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

Abstract

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.

Fluid leakage across tracheal tube cuff, effect of different cuff material, shape, and positive expiratory pressure: a bench-top study

“…This in vitro test does not attempt to simulate the complexity of the physiological conditions: the stiff cylindrical PVC trachea, the vertical position, and the dyed-water viscosity may all favor leakage across the cuff; nevertheless, this setting, which with some simplification could be used in every anesthesia department to form a proper opinion on the quality of a particular ETT, is the common in vitro method to test the efficacy of new ETT cuffs in preventing fluid leakage [9]. The cuff-sealing properties reported in several studies with these settings were recently confirmed in human studies.…”

Benchtop study of leakages across the Portex, TaperGuard and Microcuff Endotracheal tubes under simulated clinical conditions

“…Moreover, the seal between the cuff and the moist tracheal mucosa might actually be better, especially with the use of lubricant at the time of intubation. 4,11,12 The upward sweeping movement of the ciliated mucosa might also decrease aspiration. Furthermore, subglottic collections are more viscous than water, and their volume is not likely to be as high as 20 mL.…”

The role of the endotracheal tube cuff in microaspiration

“…47, 48 Blunt and colleagues 47 placed dye in the subglottic space and observed for leakage into the tracheobronchial tree in 2 different studies. In their in vitro model, leakage was 0% for cuffs treated with water-soluble gel and 100% for non-treated cuffs.…”