Strategies to prevent ventilation-associated pneumonia: the effect of cuff pressure monitoring techniques and tracheal tube type on aspiration of subglottic secretions: an in-vitro study.

BACKGROUND

Ventilation-associated pneumonia (VAP) is the commonest nosocomial infection in intensive care. Implementation of a VAP prevention care bundle is a proven method to reduce its incidence. The UK care bundle recommends maintenance of the tracheal tube cuff pressure at 20 to 30  cmH₂O with 4-hourly pressure checks and use of tracheal tubes with subglottic aspiration ports in patients admitted for more than 72  h.

OBJECTIVE

To evaluate the effects of tracheal tube type and cuff pressure monitoring technique on leakage of subglottic secretions past the tracheal tube cuff.

DESIGN

Bench-top study.

SETTING

Laboratory.

INTERVENTIONS

A model adult trachea with simulated subglottic secretions was intubated with a tracheal tube with the cuff inflated to 25  cmH₂O. Experiments were conducted using a Portex Profile Soft Seal tracheal tube with three cuff pressure monitoring strategies and using a Portex SACETT tracheal tube with intermittent cuff pressure checks.

OUTCOME MEASURES

Rate of simulated secretion leakage past the tracheal tube cuff.

RESULTS

Mean ± SD leakage of fluid past the Profile Soft Seal tracheal tube cuff was 2.25 ± 1.49  ml  min⁻¹ with no monitoring of cuff pressure, 2.98 ± 1.63  ml  min⁻¹ with intermittent cuff pressure monitoring and 3.83 ± 2.17  ml  min⁻¹ with continuous cuff pressure monitoring (P <0.001). Using a SACETT tracheal tube with a subglottic aspiration port and aspirating the simulated secretions prior to intermittent cuff pressure checks reduced the leakage rate to 0.50 ± 0.48  ml  min⁻¹ (P <0.001).

CONCLUSION

Subglottic secretions leaked past the tracheal tube cuff with all tube types and cuff pressure monitoring strategies in this model. Significantly higher rates were observed with continuous cuff pressure monitoring and significantly lower rates were observed when using a tracheal tube with a subglottic aspiration port. Further evaluation of medical device performance is needed in order to design more effective VAP prevention strategies.