drug concentration and sustained drug release with the aim of attenuating an intubation-related airway response. METHODS: ETTs and polyvinyl chloride (PVC) discs were coated with different molecular weight (MW) poly lactic-co-glycolic acid (PLGA: 50/50; MW: 3,000, 6,000, and 10,000) loaded with LDC by airbrush spray. The morphology of LDC-eluting coatings was analyzed using scanning electron microscopy. In vitro drug release was determined by ultraviolet spectrophotometer. An in vivo study was performed to investigate the differences in plasma LDC concentration, intubation tolerance, and tracheal tissue injury in rabbits undergoing intubation of blank, LDC-spray, or LDC-coated ETTs. RESULTS: Approximate 5 mg/cm(2) coatings (containing 2.5 mg/cm(2) LDC) were deposited onto the PVC discs and ETTs. While even distribution and smooth surfaces were generated in PLGA3000 + LDC and PLGA6000 + LDC coatings, PLGA10000 + LDC formed uneven and gullied coatings. Burst release within the first 4 h and sustained release for at least 5 days was achieved in vitro in PLGA + LDC coatings and the in vivo study demonstrated higher plasma LDC concentration and longer drug release duration in LDC-coated ETTs compared with LDC-spray. LDC-coated ETTs significantly improved intubation tolerance in rabbits, as measured by less general anesthetic consumption and longer tube tolerance duration in contrast to blank ETTs with or without LDC spray. Histology assessment showed less mucosal edema area in the PLGA3000 + LDC and PLGA6000 + LDC groups compared to the control, LDC-spray, and PLGA10000 + LDC groups. Among the different MW PLGAs, PLGA6000 presented optimal morphological characteristics, drug release, and anesthetic effect. CONCLUSIONS: ETTs coated with PLGA + LDC effectively attenuate an intubation-related airway response via increasing local drug concentration and extending drug action duration, which demonstrates a potential therapeutic benefit for patients undergoing intubation.