title: Tracheal mucus velocity remains normal in healthy sheep intubated with a new endotracheal tube with a novel laryngeal seal.
abstract: BACKGROUND
  Tracheal mucus velocity (TMV), an index of mucociliary clearance, is reduced markedly in patients intubated with standard endotracheal tubes (ETTs) with high-compliance low-pressure (hi-lo) cuffs. The authors developed a new ultra-thin walled ETT in which the inflatable cuff is replaced with a no-pressure seal, positioned at the level of the larynx. The seal consists of 12 to 20 toroidal layers of thin polyurethane film ("gills") at the level of the vocal cords and prevents both air leak and fluid aspiration. The authors hypothesized that ETTs with the new laryngeal seal may impair TMV less than ETTs with inflated hi-lo cuffs do.
  
  
  METHODS
  The TMV was measured in seven healthy female sheep by radiographically tracking the motion of small discs of tantalum inserted into the trachea through a bronchoscope. The TMV was measured in spontaneously breathing sheep before intubation (baseline) and after intubation with either a hi-lo ETT (control group) or after intubation with a new ETT with gills (study group). Four to six weeks later, the studies were repeated, but the sheep that were previously in the control group served as the study group, and those in the study group served as controls.
  
  
  RESULTS
  Baseline TMV did not differ in the two groups. In the control group, TMV decreased significantly (by 67%) from baseline. In the study group, TMV did not differ significantly from baseline and remained steady during 3 h of intubation.
  
  
  CONCLUSIONS
  The TMV does not change in sheep intubated with new ETTs with gills. The new ETT's may help promote a normal mucociliary clearance in patients who require ventilation.
authors.affiliation: Section of Pulmonary and Cardiac Assist Devices, National Heart, Lung, and Blood Institute, Bethesda, Maryland 20892-1590, USA.
authors.forename: R
authors.initials: R
authors.lastname: Trawöger
authors.forename: T
authors.initials: T
authors.lastname: Kolobow
authors.forename: M
authors.initials: M
authors.lastname: Cereda
authors.forename: M E
authors.initials: ME
authors.lastname: Sparacino
mesh_terms: D000818:Animals; D005260:Female; D007442:Intubation, Intratracheal / Q000295:instrumentation*; D009079:Mucociliary Clearance; D009093:Mucus / Q000502:physiology*; D012756:Sheep; D014132:Trachea / Q000502:physiology*