Massive aspiration past the tracheal tube cuff caused by closed tracheal suction system.

BACKGROUND: Aspiration past the tracheal tube cuff has been recognized to be a risk factor for the development of ventilator-associated pneumonia (VAP). This study investigated the effect of closed tracheal suctioning on aspiration of fluid past the tracheal tube cuff in an in vitro benchtop model. METHODS: High-volume low pressure tube cuffs of 7.5 mm internal diameter (ID) were placed in a 22 mm ID artificial trachea connected to a test lung. Positive pressure ventilation (PPV) with 15 cm H2O peak inspiratory pressure and 5 cm H2O positive end-expiratory pressure (PEEP) was used. A closed tracheal suction system (CTSS) catheter (size 14Fr) was attached to the tracheal tube and suction was performed for 5, 10, 15, or 20 seconds under 200 or 300 cm H2O suction pressures. Amount of fluid (mL) aspirated along the tube cuff and the airway pressure changes were recorded for each suction procedure. Fluid aspiration during different suction conditions was compared using Kruskal-Wallis and Mann-Whitney test (Bonferroni correction [α = .01]). RESULTS: During 10, 15, and 20 seconds suction, airway pressure consistently dropped down to -8 to -13 cm H2O (P < .001) from the preset level. Fluid aspiration was never observed under PPV + PEEP but occurred always during suctioning. Aspiration along the tube cuff was higher with -300 cm H2O than with -200 cm H2O suction pressure (P < .001) and was much more during 15 and 20 seconds suction time as compared to 5 seconds (P < .001). CONCLUSION: Massive aspiration of fluid occurs along the tracheal tube cuff during suction with the closed tracheal suction system.

Tracheal fluid leakage in benchtop trials: comparison of static versus dynamic ventilation model with and without lubrication.

PURPOSE: Longitudinal folds in tracheal tube (TT) cuffs cause leakage of pooled secretions past the tube cuff, and the most common in vitro method to test the efficacy of a new tube is a benchtop model using an artificial rigid trachea. This study compared the potential of a static and dynamic ventilation benchtop model and cuff lubrication in testing the tracheal sealing properties of a given TT cuff. METHODS: Static trial Six brands of 7.5 mm internal diameter (ID) cuffed TT (n = 8) with high volume-low pressure cuffs were inflated in an artificial trachea (18 mm ID) without and with lubrication. Dynamic trial The same tube cuffs, without lubrication, were subjected to positive pressure ventilation (PPV) + positive end-expiratory pressure (PEEP) of 5cmH(2)O or to PPV alone (without PEEP) or to PEEP alone (without PPV). Clear water (5 ml) was placed above the tube cuff, and fluid leakage (ml) was measured up to 60 min. RESULTS: Gel lubrication, PEEP alone and PPV + PEEP completely prevented fluid leakage across the tube cuffs in all six TT brands tested within 60 min when compared to the static unlubricated model (0% leak versus 100% leak; P < 0.01). Fluid leakage in the static unlubricated model and the PPV group was 1.38-4.76 ml and 0.23-4.47 ml, respectively. CONCLUSION: Gel lubrication, PEEP alone, and PPV + PEEP in the benchtop model had a much stronger protective effect than PPV alone on fluid leakage. Studies testing the fluid sealing efficiency of tube cuffs might be more conclusive in a static benchtop model without lubrication than in a dynamic model.