title: Effect of positive expiratory pressure and type of tracheal cuff on the incidence of aspiration in mechanically ventilated patients in an intensive care unit.
abstract: OBJECTIVE
  To test the effects of positive expiratory pressure on the leakage of fluid around cuffs of different tracheal tubes, in mechanically ventilated patients and in a benchtop model.
  
  
  METHODS
  Randomized clinical trial and experimental in vitro study.
  
  
  METHODS
  Intensive care unit of a university hospital.
  
  
  METHODS
  Forty patients recovering in the intensive care unit were ventilated in volume-controlled mode. Twenty patients were randomly intubated with Hi-Lo tubes (HL group), whereas the remaining 20 subjects were intubated with SealGuard tubes (SG group).
  
  
  METHODS
  Immediately after intubation and cuff inflation with 30 cm H2O, Evans blue was applied onto the cephalic surface of the tracheal tube cuff. A 5-cm H2O positive expiratory pressure was used during the first 5 hrs of stay, and thereafter it was removed. Bronchoscopy verified whether the dye leaked around the cuff. The experiment lasted 12 hrs. Leakage was also tested in vitro with the same tracheal tubes with incremental level of positive expiratory pressure.
  
  
  RESULTS
  At 1 hr, 5 hrs, and thereafter hourly until 12 hrs, bronchoscopy was used to test the presence of dye on the trachea caudal to the cuff. At the fifth hour, two patients of the HL group failed the test. One hour after positive expiratory pressure removal, all subjects in group HL exhibited a dyed lower trachea. On the other hand, one patient in group SG presented a leak at the eighth hour, and at the 12th hour three of them were still sealed. In vitro, the same level of positive expiratory pressure delayed the passage of dye around the cuff; after 30 mins positive expiratory pressure was removed, and in 10 mins all dye leaked only in the Hi-Lo tube.
  
  
  CONCLUSIONS
  We found that 5 cm H2O positive expiratory pressure was effective in delaying the passage of fluid around the cuffs of tracheal tubes both in vivo and in vitro. The SealGuard tube proved to be more resistant to leakage than Hi-Lo.
authors.affiliation: Department of Perioperative Medicine, Intensive Care and Emergency, Cattinara Hospital, Trieste University School of Medicine, Trieste, Italy. u.lucangelo@fmc.units.it
authors.forename: Umberto
authors.initials: U
authors.lastname: Lucangelo
authors.forename: Walter A
authors.initials: WA
authors.lastname: Zin
authors.forename: Vittorio
authors.initials: V
authors.lastname: Antonaglia
authors.forename: Lara
authors.initials: L
authors.lastname: Petrucci
authors.forename: Marino
authors.initials: M
authors.lastname: Viviani
authors.forename: Giovanni
authors.initials: G
authors.lastname: Buscema
authors.forename: Massimo
authors.initials: M
authors.lastname: Borelli
authors.forename: Giorgio
authors.initials: G
authors.lastname: Berlot
mesh_terms: D000368:Aged; D001999:Bronchoscopy; D003422:Critical Care; D004868:Equipment Failure; D006801:Humans; D015994:Incidence; D007442:Intubation, Intratracheal / Q000295:instrumentation*; D008875:Middle Aged; D008954:Models, Biological; D011175:Positive-Pressure Respiration / Q000009:adverse effects / Q000295:instrumentation / Q000379:methods*; D011312:Pressure; D053120:Respiratory Aspiration / Q000453:epidemiology* / Q000517:prevention & control*; D013997:Time Factors