title: New ultrathin-walled endotracheal tube with a novel laryngeal seal design. Long-term evaluation in sheep.
abstract: BACKGROUND
  A new endotracheal tube (ETT) was fabricated and tested in sheep. It had no tracheal cuff; airway seal was achieved at the level of the glottis through a no-pressure seal made of "gills"; the laryngeal portion was oval-shaped; and the wall thickness was reduced to 0.2 mm.
  
  
  METHODS
  Sheep were tracheally intubated either with a standard tube or with the new tube, and their lungs were mechanically ventilated for 1 or 3 days. Air leak was recorded at different peak inspiratory pressures (PIPs). Liquid seepage into the trachea was assessed using an indicator dye. Tracheolaryngeal lesions were scored grossly and histologically.
  
  
  RESULTS
  There was no air leak up to 40 cmH2O of PIP, in either group, in short- and long-term studies. Methylene blue leaked across the cuff in two sheep with standard ETTs. No dye leaked across the gills with the new ETTs. In the new ETT group, the trachea appeared better preserved, grossly and histologically, than in the standard ETT group at both 1 and 3 days (P < 0.05). At day 1, the larynx and vocal cords appeared grossly less injured in the new ETT group (P < 0.05), whereas there was no difference at day 3. Histology did not show significant difference on vocal cords, epiglottis, and larynx between the two groups at any time.
  
  
  CONCLUSIONS
  The novel, no-pressure seal design of the new ETT is highly effective in preventing air leak and aspiration. It causes no significant tracheal injury.
authors.affiliation: National Institutes of Health, National Heart, Lung, and Blood Institute, Bethesda, Maryland 20892-1412, USA.
authors.forename: C
authors.initials: C
authors.lastname: Reali-Forster
authors.forename: T
authors.initials: T
authors.lastname: Kolobow
authors.forename: M
authors.initials: M
authors.lastname: Giacomini
authors.forename: T
authors.initials: T
authors.lastname: Hayashi
authors.forename: K
authors.initials: K
authors.lastname: Horiba
authors.forename: V J
authors.initials: VJ
authors.lastname: Ferrans
mesh_terms: D000818:Animals; D005069:Evaluation Studies as Topic; D005260:Female; D006801:Humans; D001239:Inhalation / Q000502:physiology; D007442:Intubation, Intratracheal / Q000009:adverse effects / Q000295:instrumentation* / Q000379:methods; D007830:Larynx / Q000293:injuries / Q000502:physiology; D011897:Random Allocation; D012121:Respiration, Artificial; D012756:Sheep; D013997:Time Factors; D014132:Trachea / Q000293:injuries / Q000502:physiology