title: Nitrous oxide diffusion into tracheal tube cuffs: comparison of five different tracheal tube cuffs.
abstract: BACKGROUND
  The aim of this study was to investigate cuff compliance and cuff pressure during nitrous oxide exposure in the recently introduced Microcuff tracheal tube with a polyurethane cuff (Microcuff GmbH, Weinheim, Germany), and to compare it to conventional tracheal tubes with PVC cuffs.
  
  
  METHODS
  In an in vitro set up, five cuffed tracheal tubes (ID 7.0 mm) from different manufacturers (Microcuff HVLP, Portex Profile Soft Seal, Mallinckrodt HiLo, Rüsch Super Safety Clear and Sheridan CF) were studied. Pressure-volume curves were assessed and changes of cuff pressure during exposure to nitrous oxide (for 60 min; 66% N(2)O in oxygen) were recorded without and with restriction of the cuff in a trachea model. Each experiment was performed four times using two exemplars of each tube twice. Sixty-minute values of the Microcuff group were compared with the other groups using the Mann- Whitney test (P < 0.05).
  
  
  RESULTS
  The Microcuff polyurethane cuff demonstrated an intermediate cuff compliance but the highest cuff pressure increase during nitrous oxide exposure under unrestricted conditions. When inflated within the artificial trachea its cuff compliance became the highest of all tested tracheal tubes. However, exposure to N(2)O, again led to a rapid increase in cuff pressure.
  
  
  CONCLUSIONS
  The ultra-thin polyurethane tube cuff demonstrated higher permeability for nitrous oxide than conventional PVC cuffs and led to a rapid cuff pressure increase when exposed to N(2)O. Routinely checking of cuff-pressure or filling the cuff with nitrous oxide are more important than the brand of tube used.
authors.affiliation: Department of Anesthesia, University Children's Hospital, Zurich, Switzerland. alex.dullenkopf@kispi.unizh.ch
authors.forename: A
authors.initials: A
authors.lastname: Dullenkopf
authors.forename: A C
authors.initials: AC
authors.lastname: Gerber
authors.forename: M
authors.initials: M
authors.lastname: Weiss
mesh_terms: D000399:Air Pressure; D000769:Anesthesia, Inhalation / Q000295:instrumentation*; D018685:Anesthetics, Inhalation / Q000032:analysis*; D004058:Diffusion; D007442:Intubation, Intratracheal / Q000295:instrumentation*; D009609:Nitrous Oxide / Q000032:analysis*; D011140:Polyurethanes; D011143:Polyvinyl Chloride
chemical_list: D018685:Anesthetics, Inhalation; D011140:Polyurethanes; D011143:Polyvinyl Chloride; D009609:Nitrous Oxide