Effect of positive expiratory pressure and type of tracheal cuff onthe incidence of aspiration in mechanically ventilated patients inan intensive care unit

Objective: To test the effects of positive expiratory pressure onthe leakage of fluid around cuffs of different tracheal tubes, inmechanically ventilated patients and in a benchtop model.Design: Randomized clinical trial and experimental in vitrostudy.Setting: Intensive care unit of a university hospital.Patients: Forty patients recovering in the intensive care unitwere ventilated in volume-controlled mode. Twenty patients wererandomly intubated with Hi-Lo tubes (HL group), whereas theremaining 20 subjects were intubated with SealGuard tubes (SGgroup).Interventions: Immediately after intubation and cuff inflationwith 30 cm H2O, Evans blue was applied onto the cephalic surfaceof the tracheal tube cuff. A 5-cm H2O positive expiratory pressurewas used during the first 5 hrs of stay, and thereafter it wasremoved. Bronchoscopy verified whether the dye leaked aroundthe cuff. The experiment lasted 12 hrs. Leakage was also testedin vitro with the same tracheal tubes with incremental level ofpositive expiratory pressure.Measurements and Main Results: At 1 hr, 5 hrs, and thereafterhourly until 12 hrs, bronchoscopy was used to test the presenceof dye on the trachea caudal to the cuff. At the fifth hour, twopatients of the HL group failed the test. One hour after positiveexpiratory pressure removal, all subjects in group HL exhibited adyed lower trachea. On the other hand, one patient in group SGpresented a leak at the eighth hour, and at the 12th hour three ofthem were still sealed. In vitro, the same level of positive expiratorypressure delayed the passage of dye around the cuff; after30 mins positive expiratory pressure was removed, and in 10 minsall dye leaked only in the Hi-Lo tube.Conclusions: We found that 5 cm H2O positive expiratorypressure was effective in delaying the passage of fluid around thecuffs of tracheal tubes both in vivo and in vitro. The SealGuardtube proved to be more resistant to leakage than Hi-L